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Jiang Yio
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= Bone-directed Therapy
Bisphosphonates or denosumab, a fully humanized anti-RANKL monoclonal antibody, may be approved by the FDA in two situations:
Men receiving long-course ADT in combination with RT for localized prostate cancer who are found to have baseline or treatmentinduced osteopenia or osteoporosis. In this case, the goal is to increase bone mineral density and prevent osteoporosis-related fractures.
Men with mCRPC and bone metastases. In this case, the goal is to prevent SREs. Use of bisphosphonates in mCSPC did not improve SREs or OS in the STAMPEDE trial.
Renal insufficiency, osteonecrosis of the jaw, and hypocalcemia are potential adverse effects of bisphosphonates. Patients with significant dental disease or who require dental procedures should not be treated with bisphosphonates until after dental clearance. Monthly or every 3-month dosing of zoledronic acid is indicated for bone metastases, whereas yearly infusions can be used for treatment of osteoporosis.
In a phase III trial, denosumab, a RANKL inhibitor, was superior to zoledronic acid for prevention of SREs. Hypocalcemia was more common in patients treated with denosumab, and osteonecrosis of the jaw occurred infrequently in both arms.

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= 14-2 Prostate Cancer
== 14-2.1: Epidemiology
Prostate cancer is a common diagnosis, and although metastatic disease develops in a small percentage of affected patients, this translates into a large absolute number of deaths due to prostate cancer.
* About 1 in 9 American men
* Second most common cancer in American men other than skin cancer
* About 15% - 17% of men older than 50 years with occult prostate cancer
* Nearly 70% of men older than 80 years harbor occult prostate cancer
* About 1 in 41 would die of prostate cancer
* Second leading cause of cancer death in American men
Whether black men tend to have biologically more aggressive prostate cancer than nonblack men is controversial. Disparities in access to care likely explain at least some of the difference in outcomes.
There is no clear causal link between vasectomy and prostate cancer, nor does testosterone supplementation appear to increase the risk of aggressive prostate cancer.
== 14-2.2: Heredity
Prostate cancer is one of the most hereditable cancers. Clinicians should take a full history of malignancies in the family and be familiar with the link between prostate cancer and germline alterations in BRCA2 and mismatch repair genes, which are enriched among men with metastatic prostate cancer.
* 5% - 10% of all cases are hereditary
* HOXB13 G84E strongly associated with early-onset familial prostate cancer
* Germline alterations in DNA repair genes are more common in metastatic disease
* Deleterious germline mutations: BRCA2, ATM, CHEK2, BRCA1, RAD51D, PALB2
* Men with metastatic prostate cancer should undergo germline testing
[cols=",,,,",options="header",]
|===
|Gene |Prostate cancer |Aggressive cancer |Early-onset |Specific outcomes
|BRCA1 |1.07 - 3.81 | |1.82 |5.16
|BRCA2 |3.18 - 8.6 |3.18 - 4.38 |7.33 |HR for death, 2.4 - 5.48
|MMR genes |1.99 - 3.67 | |2.48 |
|HOXB13 |2.8 - 8.47 | |2.7 - 10.11 |
|===
Guidelines for referral to genetic counseling are frequently changing, but at minimum, clinicians should consider genetic counseling for all patients with metastatic castration-resistant prostate cancer (mCRPC), those with strong family histories as outlined in the preceding paragraphs, or those with alterations in DNA damage repair or mismatch repair genes identified from tumor sequencing.
*NCCN recommends germline testing for:*
* any patient with metastatic, regional, or high-risk localized prostate cancer, regardless of family history.
* patients with low- to intermediate-risk prostate cancer with intraductal histology (new in NCCN 2019 guidelines) or a "`strong family history`" of prostate cancer, meaning:
** a brother or father or multiple family members diagnosed with prostate cancer at age < 60 years
** known family history of high-risk germline alterations
** two or more relatives with breast, ovarian, or pancreatic cancer (suggesting BRCA2 alteration)
** two or more relatives with colorectal, endometrial, gastric, ovarian, pancreatic, small-bowel, urothelial, kidney, or bile duct cancer (suggesting Lynch syndrome)
** Ashkenazi Jewish ancestry, which could also prompt genetic testing
== 14-2.3: Anatomy
Prostate cancer is typically diagnosed via TRUS biopsy using a standard 12-core template to sample the posterior peripheral zone.
Anatomic location can help predict pattern of spread and treatment-related risks. Disease near the base of the gland may extend into the seminal vesicles. Disease in the apex may increase risk of positive surgical margins and urinary incontinence.
* Peripheral zone is palpable by DRE and is the site of origin of 70% of prostate cancers
* Transition zone surrounds the urethra and cannot be assessed by DRE
** Up to 20% of all prostate cancers develop in the transition zone
** BPH is more common than prostate cancer in the transition zone
* Anterior portion is generally not biopsied as part of routine prostate needle biopsy, and should be evaluated by either MRI or targeted/directed biopsy when PSA continues to rise in the setting of continued negative biopsy specimens
* If seminal vesicle involvement is suspected, then primary radiation + ADT is typically used in lieu of prostatectomy
** If the bulk of positive specimens is from the base of the gland, consider obtaining MRI to look for seminal vesicle involvement
* Apical disease poses the problem of having a higher rate of positive surgical margins, harboring an anterior tumor, and incontinence
** Patients with a bulk of positive specimens from the apex may not be optimal candidates for prostatectomy
== 14-2.4: Pathology and molecular pathogenesis
Prostate cancer can be characterized by its typical IHC profile: cytokeratin 7/20-negative, PSA-positive, AR-positive, and NKX3.1-positive.
* Androgens are the primary regulators of prostate cancer cell growth/proliferation
* AR is located on Xq11-13
* Typical IHC profile
** Negative for CK7 and CK20
** Positive for AR and PSA
** Positive for NKX3.1
*** NKX3.1 positivity is retained even in some advanced treatment-desistant prostate cancers that have lost AR/PSA expression
*** In cases of mass involving both prostate and bladder, NKX3.1 could help differentiate prostate cancer from urothelial cancer
* Gleason grading system and WHO prognostic groups
** Gleason 3+3=6: grade group 1
** Gleason 3+4=7: grade group 2
** Gleason 4+3=7: grade group 3
** Gleason 8: grade group 4
** Gleason 9-10: grade group 5
* Histology
** Prostatic intraepithelial neoplasia: 50% would be diagnosed with prostate cancere in 5 years
** More than 99% of prostate cancers are adenocarcinoma
** < 1% are pure ductal and mucinous variants
** Small cell carcinoma and mesenchymal tymors (rhabdomyosarcomas in younger patients, leiomyosarcomas in older patients) are rare
** Urothelial carcinomas of the prostate are confined to the periurethral ducts and more common among patients who have been successfully treated for non-muscle-invasive bladder cancer
** Lymphomas and leukemias may rarely occur in the prostate gland
As treatment resistance occurs, different phenotypes may emerge. Most CRPC is still driven by AR signaling, even after developing resistance to subsequent AR-directed therapies.
Some advanced CRPC may become "`androgen indifferent,`" often harboring alterations in Rb1 and p53. These may be admixed with AR-driven tumors. A subset of these cases may have neuroendocrine features, with the most extreme exhibiting small-cell morphology.
Small-cell prostate cancer is a rare subset and classically occurs with rapid visceral spread in the absence of increase in serum PSA level after a period of hormonal therapy for highgrade initial disease (de novo small-cell prostate cancer is extremely rare). It is characterized primarily by morphology, but it can also be positive on synaptophysin and/or chromogranin A staining.
* During treatment of advanced prostate cancer, multiple genomic and transcriptomatic alterations could occur as mechanisms of treatment resistance
** Most prostate cancers remain dependent on AR signaling
** A subset may become "`androgen indifferent`" and are generally characterized by alterations in RB1 and p53
** Some, but not all, of these tumors may exhibit neuroendocrine differentiation, with positive synaptophysin and/or chromogranin A staining
*** The extreme of neuroendocrine differentiation is "`small cell`" morphology, histologically similar to small cell carcinoma of the lung or other extrapulmonary sites
*** Neuroendocrine prostate cancer is associated with amplification of AURKA and MYCN, offering the opportunity for targeted therapy
*** Clinically, emergence of neuroendocrine differentiation and small cell transformation should be considered in men who develop castration-resistant disease after ADT for high-grade cancers, especially when visceral involvement is diagnosed and radiographic progression occurs in the absence of an increase in PSA
== 14-2.5: Prevention
There are no universally accepted protocols for prostate cancer prevention or screening.
5-α Reductase inhibitors decrease the incidence of prostate cancer but thus far have not shown a convincing reduction in prostate cancerspecific mortality rate. There is some ongoing concern about 5-α reductase inhibitors increasing risk of highgrade prostate cancer.
PSA-based prostate cancer screening has shown, at most, a small reduction in prostate cancerspecific mortality rate and no convincing effect on overall mortality. Screening could be more effective if targeted to higher-risk men and to the age groups most likely to benefit—younger men, rather than older men—but further studies evaluating this are underway.
For men undergoing evaluation for elevated PSA concentration, a prebiopsy MRI may help triage who requires biopsy, limiting biopsies to those with a greater likelihood of clinically significant cancer. However, this is not yet standard of care, and longer-term follow-up will be needed to see whether omitting standard 12-core biopsies in a patient with no highgrade lesions on MRI (appropriately performed and interpreted) risks under-diagnosis of clinically significant cancer.
When clinicians have adopted MRI-targeted biopsies thus far, it has typically been in one of two scenarios: (1) to supplement the standard 12-core biopsy approach, or (2) if PSA level increases significantly in the absence of aggressive disease in standard core biopsy specimens, or negative standard biopsy specimens, possibly indicating a possible anterior gland tumor.
* There is no cut point of PSA levels above or below which indicates the presence or absence of prostate cancer
* There is a continuum of risk according to PSA levels
* Despite PSA screening studies involving hundreds of thousands of men, none has demonstrated a conclusive improvement in overall survival as a result of screening
* PSA is prostate specific but not prostate cancer specific
** Half-life of PSA is 2-3 days
** Levels should remain undetectable if the prostate has been removed
** PSA > 4 ng/mL has predictive value for diagnosis of prostate cancer, but lower PSA values may also be associated with prostate cancer as well as high-grade cancers
** For men with PSA between 4 and 10, PSA velocity of at least 0.75 ng/mL/y is suspicious for cancer
** Measurements should be made on at least 3-4 consecutive occasions, usually separated by 6 months, over at least 12-18 months
** Persistence or increase of PSA while using 5-α reductase inhibitors (finasteride, dutasteride) could be associated with prostate cancer
* Abnormal DRE necessitates referral to urologist for additional diagnostic evaluation (i.e. TRUS biopsy)
* MRI guidance may be useful as first diagnostic step
== 14-2.6: Tumor staging
* Clinical T stage is assigned by DRE
* Pathologic T stage is assigned based on examination of a radical prostatectomy specimen
* Tumors detected in a biopsy specimen on the basis of elevated PSA and no palpable disease by DRE are designated T1c
* T2 disease is confined to the prostate
* T3 tumor extends through the prostate capsula (T3a) or invades the seminal vesicles (T3b)
* T4 tumors invade adjacent structures or organs
== 14-2.7: Risk stratification
Patients with localized prostate cancer can be risk-stratified on the basis of three clinical factors: T stage, Gleason score, and PSA level. Genomic testing of the cancer specimen may provide additional information about risk and progression, but this is not yet prospectively validated for decision-making.
* Localized prostate cancer is clinically heterogeneous
* Prognostic models based on initial T stage, Gleason score, and baseline PSA
* AJCC8 includes prognostic groupings including anatomic stage and PSA
[width="100%",cols="10%,10%,11%,12%,57%",options="header",]
|===
| |Low |Intermediate favorable |Intermediate unfavorable |High
|Gleason |3+3 |3+4 |4+3 |4+4, any 5
|T stage |(AND) T1 - T2a |(OR) T2b - T2c |(OR) T2 - T3 |(OR) T3
|PSA |(AND) < 10 |(OR) 10 - 20 | |(OR) > 20
|Cores involved | |(AND) < ½ |(OR) > ½ |
|Plan |Active surveillance |<- |-> |Definitive therapy
| | | | |Radical prostatectomy OR (Radiotherapy + 4-6 months ADT if unfavorable risk + 18-24 months ADT if high risk)
|===
* Role of imaging in staging
** Staging imaging typically consists of CT or MRI of the abdomen and pelvis, plus bone scan
** Low-risk disease: no routine staging imaging
** Intermediate-risk disease: if 2 of 3 risk factors present
*** Palpable nodule on DRE (cT2)
*** Gleason score 7
*** PSA concentration > 10 ng/mL
** High-risk disease: all patients
== 14-2.8: Management of Prostate Cancer by Risk
Prostatectomy, RT, and ADT all have unique adverse effect profiles. Prostatectomy can lead to urinary incontinence and erectile dysfunction, but it can help improve significant obstructive symptoms. Radiation tends to lead to irritative urine and bowel symptoms. ADT can cause vasomotor symptoms, fatigue, loss of libido, weight gain, muscle loss, and bone thinning, most of which reverse after discontinuation of ADT and recovery of testosterone.
* Management by risk
** Tumors confined to the prostate are generally managed by radical prostatectomy, radiotherapy, or in some cases active surveillance
*** Treatment decision should be made based on life expectancy, overall health status, and tumor characteristics
*** Patients with life expectancy < 5 years do not benefit from treatment of low-risk prostate cancer and therefore should undergo watchful waiting, with additional workup when patient becomes symptomatic
** Very low risk: active surveillance
** Low risk localized
*** Active surveillance
*** Interstitial prostate brachytherapy (avoid in patients with significant LUTS or recurrent UTI/prostatitis)
*** EBRT
*** Radical prostatectomy
** Intermediate and high-risk localized: if life expectancy ≥ 5 years (intermediate) or ≥ 10 years (high risk)
*** Radiotherapy
*** Prostatectomy
** Regional node-positive N1 stage IVA (nodes above aortic bifurcation considered M1 stage IVB)
*** Definitive radiotherapy to prostate and pelvic nodes + long-course ADT
*** Prostatectomy + extended lymphadenectomy + adjuvant radiotherapy + adjuvant ADT
== 14-2.9: Treatment modalities
Patients with low-risk disease may be offered active surveillance, which uses serial PSA measurements, DREs, and biopsy specimens to detect any presence of higher-risk disease, at which point definitive therapy can be offered. Sequential MRI may also be helpful. This strategy results in less treatment-associated morbidity and similar long-term cancer survival compared with immediate therapy.
* Watchful waiting
** No therapeutic intervention until symptomatic progression
** No monitoring of PSA or serial biopsies
** Appropriate for patients with limited life expectancy, based on age/comorbidities
* Active surveillance
** Delayed intention to treat
** Scheduled PSA testing, DREs, and periodic prostate needle biopsies (most protocols require repeated biopsy at 1 year)
** Treat if/when changes in Gleason score, tumor volume, or serum PSA suggest increasing disease activity
Patients with intermediate- and high-risk disease typically should receive definitive therapy, assuming a life expectancy of at least 5 (high-risk) to 10 (intermediate-risk) years (or if symptomatic). Definitive therapies include radical prostatectomy and RT. Long-term cancer survival is similar with either strategy, but adverse effect profiles differ.
* Radical prostatectomy
** Complete excise the cancer while maintaining urinary control and preserving potency
** PSA levels should decline to undetectable; any detectable or increasing PSA after prostatectomy is indication of residual or recurrent cancer
** Cancer control is assessed by PSA relapse-free survival, time to objective progression, cancer-specific survival, and overall survival
** Most men experience erectile dysfunction after radical prostatectomy
** Urinary incontinence more commonly result in poorer QoL and regret
* Radiation therapy
** EBRT, implanted radioactive seeds, or both + adjuvant ADT
** Stereotactic radiosurgery offers hypofractionated schedule with similar efficacy as standard EBRT
** Proctitis is often self-limited
*** Could be treated with steroid or mesalamine suppositories
*** Small increase in rectal cancer incidence
** Cystitis could be treated with NSAIDs or hyperbaric oxygen if refractory
* Focal therapy
** Cryosurgery
*** Minimally invasive procedure for local control
*** For disease not suitable for radical surgery or local recurrences after radiotherapy
** High-intensity focused ultrasound (hyperthermia therapy)
*** Available data do not demonstrate significant improvement compared with surgery
*** Significant increase of residual tumor in treated areas 2 years after initial treatment
For patients with intermediate- or high-risk disease undergoing RT, the addition of ADT improves biochemical DFS (intermediate risk) and OS (high risk). Duration is typically 4 to 6 months for intermediate-risk disease and 18 to 24 months for high-risk disease. ADT may be optional for favorable intermediate-risk disease.
* Neoadjuvant and adjuvant ADT
** Neoadjuvant ADT before surgery reduces rate of positive surgical margins, but did not influence overall outcomes in older trials
** Neoadjuvant and concurrent ADT provide OS benefit with radiotherapy in patients with high-risk disease
*** Optimal duration of ADT not well-defined
*** Typical course is 18-24 months
** Addition of ADT to RT not shown to improve OS in intermediate-risk disease, but improves biochemical DFS with 4-6 months of ADT
*** Typical course is 4-6 months
** Timing of ADT relative to RT does not appear to affect long-term outcomes
*** ADT is typically started 2 months before RT
*** Some clinicians add bicalutamide for first 4-6 months of ADT or until RT is completed, especially in high-risk disease, but it is uncertain whether adding bicalutamide improves outcomes
Patients with clinical or pathologic (biopsy specimen) evidence of pelvic lymph node involvement are typically treated with definitive RT plus long-course ADT, although no randomized data exist, and prostatectomy followed by adjuvant RT and ADT may also be an option.
Patients with preexisting urinary symptoms should avoid brachytherapy and may experience symptomatic benefit from radical prostatectomy.
There is little to no advantages for robotic prostatectomy versus other surgical approaches and for proton therapy versus conventional RT for clinically localized prostate cancer.
== 14-2.10: Therapy for recurrent or advanced disease
Detectable PSA after radical prostatectomy or increase in PSA concentration by 2 ng/dL or more above PSA nadir after RT is an indicator of recurrent prostate cancer. In the absence of evidence of metastatic disease on standard bone scan and CT imaging, this is termed BCR or biochemical relapse.
* Pathologic node-positive disease
** Positive lymph nodes at time of prostatectomy indicates aggressive disease at high risk of recurrence
** Adjuvant ADT improves OS and prostate cancer specific survival in patients with positive lymph nodes at time of prostatectomy
** Immediate adjuvant RT may be better than delayed (salvage) RT if risk is sufficiently high to justify some overtreatment of patients in whom disease would never have occurred
* Biochemical recurrence
** Increasing PSA level without radiograph-detectable metastases after radical prostatectomy, radiotherapy, or both
*** Any detectable PSA after radical prostatectomy
*** PSA increase by 2 ng/dL above nadir after RT (Phoenix criteria)
**** PSA may transiently increase after RT because of testosterone recovery or prostate inflammation
** Management
*** BCR post-RP
**** Adjuvant or salvage RT ± ADT ×6 months → surveillance
*** BCR post-RT
**** Rule out metastasis or local recurrence → salvage local therapies → surveillance
*** Increasing PSA without metastases
**** Observation
**** Indefinite ADT (continuous or intermittent)
*** Distant metastases
**** MCSPC
**** Metastasis-directed therapy ± ADT ± ASI
Salvage RT may be used for patients who experience BCR after radical prostatectomy, typically combined with 6 months of ADT. Conversely, salvage prostatectomy is less commonly performed after primary RT.
* Local failure
** Adjuvant and salvage RT
*** Adjuvant RT for advanced pathologic features (pT3a or pT3b) improves biochemical PFS and OS
*** To avoid risk of overtreatment, reserve adjuvant RT for very high risk pathology (e.g., seminal vesicle involvement, positive margins) and early salvage RT in more ambiguous cases (1-2 mm positive margin)
*** Salvage RT may increase prostate cancer-specific survival in men with PSA doubling time < 6 months
** Endocrine therapy
*** High-dose bicalutamide 150 mg/day ×24 months provided an OS benefit bit was associated with cardiotoxicity and gynecomastia
*** ADT with LHRH analog ×6 months, based on benefits seen in the primary treatment setting
** Salvage prostatectomy
*** Was surgical candidate at time of diagnosis, treated with RT, has life expectancy > 10 years, has no metastatic disease, has biopsy-proven persistent disease
*** Incontinence rates are high, virtually all patients are impotent after surgery
**** Also consider cryotherapy and brachytherapy
*** MRI most useful for detecting recurrence after RT
*** Prostate biopsy done to confirm diagnosis
**** Biopsy should not be done for several months after RT because of prolonged radiation effect and persistence of residual cancer cells
The optimal timing of systemic therapy for BCR is unclear. ADT will lower PSA level in this setting but its impact on OS relative to ADT at the time of metastatic disease is still unknown.
* Systemic therapy
** ADT is standard
** In patient with increasing PSA and no evidence of metastasis, intermittent androgen suppression may be reasonable alternative to continuous androgen suppression
*** Suppress for 8 months each cycle, restarting ADT when PSA > 10 ng/mL
*** Goal is to minimize adverse effects including hot flashes, loss of libido, bone loss, and muscle atrophy
Patients with BCR who are treated with ADT and whose PSA levels increase without evidence of metastases on standard bone scan and CT imaging have disease that has progressed to nmCRPC. The addition of the second-generation AR antagonists apalutamide, darolutamide, or enzalutamide prolongs metastasis-free survival in this setting.
* Nonmetastatic castration-resistant prostate cancer (nmCRPC)
** In nmCRPC (increasing PSA despite castration-level testosterone levels without radiographic evidence of metastasis by bone scan and CT), addition of second-generation AR antagonists delays onset of radiographic metastatic disease (metastasis-free survival)
*** Enzalutamide (also for mCSPC and mCRPC); risk of HTN, MI, fatigue, fall, fracture
*** Apalutamide (also for mCSPC); risk of rash, hypothyroidism, fracture
*** Darolutamide; risk of fatigue
** Metastasis-free survival is strong surrogate for OS in localized prostate cancer
*** Not clear if early ADT prolongs survival relative to ADT at time of metastasis
* Local therapy outside the prostate for oligometastatic recurrence
** Targeted RT, cryoablation, or RF ablation may delay need for systemic therapy
** Earlier detection by more sensitive imaging
*** Fluciclovine PET when CT, MRI, and bone scan are negative
**** After primary RT, residual prostate takes up fluciclovine, limiting detection of local recurrence
**** Use MRI to evaluate for local recurrence
Nonmetastatic BCR (increasing PSA on ADT) -> confirm castration -> repeat imaging ->
* Nonmetastatic (nmCRPC)
** Continue ADT until metastatic
** Or add apalutamide or enzalutamide
* Oligometastatic
** Consider targeted RT ± ADT ± ASI
* Metastatic (mCRPC)
== 14-2.11: Therapy for Metastatic Prostate Cancer
Treatment of metastatic prostate cancer is palliative, not curative, but with sequential treatments, patients may experience years of disease control.
Compared with ADT alone, the addition of docetaxel, abiraterone plus prednisone, or the AR antagonists apalutamide or enzalutamide to treatment for patients with mCSPC significantly prolongs OS. Docetaxel seems to have the most benefit for patients with high-volume disease (four or more bone metastases with one or more outside the spine and pelvis, or visceral—not nodal—metastases).
* Metastatic castration-sensitive prostate cancer (mCSPC) = metastases on imaging study and noncastration levels of testosterone
** ADT is standard systemic treatment approach for relapsed prostate cancer
*** Castrating ADT reduce serum testosterone levels (GnRH agonists/antagonists, estrogens, orchiectomy)
**** Associated with gynecomastia, impotence, loss of libido, weakness, fatigue, hot flashes, loss of muscle mass, anemia, depression, loss of bone
**** Conflicting data regarding risk of cardiovascular mortality and dementia
**** DEXA at baseline and over time to screen for osteopenia/osteoporosis
***** Usually at start of long-term ADT and after 1 year of ADT
**** FRAX score
***** Treat if justified unless testosterone recovery imminent
**** Response measured by decline in PSA, decrease in size of nodal or visceral metastases, and improvement in cancer-related symptoms
***** 60%-70% of patients with abnormal PSA would have normalization < 4 ng/mL;
****** PSA measured at 7 months after initiation is prognostic: dramatically shorter median survival for patients with PSA > 4 ng/mL and a dramatically longer median survival for patients with PSA < 0.2 ng/mL
***** 30%-50% of measurable tumor masses would regress by ≥ 50%
***** 60% of patients would have palliation of symptoms
***** 30%-40% would show improvement on bone scans;
****** Scintigraphic flare could occur between 3-6 months after initiation of therapy, not to be confused with progression of skeletal metastases
**** LHRH agonist initially increases serum testosterone level for up to a few weeks, although clinical relevance is debatable
***** Antiandrogens are sometimes used concurrently to block potential effects of the testosterone surge, starting approximately 2 weeks before LHRH agonist, especially in the setting of high-risk metastatic lesions
****** Antiandrogen + LHRH analog additionally blocks effects of adrenal androgens, which contribute 5%-45% of residual androgens after surgical castration alone
****** Nonsteroidal antiandrogens confer a small but significant improvement in 5-year survival over castration therapy alone
******* Combination treatment is generally not continued after flare period because of additional toxicity
******* Bicalutamide could paradoxically act as an AR agonist if given long-term
******** If PSA increases on bicalutamide, bicalutamide should be withdrawn and may result, in 20% of patients, in a decrease in PSA level over 1-2 months
****** Bicalutamide adverse effects include gynecomastia (treated with tamoxifen 10 mg/day or RT) and elevated transaminases (monitored periodically)
******* Typical dosing is 50 mg/day, and high doses 150 mg/day should be avoided given evidence of cardiotoxicity (heart failure or cardiac arrest)
******* Usually used with LHRH analog, but monotherapy could be used in patients who decline castration therapy or are significantly debilitated with other life-limiting comorbidities
***** GnRH antagonist or surgical castration could be used to avoid testosterone flare
*** Noncastrating AR blockade block androgen activity at the receptor
** Chemotherapy
*** Addition of docetaxel to ADT is standard option (CHAARTED, STAMPEDE, GETUG-AFU 15) for mCSPC, but benefit may be limited to those with high-volume metastatic disease or de novo low-volume disease
*** Risks of febrile neutropenia (primary prophylaxis G-CSF at investigator's discretion) and edema refractory to diuresis (prevented by steroid prophylaxis)
** Abiraterone for mCSPC
*** Similar improvement in OS compared to docetaxel
** AR antagonists for mCSPC
*** ADT + enzalutamide improved OS and PFS over ADT alone
*** ADT + apalutamide improved OS and PFS over ADT alone
** Prostate-directed therapy
*** Ongoing studies evaluating local therapies in oligometastatic CSPC
In the setting of mCRPC, abiraterone, enzalutamide, sipuleucel-T, docetaxel, radium-223, and cabazitaxel all prolong OS. Unfortunately, cross-resistance to AR-directed therapies occurs after exposure to abiraterone or enzalutamide for a prolonged period, and the efficacy of enzalutamide after abiraterone or abiraterone after enzalutamide is limited.
* Metastatic castration-resistant prostate cancer (mCRPC) = progression of metastatic disease despite castration levels of testosterone
** AR signaling continues to play a major role, so castration is maintained
** Abiraterone and enzalutamide are associated with prolonged survival and improved QoL
*** Ketoconazole was used previously
*** Abiraterone causes ACTH-mediated mineralocorticoid excess, and should be used with low-dose prednisone; blood pressure and potassium levels should be monitored
**** Prednisone 5 mg/day in castration-sensitive disease
**** Prednisone 5 mg BID in castration-resistant disease
*** Enzalutamide is highly potent AR antagonist, associated with HTN and seizures
*** AR splice variant AR-V7 lacks ligand-binding domain and confers resistance to enzalutamide and abiraterone
**** Taxane could be used
** New-onset back pain should raise concern for possible spinal cord or cauda equina disease, and an MRI of the spine should be performed if indicated
** If PSA appears to be disproportionately low for tumor burden, a repeated biopsy may indicate a neuroendocrine or small cell phenotype
** Chemotherapy for mCRPC
*** Docetaxel superior to mitoxantrone
*** Cabazitaxel is second-line after docetaxel
**** Neutropenic fever grade 3-4 is major serious toxicity, needs primary prophylaxis with G-CSF
*** Platinum-containing regimens (e.g., cisplatin/carboplatin + etoposide, carboplatin + docetaxel) for small cell histology
**** ADT should be continued because of tumor heterogeneity
** Sipuleucel-T
*** Improved OS in patients with minimally-symptomatic disease
*** No significant effect on PSA or PFS
** Immunotherapy
*** CTLA-4 and PD-1/PD-L1 inhibition had limited efficacy after failure of standard therapies
*** Small percentage of patients have MSI-H or MMR-D cancer, and may have dramatic response to pembrolizumab
** Targeted therapy
*** Olaparib use resulted in response in 33% of patients after docetaxel and one or more AR-directed therapies, more in patients with biallelic somatic or germline BRCA2 loss or ATM aberrations
*** Addition of platinum to docetaxel may be effective in patients with alterations in DNA repair genes
** Bone-directed therapy
*** Radium-223 approved to treat symptomatic bone metastases without known visceral metastases
**** Associated with increased risk of fragility fractures, to be avoided in combination with abiraterone/prednisone
*** Bisphosphonates or denosumab for patients on long-course ADT + RT with osteopenia/osteoporosis (zoledronic acid yearly, denosumab 60 mg q6months), or patients with mCRPC and bone metastases (zoledronic acid monthly or q3months, denosumab 120 mg monthly or q3months)
**** Risks of renal insufficiency, osteonecrosis of jaw, and hypocalcemia
**** Bisphosphonates should be stopped or given less frequently after 2 years of therapy, due to increased risk of atypical femoral fractures and osteonecrosis of jaw
**** Denosumab may be continued indefinitely
**** Both denosumab and zoledronic acid are given with calcium to mitigate risk of hypocalcemia, and sometimes in combination with vitamin D
* Palliation
** EBRT
** NSAID
** Mitoxantrone and prednisone
** Radium-223
*Treatment of mCSPC*
|===
| |High-volume |Low-volume
|De novo
a|ADT +
* Docetaxel
* Abiraterone
* Apalutamide
* Enzalutamide
a|ADT +
* Docetaxel
* Abiraterone
* Apalutamide
* Enzalutamide
|Recurrent |(rare)
a|ADT ±
* Apalutamide
* Enzalutamide
|===
*Systemic treatment options for mCSPC*
[mermaid, format=svg, opts=inline]
----
graph TD
Pretreated[Prior local therapy] --> mCSPC
Untreated[De novo] --> mCSPC
mCSPC --> ADT1[GnRH agonist/antagonist +/- bicalutamide,<br />or single-agent bicalutamide if frail] --> Continue1[Continue ADT] --> |Progression| mCRPC
mCSPC --> |Especially if high volume| ADT2[ADT + docetaxel x6 cycles] --> Continue1
mCSPC --> ADT3[ADT + abiraterone<br />ADT + apalutamide<br />ADT + enzalutamide] --> Continue2[Continue ADT + ASI] --> |Progression| mCRPC
----
*Treatment options for mCRPC*
[mermaid, format=svg, opts=inline]
----
graph TD
ADT[ADT +/- prior docetaxel] --> |Progression| Progression{ }
Abiraterone --> |Progression| Enzalutamide --> |Progression| NGS[Biopsy for NGS]
Enzalutamide --> |Progression| Abiraterone --> |Progression| NGS
Progression --> Docetaxel --> |Progression| Cabazitaxel
Progression --> Abiraterone --> |AR-V7| Docetaxel
Progression --> Enzalutamide --> |AR-V7| Docetaxel
Docetaxel --> |Progression| NGS
NGS --> |DDR alteration| PARPi
NGS --> |MSI-high| PD-1i
Bone1[Bone-predominant mCRPC] --> Radium-223
Bone2[Bone metastases in mCRPC] --> BoneTx[Add bisphosphonate or denosumab]
----
## 14-2.12: Survivorship and Elderly Considerations
* Many men would be cured of prostate cancer by RT or surgery
* Adverse effects may be particularly pronounced in older men
* Therapy-related adverse effects include urinary incontinence, erectile dysfunction, and post-treatment psychosocial issues
* ADT is associated with decreased libido, impotence, decreased lean body mass and muscle strength, increased fat mass, decreased QoL, and osteoporosis
* Long-term ADT could be associated with metabolic complications such as insulin resistance, hyperglycemia, metabolic syndrome, and potentially an increased risk of cardiovascular events
* Men on long-term ADT should be monitored for development of diabetes and dyslipidemia
* Men with previous cardiovascular disease may be at increased risk of cardiovascular morbidity while receiving ADT
* ADT may be associated with development of depression
* Risks of ADT are likely justified in the setting of intermediate- to high-disk localized or metastatic disease in which clear survival advantages have been established