SUMMARY: The American Society of Clinical Oncology (ASCO) recently endorsed the Clinical Practice Guidelines recommended by the American Urological Association (AUA)/American Society for Radiation Oncology (ASTRO), on Adjuvant and Salvage Radiotherapy after Prostatectomy. These guidelines target Medical and Radiation Oncologists, Primary care providers, Urologists, other health care providers and address patient counseling, use of radiotherapy in the adjuvant and salvage settings, definition of biochemical recurrence and restaging evaluation. The following are the ASCO Key Recommendations for Adjuvant and Salvage Radiotherapy after Prostatectomy:
1. Patients who are being considered for management of localized prostate cancer with radical prostatectomy should be informed of the potential for adverse pathologic findings that portend a higher risk of cancer recurrence and that these findings may suggest a potential benefit of additional therapy after surgery.
2. Patients with adverse pathologic findings, including seminal vesicle invasion, positive surgical margins, and extraprostatic extension, should be informed that adjuvant radiotherapy, compared with radical prostatectomy only, reduces the risk of biochemical Prostate Specific Antigen (PSA) recurrence, local recurrence, and clinical progression of cancer. They should also be informed that the impact of adjuvant radiotherapy on subsequent metastases and overall survival is less clear; one of two randomized controlled trials that addressed these outcomes indicated a benefit, but the other trial did not demonstrate a benefit defined as reduced risk of metastasis and death.
3. Physicians should “OFFER” adjuvant radiotherapy to patients with adverse pathologic findings at prostatectomy, including seminal vesicle invasion, positive surgical margins, or extraprostatic extension, because of demonstrated reductions in biochemical recurrence, local recurrence and clinical progression.
4. Patients should be informed that the development of a PSA recurrence after surgery is associated with a higher risk of development of metastatic prostate cancer or death resulting from the disease. Congruent with this clinical principle, physicians should regularly monitor PSA after radical prostatectomy to enable early administration of salvage therapies if appropriate.
5. Clinicians should define biochemical recurrence as a detectable or increasing PSA value after surgery that is more than 0.2 ng/mL, with a second confirmatory level more than 0.2 ng/mL.
6. A restaging evaluation in a patient with a PSA recurrence may be considered although it is not clear at this time which imaging modalities to use, as all imaging modalities have limited sensitivity and specificity in the low PSA range.
7. Physicians should “OFFER” salvage radiotherapy to patients with PSA or local recurrence after radical prostatectomy, in whom there is no evidence of distant metastatic disease.
8. Patients should be informed that the effectiveness of radiotherapy for PSA recurrence is greatest when administered at lower levels of PSA (less than 1 ng/ml). Salvage radiotherapy in this patient population with a short PSA doubling time, has been shown to improve overall survival.
9. Patients should be informed of the possible short and long term urinary, bowel, and sexual adverse effects of radiotherapy as well as of the potential benefits of controlling disease recurrence.
This endorsement was made with certain qualifying statements, clarifying certain aspects of these guidelines.
a) The word “OFFER” should be interpreted as having a detailed discussion with the patient about the risks and benefits of adjuvant radiation.
b) Even though 0.2 ng/mL is considered a reasonable cut point for PSA recurrence, the benefits of using this cut point versus other cut points remains unclear.
c) Patient’s who have the greatest benefit in absolute risk reduction from adjuvant RT, are those with adverse pathologic findings as noted in the guidelines, with a high risk of recurrence or clinical progression.
In conclusion, the decision to administer adjuvant or salvage radiotherapy should be made by the patient and multidisciplinary treatment team, after discussing the risks and benefits of such intervention. Freedland SJ, Rumble RB, Finelli A, et al. J Clin Oncol 2014;32:3892-3898
The development and progression of prostate cancer is driven by androgens. Androgen Deprivation Therapy (ADT) has therefore been the cornerstone of treatment of advanced prostate cancer and is the first treatment intervention for hormone sensitive prostate cancer. Chemotherapy is usually considered for patients who progress on hormone therapy and TAXOTERE® (Docetaxel) has been shown to improve Overall Survival (OS) of metastatic prostate cancer patients, who had progressed on androgen deprivation therapy. It is not clear however, whether ADT is more effective with or without TAXOTERE®, when treating patients with metastatic prostate cancer. To address this further, a randomized phase III trial (E3805) was conducted to assess the benefit of upfront treatment with a combination of chemotherapy and hormonal therapy, in patients with metastatic hormone sensitive prostate cancer. Seven hundred and ninety (N=790) patients with newly diagnosed metastatic prostate cancer were randomly assigned to receive either Androgen Deprivation Therapy alone (N=393) or ADT plus TAXOTERE® (N=397). Androgen Deprivation Therapy consisted of either Luteinizing Hormone Releasing Hormone (LHRH) agonist therapy, LHRH antagonist therapy, or surgical castration. Chemotherapy consisted of TAXOTERE®, started within 4 months of starting ADT, dosed at 75 mg/m2 given every 3 weeks for a maximum of six cycles. The median age of patients was 63 years and approximately two-thirds of patients had high-volume disease, with either extensive liver or bone metastases. The primary endpoint of this study was Overall Survival. At a median follow up of 29 months, the median Overall Survival was 42.3 months in the ADT group and 52.7 months in the ADT plus TAXOTERE® group (HR=0.63; P<0.0006). This benefit was even more significant in patients with high volume disease (32.2 vs 49.2 months for ADT and ADT plus TAXOTERE® respectively, HR=0.62; P<0.0012). At 12 months, the proportion of patients with PSA levels less than 0.2 ng/mL was 9.4% in the ADT alone group vs 19.7% in the ADT plus TAXOTERE® group (P < 0.0001). The median time to clinical progression was 19.8 months in the ADT alone group vs 32.7 months in the ADT plus TAXOTERE® group (P < 0.0001). The authors concluded that this is the first study to demonstrate survival benefit in patients with newly diagnosed metastatic prostate cancer. This survival benefit with Androgen Deprivation Therapy and TAXOTERE® is even more so, in patients with high volume disease and should be considered standard treatment for those patients who are fit to receive TAXOTERE® based therapy. Sweeney C, Chen Y, Carducci MA, et al. 2014 ASCO Annual Meeting; LBA2
Upon progression {described as Castrate Resistant Prostate Cancer (CRPC), as these tumors are not androgen independent and continue to rely on Androgen Receptor signaling} two agents are presently available for metastatic CRPC. They include ZYTIGA® (Abiraterone) and XTANDI® (Enzalutamide). Both these agents have been shown to improve survival in metastatic CRPC. ZYTIGA® inhibits CYP 17A1 enzyme and depletes adrenal and intratumoral androgens, thereby impairing AR signaling. XTANDI® competes with Testosterone and Dihydrotestosterone and avidly binds to the Androgen Receptor, thereby inhibiting AR signaling and in addition inhibits translocation of the AR into the nucleus and thus inhibits the transcriptional activities of the AR. About 20-40% of the patients do not respond to these newer agents and even those who respond will invariably develop resistance to these drugs. This again has been attributed to persistent AR signaling by variant forms of Androgen Receptor, generated through somatic mutation or aberrant RNA splicing. Androgen Receptor Variant AR-V7 can be detected in the circulating tumor cells. AR-V7 does not have the domain to bind androgens and may be associated with resistance to XTANDI®. Further AR-V7 is constitutively active and can independently activate transcription factors and therefore is not effected by androgen depleting agents including ZYTIGA®. With this background, the authors hypothesized that detection of Androgen Receptor variant AR-V7 in circulating tumor cells from men with metastatic prostate cancer would be associated with resistance to both ZYTIGA® and XTANDI®. In this prospective study which enrolled patients with Castrate Resistant Prostate Cancer (CRPC), 31 patients received treatment with ZYTIGA® and 31 patients received treatment with XTANDI®. Levels of AR-V7 in circulating tumor cells of these patients were analyzed using quantitative Reverse Transcriptase – Polymerase Chain Reaction assay. The primary endpoint was association between AR-V7 status (positive versus negative) and Prostate Specific Antigen (PSA) response rates and secondary endpoints included freedom from PSA progression (PSA Progression Free Survival), clinical or radiographic Progression Free Survival, and Overall Survival. The authors noted that patients with detectable AR-V7 in circulating tumor cells had no response to ZYTIGA® or XTANDI® as measured by serum PSA level reduction of 50% or more and also had a shorter Progression Free Survival and Overall Survival. Also of interest, the prevalence of detectable AR-V7 in circulating tumor cells before treatment with ZYTIGA® and XTANDI® was 9-15% whereas it increased to approximately 50% after disease progressed during treatment with either of these two drugs. This suggested a common mechanism of resistance to both drugs. The authors concluded that detection of AR-V7 in circulating tumor cells from patients with Castration Resistant Prostate Cancer, may be associated with resistance to ZYTIGA® and XTANDI® and if further validated, could be used as a biomarker. Antonarakis ES, Lu C, Wang H, et al. N Engl J Med 2014; 371:1028-1038
The American Urological Association suggested that a PSA of 0.2 ng/mL or higher defines PSA failure or relapse, after Radical Prostatectomy. A PSA rise of 2 ng/ml or more above post Radiation Therapy nadir, is considered PSA failure or relapse. Approximately 35% of the patients with prostate cancer will experience PSA only relapse within 10 years of their primary treatment and a third of these patients will develop documented metastatic disease within 8 years following PSA only relapse. Prostate cancer patients who had thought that they were cured, consequently can experience considerable mental anguish and anxiety, based on these laboratory findings. Androgen Deprivation Therapy (ADT) is often initiated following PSA only relapse with the intent of delaying disease progression although the role of ADT and optimal timing to start ADT (Immediate vs deferred ADT) in this patient population is unknown. Further, ADT can be associated with side effects such as fatigue, loss of muscle mass, impotence, anemia, osteoporosis, etc., which in turn can have a significant negative impact on an individual’s quality of life. In order to determine the significance of benefit if any, with starting ADT while patients are asymptomatic, the authors analyzed data on more than 14,000 patients included in a prospective registry called CaPSURE (Cancer of the Prostate Strategic Urologic Research Endeavor) and of them studied 2,022 men, who had experienced a PSA only relapse following curative surgery or radiation. These patients had clinical stage T3a,N0M0 or lower stage prostate cancer and experienced PSA only relapse (defined as PSA of 0.2 ng/mL or higher after Radical Prostatectomy or three rising PSA values one month apart following radiation treatment. Patients with symptoms, documented metastatic disease by CT scan or bone scan and ADT in the previous 12 months were excluded. Patients in the” Immediate treatment group” initiated ADT within 3 months of PSA relapse and those in the “Deferred treatment group” initiated ADT, 2 or more years after PSA relapse or when they presented with metastasis, symptoms or had a short PSA doubling time. The median age was 69 years, 34% had a Gleason score >7 and 32% received radiotherapy as primary treatment. The median time from primary treatment to PSA relapse was 27 months. Patients were followed for a median of 52.3 months after PSA relapse. The Five-year survival rate for Patients in the” Immediate treatment group” was 85.1% and for those in the “Deferred treatment group” was 87.2% with no significant difference in the all cause mortality. The 10 year survival was identical in both groups at 71.6%. The authors concluded that there is little or no survival benefit for Immediate ADT initiation compared with Deferred ADT initiation (at clinical progression or at least two years after PSA relapse) among prostate cancer patients with PSA only relapse. Therefore delaying ADT for at least 2 years after PSA relapse, following curative therapy for prostate cancer does not worsen overall survival. The findings from this large observational study will need further validation and a randomized phase III trial is underway to confirm these findings. Garcia-Albeniz X, Chan JM, Paciorek AT, et al. J Clin Oncol 32:5s, 2014 (suppl; abstr 5003)
Based on the recent research, it appears that there is an indirect link between mutations of the Androgen Receptor gene and the initiation and promotion of prostate cancer. On the contrary, low testosterone levels prior to therapy may be an independent predictor of a more aggressive disease, with an increased likelihood of extra-prostatic disease at the time of diagnosis and unfavorable treatment response. The current recommendations are to exclude prostate cancer before initiating testosterone replacement therapy in hypogonadal men over age 40, with a digital rectal examination (DRE) and PSA level and to closely monitor in the first year of testosterone replacement with DRE and PSA evaluations every 3 months and then semiannually. These recommendations are arbitrary, and not supported by published data. To determine the incidence/risk of prostate cancer with testosterone replacement therapy, the authors in this study reviewed the outcomes of 942 men in three cohorts, with testosterone levels less than or equal to 12.1 nmol/L from three German centers, who had received testosterone undecanoate for up to 16 years. The incidence of prostate cancer in cohort A (N=300) was 39.4 per 10,000 person-years (39.4 cases per 10,000 persons followed for 1 year), in cohort B (N=261) was 54.5 per 10,000 person-years (54.5 cases per 10,000 persons followed for 1 year) and in cohort C (N=381), no person was diagnosed with prostate cancer. The authors pointed out that the incidence of prostate cancer in the Prostate, Lung, Colorectal, and Ovarian (PLCO) Cancer Screening Trial was 116 per 10,000 person-years. Even though this review of registry data cannot be directly compared with screening trials, the authors concluded that based on their registry studies, long-term testosterone treatment in hypogonadal men does not appear to increase prostate cancer risk. A recently published article, in the Annals of Pharmacotherapy by Baillargeon, et al. concluded that there was no increased risk of myocardial infarction when hypogonadal patients over age 65, were treated with intramuscular testosterone. As the debate continues on the risk/ benefits of testosterone replacement therapy, the heightened awareness will probably bring about more responsible prescribing of testosterone supplements. Haider A, Zitzmann M, Yassin A. J Clin Oncol 32, 2014 (suppl 4; abstr 119)
Radium Ra 223 dichloride (XOFIGO®) is a bone seeking alpha particle emitter and by virtue of its chemical similarity to calcium is preferentially taken up by the bone and forms complexes with bone mineral, hydroxyapatite, in areas where there is increased bone turnover, such as bone metastases. XOFIGO® induces double stranded DNA breaks resulting in antitumor effects and has a very short range in tissues (around 2 and 10 cells), quickly losing energy, compared to beta or gamma radiation. The end result is less damage to the adjacent healthy tissues. Further, unlike Ra-226 which was first isolated by Madame Curie, XOFIGO® has a short half life of 11.4 days and rapidly decays, preventing significant radiation exposure. The ALSYMPCA (ALpharadin in SYMptomatic Prostate CAncer patients) study is a randomized, double-blind, phase III trial, in which 921 patients with Castrate Resistant Prostate Cancer (CRPC) with 2 or more symptomatic bone metastases and no known visceral metastases, were randomly assigned in a 2:1 ratio to receive either XOFIGO® along with best supportive care (N=614) or placebo with best supportive care (N=307). Enrolled patients either progressed on or had not received TAXOTERE® (Docetaxel) for a variety of reasons and 42% of the enrolled patients were chemotherapy naïve.
The primary endpoint was Overall Survival and secondary endpoints included time to first symptomatic skeletal event, time to increase in total alkaline phosphatase level and PSA level. This study was stopped earlier than planned, as there was a significant increase in the median overall survival in the XOFIGO® group compared to placebo group, with a 30% reduction in the risk of death (14.9 months vs 11.3 months, HR=0.70, P<0.001). All secondary endpoints favored XOFIGO® as well. The most common adverse events were cytopenias, majority of which were Grades 1 and 2 and discontinuation rates due to adverse events were lower in the XOFIGO® group (17%) compared to 21% for the Placebo group. At 1.5 years, the incidence of myelosuppression was 3%, there were no grade 3 or 4 non-hematologic toxicities and no reports of secondary malignancies in the XOFIGO® group. The authors concluded that based on the long term safety data, XOFIGO® has an excellent side-effect profile in patients with CRPC. Unlike the bone seeking beta emitters such as Strontium-89 and Samarium-153, XOFIGO®, an alpha emitter, is the only agent that has been shown to improve overall survival. Studies are underway evaluating the efficacy of chemotherapy in combination with XOFIGO®, in patients with CRPC and associated bone metastases. Nilsson S, Vogelzang NJ, Sartor AO, et al. J Clin Oncol 32, 2014 (suppl 4; abstr 9)
Abiraterone acetate (ZYTIGA®) is a novel, targeted, oral androgen biosynthesis inhibitor that decreases androgen production in the adrenal glands, testes and prostate cancer cells by inhibiting a steroidal enzyme CYP17A. Phase III trials have demonstrated that treatment with ZYTIGA® prolongs overall survival in metastatic CRPC patients, who had progressed after TAXOTERE® (Docetaxel) therapy, as well as those who are chemotherapy naive. ZYTIGA® delays deterioration of performance status, progression of fatigue and pain as well as development of skeletal related events, in TAXOTERE® refractory patients. It is important that any treatment considered for patients with asymptomatic or mildly symptomatic CRPC improves overall survival without negatively impacting Quality of Life. To address this further, the authors analyzed patient reported data related to pain and Quality of Life from a large randomized clinical trial. Of the 1088 chemotherapy-naïve, asymptomatic or mildly symptomatic CRPC patients randomized in this double-blind study, 546 patients received ZYTIGA® 1000 mg PO plus prednisone 5 mg twice daily and 542 patients received placebo plus prednisone. At the time of the planned interim analysis, ZYTIGA® improved radiographic progression-free survival, overall survival, and significantly delayed the initiation of chemotherapy. The authors in this publication reported the data related to pain and Quality of Life of these patients, at the time of the second preplanned interim analysis. Pain was assessed with the Brief Pain Inventory-Short Form (BPI-SF) questionnaire, which is a validated instrument to assess pain and Health Related Quality of Life (HRQoL) was measured with the Functional Assessment of Cancer Therapy—Prostate (FACT-P) questionnaire, which is a validated tool for metastatic CRPC. At a median follow-up of 22.2 months, the median time to progression of pain intensity was longer in patients receiving ZYTIGA® plus prednisone vs placebo plus prednisone (26.7 months vs 18.4 months, HR=0.82, P=0.049). The median time for pain to progress and interfere with daily activities was 10.3 months for ZYTIGA® vs 7.4 months for placebo (HR= 0.79, P=0.005). The median time to deterioration of HRQoL was longer in patients receiving ZYTIGA® plus prednisone vs those receiving placebo plus prednisone, as assessed by the FACT-P total score (12.7 months vs 8.3 months, HR=0.78, P=0.003). The authors concluded that ZYTIGA® given along with prednisone delays patient-reported pain progression and deterioration of HRQol, in chemotherapy-naive patients with metastatic CRPC, without compromising efficacy. Basch E, Autio K, Ryan CJ, et al. The Lancet Oncology 2013;14:1193 -1199
The SELECT trial, which began in 2001, was stopped early in 2008, as Selenium and Vitamin E, taken alone or together for an average of five and a half years did not decrease the incidence of prostate cancer. In 2011, an update on the SELECT trial data suggested that men who were randomized to the vitamin E alone had a 17 percent increased risk of prostate cancer compared to those men taking placebo. The authors in this case–cohort study continued follow up of the SELECT trial participants and with the Selenium levels data from toenail clippings, compared the effect of Selenium and Vitamin E, taken either alone or together, on the risk of prostate cancer, among 1739 men who were diagnosed with prostate cancer, of whom 489 participants developed high-grade prostate cancer. The control group for comparison was a random sample of 3117 men without prostate cancer and they were matched to the cases by race and age. It was noted that an individual’s baseline Selenium level, in the absence of supplementation, was not associated with prostate cancer risk. However, in men who had high baseline Selenium levels, Selenium supplements almost doubled (91%) the risk of high grade prostate cancer (P=0.007). Conversely, Vitamin E supplements had no effect among men with high baseline Selenium levels but doubled the risk of high grade prostate cancer among men with low baseline Selenium levels. Frankel et al. in an accompanying editorial point out that the dose of Vitamin E in the SELECT trial was significantly higher (400 IU/day) than the dose that was selected in the Alpha-Tocopherol Beta Carotene (ATBC) Cancer Prevention trial (50 IU/day), a study that was designed to test Vitamin E and beta carotene for lung cancer prevention in smokers. In the ATBC trial, a decrease in the incidence of prostate cancer incidence was observed, although this was a secondary finding and this study was not designed to determine prostate cancer risk. They comment that high doses of Vitamin E (Alpha-Tocopherol), suppresses the more potentially beneficial serum Gamma-Tocopherol which is the prevalent dietary form of Vitamin E in the United States. Selenium deficiency in the U.S. is not common and any benefit with Selenium supplements can only be seen in those who are Selenium deficient and high doses may be detrimental. The authors concluded that in the SELECT trial, the combination of both Vitamin E and Selenium did not reduce the risk of prostate cancer or any other cancer or heart disease and was in fact harmful for a significant number of individuals. Therefore, men 55 years of age or more should avoid Vitamin E or Selenium supplements at doses that exceed the recommended dietary intake. Kristal AR, Darke AK, Morris JS, et al. J Natl Cancer Inst; First published online 22 February 2014, doi: 10.1093/jnci/djt456
XTANDI® (Enzalutamide) is a second-generation anti-androgen with no reported agonistic effects. It competitively inhibits androgens and AR binding to androgens as well as AR nuclear translocation and interaction with DNA. It thus inhibits several steps in the AR signaling pathway. XTANDI® was first approved by the FDA in 2012, for the treatment of patients with metastatic CRPC who have previously received TAXOTERE® (Docetaxel) based chemotherapy. The PREVAIL study is a double-blind, placebo-controlled, phase III trial in which 1,717 chemotherapy-naive patients with mCRPC (metastatic Castrate Resistant Prostate Cancer) were randomly assigned 1:1 to receive either XTANDI® 160 mg/day or placebo. Prior treatment with surgery or radiation therapy for their primary tumor, as well as hormonal intervention with a LHRH (Luteinizing Hormone Releasing Hormone) agonist or first-generation anti-androgen was allowed. The two co-primary endpoints were Overall Survival (OS) and radiographic Progression Free Survival (rPFS), as measured by bone scans and CT scans. At the time of preplanned interim analysis, XTANDI® demonstrated a statistically significant benefit over placebo with a 30% reduction in risk of death (OS: HR= 0.70; P< 0.0001) and an 81% reduction in risk of radiographic Progression Free Survival (rPFS: HR 0.19; P< 0.0001). Further, the response rates were meaningful with 20% complete responses and 39% partial responses (59% Response Rate) compared with 5% Response Rate in the placebo group (P<0.0001). XTANDI® also significantly delayed the median time to chemotherapy by 17 months compared with those who took placebo (P<0.0001). Based on the results of this interim analysis, the Independent Data Monitoring Committee recommended stopping the study and allowing patients in the placebo group to receive XTANDI®. XTANDI® was well tolerated and the most common side effects were hot flashes, weight gain, fatigue, constipation, back and joint pain. The authors concluded that XTANDI® significantly improves OS and rPFS in patients with chemotherapy-naive mCRPC and can significantly delay the need for chemotherapeutic intervention. Beer TM, Armstrong AJ, Sternberg CN, et al. J Clin Oncol 32, 2014 (suppl 4; abstr LBA1)