Survival benefit for early hormone ablation in biochemically recurrent prostate cancer

The impact of timing of salvage hormonal therapy on survival after brachytherapy for prostate cancer

PURPOSE

We aimed to evaluate the impact of timing of androgen deprivation therapy (ADT) on survival in a cohort of patients with biochemical recurrence (BCR) after brachytherapy treatment for prostate cancer.

METHODS AND MATERIALS

We retrospectively identified 2366 men receiving permanent prostate brachytherapy with or without external beam radiation therapy. Patients experiencing BCR were stratified by receipt of immediate or delayed (≥3 months) ADT and prostate-specific antigen (PSA) failure threshold of 10 ng/mL. Prostate cancer-specific mortality (PCSM) and all-cause mortality (ACM) were evaluated using Fine-Gray's competing risks regression and Cox proportional hazard model, respectively.

RESULTS

We identified 109 patients in the study cohort treated with ADT for BCR, followed for a median of 11.4 years. Competing risk regression revealed that there was no difference in PCSM for patients receiving delayed vs. immediate ADT (hazard ratio [HR], 0.94; 95% confidence interval [CI]: 0.44-2.00: p = 0.871) or for those initiating hormonal therapy at PSA threshold of 10 vs. <10 ng/mL (HR, 0.85; 95% CI: 0.41-1.75; p = 0.649); similarly, there was no difference in ACM. PSA doubling time <6 months (HR, 2.52; 95% CI: 1.22-5.23; p = 0.013), time to BCR <3 years (HR, 3.27; 95% CI: 1.67-6.42; p = 0.003), and permanent prostate brachytherapy with external beam radiation therapy (HR, 5.21; 95% CI: 2.05-13.26; p = 0.001) were significantly associated with PCSM, as well as ACM.

CONCLUSIONS

Among a cohort of brachytherapy patients, we identified no significant difference in survival for delayed salvage hormonal therapy. Shorter PSA doubling time and time to BCR are significantly associated with adverse outcomes, and these patients should be considered for immediate salvage therapy.

Less advanced disease at initiation of salvage androgen deprivation therapy is associated with decreased mortality following biochemical failure post-salvage radiation therapy

BACKGROUND

The optimal clinical context for initiation of salvage androgen deprivation therapy (SADT) following the biochemical recurrence of localized prostate cancer remains controversial. We chose to investigate if disease burden at time of SADT initiation is associated with clinical outcomes following biochemical failure (BF) post-salvage radiation therapy (SRT).

METHODS

Medical records of 575 patients receiving SRT at a single institution from 1986-2010 were retrospectively reviewed. Of 250 patients experiencing BF post-SRT, 172 had a calculable prostate-specific antigen doubling time (PSADT) prior to SADT initiation. These patients comprise the analyzed cohort and were divided into four groups based on characteristics at SADT initiation: those with PSADTs >3 months without distant metastasis (DM) (group 1 [less advanced disease], n=62), those with PSADTs <3 months without DM (group 2 [more advanced disease], n=28), those with DM (group 3 [more advanced disease], n=32), and those not receiving SADT during follow-up (group 4, n=50). Endpoints included prostate cancer-specific mortality (PCSM) and overall mortality (OM). Kaplan-Meier methods were used to estimate survival, and Cox proportional hazards models were used for multivariate analysis.

RESULTS

Median follow-up post-SRT was 7.9 years. Patients starting SADT with more advanced disease were at significantly increased risk for PCSM (hazard ratio [HR]:2.8, 95% confidence interval [CI]: 1.4-5.6, p=0.005) and OM (HR:1.9, 95% CI: 1.0-3.5, p=0.04) compared to those receiving SADT with less advanced disease. PCSM and OM did not significantly differ between groups 1 and 4 or groups 2 and 3. Of note, patients in group 4 had very long PSADTs (median = 27.0 months) that were significantly longer than those of group 1 (median = 6.0 months) (p<0.001). Multivariate analysis including groups 1-3 found a pre-SADT PSADT <3 months to be the most significant predictor of PCSM (HR:4.2, 95% CI: 1.6-11.1, p=0.004) and the only significant predictor of OM (HR:2.9, 95% CI: 1.3-6.7, p=0.01).

CONCLUSIONS

Less advanced disease at initiation of SADT is associated with decreased PCSM and OM following BF post-SRT; however, observation may be reasonable for patients with very long PSADTs. A PSADT <3 months prior to SADT initiation significantly predicts an increased risk of PCSM and OM in this patient demographic.

Metastasis-free survival is associated with overall survival in men with PSA-recurrent prostate cancer treated with deferred androgen deprivation therapy

BACKGROUND

Clinical trials in men with biochemically recurrent prostate cancer (BRPC) have been hampered by long survival times, making overall survival (OS) a difficult end point to reach. Intermediate end points are needed in order to conduct such trials within a more feasible time frame.

PATIENTS AND METHODS

This is a retrospective analysis of 450 men with BRPC following prostatectomy treated at a single institution between 1981 and 2010, of which 140 developed subsequent metastases. Androgen deprivation therapy (ADT) was deferred until after the development of metastases. Cox regression models were developed to investigate factors influencing OS.

RESULTS

Median metastasis-free survival (MFS) was 10.2 years [95% confidence interval (CI) 7.6-14.0 years]; median OS after metastasis was 6.6 years (95%CI 5.8-8.4 years). Multivariable Cox regressions identified four independently prognostic variables for OS: MFS (HR 0.77; 95% CI 0.63-0.94), number of metastases (≤3 versus ≥4; HR 0.50; 95% CI 0.29-0.85), pain (absent versus present; HR 0.43; 95% CI 0.25-0.72), and bisphosphonate use (yes versus no; HR 0.60; 95% CI 0.37-0.98).

CONCLUSIONS

MFS emerged as an independent predictor of OS in men with BRPC treated with deferred ADT after the development of metastases. MFS may be a reasonable intermediate end point in future clinical trials. This observation requires prospective validation.

Early salvage hormonal therapy for biochemical failure improved survival in prostate cancer patients after neoadjuvant hormonal therapy plus radiation therapy--a secondary analysis of irish clinical oncology research group 97-01

PURPOSE

To assess the survival benefit of early vs late salvage hormonal therapy (HT), we performed a secondary analysis on patients who developed recurrence from Irish Clinical Oncology Research Group 97-01, a randomized trial comparing 4 vs 8 months neoadjuvant HT plus radiation therapy (RT) in intermediate- and high-risk prostate adenocarcinoma.

METHODS AND MATERIALS

A total of 102 patients from the trial who recurred were analyzed at a median follow-up of 8.5 years. The patients were divided into 3 groups based on the timing of salvage HT: 57 patients had prostate-specific antigen (PSA)≤10 ng/mL and absent distant metastases (group 1, early), 21 patients had PSA>10 ng/mL and absent distant metastases (group 2, late), and 24 patients had distant metastases (group 3, late). The endpoint analyzed was overall survival (OS) calculated from 2 different time points: date of enrolment in the trial (OS1) and date of initiation of salvage HT (OS2). Survival was estimated using Kaplan-Meier curves and a Cox regression model.

RESULTS

The OS1 differed significantly between groups (P<.0005): OS1 at 10 years was 78% in group 1, 42% in group 2, and 29% in group 3. The OS2 also differed significantly between groups (P<.0005): OS2 at 6 years was 70% in group 1, 47% in group 2, and 22% in group 3. Group 1 had the longest median time from end of RT to biochemical failure compared with groups 2 and 3 (3.3, 0.9, and 1.7 years, respectively; P<.0005). Group 1 also had the longest median PSA doubling time compared with groups 2 and 3 (9.9, 3.6, and 2.4 months, respectively; P<.0005). On multivariate analysis, timing of salvage HT, time from end of RT to biochemical failure, and PSA nadir on salvage HT were significant predictors of survival.

CONCLUSION

Early salvage HT based on PSA≤10 ng/mL and absent distant metastases improved survival in patients with prostate cancer after failure of initial treatment with neoadjuvant HT plus RT.

Changes in PSA kinetics predict metastasis- free survival in men with PSA-recurrent prostate cancer treated with nonhormonal agents: combined analysis of 4 phase II trials

BACKGROUND

Several phase II trials in men with noncastrate PSA-recurrent prostate cancer have assessed the impact of novel nonhormonal agents on PSA kinetics. However, it is unknown whether changes in PSA kinetics influence metastasis-free survival (MFS).

METHODS

We performed a retrospective post hoc analysis of 146 men treated in 4 phase II trials examining the investigational agents marimastat (a matrix metalloproteinase inhibitor; n = 39), imatinib (a tyrosine kinase inhibitor; n = 25), ATN-224 (a copper/zinc-superoxide dismutase inhibitor; n = 22), and lenalidomide (an antiangiogenic/immunomodulatory drug; n = 60). We investigated factors influencing MFS, including within-subject changes in PSA kinetics (PSA slope, doubling time, and velocity) before and after treatment initiation.

RESULTS

After a median follow-up of 16.8 months, 70 patients (47.9%) developed metastases. In multivariable Cox regression models, factors that were independently predictive of MFS after adjusting for age and other clinical prognostic variables were baseline PSA doubling time (PSADT) (P = .05), baseline PSA slope (P = .01), on-study change in PSADT (P = .02), and on-study change in PSA slope (P = .03). In a landmark Kaplan-Meier analysis, median MFS was 63.5 months (95% confidence interval [CI], 34.6-not reached) and 28.9 months (95% CI, 13.5-68.0) for men with or without any decrease in PSA slope by 6 months after treatment, respectively.

CONCLUSIONS

This hypothesis generating analysis suggests that within-subject changes in PSADT and PSA slope after initiation of experimental therapy may correlate with MFS in men with biochemically recurrent prostate cancer. If validated in prospective trials, changes in PSA kinetics may represent a reasonable intermediate end point for screening new agents in these patients.

Risk stratification in the hormonal treatment of patients with prostate cancer

Prostate cancer (PCa) is the most common type of cancer found in American men, other than skin cancer. The American Cancer Society estimates that there will be 186,320 new cases of prostate cancer in the United States in 2008. About 28,660 men will die of this disease this year and PCa remains the second-leading cause of cancer death in men. One in six men will get PCa during his lifetime and one in 35 will die of the disease. Today, more than 2 million men in the United States who have had PCa are still alive. The death rate for PCa continues to decline, chiefly due to early detection and treatment, and improved salvage therapy such as hormone therapy (HT). HT continues to be a mainstay for primary-recurrent PCa and locally-advanced PCa. However, HT is associated with many undesirable side effects including sexual dysfunction, osteoporosis and hot flashes, all of which can lead to decreased quality of life (QOL). These risks are seen in both long- and short-term HT regimens. Additionally, research in recent years has revealed trends related to clinico pathological variables and their predictive ability in HT outcomes. Awareness of the potential adverse effects, the risks associated with HT and the prognostic ability of clinical and pathological variables is important in determining optimal therapy for individual patients. A rigorous evaluation of the current scientific literature associated with HT was conducted with the goal of identifying the most favorable balance of benefits and risks associated with HT.

Androgen suppression strategies for prostate cancer: is there an ideal approach?

Androgen suppression therapy (AST) was first described in 1941 as a treatment of prostate cancer (PCa) and remains the mainstay of therapy in patients with hormone-naïve metastatic disease. It also is used in locally advanced or recurrent disease and in combination with radiation therapy in patients with higher-risk features. Several approaches to AST have been developed as a result of increased understanding of the pathways controlling testosterone production. Increased recognition of the side effects has resulted in strategies to minimize complications associated with AST. Attempts to reduce AST adverse effects include intermittent hormonal therapy and methods to reduce amount of intracellular androgens without reducing the circulating testosterone levels.

The natural history of metastatic progression in men with prostate-specific antigen recurrence after radical prostatectomy: long-term follow-up

OBJECTIVE

To describe metastasis-free survival (MFS) in men with prostate-specific antigen (PSA) recurrence following radical prostatectomy, and to define clinical prognostic factors modifying metastatic risk.

PATIENTS AND METHODS

We conducted a retrospective analysis of 450 men treated with prostatectomy at a tertiary hospital between July 1981 and July 2010 who developed PSA recurrence (≥0.2 ng/mL) and never received adjuvant or salvage therapy before the development of metastatic disease. We estimated MFS using the Kaplan-Meier method, and investigated factors influencing the risk of metastasis using Cox proportional hazards regression.

RESULTS

Median follow-up after prostatectomy was 8.0 years, and after biochemical recurrence was 4.0 years. At last follow-up, 134 of 450 patients (29.8%) had developed metastases, while median MFS was 10.0 years. Using multivariable regressions, two variables emerged as independently predictive of MFS: PSA doubling time (<3.0 vs 3.0-8.9 vs 9.0-14.9 vs ≥15.0 months) and Gleason score (≤6 vs 7 vs 8-10). Using these stratifications of Gleason score and PSA doubling time, tables were constructed to predict median, 5- and 10-year MFS after PSA recurrence. In different patient subsets, median MFS ranged from 1 to 15 years.

CONCLUSIONS

In men undergoing prostatectomy, MFS after PSA recurrence is variable and is most strongly influenced by PSA doubling time and Gleason score. These parameters serve to stratify men into different risk groups with respect to metastatic progression. Our findings may provide the background for appropriate selection of patients, treatments and endpoints for clinical trials.

Long-term overall survival and metastasis-free survival for men with prostate-specific antigen-recurrent prostate cancer after prostatectomy: analysis of the Center for Prostate Disease Research National Database

OBJECTIVE

• To describe metastasis-free survival (MFS) and overall survival (OS) among men with prostate-specific antigen (PSA)-recurrent prostate cancer after radical prostatectomy who did not receive additional therapy until metastasis, using a multicentre database capturing a wide ethnic mix.

PATIENTS AND METHODS

• A retrospective analysis of the Center for Prostate Disease Research National Database (comprised of five US military hospitals and one civilian centre) was performed for patients with PSA relapse (≥ 0.2 ng/mL) after radical prostatectomy who had no additional therapy until the time of radiographic metastatic disease. • We investigated factors influencing metastasis and all-cause mortality using univariate and multivariate Cox regression analysis.

RESULTS

• There were a total of 346 men who underwent radical prostatectomy between May 1983 and November 2008 and fulfilled the entry criteria. All patients had information on survival and 190 men had information on metastasis. Among patients with survival data (n= 346), 10-year OS was 79% after a median follow-up of 8.6 years from biochemical recurrence. • Among men with metastasis data (n= 190), 10-year MFS was 46% after a median follow-up of 7.5 years. • In Cox regressions, four clinical factors (Gleason score, pathological stage, time to PSA relapse and PSA doubling time), as well as age, were predictive of OS and/or MFS in univariate analysis, although only PSA doubling time (≥ 9 vs 3-8.9 vs <3 months) remained independently predictive of these outcomes in multivariate analysis (P < 0.001).

CONCLUSIONS

• This multicentre multi-ethnic dataset shows that OS and MFS can be extensive for men with PSA-recurrent prostate cancer, even in the absence of further therapy before metastasis. • This unique patient cohort, the second largest of its type after the Johns Hopkins cohort, confirms that PSA doubling time is the strongest determinant of OS and MFS in men with PSA-recurrent disease. • Longer follow-up and more events will be required to determine whether other variables may also contribute to these outcomes.

Combined low-dose flutamide plus finasteride vs low-dose flutamide monotherapy for recurrent prostate cancer: a comparative analysis of two phase II trials with a long-term follow-up

OBJECTIVE

To compare the efficacy and tolerability of peripheral androgen blockade using combined low-dose flutamide plus finasteride vs low-dose flutamide monotherapy for treating biochemical relapse after the definitive management of prostate adenocarcinoma.

PATIENTS AND METHODS

Fifty-six men treated for biochemical relapse of prostate cancer were enrolled prospectively in a phase II trial at the Walter Reed Army Medical Center from 1997 to 2001. Thirty-six men were treated with flutamide (125 mg twice daily) and finasteride (5 mg twice daily), and 20 men received low-dose flutamide only after biochemical recurrence (prostate-specific antigen, PSA, level > or =0.4 ng/mL). Cox proportional hazards analyses were used to compare the risk of progression between the groups.

RESULTS

Patients on combined and monotherapy had a median follow-up of 54 and 43.5 months, respectively. Seven men (19%) in the combined arm remain in the study with no progression, while five (25%) on monotherapy continue and are progression-free. Men on combined therapy had a greater decrease in their PSA level (P = 0.002). Multivariate analysis showed that men on combined therapy had significantly less risk of progression than men on monotherapy (hazard ratio 0.21, 95% confidence interval 0.07-0.63, P = 0.005). There was no significant difference in the frequency of side-effects between the groups. Toxicities were reported to be mild.

CONCLUSIONS

Our analysis suggests the therapeutic value of low-dose flutamide alone or combined with finasteride as first-line agents in a possible graduated approach for treating PSA-only recurrent prostate cancer. Due to unwanted metabolic effects associated with traditional hormonal agents, phase III trials comparing both regimens with current therapies are warranted.

Does prostate cancer co-opt the developmental program?

The hypothesis that cancer is a caricature of normal development and tissue renewal was originally based on descriptive studies of normal tissues and cancers. The concepts that arose from these studies were that both normal tissues and tumors are sustained by a self-renewing population of stem cells that initially gives rise to undifferentiated and highly proliferative progeny. Eventually, derivatives of these proliferating cells become growth quiescent and express differentiation markers characteristic of the organs within which they reside. A major difference between normal tissues and tumors is the impairment of differentiation in tumors such that undifferentiated, mitotically active cells accumulate in tumors. An important feature of the model is the idea that the biology of the undifferentiated and proliferating cell populations in tumors is governed by the same pathways that regulate normal development and tissue renewal. At the time these ideas were formulated, we lacked sufficient understanding of the molecular and cellular basis of prostate development and cancer progression to evaluate the validity of these ideas for understanding prostate cancer. Research in recent years has validated the prediction that cells with stem cell-like properties are a critical source of new cells both during prostate development and during prostate cancer progression. It is also the case that many of the genes that regulate prostatic development re-appear during prostate cancer progression. A closer examination of the best understood of these developmental regulatory pathways, the androgen-signaling pathway, reveals important differences between normal development and tumors. This pathway is co-opted in prostate cancer by genetic and epigenetic changes that alter the molecular details of how signaling is initiated and alter the transcriptional outcome of signaling by silencing key targets of androgen signaling and fusing androgen-responsive promoters to new genes to create new targets for androgen signaling. Future research is needed to understand if other developmental regulatory pathways are altered during prostate progression in a manner analogous to the androgen signaling pathway.

The benefits of early androgen blockade

Altering the effects of testosterone on prostate cancer cells by blocking androgen production or action is a critical part of treating this malignancy. The appropriate timing of androgen blockade for advanced prostate cancer is controversial. Despite many phase-III studies, gaps in clinical information still remain, and some questions are still not conclusively answered. This review concentrates on high-level evidence to address common clinical situations in advanced and metastatic prostate cancer. Additionally, the side-effects of androgen blockade have become increasingly visible and relevant.