Androgen Deprivation Therapy and Overall Survival for Gleason 8 Versus Gleason 9-10 Prostate Cancer.

BACKGROUND

While the addition of androgen deprivation therapy (ADT) to external beam radiation therapy (EBRT) is known to improve overall survival (OS) in Gleason 8-10 (Grade Group 4-5) prostate cancer (PCa), it has been hypothesized that Gleason 9-10 disease, which is less differentiated than Gleason 8 disease, may be less sensitive to ADT.

OBJECTIVE

To examine the association between ADT and OS for Gleason 8 versus Gleason 9-10 PCa.

DESIGN, SETTING, AND PARTICIPANTS: A retrospective cohort study of 20 139 men from the National Cancer Database with localized or locally advanced, Gleason 8-10 PCa who received EBRT. Data were collected from 2004 to 2012.

INTERVENTION

ADT.

OUTCOME MEASUREMENTS AND STATISTICAL ANALYSIS

Cox proportional hazards regression was used to examine the association between ADT and OS.

RESULTS AND LIMITATIONS

Overall, 9509 (78%) of the 12 160 men with Gleason 8 disease and 6908 (87%) of the 7979 men with Gleason 9-10 disease received ADT. On multivariable analysis, ADT was associated with a significant improvement in OS for Gleason 8 patients (adjusted hazard ratio 0.78, 95% confidence interval 0.70-0.87, p<0.001) but not for Gleason 9-10 patients (adjusted hazard ratio 0.96, 95% confidence interval 0.84-1.11, p=0.6), with a significant interaction (p=0.020). A higher Gleason score (8, 9, 10) correlated with an increased adjusted hazard ratio for the association between ADT and OS (p=0.042). Our study may be limited by the relatively short follow-up (median of 4.0 yr).

CONCLUSIONS

In contrast to the significant survival advantage of ADT for Gleason 8 disease, our results suggest that Gleason 9-10 disease derives less survival benefit from ADT and that a higher Gleason score predicts lesser benefit. Consideration should be given to treatment intensification for Gleason 9-10 patients through enrollment in clinical trials or potentially adding novel antiandrogens or docetaxel, which have shown efficacy in both castration-resistant and castration-sensitive settings.

PATIENT SUMMARY

In this study, we examined the effect of androgen deprivation therapy (ADT) for Gleason 8 (Grade Group 4) versus Gleason 9-10 (Grade Group 5) prostate cancer. We found that Gleason 9-10 disease may derive a smaller survival benefit from ADT than Gleason 8 disease.