Potential predictor of treatment outcomes for metastatic castration-resistant prostate cancer

This study analyzed predictors of treatment outcomes for metastatic castration-resistant prostate cancer (mCRPC). Researchers concluded that testosterone levels before treatment can help predict overall survival in men with mCRPC. 

Hormone therapy is the standard of care for advanced prostate cancer, including prostate cancer that has spread to distant organs (metastatic). Hormone therapy targets male hormones (such as testosterone) and reduces their effect on cancer cell growth. Reducing testosterone to very low (castration) levels is often the treatment goal of hormone therapy.

Over time, many men stop responding to standard hormone therapy, resulting in the cancer progressing and continuing to spread. This is known as metastatic castration-resistant prostate cancer (mCRPC). Advances in treatment options for mCRPC have significantly improved survival. These include newly developed, secondary hormone therapies (such as abiraterone [Zytiga] and enzalutamide [Xtandi]), and chemotherapies (such as docetaxel [Taxotere] and cabazitaxel [Jevtana]).

However, not all men respond equally to these secondary treatment options. Predicting treatment success has become increasingly important to help optimize the right choice of therapy for each patient.

This study analyzed testosterone levels and other potential predictors of treatment success in 101 men with mCRPC. Blood tests were performed in all men within 1 month before starting chemotherapy for mCRPC. Men were divided according to their testosterone levels being higher (52 men) or lower (49 men) than the average (11.5 ng/dL). 40.6% of men received secondary hormone therapy after failure of first-line chemotherapy.

Average overall survival (time from treatment until death from any cause) was 32.7 months among men with higher testosterone levels. This was significantly longer than 22.4 months among men with lower testosterone levels before treatment.

The response to first-line chemotherapy (based on blood tests) was similar in men with higher (57.7%) and lower (61.2%) testosterone levels. However, 55.6% of men with higher testosterone levels undergoing secondary hormone therapy responded to treatment (based on blood tests). This was significantly greater compared to only 21.7% of men with lower testosterone levels.

The presence of anemia (low red blood cell count) also reduced overall survival (about 2.4-fold). Having both anemia and lower testosterone levels was associated with the shortest overall survival (average 17.9 month) compared to having one (average 22.4 months) or none of them (average 38.1 months).

Researchers concluded that testosterone levels before treatment can help predict overall survival in men with mCRPC undergoing chemotherapy. Testosterone levels may be useful for men considering secondary hormone therapy after chemotherapy.