Second-line treatments for metastatic castration-resistant prostate cancer

This study aimed to investigate treatments given after chemotherapy and hormonal therapy for metastatic prostate cancer, resistant to castration. This study found some benefit in abiraterone (Zytiga) or enzalutamide (Xtandi) but not in using docetaxel (Taxotere) again.

Androgen deprivation therapy (ADT) is a treatment used for men with prostate cancer that has spread (or metastasized). ADT lowers the level of male hormones like testosterone active in cancer growth. ADT can be used with a chemotherapy called docetaxel. This treatment is the gold standard for patients whose hormone levels have not been targeted by treatment previously, also called castration-naive metastatic prostate cancer (mCNPC).

Eventually, some men become resistant to these therapies. This is known as castration-resistant metastatic prostate cancer (mCRPC). Some options for these patients include abiraterone or enzalutamide, which are hormonal therapies or using docetaxel again. It is not clear which therapy is most effective. 

This study aimed to compare different regimes for patients with mCRPC.  In this study, 245 men received at least one anticancer treatment for mCRPC: 134 patients received ADT alone and 111 received ADT plus docetaxel. Patients were followed for an average of 8.4 years. 

Patients who received docetaxol again had limited benefit (14% of patients had a 50% drop in prostate specific antigen, or PSA, a protein present in prostate cancer). In men treated with ADT plus docetaxel, abiraterone or enzalutamide led to PSA drops of greater than 50% in 53%. 

This study found some benefit for mCRCP patients using abiraterone or enzalutamide but not in using docetaxel again.

It was difficult to draw conclusions between the two groups in this study as the treatment protocols they had used differed. The number of patients using the hormone treatment were small. 

This study is of limited use in deciding on treatment plans.