Evaluating the effectiveness of androgen receptor-targeted therapy plus radiotherapy in patients with metastatic castration resistant prostate cancer.

This study evaluated the effectiveness of radiotherapy (RT) plus androgen receptor-targeted therapy (ARTT) on oligo-progressive sites for the treatment of patients with metastatic castration-resistant prostate cancer (mCRPC). The data showed that RT on oligo-progressive sites was safe and effective in prolonging treatment with ARTT in patients with mCRPC.

Oligometastatic PC is cancer that is no longer confined to the prostate gland. However, it has not yet become widespread to surrounding organs. It is usually treatable with curative therapy. This can include prostate surgery or radiation therapy (RT). One form of oligometastatic cancer is oligo-progressive castration-resistant prostate cancer (oligo-CRPC). Metastatic CRPC is an aggressive form of PC that has spread beyond the prostate gland and is no longer responsive to hormonal therapy such as androgen-deprivation therapy (ADT). ADT prevents cancer cell growth by reducing the production of androgens (male sex hormones such as testosterone) and is the standard of care for PC.

Another treatment option for patients with advanced PC includes ARTT. ARTT like abiraterone acetate (Zytiga) and enzalutamide (Xtandi) block the effect of male sex hormones (such as testosterone) to stop tumor growth. However, whether ARTT plus RT is effective for the treatment of patients with oligo-progressive mCRPC is still unknown.

This study involved 42 men with mCRPC. All patients received RT on oligo-progressive sites during ARTT. 28 patients received ARTT with abiraterone acetate. 14 patients received ARTT with enzalutamide. The average follow-up time was 28 months.

The average overall survival (OS) was 32.5 months. Overall, 71.6% of the patients were alive after 1 year and 64.1% of the patients were alive after 2 years. The average OS for patients who received ARTT with abiraterone acetate was 32.4 months and 18 months for patients who received ARTT with enzalutamide.

The average OS for patients that received RT 6 months within starting ARTT was 23.4 months and 45.5 months for patients that received RT 6 months after starting ARTT.

The average survival without progression or cancer worsening was 19.8 months. 67.2% of the patients were alive without progression or cancer worsening after 1 year and 47.4% after 2 years. The average survival without progression or cancer worsening for patients who received ARTT with abiraterone acetate was 26 months and 19.8 months for patients who received ARTT with enzalutamide.

The average survival without progression or cancer worsening for patients that received RT 6 months within starting ARTT was 9.2 months and 30 months for patients that received RT 6 months after ARTT.

This study concluded that RT on oligo-progressive sites was safe and effective in prolonging treatment with ARTT in patients with mCRPC.

This study looked back in time at medical records. The sample size was very small. There was no control group of patients for comparison who did not receive RT. This study was only conducted at a single institution in Italy.