Evaluating the long-term outcomes of radiotherapy added to standard therapy for men with metastatic prostate cancer.

The study investigated whether radiotherapy (RT) addedd to standard of care (SOC) treatment would be beneficial for men with metastatic (spread) prostate cancer (mPC). The study showed that adding RT to SOC improved the survival of men with low burden (defined as fewer than 10 lesions, no greater than 3cm in diameter) mPC.

Prostate cancer is the most common cancer in men and RT is a widely used radical treatment for non-metastatic prostate cancer. In men with newly diagnosed PC, it has been shown that RT improves the outcomes of patients with a low metastatic burden (fewer than 10 metastatic lesions with a lower than 3cm diameter). However, it is not known whether RT added to SOC treatment would also benefit patients with higher metastatic burden in the long term. 

This study involved 2061 men diagnosed with mPC from the UK and Switzerland. Patients were randomly assigned to 1 of 2 groups. Group 1 included 1029 men that were treated with SOC and group 2 included 1032 men that received SOC and RT. SOC included hormonal therapy with or without docetaxel (Taxotere) chemotherapy. Patients were followed up for an average of 61.3 months. 

Overall, patients in group 2 with a low metastatic burden had a 36% higher chance of a longer survival compared to group 1. The overall survival was 63.6 months for patients in group 1 with a low metastatic burden compared to 85.5 months for patients in group 2. 

In patients with a high metastatic burden, RT added to SOC did not improve survival compared to SOC alone. Patients with a high metastatic burden in group 1 had an overall survival of 41.2 months compared to 38.8 months for patients in group 2. 

There was no significant difference between groups in terms of side effects and quality of life. 

The study concluded that adding RT to SOC improved the survival of patients with low-burden metastatic prostate cancer, but not in those with a high metastatic burden. The authors suggested that RT should be added to SOC in patients with newly diagnosed low burden mPC.

As this study was conducted between 2013 and 2016 newer imaging techniques like PSMA (Prostate-specific membrane antigen), PET-CT and MRI were unavailable. The SOC tratment of mPC has also changed.