Evaluating the effectiveness and safety outcomes of second radiation therapy in patients with locally recurrent prostate cancer.

This study investigated the effectiveness and safety of re-irradiation for the treatment of patients with locally recurrent prostate cancer. The data showed that the use of re-irradiation in these patients was associated with good outcomes and low toxicity.

Radiotherapy (RT) is an effective treatment for localized prostate cancer (PCa). There are many different types of RT used to treat PCa. Brachytherapy (BT) is a type of RT that uses a radioactive implant device into the cancer tissue. It slowly releases radiation and kills cancer cells over time. Stereotactic body radiation therapy (SBRT) is a special type of RT that uses a high dose of radiation and targets a specific area from different angles. This technique precisely kills the cancer cells while reducing the damage to healthy tissues. External beam radiation therapy (EBRT) is another type of RT which involves directing high-energy rays from outside the body at the tumor site to kill cancer cells.

Despite these accurate RT treatments, nearly one-third of the patients experience biochemical recurrence (BCR). If after treatment, the prostate-specific antigen (PSA: a protein made by cells of the prostate gland that increases in PCa) levels increased by 0.2 ng/ml from the lowest value it was considered as evidence of BCR. Re-irradiation (Re-I) involves repeat administration of RT to a previously exposed region of the body. The effectiveness and safety of Re-I after a recurrence of previously irradiated PCa are still not clear.

This study analyzed the results of 39 studies that involved 1967 patients with PCa. Patients in these studies underwent Re-I after a recurrence of PCa. BT was used in 28 studies and included 1484 patients. SBRT was used in 11 studies and included 483 patients. The average follow-up time was 47.5 months for BT and 25.4 months for SBRT.

For patients treated with a low dose rate (LDR) of BT, 71% were alive without BCR after 2 years and 52.5% were alive without BCR after 5 years. For patients treated with a high dose rate (HDR) of BT, 74% were alive without BCR after 2 years and 51% were alive without BCR after 5 years. For patients treated with SBRT, 54.9% were alive without BCR after 2 years.

7.4% of the patients treated with LDR-BT, 2% of the patients treated with HDR-BT, and 1.8% of the patients treated with SBRT experienced immediate genital and urinary side-effects. 13.6% of the patients treated with LDR-BT, 7.9% of the patients treated with HDR-BT, and 2.7% of the patients treated with SBRT experienced late genital and urinary side-effects.

6.5% of the patients treated with LDR-BT, 0% of the patients treated with HDR-BT, and 0.5% of the patients treated with SBRT experienced immediate gastrointestinal side-effects. 6.4% of the patients treated with LDR-BT, 0.1% of the patients treated with HDR-BT, and 0.2% of the patients treated with SBRT experienced late gastrointestinal side-effects.

This study concluded that salvage reirradiation using HDR-BT or SBRT provided similar biochemical control with low levels of late toxicity in patients with recurrent PCa.

Most studies analyzed had a small number of participants. Future randomized controlled studies directly comparing BT and SBRT and evaluating patient-reported outcomes and cancer control outcomes are needed.