MedWire News: Among men with pathologic T3N0M0 prostate cancer, adjuvant radiotherapy after radical prostatectomy significantly reduces the metastasis risk and improves survival, US and Canadian study findings indicate.

A significant proportion of men undergoing radical prostatectomy for prostate cancer have positive surgical margins and/or seminal vesicle invasion, placing them at increased risk for cancer recurrence. The use of adjuvant radiotherapy to treat these high-risk patients remains a matter of debate.

To examine the long-term outcomes of patients treated with adjuvant radiotherapy, Ian Thompson, from the University of Texas Health Science Center at San Antonio, and colleagues randomly assigned 425 men with pathologic T3N0M0 prostate cancer after radical prostatectomy to receive 60–64 Gy adjuvant radiotherapy (n=211) or observation (n=214).

The median ages of patients in the treatment and observation groups were 65 years and 64 years, respectively, and the respective follow-up periods were 12.5 years and 12.5 years. Ultimately, 70 men from the observation group received radiotherapy.

By the end of the analysis, 54% of the observation group had died or developed metastatic disease, at a median metastasis-free survival 12.9 years, compared with 43% of those in the adjuvant radiotherapy group, at a median metastasis-free survival of 17.7 years.

The hazard ratio for metastasis-free survival with adjuvant radiotherapy was 0.71, and the number needed to treat to prevent one case was 12.2, the team notes in The Journal of Urology.

Fifty-two per cent of the observation group and 41% of the radiotherapy group died, and they had median overall survival rates of 13.3 years and 15.2 years, respectively. The hazard ratio for overall survival with adjuvant radiotherapy was 0.72, and the number needed to treat to prevent one death was 9.1.

The researchers conclude: “Adjuvant radiotherapy within 18 weeks after radical prostatectomy in a man with pT3N0M0 prostate cancer significantly reduces the risk for prostate-specific antigen recurrence, metastasis, and the need for hormonal therapy, and significantly increases survival.”