Adjuvant radiotherapy for pathologic stage T3/4 adenocarcinoma of the prostate: ten-year update

To determine the role of adjuvant postoperative radiotherapy (RT) following radical prostatectomy (RP) in a group of patients with pathologic Stage T3/4 adenocarcinoma of the prostate followed for a median of 10 years after treatment.

Between 1970 and 1983, 159 patients underwent RP for newly diagnosed adenocarcinoma of the prostate and were found to have pathologic Stage T3/4. Forty-six received adjuvant RT and 113 did not. Radiotherapy usually consisted of 45-50 Gy to the whole pelvis followed by a boost to the prostate bed of 10-15 Gy, to a total dose of 55-65 Gy. Patients were analyzed with respect to survival, disease-free survival, local control, and freedom from distant metastases. A rising prostate-specific antigen in the absence of other evidence of relapse was scored as a separate category of recurrence.

Both groups of patients have been followed for a median of 10 years. The actuarial survival at 10 and 15 years was 62% and 62% for the RT group compared to 52% and 37%, respectively, for the RP group (p = 0.18). The disease-free survival for the Rt group was 55% and 48% at 10 and 15 years, respectively, compared to 37% and 33% for the RP group (p = 0.16). Similarly, there was no difference in the rate of distant metastases between the two groups. In contrast, the local relapse rate was significantly reduced by the addition of postoperative radiotherapy. The actuarial local control rate at 10 and 15 years was 92% and 82%, respectively, for the RT group vs 60% and 53% for the RP group (p = 0.002).

While postoperative pelvic RT significantly improves local control compared to RP alone for pathologic Stage T3/4 prostate cancer, it has no impact on distant metastases and consequently does not improve survival. These data are consistent with the conclusion that many patients with pathologic Stage T3/4 prostate cancer have occult metastases at presentation and will not be cured by local therapies alone. The optimal treatment for this patient population remains to be established.