Favorable outcome of intraoperative radiotherapy to the primary site in patients with metastatic prostate cancer.

Abstract

The aim of this study was to determine whether local radiotherapy to the prostate by intraoperative radiotherapy (IORT) increases the overall and cancer-specific survival rates of patients with metastatic prostate cancer. Between 1993 and 2000, 102 patients with prostate cancer were treated with a combination of (a) IORT of the prostate (25 or 30Gy per fraction); (b) external beam radiotherapy of the prostate (30Gy in 10 fractions), starting approximately 1week post-operatively; and (c) endocrine treatment. Of these, 16 patients had stage D1 disease (D1 IORT group), 32 had stage D2 disease without visceral metastasis (D2 IORT group), and 38 had stage D2 disease without visceral metastasis and did not receive local therapy (D2 control group). Overall and cancer-specific survival rates were compared. The 5- and 10-year cancer-specific survival rates were 75.9 and 52.7%, respectively, in the (D1+D2) IORT group and 45.8 and 33.5%, respectively, in the D2 control group, with cancer-specific survival being significantly longer in the D2 IORT than in the D2 control group (P=0.030). Univariate and multivariate reduced-rank regression analyses showed that extent of skeletal disease Grade 4 and non-regional lymph node metastasis were significantly prognostic of poorer cancer-specific survival (P<0.001 each). Local radiotherapy to the prostate by IORT in patients with metastatic prostate cancer may contribute to better survival, especially in patients without extent of skeletal disease Grade 4 or non-regional lymph node metastasis.