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

Background 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. Methods Between 1993 and 2000, 102 patients with prostate cancer were treated with a combination of (a) IORT of the prostate (25 or 30 Gy per fraction); (b) external beam radiotherapy of the prostate (30 Gy in 10 fractions), starting approximately 1 week 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. Results 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). Conclusions 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.