The external radiotherapy with three-dimensional conformal boost after the neoadjuvant androgen suppression for patients with locally advanced prostatic carcinoma.

PURPOSE

To analyze the results in patients with locally advanced prostatic carcinoma treated by hormonal therapy followed by external radiotherapy using three-dimensional conformal radiation therapy (3D-CRT) boost.

METHODS AND MATERIALS

From 1987 to 1995, 46 patients with histologically proven locally advanced adenocarcinoma of the prostate were treated with 3D-CRT at the National Cancer Center Hospital, Tokyo. The neoadjuvant androgen suppression started immediately after the diagnosis followed by radical radiation therapy, according to the prospective protocol. They were treated with photons of 6-14 MV for wide fields and the boost, of which a multiple-leaf collimator of 2-cm width was available. The boosted dose was delivered with the rotational 3D-CRT, after the delivery of whole pelvis 4-field box from a dose of 40-46 Gy up to 66 Gy. The planning target volume encompassed 1 cm outside throughout the clinical target volume, and the prostate and the seminal vesicles were included in the boost field.

RESULTS

The 3D-CRT boost treatment completed as planned in all 46 patients. The median follow-up for all the patients was 60 months (range, 5-120 months). Nineteen of 46 patients died. Of these, 11 patients died of the intercurrent diseases. For all 46 patients, the 5- and 8-year overall survival rates were 61.3% and 42.4%, and the 5- and 8-year cause-specific survival rates were 82.4% and 64.4%, respectively. The prostate-specific antigen (PSA) relapse-free rates for 5- and 8-year were 64.6% and 52.5%, and the clinical local control rates for 5 and 8 years were 75.3% and 69.9%, respectively. The preradiation therapy PSA and the Gleason score were the factors that significantly associated with PSA relapse-free survival. Sixteen of 46 patients (35%) showed at least one form of late toxicities. Of these, 3 patients experienced late complications of Grade 3 (urinary, 2, proctitis, 1).

CONCLUSION

The treatment results were fairly good and were consistent with those in Western countries, indicating that this study shows the preliminary status of 3D-CRT for the locally advanced prostate cancer in Japan. Preradiation therapy PSA seems to be a significant predictor of PSA relapse-free survival (p = 0.004) after neoadjuvant androgen suppression.