Locally advanced prostate cancer treated with concomitant radiation and 5-fluorouracil: Southwest Oncology Group Study 9024.

Abstract

Radiation is considered the standard treatment for locally advanced (T3 and T4) prostate cancer but cure with radiation alone is infrequent. Studies have shown that adding androgen ablation improves the results but there is still much room for improvement. We performed a phase II multi-institutional study to explore the feasibility of concomitant chemoradiotherapy.
Eligible patients had prostate cancer with clinical evidence of invasion through the prostatic capsule or into the seminal vesicles without evidence of nodal or distant metastasis. Prior prostatectomy was not allowed and patients could not be candidates for surgical resection due to medical reasons or refusal of surgery. Radiation consisted of 7,020 cGy in 39 fractions. Continuous infusion 5-fluorouracil at a dose of 200 mg/m2 daily was started on day 1 and continued 7 days weekly until the last day of radiation.
All 30 eligible patients were evaluated for toxicity. Diarrhea was the most common toxicity with grade 3 and 4 diarrhea in 2 and 1 patients, respectively. The only other grade 4 toxicity was hemorrhagic cystitis in 1 patient. There was 1 incident each of grade 3 stomatitis, congestive heart failure, edema, proctitis and hematuria. No patient with grade 3 or 4 toxicity required treatment delay. Ten patients (33%) achieved a negative biopsy and 13 (43%) achieved prostate specific antigen less than 1.0 ng/ml. Six patients (20%) achieved a complete response, defined as negative biopsy and prostate specific antigen less than 1.0 (95% CI 8 to 39). Patients without any biopsies or without prostate specific antigen followup were assumed to be nonresponders.
Toxicity was acceptable. The modest response rate indicates that better chemotherapy that improves local and systemic failure is necessary to improve the results. This study confirms the feasibility of a combined chemoradiotherapy approach.