Post-operative radiochemotherapy for gastric cancer: adoption and adaptation

Intergroup study 0116 (INT-0116) showed an 11% absolute improvement in 3-year survival with post-operative radiochemotherapy for gastric cancer, but reported 33% severe acute GI toxicity using conventional simulation with large fields. We adapted the treatment using conformal radiotherapy techniques and assessed toxicity and outcome in 20 consecutive patients.

A conformal radiotherapy technique previously developed for gastric lymphoma was adapted to treat the target volume defined in INT-0116. The five-field plan used a large anterior field, plus asymmetrically matched upper AP:PA fields and lower lateral fields. Consecutive patients with ECOG PS 0-2 and stage IB-IV non-metastatic gastric cancer were treated with 5-FU (425 mg/m2 daily x 5 days) and leucovorin (20 mg/m2 daily x 5 days) for one cycle prior to and two cycles following concurrent radiation (45 Gy/25 fractions) with identical drug dosages on the first 4 and last 3 days of radiation. Acute toxicity was prospectively recorded weekly using RTOG and NCI common toxicity criteria. Patient charts were reviewed in November 2003 and late toxicity and outcome were recorded.

Nineteen of 20 patients completed radiotherapy and 14 completed all chemotherapy cycles. One patient died of neutropenic sepsis. Maximum acute toxicity [grade (number)] was: 5(1), 4(0), 3(4), 2(10), 1(4), 0(1). There were two grade 1 late toxicities. Two-year overall survival is 70% (95% confidence interval: 50-90).

Conformal radiotherapy may improve acute toxicity (25% grade 3 or greater toxicity as compared with 41% reported in INT-0116). Survival is comparable to that achieved in the INT-0116 treatment arm (approximately 60% at 2 years). INT-0116 results can be achieved outside a study setting; however, further efforts to improve treatment efficacy and minimize toxicity are warranted.