Five fractions of radiation therapy followed by 4 cycles of FOLFOX chemotherapy as preoperative treatment for rectal cancer

Background Preoperative radiation therapy with 5-fluorouracil chemotherapy is a standard of care for cT3-4 rectal cancer. Studies incorporating additional cytotoxic agents demonstrate increased morbidity with little benefit. We evaluate a template that: (1) includes the benefits of preoperative radiation therapy on local response/control; (2) provides preoperative multidrug chemotherapy; and (3) avoids the morbidity of concurrent radiation therapy and multidrug chemotherapy. Methods and Materials Patients with cT3-4, any N, any M rectal cancer were eligible. Patients were confirmed to be candidates for pelvic surgery, provided response was sufficient. Preoperative treatment was 5 fractions radiation therapy (25 Gy to involved mesorectum, 20 Gy to elective nodes), followed by 4 cycles of FOLFOX [5-fluorouracil, oxaliplatin, leucovorin]. Extirpative surgery was performed 4 to 9 weeks after preoperative chemotherapy. Postoperative chemotherapy was at the discretion of the medical oncologist. The principal objectives were to achieve T stage downstaging (ypT < cT) and preoperative grade 3+ gastrointestinal morbidity equal to or better than that of historical controls. Results 76 evaluable cases included 7 cT4 and 69 cT3; 59 (78%) cN+, and 7 cM1. Grade 3 preoperative GI morbidity occurred in 7 cases (9%) (no grade 4 or 5). Sphincter-preserving surgery was performed on 57 (75%) patients. At surgery, 53 patients (70%) had ypT0-2 residual disease, including 21 (28%) ypT0 and 19 (25%) ypT0N0 (complete response); 24 (32%) were ypN+. At 30 months, local control for all evaluable cases and freedom from disease for M0 evaluable cases were, respectively, 95% (95% confidence interval [CI]: 89%-100%) and 87% (95% CI: 76%-98%). Cases were subanalyzed by whether disease met requirements for the recently activated PROSPECT trial for intermediate-risk rectal cancer. Thirty-eight patients met PROSPECT eligibility and achieved 16 ypT0 (42%), 15 ypT0N0 (39%), and 33 ypT0-2 (87%). Conclusion This regimen achieved response and morbidity rates that compare favorably with those of conventionally fractionated radiation therapy and concurrent chemotherapy.