At present, acceptable postoperative therapy for patients with stage II or III rectal cancer not enrolled in clinical trials includes continuous-infusion 5-FU during 45 Gy to 55 Gy pelvic radiation and four cycles of adjuvant maintenance chemotherapy with bolus 5-FU with or without modulation with LV.
An analysis of patients treated with postoperative chemotherapy and radiation therapy suggests that these patients may have more chronic bowel dysfunction compared with those who undergo surgical resection alone. Improved radiation planning and techniques can be used to minimize treatment-related complications. These techniques include the use of multiple pelvic fields, prone positioning, customized bowel immobilization molds (belly boards), bladder distention, visualization of the small bowel through oral contrast, and the incorporation of three-dimensional or comparative treatment planning.[21,22]
The Role of Oxaliplatin for Localized Disease
Based on the results of several studies, oxaliplatin does not appear to add any benefit in terms of primary tumor response, but it has been associated with increased acute treatment-related toxicity.
Oxaliplatin has significant activity when combined with 5-FU-LV in patients with metastatic colorectal cancer. In the randomized Multicenter International Study of Oxaliplatin/5-Fluorouracil/Leucovorin in the Adjuvant Treatment of Colon Cancer (MOSAIC) study, the toxic effects and efficacy of FOLFOX4 (a 2-hour infusion of 200 mg/m2 LV, followed by a bolus of 400 mg/m2 5-FU, and then a 22-hour infusion of 600 mg/m2 5-FU on 2 consecutive days every 14 days for 12 cycles, plus a 2-hour infusion of 85 mg/m2 oxaliplatin on day 1, given simultaneously with the LV) were compared with the same 5-FU-leucovorin regimen without oxaliplatin when administered for 6 months. Each arm of the trial included 1,123 patients.
Preliminary results of the study, with 37 months of follow-up, demonstrated a significant improvement in DFS at 3 years (77.8% vs. 72.9%; P = .01) in favor of FOLFOX4. When initially reported, there was no difference in OS.[Level of evidence: 1iiDii] Further follow-up at 6 years demonstrated that the OS for all patients (both stage II and stage III) entered into the study was not significantly different (OS = 78.5% vs. 76.0%; HR, 0.84; 95% CI, 0.71–1.00). On subset analysis, the 6-year OS in patients with stage III colon cancer was 72.9% in the patients receiving FOLFOX and 68.9% in the patients receiving 5-FU/LV (HR, 0.80; 95% CI, 0.65–0.97, P = .023).[Level of evidence: 1iiA] Patients treated with FOLFOX4 experienced more frequent toxic effects, consisting mainly of neutropenia (41% >grade 3) and reversible peripheral sensory neuropathy (12.4% >grade 3). These results are still preliminary, and additional information with regard to OS is anticipated. Nevertheless, these data suggest that FOLFOX4 may be a therapeutic option for patients with resected stage III colon cancer.