Phase II trial of concomitant neoadjuvant chemotherapy with oxaliplatin and capecitabine and intensity-modulated radiotherapy (IMRT) in rectal cancer.

Introduction And Purpose: The purposes of this study are to evaluate the activity and safety of preoperative intensity-modulated radiotherapy and concurrent capecitabine and oxaliplatin (Xelox), the accuracy of preoperative magnetic resonance (MRI) for predicting pathologic results, and the correlation between carcinoembryonic antigen (CEA) and the existence of a pathologic complete response (pCR).

Patients And Methods: Twenty-seven patients (pt) with T3/T4N0/N+ rectal cancer were included. Capecitabine was administered at 825 t.i.d. mg/m2 the days of the radiotherapy (RT), and oxaliplatin was administered weekly at 50 mg/m2. RT was planned to 50.4 Gy. Surgery was scheduled 6 to 8 weeks after completion of Xelox RT. Before the intervention, a pelvic MRI was performed and a CEA level was determined.

Results: After Xelox RT, 7 pt had pCR (26%), 2 pt progression disease, and 18 pt tumor downstaging. Presurgical MRI did not predict the pathological result in 21 pt. Main side effects were diarrhea grade (G) 3 in four pt, hand and foot G1 five Pt and G2 four pt. Paresthesias G1 ten pt, G2 seven pt, and leukopenia six pt G1. Median RT dose was 49.7 Gy (47.5-50.4 Gy). At a mean follow-up of 22.5 months, four pt presented metastatis. Mean pretreatment CEA was 6.8 ng/mL (2.1-17.0). A difference statistically significant when compared pretreatment CEA with presurgical CEA (p < 0.001) was detected. We found a nadir of <5 ng/mL as significantly associated with pCR (p = 0.036).

Conclusion: Preoperative chemoradiotherapy with oxaliplatin and capecitabine is safe and well tolerated, and offers an interesting ratio of pCR and of tumor downstaging. Presurgical CEA level should be studied as predictors of pCR.