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Predictive Factors of Pathologic Complete Response After Neoadjuvant Chemoradiation for Rectal Cancer

Kalady, Matthew F. MD*†; de Campos-Lobato, Luiz Felipe MD*; Stocchi, Luca MD*; Geisler, Daniel P. MD*; Dietz, David MD*; Lavery, Ian C. MD*; Fazio, Victor W. MD*

doi: 10.1097/SLA.0b013e3181b91e63
Original Articles

Objective: This study evaluates factors associated with a pathologic complete response (pCR) after neoadjuvant chemoradiation for rectal cancer.

Summary Background Data: Approximately 20% of rectal cancer patients undergoing neoadjuvant chemoradiation achieve pCR, which has been associated with decreased local recurrence and improved recurrence-free survival. Means of predicting pCR remain incompletely defined.

Methods: A total of 306 consecutive patients with stage II or stage III rectal cancer who underwent neoadjuvant chemoradiation then surgery between 1997 and 2007 were identified from a single-institution. Sixty-four patients with concurrent inflammatory bowel disease, hereditary colorectal cancer, other malignancy, urgent surgery, incomplete chemoradiation, or insufficient data were excluded. All patients received neoadjuvant 5-FU-based chemotherapy and external beam radiation. Histologic response was categorized as pCR or not-pCR, which defined the 2 study cohorts. Variables were analyzed by univariate and multivariate analysis with pCR as the dependent variable. Fisher exact test, χ2, Wilcoxon rank-sum, and logistic regression were used for analysis. P < 0.05 was considered statistically significant.

Results: Of the total patients, 242 were studied, including 58 (24%) that achieved pCR. The 2 groups were statistically similar in terms of age, gender, body mass index, tumor differentiation, radiation dose, and pretreatment stage. On multivariate analysis, an interval ≥8 weeks between treatment completion and surgical resection was significantly associated with a higher rate of pCR, which correlated with decreased local recurrence and improved overall survival.

Conclusion: Despite traditional beliefs that certain patient and tumor factors influence pCR, an extended interval between completion of neoadjuvant therapy and surgery was the single most important determinant in achieving a pCR.

This study evaluated factors associated with a pathologic complete response after neoadjuvant chemoradiation for rectal cancer. Univariate and multivariate analysis of 242 patients revealed that an interval ≥8 weeks between completion of neoadjuvant therapy and surgery was a significant determinant in achieving a pathologic complete response.

From the *Department of Colorectal Surgery, Digestive Disease Institute, and †Department of Cancer Biology, Cleveland Clinic, Cleveland, OH.

Presented at the American Surgical Association annual meeting in Indian Wells, CA; April 24th, 2009.

Reprints: Matthew F. Kalady, MD, 9500 Euclid Avenue, A30, Cleveland, OH 44195. E-mail: kaladym@ccf.org.

© 2009 Lippincott Williams & Wilkins, Inc.