Molecular Genetic Changes Associated With Colorectal Carcinogenesis Are Not Prognostic for Tumor Regression Following Preoperative Chemoradiation of Rectal Carcinoma

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• 作者：N. Peter Zauber ; Steven P. Marotta ; Errol Berman ; Alison Grann ; Maithili Rao ; Naga Komati ; Kezia Ribiero ; D. Timothy Bishop
• 刊名：International Journal of Radiation Oncology*Biology*Physics
• 出版年：2009
• 出版时间：1 June 2009
• 年：2009
• 卷：74
• 期：2
• 页码：472-476
• 全文大小：95 K

文摘

Purpose

Preoperative chemotherapy and radiation has become the standard of care for many patients with rectal cancer. The therapy may have toxicity and delays definitive surgery. It would therefore be desirable to identify those cancers that will not regress with preoperative therapy. We assessed a series of rectal cancers for the molecular changes of loss of heterozygosity of the APC and DCC genes, K-ras mutations, and microsatellite instability, changes that have clearly been associated with rectal carcinogenesis.

Methods and Materials

Diagnostic colonoscopic biopsies from 53 patients who received preoperative chemotherapy and radiation were assayed using polymerase chain reaction techniques followed by single-stranded conformation polymorphism and DNA sequencing. Regression of the primary tumor was evaluated using the surgically removed specimen.

Results

Twenty-three lesions (45 % ) were found to have a high degree of regression. None of the molecular changes were useful as indicators of regression.

Conclusions

Recognized molecular changes critical for rectal carcinogenesis including APC and DCC loss of heterozygosity, K-ras mutations, and microsatellite instability are not useful as indicators of tumor regression following chemoradiation for rectal carcinoma.