Diabetes mellitus affects response to neoadjuvant chemoradioterapy in the management of locally advanced rectal cancer

Purpose:Although diabetic patients with rectal cancer have poorer outcomes than their nondiabetic counterparts, only a few studies have looked at diabetics? response to neoadjuvant chemoradiotherapy as an explanation fort his disparity. This study compares the neoadjuvant chemoradiotherapy response in diabetic and nondiabetic patients with locally advanced rectal cancers.Methods:This is a single institution, retrospective review of locally advanced rectal cancer patients who received neoadjuvant chemoradiotherapy followed by curative resection from june 1993 to october 2009. Pretreatment TNM (tumor ? node ? metastasis) staging was determined using magnetic resonance imaging, endorectal ultrasound and computed tomography scan. Posttreatment staging was determined by pathological review.Results:141 patients were included to this study. 23 of these patients were diabetics and the remaining 118 were nondiabetics. When the pretreatment staging reviewed; in diabetic group, 6 (26.1 %) patints had stage 2, 17 (73.9 %) patients had stage 3 disease and in nondiabetic group, 19 (16.1 %) patients had stage 2, 99 (83.9 %) patients had stage 3 disease. All the patients, who were included to this study, completed the neoadjuvant chemoradiotherapy, that was planned at Dokuz Eylül colon and rectum cancer council. Nondiabetic patients had a higher rate of tumor downstaging although not statistically significant (diabetics; 52.2 % ? nondiabetics; 63.6 %, p=0.428). As an interesting finding; diabetic patients had a higher rate of nodal downstaging although not statistically significant (diabetics; 60.9 % ? nondiabetics; 52.5 %, p=0.614). While none of the diabetics patients achieved a pathologic complete response, 8 (% 6.8) of nondiabetics did. Nondiabetic patients had a higher rate of neoadjuvant chemoradiotherapy response according to Wheeler?s tumor regression grade, although not statistically significant (diabetics; 73.9 % ? nondiabetics; 79.7 %, p=0.736). Local progression rates were similar in both groups (diabetics: %4.3, nondiabetics: % 4.2).Conclusion:The size of our study was small, however; our results did not offer rational arguments of, neoadjuvant chemoradiotherapy in locally advanced rectal cancer is less effective in diabetic patients than in nondiabetics.Key words: rectal cancer ? chemotherapy ? radiotherapy ? diabetes