Effect of Neoadjuvant Systemic Chemotherapy With or Without Chemoradiation on Bowel Function in Rectal Cancer Patients Treated With Total Mesorectal Excision.

<bold>Background: </bold>Neoadjuvant chemoradiation (CRT) impairs bowel function in patients with rectal cancer treated with total mesorectal excision (TME). The impact of other forms of neoadjuvant therapy such as neoadjuvant chemotherapy alone (NC) and induction chemotherapy followed by CRT (total neoadjuvant therapy or TNT) on postoperative bowel function has not been investigated.<bold>Methods: </bold>We conducted a retrospective review of 176 rectal cancer patients treated between November 1, 2011, and August 31, 2017. All patients completed the MSKCC Bowel Function Instrument (BFI), a validated bowel function questionnaire, at least 6 months after TME and/or ileostomy reversal. Differences in BFI scores were compared across four groups (surgery alone, CRT, NC, and TNT) and also according to exposure to neoadjuvant RT and neoadjuvant chemotherapy. A multivariable linear regression model was used to evaluate the independent relationship between exposure to neoadjuvant RT or chemotherapy and BFI.<bold>Results: </bold>BFI total scores were significantly different between the four groups (p = 0.008). Exposure to RT correlated with worse BFI total scores (p = 0.002), and no differences were found in BFI total score after exposure to neoadjuvant chemotherapy (p = 0.92). In a linear regression model, only exposure to RT (β = - 5.1; 95% CI - 8.9 to - 1.3; p = 0.008) and tumor distance from the anal verge (β = 1.23; 95% CI 0.48 to 1.97; p = 0.001) were significantly correlated with BFI total score.<bold>Conclusion: </bold>NC, whether administered alone or added to CRT, does not seem to impair bowel function. These data should be used to counsel rectal cancer patients when discussing neoadjuvant therapy options. [ABSTRACT FROM AUTHOR]