Is BMI a Factor in Compliance to Adjuvant Chemotherapy for Locally Advanced Rectal Cancer?

Compliance to adjuvant chemotherapy (AC) for patients undergoing rectal surgery ranges from 43% to 73.6%. Reasons reported for not initiating or completing AC include onset of postoperative complications, drug toxicity, disease progression and/or patient preferences. Little is known regarding the impact of obesity on the compliance to AC in this setting. This multicenter, retrospective study analyzed compliance to AC and treatment-related morbidity in 511 patients having undergone surgery with curative intent for rectal cancer in six Italian colorectal centers between January 2013 and December 2017. 70 patients were obese (BMI 30 kg/m2). The proportion of open procedures (22.9% vs. 13.4%) and conversions (14.3% vs. 4.8%) was greater in obese compared to non-obese patients (p 0.001). Median hospital stay was one day longer for obese patients (9 days vs. 10 days, p=0.038) while there was no statistically significant difference in the complication rate, whether overall (58.6% in obese vs. 52.3% in non-obese) or with a Clavien-Dindo score 3 (17.1% vs 10.9%). AC was offered to 49/70 (70%) patients in the obese group and 306/441 (69.4%) in the non-obese group (p=0.43). There was no statistically significant difference in AC compliance: 18.4% and 22.9% did not start AC, while 36.7% and 34.6%, started AC but did not complete the scheduled treatment (p=0.79) in the obese and non-obese group, respectively. Overall, 55% of patients who started AC successfully completed their adjuvant treatment. Obesity did not impact compliance to AC for locally advanced rectal cancer: compliance was poor in obese and non-obese patients with no statistically significant difference between the two groups. Major complication rate was not statistically significantly affected by increased BMI.