The utility of cardiopulmonary exercise testing (CPET) in predicting perioperative outcomes for patients undergoing complex rectal cancer surgery.

Abstract

Locally advanced rectal cancers may require beyond total mesorectal excision, including extensive procedures, such as total pelvic exenteration. These operations carry significant morbidity. Cardiopulmonary exercise testing is utilized to assess physiological fitness before major surgery. However, limited evidence exists regarding its predictive value in beyond total mesorectal excision. This study aimed to determine whether preoperative cardiopulmonary exercise testing parameters are associated with postoperative morbidity following beyond total mesorectal excision, with subgroup analysis of patients undergoing total pelvic exenteration. A retrospective cohort study was conducted at a tertiary center, including consecutive patients who underwent cardiopulmonary exercise testing prior to beyond total mesorectal excision between 2014 and 2021. Associations between anaerobic threshold (AT VO₂) and peak oxygen consumption (VO₂ peak) with major perioperative morbidity (Clavien-Dindo ≥3) were investigated. Receiver operating characteristic analysis identified optimal cutoff values, which were used to dichotomize patients into low- and high-risk groups. Groups were compared using χ² and Mann-Whitney U tests. A total of 116 patients were included, of whom 62 underwent total pelvic exenteration. In the overall beyond total mesorectal excision cohort, cardiopulmonary exercise testing parameters could not demonstrate any significant correlation with postoperative outcomes. However, in the total pelvic exenteration subgroup, both AT VO₂ (area under the curve 0.68; P = .035) and VO₂ peak (area under the curve 0.73; P = .013) were associated with significant morbidity. Receiver operating characteristic-derived thresholds (AT VO₂ <11.45 mL/kg/min; VO₂ peak <19.15 mL/kg/min) identified higher complication rates (30-31% vs 6-7%) and longer hospital stay. Cardiopulmonary exercise testing seems to present an exploratory association with perioperative morbidity in patients undergoing total pelvic exenteration but did not show any significant association across the broader beyond total mesorectal excision cohort. Incorporating cardiopulmonary exercise testing into preoperative assessment may support risk stratification and targeted optimization before complex rectal cancer surgery.