Background

The mesorectal fat area (MFA) at the tip of the ischial spines on magnetic resonance imaging has been used to characterize mesorectal morphology. Recent studies reported that a larger MFA correlated with difficulties in rectal cancer surgery. However, the relationship between MFA and rectal cancer prognosis remains unclear. This study evaluated the impact of MFA on recurrence following robotic total mesorectal excision (TME) for rectal cancer.

Methods

Patients who underwent robotic TME for lower rectal cancer from December 2011 to December 2016 were enrolled. Cox regression analysis was performed to determine variables associated with relapse-free survival (RFS). Patients were divided into groups based on MFA, and RFS was compared.

Results

Of 230 patients, 173 (75.3%) were male. The median age was 63 years, and median MFA was 19.7 cm². In multivariate analysis, smaller MFA (hazard ratio [HR], 0.93; 95% confidence interval [CI], 0.88–0.97; p < 0.01), p/yp stage II (HR, 3.81; 95% CI, 1.40–10.35; p < 0.01), and p/yp stage III (HR, 5.35; 95% CI, 1.88–15.27; p < 0.01) were independently associated with worse RFS. Sex, body mass index, and visceral fat area were not correlated with RFS. In the median follow-up period of 60.8 months, patients with MFA < 19.7 cm² had a significantly lower 5-year RFS rate (72.7%) than those with MFA ≥ 19.7 cm² (85.0%).

Conclusions

Smaller MFA was associated with worse RFS in patients undergoing robotic TME for lower rectal cancer. MFA is considered to be a prognostic factor in rectal cancer.