Abdominal adipose tissue quantification and distribution with CT: prognostic value for surgical and oncological outcome in patients with rectal cancer

Objectives: Obesity is a known factor of poor surgical and oncological outcomes in patients who undergo surgery for colorectal cancer. There are physiological differences between abdominal visceral and subcutaneous adipose tissue. Evaluation of its quantity and distribution is possible with routine clinical imaging techniques, such as computed tomography. The goal of this study was to explore the associations and find correlations of fat measurements and distribution with surgical morbidity, long-term mortality and disease progression in patients who underwent surgery for rectal cancer.

Methods: Patients who underwent rectal cancer resection between 2006 and 2016 were included in this retrospective study. Computed tomography fat area measurements were assessed on preoperative computed tomography scans and were compared with postoperative outcomes (local and general complications), long-term survival and oncological response.

Results: Of 202 patients included, 50 (25%) died with a median survival time of 34 months, and 152 (75%) were still alive at the end of the study. Death and disease progression were significantly associated with a high intermuscular/subcutaneous fat ratio at the L4-L5 level, with a cut-off established at 0.12 (p < 0.05). Patients with a low (< 1.15) subcutaneous/visceral fat ratio at the L2-L3 level experienced significantly more local complications (p < 0.05).

Conclusions: This study suggests that patients with a low subcutaneous fat area/visceral fat area ratio had more local postoperative complications and that a high intermuscular fat area/subcutaneous fat area ratio was associated with worse survival outcomes, as well as a high postoperative complication rate.

Key points: • A low subcutaneous/visceral fat ratio seems to be associated with more local postsurgery complications in patients with rectal cancer, while a high intermuscular/subcutaneous fat ratio seems to be associated with worse survival and oncological outcomes. • A high intermuscular/subcutaneous fat ratio seems to be associated with worse survival outcomes or progressing disease, as well as a higher postoperative complication rate. • Computed tomography abdominal fat area measurements are correlated with one another on multiple anatomical levels.