Preoperative psoas muscle index a modern prognostic factor in the follow-up of patients with rectal cancer who underwent surgery

Background: The incidence of rectum cancer is rising worldwide. New prognostic factors need to be applied to improve patients’ prognosis. The incidence of sarcopenia has been observed in various malignancies. The quantity of skeletal muscle mass is reflected in the psoas muscle index (PMI), suggesting the presence of sarcopenia. Our aim is to investigate the association of postoperative prognosis of patients with rectum cancer with the occurrence of preoperative sarcopenia with quantitative and qualitative reduction of skeletal muscle mass.

Material and method: We performed a multidisciplinary research and we examined patients diagnosed with rectal cancer. The PMI was determined at the lower edge of the L3 vertebral body, using CT scan. We present our research partial results within three cases.

Results: The PMI of three male patients with rectum cancer who received neoadjuvant chemoradiotherapy was: Case 1 has a PMI of 7.378 cm²/m², the mean psoas muscle density was 50.14 UH. Case 2 has a PMI of 6,942 cm²/m² and a mean psoas density of 43.81 UH. Case 3 has a PMI of 8.4885 cm²/m² and an average density of 43.85 UH in the right and left psoas.

Conclusions: The PMI value can be calculated with simple radiologic measurements, thus determining the diagnosis of sarcopenia. Calculations are performed using standard preoperative CT-scans. A PMI value above the threshold limit is promising in the short term, but in the long term it is not responsible for the deterioration of patients’ general condition and tumor recurrence.