Introduction: Nutritional status and body composition parameters would seem to be reasonable prognostic factors in patients with colorectal cancer (CRC). The study aimed to investigate the relationships between numerous parameters of nutritional status and prognosis in patients undergoing surgery due to CRC.

Material and methods: Clinical nutritional assessment and biochemical determinations were performed on 110 patients who underwent elective surgery due to primary CRC. Body composition was also analyzed using bioelectrical impedance (BIA) and computed tomography (CT) scans at the third lumbar (L3) vertebra using OsiriX software.

Results: Patients who failed to attend a visit 3 months after surgery (n = 15; 13.6%) were more likely to be sarcopenic, with lower baseline functional status, handgrip strength, skeletal muscle (SM) parameters in BIA and a smaller SM area in CT. Compared to those who died during, on average, 3.6 years of follow-up (n = 33; 30%), patients who survived had, at baseline, a significantly higher Mini-Nutritional Assessment (MNA) score, lower waist-to-height ratio (WHtR), and higher scores on functional status scales. In a Cox’s proportional-hazards model, in addition to an advanced WHO CRC stage, scores for MNA (HR; 95% CI: 0.85; 0.74–0.98; p = 0.021), Patient-Generated Subjective Global Assessment (PG-SGA), instrumental activities of daily living (IADL), and WHtR (3.68; 1.03–13.13; p = 0.049) were independent risk factors for death.

Conclusions: Patients’ functional status 3 months after surgery due to CRC was related to baseline SM strength, mass, and functional performance, whereas 3.5-year mortality was associated with lower MNA and IADL scores and higher WHtR and PG-SGA scores.