Early skeletal muscle mass decline is a prognostic factor in patients receiving gemcitabine plus nab-paclitaxel for unresectable pancreatic cancer: a retrospective observational study

Purpose: Patients with pancreatic cancer often have cancer cachexia at diagnosis. Recent studies suggested that loss of skeletal muscle mass was related to cancer cachexia, which hindered continuance of chemotherapy and could be one of prognostic factors in pancreatic cancer, however the association remains unclear in patients receiving gemcitabine and nab-paclitaxel (GnP). Methods: We retrospectively studied 138 patients with unresectable pancreatic cancer receiving first-line GnP at the University of Tokyo from January 2015 to September 2020. We calculated body composition in CT images before chemotherapy and at initial evaluation, and evaluated the association of both body composition before chemotherapy and its changes at initial evaluation. Results: Compared by skeletal muscle mass index (SMI) change rate between pre-chemotherapy and initial evaluation, there were statistically significantly differences in the median OS: 16.3 months (95%CI 12.3–22.7) and 10.3 months (95%CI 8.3–18.1) between SMI change rate ≥ -3.5% and < -3.5% groups (P = 0.01). By multivariate analysis for OS, CA19-9 (HR 3.34, 95%CI 2.00–5.57, P < 0.01), PLR (HR 1.68, 95%CI 1.01–2.78, P = 0.04), mGPS (HR 2.32, 95%CI 1.47–3.65, P < 0.01) and relative dose intensity (HR 2.21, 95%CI 1.42–3.46, P < 0.01) were significantly poor prognostic factors. SMI change rate (HR 1.47, 95%CI 0.95–2.28, P = 0.08) showed a trend to poor prognosis. Sarcopenia before chemotherapy was not significantly associated with PFS or OS. Conclusion: Early skeletal muscle mass decline was associated with poor OS. Further investigation is warranted whether the maintenance of skeletal muscle mass by nutritional support would improve prognosis.