Computed tomography-based analyses of baseline body composition parameters and changes in breast cancer patients...

Body composition parameters including muscle and adipose tissue measurements have emerged as prognostic factors in cancer patients. Besides cell cycle regulation, CDK 4 and 6 also control metabolic processes (lipid synthesis, glycolysis, and mitochondrial function). We studied the impact of baseline body composition parameters on response to CDK 4/6 inhibition and changes on body composition during treatment.

Retrospective study of 50 patients treated at Institut Jules Bordet between December 2016 and August 2019 with endocrine therapy and CDK 4/6 inhibitor as first or second-line treatment for metastatic breast cancer (BC). CT-based body composition analysis was performed at 3 time points. Cox regression and Kaplan-Meier method were used for the association with Progression-free survival (PFS). Changes in body composition parameters were described in means and compared using paired sampled T test.

Baseline sarcopenia was present in 40% of patients and associated with a significantly worse PFS compared to patients without sarcopenia (20.8 vs 9.6 months, HR 2.52; 95% CI 1.02-6.19, p = 0.037). Patients with higher visceral fat index and higher visceral fat density had better PFS (20.8 vs 10.4 months, HR 0.40; 95% CI 0.16-0.99 p = 0.041-stratified for treatment line). No significant alterations in body composition parameters during treatment were observed.

Sarcopenia is a potential early marker of poor prognosis among patients with metastatic BC treated with CDK 4/6 inhibitors. CT scan evaluation of sarcopenia and adiposity revealed significant prognostic information. Visceral fat could also play an important role in response to CDK 4/6 inhibitors, deserving further investigation.