Background Low muscle mass (LMM) and low muscle attenuation (LMA) reflect low muscle quantity and low muscle quality, respectively. Both are associated with a poor outcome in several types of solid malignancies. This study determined the association of skeletal muscle measures with overall survival (OS) and time to next treatment (TNT). Patients and methods A skeletal muscle index (SMI) in cm2/m2 and muscle attenuation (MA) in Hounsfield units (HU) were measured using abdominal CT-images of 166 patients before start of first-line chemotherapy for metastatic breast cancer. Low muscle mass (SMI <41 cm2/m2), sarcopenic obesity (LMM and BMI ≥30 kg/m2) and low muscle attenuation (MA <41 HU and BMI <25 kg/m2 or MA <33 HU and BMI ≥25 kg/m2) were related to OS and TNT. Results The prevalence of LMM, sarcopenic obesity and LMA were 66.9%, 7.2% and 59.6% respectively. LMM and sarcopenic obesity showed no significant association with OS and TNT, whereas LMA was associated with both lower OS (HR 2.04, 95% CI 1.34–3.12, p = 0.001) and shorter TNT (HR 1.72, 95% CI 1.14–2.62, p = 0.010). Patients with LMA had a median OS and TNT of 15 and 8 months respectively, compared to 23 and 10 months in patients with normal MA. Conclusion LMA is a prognostic factor for OS and TNT in metastatic breast cancer patients receiving first-line palliative chemotherapy, whereas LMM and sarcopenic obesity are not. Further research is needed to establish what impact LMA should have in daily clinical practice.

, , , ,,
The Breast
Erasmus MC: University Medical Center Rotterdam

Rier, H., Jager, A., Sleijfer, S., van Rosmalen, J., Kock, M. C. J. M., & Levin, M.-D. (2017). Low muscle attenuation is a prognostic factor for survival in metastatic breast cancer patients treated with first line palliative chemotherapy. The Breast, 31, 9–15. doi:10.1016/j.breast.2016.10.014