Prevalence and survival implications of malnutrition and sarcopenia in metastatic breast cancer: A longitudinal analysis

Malnutrition and sarcopenia are challenges for patients with metastatic breast cancer and have been proposed as independent prognostic factors. Very few studies have addressed the temporal evolution of these parameters and, notably, the separate and combined analysis of sarcopenia and malnutrition. This study aimed to i) determine the prevalence of malnutrition and sarcopenia, individually and combined, and their evolution over time, ii) identify risk factors for each condition, and iii) explore their impact on overall survival (OS).

This retrospective study was conducted on 111 patients treated for at least a third-line metastatic breast cancer at the Institut Curie between January 1st and March 31st, 2018. Solitary malnutrition was defined from weight loss and body mass index values while solitary sarcopenia was defined solely based on low muscle mass. We analyzed solitary malnutrition, solitary sarcopenia, and then malnutrition with or without sarcopenia, at three key stages (T1: diagnosis of metastasis, T2: initiation of third-line treatment, and T3: 3-month re-evaluation). Univariate and multivariate logistic regression analyses were conducted to investigate the risk factors. We performed Cox proportional hazards analyses for each variable.

At T1, the prevalence of solitary malnutrition, solitary sarcopenia and malnutrition with or without sarcopenia was 18.6%, 36.1% and 48.9% respectively, increasing to 27.7%, 45.5% and 56.6% at T2. At T2, in multivariate logistic regression analyses, patients aged over 60 years were at an elevated risk of experiencing solitary malnutrition as well as malnutrition with or without sarcopenia, but not solitary sarcopenia. In multivariate analyses, solitary malnutrition was significantly associated with poorer OS (HR 2.2 [95% CI 1.1-4.1], p = 0.02), while solitary sarcopenia and malnutrition with or without sarcopenia showed no association.

Solitary malnutrition and sarcopenia were highly prevalent in patients with metastatic breast cancer, affecting around a quarter and half of patients respectively at third-line treatment initiation. Notably, solitary malnutrition emerged as a prognostic factor for overall survival, whereas no significant association was observed for solitary sarcopenia or malnutrition with or without sarcopenia. This highlights the critical need for early identification of patients at risk of malnutrition and the importance of timely intervention.