Measurement of mid-arm muscle circumference and prognosis in stage IV non-small cell lung cancer patients.

Overall survival (OS) varies widely in patients with stage IV non-small cell lung cancer (NSCLC). Strong prognostic factors are still needed to improve decision-making regarding standard treatment options, to stratify patients for inclusion in innovative therapeutic trials and to identify patients who would be best treated with palliative care rather than with systemic chemotherapy. Mid-arm muscle circumference (MAMC) is a bedside anthropometric measurement that estimates somatic protein reserve, an early indicator of nutritional depletion. This measurement is simple, non-invasive, objective and inexpensive to perform. We evaluated MAMC as a potential prognostic factor in patients with stage IV NSCLC. A total of 56 non-selected consecutive patients with stage IV NSCLC were evaluated. The MAMC measurement results for these patients were expressed as a percentage of the expected reference values, adjusted for gender and age. Patients were categorized as normal (MAMC ≥90%) or depleted (MAMC <90%). The mean age of patients was 63 years (range 47-80), and the mean MAMC was 89 (range 66-122), with 55% of patients classified as depleted. The median OS was 6.2 months (95% CI, 5.1-7.3). In the subgroup with normal MAMC, the median OS was 10.2 months (95% CI, 9.2-11.1). In patients classified as depleted, the median OS was 5.0 months (95% CI, 4.2-5.8). The difference in OS between these two subgroups was highly significant (p<0.001 by the log-rank test; HR=0.21; 95% CI, 0.09-0.5 for patients with normal MAMC). In a multivariate analysis with Karnofsky status, age and gender as covariates, the difference in OS between the MAMC groups remained statistically significant (p<0.001, according to the Cox proportional hazards model). MAMC is a strong independent prognostic factor in stage IV NSCLC patients. Patients with MAMC <90% of the expected value had poor OS.