FIT: Functional and imaging testing for patients with metastatic cancer.

BACKGROUND Selecting study endpoints in prospective cancer cachexia trials remains poorly defined. The aim of this study was to further evaluate associations in changes in weight, body composition, functional outcomes, and patient-reported outcomes (PROs) in patients with metastatic cancer. METHODS We completed a 2-year (2016-2018) observational study in patients with metastatic solid cancer and ECOG performance status 0 to 2 while receiving chemotherapy and/or immunotherapy. We completed assessments at study enrollment and 3 months from enrollment. We analyzed longitudinal changes in weight and body composition using validated methods. Functional assessments included the 6-Min Walk Test, Timed Up and Go Test, and Short Physical Performance Battery. PROs included the Functional Assessment of Anorexia/Cachexia Therapy and Functional Assessment of Cancer Therapy Fatigue. We analyzed changes in body composition and functional assessment using paired t tests. Additionally, we utilized linear regression models to assess relationships between changes in body composition and function outcomes and PROs, adjusting for age and sex. RESULTS A total of 57 patients completed baseline assessments, but 19 patients did not complete 3-month assessments (5 died, 1 hospice, 13 withdrew). Of the 38 patients with complete data, the mean age was 61.8 years and 47% were female. Metastatic cancer types included 71% gastrointestinal, 13% lung, and 8% gynecologic. Half received chemotherapy, 16% immunotherapy, and 34% a combination. From enrollment to 3 months, we did not observe a change in weight or skeletal muscle but did find an increase in total adipose tissue (16.9 ± 52.4 cm2, 95% CI - 33.79-0.63; p = 0.059; ~ 1.5 pounds). We did not observe any association with changes in weight with any functional outcomes or PROs. However, greater losses in skeletal muscle were associated with greater declines in physical function (6-Min Walk Test [B = 0.04, p = 0.01], Short Physical Performance Battery [B = 2.44, p < 0.01]). CONCLUSIONS Patients with metastatic cancer receiving cancer-directed therapy may not experience a change in body weight. However, we found an association between losses in skeletal muscle and greater declines in physical function. Therefore, when selecting study endpoints, prospective cancer cachexia studies may consider selecting changes in body composition over weight.