BMI is a risk factor for survival in patients newly diagnosed with multiple myeloma, new research shows.

Data from 1,120 patients (61% male, median age 63) in the US Multiple Myeloma Research Foundation CoMMpass registry revealed that both underweight and severely obese patients had lower median progression free survival (PFS) and overall survival (OS) compared to those with a normal, overweight, or moderately obese BMI. 

Patients who were significantly underweight when diagnosed with multiple myeloma were found to have a 132% increased risk of death from any cause versus those of normal weight.

“Given that age, ISS [International Staging System ], CCI [Charlson Comorbidity Index], and cytogenetic risk were not altered in underweight (vs. normal weight) patients, we speculate that the observed adverse outcomes in this subgroup maybe due to high ECOG (i.e., poor performance status) and disease-related weight loss,” they said, in a paper published in Blood Cancer Journal.

The data was also suggestive of a link between being severely obese and having a higher risk of progression (HR: 1.29) and death (HR: 1.43) compared to newly diagnosed patients with normal BMI, “although differences between groups did not achieve statistical significance”, according to the research team at the Myeloma Service, Department of Medicine, Memorial Sloan Kettering Cancer Center, New York.

“This is biologically plausible and could reflect a worse ECOG performance status in the severely obese patients, which may render them less likely to tolerate full dose induction or transplant regimens,” the authors noted.

“For example, we observed that participants in the newly diagnosed MM cohort were less likely to receive carfilzomib-based therapy if they had an elevated BMI. Another mechanism may be that of increased adipocytes in the bone marrow niche of severely obese patients. Higher BMI correlates with higher levels of bone marrow adipocytes, which in turn can provide a favourable microenvironment for MM cell growth.”

Key study limitations included a lack of weight measurement before and during the study as well as use of BMI instead of newer body composition assessments. As such, “future studies of weight trajectories and body composition may help clarify [the study’s] observations,” the authors suggested.

“Additionally, clinical research to understand if patients with extreme BMI may benefit from weight management strategies to improve outcomes may be of importance”, they said.