Impact of Body Mass Index (BMI) On Overall Survival in Myeloma

Excess body weight has been identified as a risk factor for developing myeloma. From a meta-analysis of 15 cohort studies evaluating myeloma incidence and 5 others on mortality, the risk of multiple myeloma was significantly elevated among overweight patients and obese patients. Interleukin-6 (IL-6) promotes normal plasma cell development and proliferation of myeloma cells in culture. A polymorphism (allele 174C) in the IL-6 gene promoter is associated with obesity and hence, the hypothesis that overweight may be a surrogate for IL-6 promoter genotypes, and associated with increased risk of plasma cell neoplasms has been proposed. However, data is limited in evaluating the outcomes in these patients, based on BMI. We have evaluated the impact of BMI on overall survival in patients with myeloma.

We have evaluated a total of 589 patients that underwent ASCT during the period January 2005 through June 2011 from our myeloma database. The median time of follow up is 50 months in all patients and 23 months post ASCT. We used IBM SPSS version 20 to generate the survival statistics.

The median patient age at the time of diagnosis and at ASCT is 57 years (range, 26–77) and 59 years (range, 26–78), respectively. Patient characteristics: 55%/45% male/female; 56%/36% white/black; ISS stage I/II/III 38%/19%/43%; ASCT conditioning melphalan 140/200 15%/85%. At a median follow up of 50 months from the time of diagnosis and 23 months from the time of ASCT, 75% of the patients are expected to be alive at 109 months. OS was not statistically different between the groups stratified on gender and race. OS from the time of diagnosis and from the time of ASCT was not statistically significant in patients stratified by BMI 18.5–24.9; 25–29.9; 30–34.9; 35–39.9 and ≥40. However, for the patient group with BMI<18.4 vs. ≥18.5; the OS from the time of diagnosis (75% survival: 55 months vs. 109 months; p=0.018) and from the time of ASCT (median OS: 43 months vs. NR; p=0.017) was significantly different, in favor of the BMI≥18.5 group.

Our results suggest that patients that received ASCT have significant survival benefit. Higher BMI does not confer a negative impact on the prognosis of obese patients, as they actually have better survival after ASCT. Patients that are underweight (BMI<18.4) have inferior survival as those with higher BMI. This effect is possibly related to cancer cachexia or malnutrition, or increased toxicity from the conditioning regimen.

Kaufman:Millenium: Consultancy; Celgene: Consultancy; Novartis: Consultancy; Onyx Pharmaceuticals: Consultancy. Waller:Outsuka: Research Funding.