ASPO Abstracts
A prospective analysis of sedentary behavior and risk of multiple myeloma in three large cohorts
Category: Lifestyles Behavior, Energy Balance & Chemoprevention
Conference Year: 2021
Abstract Body:
Purpose of the study
The proposed biological mechanisms between sedentary behavior and cancer are mediated by adiposity, sex
hormones, inflammation, and vitamin D. These four factors have also been shown to affect immune function and
oncogenesis of blood cells, resulting in high multiple myeloma (MM) risk. Therefore, we undertook the present
study to examine the association of sedentary behavior assessed as time sitting while watching television (TV),
with the risk of MM.
Methods
We prospectively followed 104,675 women in the Nurses' Health Study (NHS) (1992-2014), 115,344 women in the
NHS II (1991-2014), and 48,257 men in the Health Professional Follow-up Study (HPFS) (1988-2014). Time spent
sitting watching TV was assessed at baseline and subsequently updated. To better represent long-term behavior
and minimize random within-person variation, we calculated cumulative average hours of sitting time per day
across each 2-year follow-up interval. Trained personnel blinded to exposure status reviewed medical records to
confirm the occurrence and date of MM (ICD-8=203) diagnoses through 2014. Hazard ratios (HRs) and 95%
confidence intervals (CIs) were estimated using Cox proportional hazards models in each cohort and then pooled
using a fixed-effects model with inverse variance weighting. Cox proportional hazard models were stratified by age
and follow-up cycle and adjusted for body mass index and physical activity.
Results
We documented 443 cases of MM (217 from NHS, 54 from NHS II, and 172 from HPFS) during follow-up. On
average, the time spent sitting watching TV was 1.8 hours/day in the NHS, 1.3 hours/day in NHSII, and 1.6
hours/day in HPFS. In the pooled analysis, compared to participants with ≤1 hour/day of sedentary TV screen
time, those with >2 hours/day had a multivariable HR of 0.97 (95% CI: 0.72-1.31). Sitting during TV screen time
was also not associated with MM risk when modeled as a continuous variable (per 1 hour/day increase, HR= 1.00,
95% CI: 0.94-1.07). This association was similar in both women and men (per 1 hour/day increase, in women
HR=1.01, 95% CI: 0.93-1.09; in men HR=0.97, 95% CI: 0.84-1.13).
Conclusion
In these cohorts with relatively low levels of time spent sitting watching TV, the findings do not support an
association with MM risk.
Keywords: Sitting watching TV, multiple myeloma, cohort studies