Indoor wood-burning from stoves and fireplaces and incident lung cancer among Sister Study participants
Suril Mehta, Martin Hodgson, Ruth M. Lunn, Claire E. Ashley, Whitney D. Arroyave, Dale P. Sandler, Alexandra J. White
Abstract
Epidemiological studies conducted mostly in low- and middle-income countries have found a positive association between household combustion of wood and lung cancer. However, most studies have been retrospective, and few have been conducted in the United States where indoor wood-burning usage patterns differ. We examined the association of exposure to indoor wood smoke from fireplaces and stoves with incident lung cancer in a U.S.-wide cohort of women. We included 50,226 women without prior lung cancer participating in the U.S.-based prospective Sister Study. At enrollment (2003-2009), women reported frequency of use of wood-burning stoves and/or fireplaces in their longest-lived adult residence. Cox regression was used to estimate adjusted hazard ratios (HRadj) and 95% confidence intervals (CI) for the association between indoor wood-burning fireplace/stove use and incident lung cancer. Lung cancer was self-reported and confirmed with medical records. During an average 11.3 years of follow-up, 347 medically confirmed lung cancer cases accrued. Overall, 62.3% of the study population reported the presence of an indoor wood-burning fireplace/stove at their longest-lived adult residence and 20.6% reported annual usage of ≥30 days/year. Compared to those without a wood-burning fireplace/stove, women who used their wood-burning fireplace/stove ≥30 days/year had an elevated rate of lung cancer (HRadj = 1.68; 95% CI = 1.27, 2.20). In never smokers, positive associations were seen for use 1-29 days/year (HRadj = 1.64; 95% CI = 0.87, 3.10) and ≥30 days/year (HRadj = 1.99; 95% CI = 1.02, 3.89). Associations were also elevated across all income groups, in Northeastern, Western or Midwestern U.S. regions, and among those who lived in urban or rural/small town settings. Our prospective analysis of a cohort of U.S. women found that increasing frequency of wood-burning indoor fireplace/stove usage was associated with incident lung cancer, even among never smokers.