Cigarette smoking and risk of epithelial ovarian cancer

An increased risk of mucinous ovarian tumors among cigarette smokers has been observed in multiple studies. The association of smoking with other histologic types of ovarian cancer is less clear, but potentially holds greater importance for prevention of disease incidence and mortality.

In a population-based study of 812 women with ovarian cancer diagnosed in western Washington State from 2002-2005 and 1,313 controls, we assessed the risk associated with cigarette smoking, with a particular focus on tumor subgroups jointly classified according to the degree of invasiveness and histology. Information was collected through in-person interviews, and logistic regression was used to calculate odds ratios (ORs) and 95% confidence intervals (CIs).

The incidence of both borderline and invasive mucinous ovarian tumors was increased among women with a history of cigarette smoking (ORs and 95% CIs = 1.8, 1.2-2.9, and 1.8, 0.8-4.3, respectively). Increases in risk of these tumor types were most evident among women with greater smoking duration and pack-years of exposure, and among those who had smoked within the prior 15 years. We noted no clear patterns of risk of serous tumors with duration or pack-years of smoking; however, risk of these tumor types was somewhat elevated among women who had smoked within the previous 15 years (for borderline serous tumors, OR and 95% CI = 1.5, 0.9-2.3; for invasive serous tumors, OR and 95% CI = 1.4, 1.1-1.9). The risk of endometrioid, clear cell, and the remaining histologic types of invasive ovarian cancer was not increased among smokers.

In the aggregate, evidence is insufficient to determine whether smoking is linked with risk of serous or other non-mucinous histologic types of ovarian cancer. Studies that employ additional histopathologic and molecular techniques to more accurately delineate subsets of tumors may improve our understanding of the impact of smoking on ovarian cancer risk.