Epithelial ovarian cancer subtypes attributable to smoking in the Norwegian Women and Cancer Study, 2012

Abstract

Among European women, ovarian cancer is the fifth most common cancer. Smoking is an established risk factor for mucinous tumors. We estimated the impact of smoking in Norwegian women using population attributable fractions (PAFs) of epithelial ovarian cancer (EOC), by invasiveness and by histological subtypes in the Norwegian Women and Cancer Study with an average of 13.2 years of follow‐up. During >2 million person‐years, a total of 915 incident EOC cases, of which 667 (73%) invasive and 248 (27%) borderline, were identified among 154,234 women aged 34–70 years at enrolment. Compared with never smokers, current smokers had a nonstatistically significant increased risk of mucinous tumors (hazard ratio [HR] = 1.67 [95% confidence interval, (CI), 0.96–2.96]) and more than twice statistically significant risk of borderline mucinous tumors (HR = 2.17 [95% CI, 1.06–4.45]). The corresponding PAF estimates were 16.5% for mucinous and 25% for borderline mucinous. We found that among middle‐aged women, one in six mucinous tumors and one in four borderline mucinous tumors could have been prevented if women did not smoke.

Association between Cigarette Smoking and Histotype-Specific Epithelial Ovarian Cancer: A Review of Epidemiologic Studies

“…Seven cohort studies presented results on overall ovarian cancer risk (21)(22)(23)(24)(25)(26)32). Among them only one reported an increased risk associated with current smoking (HR ¼ 1.4; 95% CI, 1.0-1.8), when borderline and invasive cases were combined (25).…”

Smoking and risk of ovarian cancer by histological subtypes: an analysis among 300 000 Norwegian women

“…The few prospective cohort studies that have investigated the association between measure of smoking exposure and the risk of subtypes of OC (Tworoger et al , 2008; Gram et al , 2012; Licaj et al , 2016) found no association between smoking duration and mucinous OCs. Each 20 additional pack-years in ever compared with never smokers was associated with a significant 20% higher risk of invasive mucinous OC (Wentzensen et al , 2016).…”

“…In a recent study (Wentzensen et al , 2016), number of pack-years, which was the only measure of smoking exposure studied, was associated with a higher risk of invasive mucinous OC among ever smokers. Two reports from the same study population found a positive association between number of cigarettes smoked per day, smoking duration in years, and the risk of borderline OC (Gram et al , 2008; Licaj et al , 2016). One reason for the variation in these results may be the different methods employed to assess and analyse these measures of smoking exposure.…”

“…Moreover, few prospective studies have investigated the association between these measures of smoking exposure and histological subtypes of OC (Gram et al , 2008; Tworoger et al , 2008; Gram et al , 2012; Licaj et al , 2016; Wentzensen et al , 2016), and the results of the prospective studies are inconsistent. None of them found an association between mucinous OC and smoking duration, and only one (Gram et al , 2012) reported that mucinous OC was associated with the number of cigarettes smoked per day.…”

Does an epidemiological comparison support a common cellular lineage for similar subtypes of postmenopausal uterine and ovarian carcinoma? The Norwegian Women and Cancer Study

“…Adiposity increases the risk of uterine carcinoma but is less associated with ovarian carcinoma . Smoking is associated with lower risk of uterine carcinoma but not with overall risk of ovarian carcinoma . Several studies have compared risk estimates for subtypes of uterine or ovarian carcinoma to determine if they have different risk factors .…”