Early-life secondhand smoke exposure implicated in ovarian cancer
12 Mar 2021
Children who live with parents who smoke are at risk of developing ovarian cancer, especially for nonserous or low-grade serous tumours, as adults, a study suggests.
The analysis included 110,305 Nurses’ Health Study (NHS) participants (1976–2016; median age at baseline, 42 years) and 112,859 NHSII participants (1989–2017; median age at baseline, 35 years). Ovarian cancer was diagnosed in 2,853 individuals overall (2,184 from NHS, 669 from NHSII) at a median age of 62 years.
Of the cancer cases, 1,750 were epithelial ovarian tumours, primary peritoneal or fallopian tube cancer cases (1,511 invasive, 169 borderline, 70 unknown morphology; 1,020 high-grade serous/poorly differentiated histology, 56 low-grade serous, 115 mucinous, 196 endometrioid, 97 clear cell, and 266 tumour with other/unknown histotypes). The remaining 105 cancers were of the ovary (eg, sex cord stromal, germ cell, fibro-thecoma).
The women whose parents smoked at home in the NHS cohort tended to be current smokers. Their peers in the NHSII cohort were more likely to have menarche before age 12, be current smokers, and have higher body mass index at ages 10 and 18.
Overall, ovarian cancer risk was similar among participants whose mothers smoked during pregnancy relative to those who did not (hazard ratio [HR], 1.05). However, a risk increase was seen among women who themselves were never smokers (HR, 1.38) but not among ever smokers (HR, 0.86; pheterogeneity=0.02).
Compared with never smoking, early initiation of smoking was not associated with ovarian cancer risk (age <18: HR, 0.98; age ≥18: HR, 1.02). These associations did not differ by histotype (pheterogeneity≥0.35).
Finally, parental smoking at home during childhood/adolescence contributed to a 15-percent increased risk of ovarian cancer in adulthood (HR, 1.15), and this association was suggestively stronger among women with nonserous/low-grade serous tumours (HR, 1.28) versus high-grade serous/poorly differentiated tumours (HR, 1.09; pheterogeneity=0.25).