Breast cancer incidence in women prenatally exposed to maternal cigarette smoke

Prenatal hormone exposure may affect future breast cancer risk

DES Follow-up Study Summary

National Cancer Inst logo image
These 2005 study results provide further evidence supporting the hypothesis that prenatal hormone exposure may affect future breast cancer risk.

Fetal exposure to maternal pregnancy hormones may influence future breast cancer risk and cigarette smoking is among the factors believed to alter pregnancy hormone levels. Specifically, total pregnancy estrogen levels are slightly decreased among pregnant women who smoke relative to women who do not. More pronounced reductions of pregnancy estiol (E3) and estradiol (E2) were observed among smoking women. Possibly, women prenatally exposed to maternal cigarette smoke may have reduced breast cancer risk as an adult. The National Cooperative DES Adenosis (DESAD) Project was a prospective study of the effects of prenatal Diethylstilbestrol (DES) exposure. When women were enrolled in the study from 1975 through 1981, their mothers were questioned about their health habits including cigarette smoking during their pregnancy with the study participant. Using responses to this question provided by the mothers at the start of the study, investigators were able to compare the breast cancer rates among women who were and were not prenatally exposed to maternal cigarette smoke. Investigators observed a 51% decrease in breast cancer rates among women whose mothers smoked while pregnant with them compared to women who were not prenatally exposed to maternal cigarette smoke. Daughters of women who smoked 15 or fewer cigarettes per day during the pregnancy appeared to have a 65% reduction in breast cancer rates compared to women whose mothers did not smoke during pregancy. The adverse effects of prenatal cigarette smoke exposure far outweigh any benefit from possible reduction of breast cancer risk. These study results do, however, provide further evidence supporting the hypothesis that prenatal hormone exposure may affect future breast cancer risk.

2005 Study Abstract

BACKGROUND:
Clinical studies show that maternal cigarette smoking reduces pregnancy estrogen levels. Women prenatally exposed to maternal cigarette smoke may, therefore, have a lower breast cancer risk because the fetal mammary gland’s exposure to maternal estrogen is decreased. Associations between prenatal maternal cigarette smoke exposure and breast cancer, however, have not been observed in previous case-control studies that relied on exposure assessment after the onset of cancer. At the start of this study, cigarette smoking history was obtained directly from the mother.

METHODS:
The National Cooperative DES Adenosis project was a follow-up study of health outcomes in women prenatally exposed to diethylstilbestrol (DES). At the start of the study, women’s mothers provided information about cigarette smoking habits during the time they were pregnant with the study participant. In the current study, the breast cancer rates are compared among 4031 women who were or were not prenatally exposed to maternal cigarette smoke. The resultant relative rate (RR) is adjusted for potential confounding by other breast cancer risk factors using Poisson regression modeling.

RESULTS:
Fetal exposure to maternal cigarette smoke appeared to be inversely associated with breast cancer incidence (RR = 0.49; 95% confidence interval [CI] = 0.24-1.03). The inverse association was more apparent among women whose mothers smoked 15 cigarettes or fewer per day than among daughters of heavier smokers. There were, however, too few cases to precisely estimate a possible dose-response relationship.

CONCLUSION:
These results support the hypothesis that in utero exposure to maternal cigarette smoke reduces breast cancer incidence.

Sources

  • Breast cancer incidence in women prenatally exposed to maternal cigarette smokeNCBI, PMID: 15824550, 2005 May;16(3):342-5.
  • NCI, DES Follow-up Study Published Papers.
More DES DiEthylStilbestrol Resources

Author: DES Daughter

Activist, blogger and social media addict committed to shedding light on a global health scandal and dedicated to raise DES awareness.

Have your say! Share your views

Fill in your details below or click an icon to log in:

WordPress.com Logo

You are commenting using your WordPress.com account. Log Out /  Change )

Google+ photo

You are commenting using your Google+ account. Log Out /  Change )

Twitter picture

You are commenting using your Twitter account. Log Out /  Change )

Facebook photo

You are commenting using your Facebook account. Log Out /  Change )

Connecting to %s

This site uses Akismet to reduce spam. Learn how your comment data is processed.