Smoking and Breast Cancer

Smoking may increase women's breast-cancer risk by 6% or more.
USA Today (1/25, Szabo) reports that any history of smoking increases a woman's "chance of breast cancer by 6 percent," according to a study in the Archives of Internal Medicine. The analysis, which is "believed to be the largest ever to address the question," is based on data from the Nurses' Health Study and included "more than 111,000 women followed from 1976 to 2006." According to CNN /Health (1/25, Gardner), study participants "reported 8,772 cases of invasive breast cancer during" that 30-year timeframe.
The Los Angeles Times (1/25, Kaplan) "Booster Shots" blog notes that the researchers flagged "polycyclic aromatic hydrocarbons, aromatic amines and N-nitrosamines" found in tobacco smoke as contributors to breast cancer. The risk was higher for women who "started smoking before age 17, smoked at least 25 cigarettes per day at any point in their lives, and smoked for at least 20 years." The risk of breast cancer was 25-percent higher for women who "picked up the habit before age 18, smoked for at least 36 years and smoked at least 26 cigarettes per day."