Young women who smoke have a significantly higher risk of developing most common type of breast cancer, a study shows.
The majority of recent studies evaluating the relationship between smoking and breast cancer risk among young women have found that smoking is linked with an increased risk.
The present study, published in the online journal Cancer, evaluates the risks according to different subtypes of breast cancer.
To investigate, Christopher Li of the Fred Hutchinson Cancer Research Centre in Seattle, and his colleagues conducted a population-based study consisting of 778 patients with estrogen receptor positive breast cancer and 182 patients with triple-negative breast cancer.
Estrogen receptor positive breast cancer is the most common subtype of breast cancer, while triple-negative breast cancer is less common but tends to be more aggressive.
The researchers found that young women who were current or recent smokers and had been smoking a pack a day for at least 10 years had a 60 percent increased risk of estrogen receptor positive breast cancer.
"This study suggests that with respect to breast cancer, smoking may increase the risk of the most common molecular subtype of breast cancer but not influence risk of one of the rarer, more aggressive subtypes," said Li.