A majority of studies have linked smoking to an increase risk of breast cancer among young women, but not until now has a study evaluated risks according to different subtypes of breast cancer.
“The health hazards associated with smoking are numerous and well-known,” said study author Christopher Li, MD, PhD in a press release.
Researchers at the Fred Hutchinson Cancer Research Center in Seattle found young women who smoke and have been smoking a pack a day for a decade or more have a significantly increased risk of developing the most common type of breast cancer.
They also found overall women who smoke have a higher risk for developing the disease.
During the study, researchers followed 778 patients with estrogen receptor positive breast cancer and 182 patients with triple-negative breast cancer.
Study participants ranged in age from 20 to 44 years old who had been diagnosed with disease from 2004-2010 in Seattle. Also included in the study were 938 cancer-free controls.
Estrogen receptor positive breast cancer is the most common subtype of breast cancer. Whereas triple-negative breast cancer is less common but tends to be more aggressive.
Researchers found 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.
However, smoking was not related to a woman’s risk of triple-negative breast cancer.
“This study adds to our knowledge in suggesting 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.
The new findings are published online in Cancer, a peer-reviewed journal of the American Cancer Society.