As if we didn't get enough warnings this week of the hazards of smoking -- a new study links it to increased risk of breast cancer.

The increased risk was modest, and pertains only to women who smoked before menopause, according to the research appearing in the latest Archives of Internal Medicine. The data was gleaned from the long-running Nurse's Health Study, where Harvard researchers examined the records of nearly 112,000 women between 1976 and 2000, checking for women who smoked or who were around secondhand smoke.

Some 8,772 breast cancer cases developed during a follow-up. People who smoked a lot in their youth for a long amount of time were most likely to develop breast cancer, the report concluded. Meanwhile, not smoking or exposure to parents who smoked at home were not related to increased risk for breast cancer.

The carcinogens in cigarettes have long been known to cause lung cancer, as well as several other types including kidney, bladder and pancreatic cancers, according to the National Cancer Institute. But the relationship with breast cancer has been inconclusive for years.

The new study says it's the largest thus far to examine the risk associated between tobacco use and breast cancer. Past studies have tried to investigate the link, but their results were mixed and the relationship was unclear. This study, however, found that smoking impacts a woman's cancer risk depending on her age and hormones may be at play.

“Smoking before menopause was positively associated with breast cancer risk, and there were hints from our results that smoking after menopause might be associated with a slightly decreased breast cancer risk,” the study states. “This difference suggests an antiestrogenic effect of smoking among postmenopausal women that may further reduce their already low endogenous estrogen levels.”

Associated Press photo