It’s hard to think of a worse habit than smoking. Smoking can not only be blamed for increasing cancer risk by 30 percent, but has also been conclusively connected to an elevated risk of fourteen different cancers. If a 2017 report is correct, breast cancer deserves to be the 15th disease on this list.

Two Groups, Different Results

Appearing in the journal Breast Cancer Research, this report was authored by a team of researchers from the London-based Institute for Cancer Research. For their study, the authors examined 1,815 women who had been previously diagnosed with invasive breast cancer. Some of these women were committed smokers, while others had wisely avoided these notorious tobacco products.

The authors found that, compared to non-smoking females, women who smoked were 35% likelier to develop breast cancer. Furthermore, the report noted that participants who either a) began smoking before they started menstruating or b) had a close family history of breast cancer faced the great risk of developing this deadly disease.

Long-Lasting Damage

These findings raise a pertinent question: Do women who quit smoking reduce their breast cancer risk? The authors’ answer to this question is not encouraging; the study determined that even after kicking their smoking habit, such women still faced an elevated breast cancer risk for twenty years or longer. Fortunately, this increased risk does appear to erode over time.

Hindering Treatment

In addition to making breast cancer a bigger threat, smoking can also interfere with cancer treatments. This finding comes from a separate study from a team of Swedish researchers, who examined over 1,000 breast cancer patients. Specifically, this team noted that aromatase inhibitors were less effective in female smokers than in their non-smoking counterparts. In fact, the cancer recurrence rate was three times higher for women who smoked.