Women prescribed the drug tamoxifen to reduce their risk of breast cancer are less likely to continue taking the drug if they smoke and drink, according to a new nationwide study. Tamoxifen has been used for a decade to reduce the risk of breast cancer in women who are at increased risk of developing breast cancer.

The study of 11,000 women found those who had more than one drink a day were less likely to adhere to their medication regimen after one month compared with nondrinkers, HealthDay reports. Women who smoked were also less likely to stick with their medication schedule. Women’s physical activity levels and obesity did not affect whether they continued to take the medication, the researchers note in Cancer Prevention Research. This indicates that a woman’s decision to stick to the medication regimen is not simply linked to unhealthy behavior in general, they said.

The findings suggest some women at high risk for breast cancer may need extra support to stick to their medication regimen, according to lead researcher Stephanie R. Land. “Patients shouldn’t be afraid to ask for support from their social network and health care community,” she said in a news release. “Health care providers need to know that smokers and drinkers may need additional support. This medication has been shown to prevent breast cancer, but that benefit will only translate if women follow the regimen and maintain it.”