LUND, Sweden, June 17 (UPI) -- Smoking cigarettes is bad for health, but a new study shows smokers who do not quit while undergoing treatment for breast cancer could be risking the efficacy of their treatment.
Researchers in Sweden found the effects of one breast cancer treatment are lessened in patients who do not quit smoking cigarettes, while smoking appeared not to have a great effect on the efficacy of three others.
In addition to lowering the effects of anti-cancer treatment by continuing to smoke, the researchers found smokers had an increased risk of dying, either from cancer or from other illnesses possibly connected to the habit.
Most surprising to the researchers, however, was the number of patients who decide against quitting when diagnosed with cancer and starting treatment, suggesting more needs to be done to help them stop smoking.
"That was unexpected," Dr. Helena Jernström, a researcher and associate professor at Lund University, said in a press release. "Smoking is not health-promoting in any way, after all, so it is always beneficial to stop. But these findings show that patients who smoke need more support and encouragement to quit."
For the study, published in the British Journal of Cancer, researchers followed 1,016 breast cancer patients diagnosed between 2002 and 2012 from the time they were booked for surgery for a median of 5.1 years. Roughly one in five patients reported they were regular or "social" smokers, with the effects analyzed based on the type of treatment they received for cancer.
Overall, there was no significant association between smoking and the risk of breast cancer events.
For the 309 patients treated with aromatase inhibitors, especially those over age 50, smoking was linked to breast cancer events, distant metastasis and death. In patients who smoke treated with the drug tamoxifen, radiotherapy or chemotherapy, however, no significant risk for breast cancer events or distant metastasis was detected.
Aside from suggesting doctors work more closely with patients who have cancer to quit smoking, the researchers say smoking status should be considered when prescribing therapies for breast cancer.