Common breast cancer treatment works less in smokers

A common treatment for breast cancer is less effective in smokers as compared to non-smoking counterparts, according to a new study.

Principal investigator Helena Jernstrom said that smokers who were treated with aromatase inhibitors had a three times higher risk of recurrence of breast cancer compared with the non-smokers who got the same treatment.

Jernstrom added that the Lund University study also showed that the smokers also had an increased risk of dying, either from the breast cancer or from other illnesses, during the time we followed them.

The researchers followed 1,016 patients in southern Sweden who were diagnosed with breast cancer between 2002 and 2012. At the time when they were booked in for surgery, they were asked whether they were smokers or non-smokers. Approximately one in five women stated that she was either a regular smoker or a "social smoker". The impacts of smoking were analysed depending on what type of breast cancer treatment the patients received after their surgeries.

What the study shows most clearly is that women over the age of 50, treated with aromatase inhibitors, are affected by smoking. This treatment against breast cancer prevents the body from generating oestrogen in fatty tissue and thereby reduces the risk of recurrence in women with oestrogen-receptive positive breast cancer.

One finding which surprised the researchers was that so few patients quit smoking during their treatment, despite being informed of the importance of doing so. Out of a total of 206 smokers, only ten per cent stopped smoking in the first year after their surgery, a number so small that the researchers could not study whether giving up smoking during treatment had any effect.

The study is published in the British Journal of Cancer.