London: Common treatment for breast cancer works less in women who smoke, according to a new study which also found that smokers have three times higher risk of recurrence of the deadly disease.
The researchers followed 1,016 patients in 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. About one in five women stated that she was either a regular smoker or a "social smoker".
"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," said Helena Jernstrom from Lund University in Sweden.
"The study also showed that the smokers also had an increased risk of dying, either from breast cancer or from other illnesses, during the time we followed them," said Jernstrom.
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.
"The treatment with aromatase inhibitors worked significantly better in the non-smoking patients," said Jernstrom.
"However, we saw little or no difference between smokers and non-smokers among patients treated with the drug tamoxifen, radiotherapy or chemotherapy," she said.
"More studies are needed, but our findings are important as many breast cancer patients receive this type of treatment," said Jernstrom.
Researchers also found that very 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.
"These findings show that patients who smoke need more support and encouragement to quit," said Jernstrom.
The study is published in the British Journal of Cancer.
