White women in their pre-menopause phase of life have double the risk for breast cancer if they are smokers. A recent case-control study revealed that it is because of the ‘BRCA1 or BRCA2 gene-mutation’.
Results of the study and the investigation report have been published in the journal “Breast Cancer Research and Treatment”. This report established the fact that the women who were smoking for last five or more five pack-years have twice the risk as non-smokers to have breast cancer.
Researchers from the Ontario Cancer Genetics Network expressed, “Because 20-60% of BRCA1/2 carriers do not develop breast cancer, there are likely to be other genetic or environmental factors that modify risk,“.
This study involved all non-Hispanic white women aged less than 50 years and having a relationship with the deleterious’ BRCA1 or BRCA2 mutation’. It also included an examination and identification of 323 cases and 481 controls, all from a ‘multi-national breast cancer family registry’.
The “odds-ratio” has an interesting relationship with the mutating genes. The ratio associated with smoking came out to be 2.3 for the ‘BRCA1 mutation carriers’ and 2.6 for ‘BRCA2 mutation carriers’. There exists a significant relationship between risk and the time period with respect to the mutation carrier rate. The investigations reported that the risk increased 7% per five pack-years in carriers of both the mutation.
“Previous studies in prevalent mutation carriers have not shown smoking to increase risk of breast cancer but are prone to bias, because smoking decreases survival after breast cancer,” the researchers from the Ontario Cancer Genetics Network remarked.
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