Passive Smoking and Breast Cancer - a Suspicious Link

Breast cancer is the most common malignancy of women in the world. The disease is caused by infectious and non-infectious, environmental and lifestyle factors. Tobacco smoke has been one of the most widely studied environmental factors with possible relevance to breast cancer. The purpose of this study was to assess the impact of tobacco smoking in breast cancer patients in a hospital based cohort and to establish prognostic implications if any.

A retrospective audit of 100 women with pathological diagnosis of invasive breast cancer was included in this study. The verbal questionnaire elicited information on current and previous history of exposure to smoking in addition to active smoking. All analyses were adjusted for potential confounders, including stage at presentation, alcohol intake, hormonal replacement therapy, oral contraceptive intake, obesity and menopausal status.

The mean age at presentation of breast cancer was 51.4 ± 10.86 years. Mean age of presentation was 53.1±11.5 and 45.7±11.9 years in never smokers and passive smokers, respectively. Age at presentation varied widely in patients exposed to tobacco smoke for >10 years in childhood from 40.3± 12.0 years to 47.7± 13.9 in patients exposed for > 20 years as adults. Among passive smokers, 60.9% were premenopausal and 39.1% of patients were postmenopausal. In never smokers, 71.4% were post menopausal. Expression of receptors in non-smokers vs passive smokers was comparable with no significant differences. Metastatic potential in lung parenchyma was slightly elevated in passive smokers as compared to never smokers although statistically non-significant.

An inverse relationship exists between the intensity and duration of smoking and the age at presentation and poor prognostic factors. The results strongly suggest efforts should be taken to prevent smoking, encourage quitting and restrict exposure to second hand smoke in India.