Both active and passive smoking of tobacco may spur the formation and spread of cancerous cells and tumors in the breast.

This study evaluated the connection between tobacco smoking and the subsequent development of breast cancer using a meta-analytic approach. Researchers compiled data and evidence extracted from 2,326,987 women who participated in 77 published studies.

Researchers noted that the greater the exposure to tobacco smoke, the higher a woman's risk of having breast cancer. This study documented that both active and passive smoking of tobacco may increase a woman's susceptibility to breast cancer.