Increases in breast cancer risk, relative to how long a woman has smoked or the number of cigarettes she smoked a day, have been found in several studies. However, the relationship between breast cancer and the level of smoking exposure is not as clear as it is for lung cancer. For example, people who smoke the least (or for the shortest time) have the lowest risk of lung cancer, while people who smoke the most (or for the longest time) have the highest risk. People who smoke amounts between these two extremes, have risks that fall between the two extremes. This is called a “dose-relationship” between.
