Young women who experience multiple stressful life events are at greater risk of developing breast cancer. On the other hand, a general feeling of happiness and optimism may help guard against the disease.
A team of researchers investigated the role of severe life events, such as losing a parent before age 20, in breast cancer risk. They found that women who had experienced two or more severe or mild-to-moderate life event were 62 percent more likely to have breast cancer. Women with breast cancer were also statistically more likely to have higher scores for depression and lower score for happiness and optimism.
However, women with a "general feeling of happiness and optimism" had a 25 percent lower risk of having been diagnosed with breast cancer.