A 2007 article in Epidemiology followed more than 12,000 Dutch women for 13 years. During that time, 252 women passed away. The researchers compared the mortality rates between left-handers and right-handers and found that left-handers had a 70% higher risk of dying from cancer and twice the risk of dying from breast cancer. They were also four times more likely to die from colorectal cancer. The researchers said that the research findings were limited by the small number of people who died during the study.
A 2007 commentary in Epidemiology criticized much of the research on left-handedness. The author wrote, “At this point, I should disclose that I am left-handed, and having successfully dodged a number of disorders, I doubt that my left hand is prematurely pulling me toward my grave. However, I am not alone in thinking that the literature on handedness suffers from a number of ills, irrespective of the putative illnesses suffered by left-handers.”
The confusion of the research on the link between breast cancer and left-handedness was enough for Susan G. Komen to consider it to be a myth. The organization noted that several other studies have found left-handed people don’t have an increased risk for breast cancer.