These days, thanks to advances in treatment and detection, millions of women survive breast cancer. But surviving the disease doesn’t necessarily mean the entire battle is over, a population-based study of breast cancer survivors in Sweden and Denmark, published Wednesday in the New England Journal of Medicine, seems to suggest.
Assessing a total of 2,168 women whose breast cancer was treated with radiation therapy between 1958 and 2001, a team of researchers found that women’s chances of having a major coronary event — a heart attack, bypass surgery or heart disease death — rose in proportion with the radiation dose they received, even at the lower doses of radiation delivered in newer treatments.
In all, 963 of the women in the study had major coronary events.
Forty-four percent of these took place within 10 years of the cancer diagnosis, but 33% occurred 10 to 19 years later, and 23% occurred 20 or more years later. Estimating the amount of radiation the women had received to their hearts over the course of their breast cancer treatment, the researchers also calculated that the rate of major coronary events increased 7.4% per gray (a unit of absorbed dose) of radiation.
Women with cancers in the left breast, which is closer to the heart, had higher rates of coronary events than women treated for tumors in the right breast.