Heart Disease Killing Breast Cancer Survivors – The further along women are from a diagnosis of breast cancer, the more likely they are to die from noncancer-related causes — most commonly heart disease, report US researchers.
The findings come from a population-based study of more than 750,000 US women diagnosed with breast cancer in the 15 years since the turn of the century.
The proportion of deaths attributable to noncancer causes rose from about 28% in the first year after diagnosis to just over 60% in women who survived for more than 10 years.
Notably, women who survived that long had a significantly increased risk of both heart disease and Alzheimer’s disease compared with the general population.
The team says the findings “provide important insight into how breast cancer survivors should be counselled regarding future health risks.”
The research, published online in the journal Cancer on December 16, was led by Mohamad Bassam Sonbol, MD, an oncologist from the Mayo Clinic in Phoenix, Arizona.
Speaking to Medscape Medical News, Sonbol said the risk of noncancer-related causes of death “is something we’ve been suspecting before…but now we’re showing it objectively”.
Explaining the findings, he said that some of the women who died of noncancer-related causes may have been cured of their disease whereas, for others, the breast cancer may have been converted into something like a chronic disease.
“For example, if it’s a metastatic hormone positive breast cancer,” he said, “some of the women are living for years and their cancer is under control with their systematic therapy, so that’s when other causes are contributing to death.”
Sonbol added that the high rates of death from heart diseases are likely related to chemotherapy- and radiotherapy-related toxicity.
“We know some chemotherapies such as anthracyclines and other chemotherapies that are more targeted therapy — so, the HER2-directed therapies — can affect the heart function and women can have problems in the long run,” he said.
He added that many women, especially those who have a breast cancer diagnosis in the left breast, “can have long-term problems related to coronary artery disease and heart problems…when they get radiation as part of curative therapy”.
All this means that survivorship clinics will have to work closely with primary care physicians for long-term follow-up and address issues other than breast cancer that may arise.
Sonbol said: “I do think that future follow-up will take our data into consideration to be vigilant about primary prevention and secondary prevention as well.”
Although breast cancer remains the most common primary malignancy in women, and the second most common cause of cancer-related mortality, there have been dramatic improvements in survival rates over the last four decades.
This, the authors argue, means that women may live long enough after being diagnosed with breast cancer that noncancer-related causes may significantly affect their overall survival.