Although breast cancer treatments can cause heart damage, patients who receive radiotherapy or chemotherapy are not more likely to die of heart disease than the average population, a large U.S.-based registry study shows.
These findings suggest that regular screenings and good risk management for heart issues in breast cancer patients are making up for the increased risk of heart disease and heart-related mortality associated with the therapies.
The study, “Long-term heart-specific mortality among 347 476 breast cancer patients treated with radiotherapy or chemotherapy: a registry-based cohort study,” was published in the European Heart Journal.
While breast cancer survival has improved over the past decades, treatment-adverse outcomes, especially to the heart, remain a major concern.
“A number of clinical trials have suggested that both chemotherapy and radiotherapy are associated with the risk of suffering heart disease as a consequence of treatment,” Hermann Brenner, MD, the study’s lead author, from the German Cancer Research Center (DKFZ) in Heidelberg, said in a press release.
To determine heart-specific mortality in breast cancer patients relative to the general population, Brenner and his team analyzed roughly 350,000 breast cancer patients from the Surveillance, Epidemiology, and End Results-18 (SEER-18) database, which includes data from 18 regional cancer registries throughout the U.S.
Patients were diagnosed between 2000 and 2011 and followed until 2014. Treatment included radiotherapy or chemotherapy.
Researchers compared deaths from heart problems in breast cancer patients, treated with radiotherapy or chemotherapy, with that of the general population. They found the long-term risk of death from heart disease is not increased in breast cancer patients, compared with the average female population.
In fact, “compared with the general population, heart-specific mortality of breast cancer patients treated with radiotherapy or chemotherapy was lower,” the researchers wrote.
However, they cautioned that “these results have to be carefully interpreted as patients who received radiotherapy or chemotherapy significantly differed from patients who did not receive these treatments in terms of their baseline characteristics such as younger age at diagnosis, higher stage, higher grading, and molecular subtype status.”
In the subgroup of HER2-positive breast cancer patients, who commonly receive targeted chemotherapy, the results also showed no increased risk for heart-specific mortality relative to HER2-negative patients.
“At first, we were also surprised by this result,” said Janick Weberpals, PhD, the study’s initial author. “But we assume that our study paints a more realistic picture of the actual situation of treatment than clinical trials.”
Clinical trials are ruled by specific eligibility criteria while cancer registries include all breast cancer patients without criteria restrictions.
Good risk management in hospitals — assessing a patient’s risk for heart disease and taking it into account when choosing the adequate therapy — may explain these results. Assessing a patient’s heart health regularly throughout the treatment course also allows for early detection of potential adverse effects, providing oncologists with the opportunity to adjust the therapy and include heart treatment quickly.
“We consider the result of our study to be very positive for the treatment of breast cancer,” Brenner said. “It is particularly good news for the large number of affected patients that if they are in good medical care and have survived breast cancer, they do not need to be more worried about deadly heart diseases than women at the same age without breast cancer.”
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