NEW YORK, Oct 22 (Reuters Health) -- Radiation therapy after mastectomy does not appear to increase the risk of heart disease in breast cancer patients, according to Danish researchers reporting in The Lancet this week.
Lead researcher Dr. Inger Hojris of Aarhus University Hospital, Denmark, told Reuters Health that "the most important message from our study is that postmastectomy irradiation can be given without injury to the heart, if appropriate treatment techniques are used."
Hojris and colleagues in the Danish Breast Cancer Cooperative Group analyzed data from more than 3,000 women enrolled in two Danish trials to determine whether radiation therapy would impact on the development of ischemic heart disease in women identified as high-risk for breast cancer recurrence.
As to why ischemic heart disease might be a consequence of radiotherapy, the researchers explain that in patients with cancer of the left breast, one of the arteries supplying blood to the heart "receives a substantial radiation dose because the artery lies within or near the target (area)."
The investigators found that "the cumulative survival at 12 years (of follow-up) was significantly better among women in the (radiation therapy) group than those in the no-radiotherapy group." And, there was apparently no discernible difference in the occurrence of ischemic heart disease between the two groups, suggesting that concerns about a heightened risk of eventual cardiac problems in the radiotherapy group were unfounded. In contrast, earlier research had indicated that death from cardiac causes was, in fact, influenced by receipt of radiation therapy.
In an e-mail reply to a query from Reuters Health, Hojris noted that "the number of patients suffering from ischemic heart disease in the radiotherapy group compared with the no-radiotherapy group did not increase with time (since) treatment, and there was no increase among patients treated for left-sided breast cancer compared to patients treated for right-sided breast cancer."
Hojris noted that her team's study "gives further support for the use of postoperative radiotherapy in patients with high risk of (disease) recurrence." Although "further follow-up is necessary to rule out harmful effects on the heart after more than 12 years," Hojris emphasizes that "the follow-up period was long enough to show a significant survival benefit from systemic treatment plus irradiation compared with system treatment (chemotherapy\hormonal therapy) alone."
The authors also point out that "the total time patients were followed up was longer in the radiotherapy group than in the no-radiotherapy group because significantly more patients in the no-radiotherapy group died from cancer (recurrence)."
According to Hojris, she and her team "are now planning to investigate the occurrence of ischemic heart disease among patients given radiotherapy after breast-conserving treatment and apart from this, we are currently investigating other treatment-related complications."
