NEW YORK (Reuters Health) – Women with early-stage cancer of the left breast who are treated with radiation as a component of breast-sparing treatment, have an increased risk of developing radiation-related coronary damage, researchers report.

Nevertheless, "the benefits of radiation therapy for breast cancer still clearly outweigh the risks," Dr. Candace R. Correa told Reuters Health. "However," she added, "there may still be room for improvement in radiation techniques," when radiation is applied to the breast on the same side as the heart.

Correa, at the University of Michigan, Ann Arbor, and colleagues examined the medical records of 961 stage I-II breast cancer patients to look into this issue of radiation damage to the heart's arteries.

At the time they were diagnosed, women with left-sided and those with right-sided breast cancers had the same likelihood of developing coronary artery disease. At an average of 12 years after radiation treatment, 46 of the 485 left-sided women and 36 of 476 in the right-sided group had needed cardiac stress testing, the team reports in the Journal of Clinical Oncology.

The results showed that among those tested, 59 percent in the left-sided group had abnormalities, significantly more than the eight percent in the right-sided group.

"Careful monitoring and long-term follow-up to assess these risks ... is important," Correa stressed.

For patients, she added, "it is most prudent to optimize their cardiovascular health by living a healthy lifestyle and speaking with their doctors about risk reduction tools and interventions that may be appropriate for their situation."