Recent results from a study published in the International Journal of Radiation Oncology • Biology • Physics (Red Journal), the official scientific journal of the American Society for Radiation Oncology (ASTRO), show that overall survival in breast cancer patients who underwent breast-conserving surgery and adjuvant external beam radiation therapy, is independent of tumor laterality (left vs right-side).
Even though radiation therapy improves local-regional recurrence, breast cancer survival after breast-conserving surgery and overall survival after mastectomy, some studies have shown an increase in cardiac mortality.
Nonetheless, these studies used earlier forms of radiation therapy, and did not employ CT-based planning, that can help to preserve the surrounding tissues and avoid unwanted cardiac side effects.
In the recent study “Breast Cancer Laterality Does Not Influence Survival in a Large Modern Cohort: Implications for Radiation-Related Cardiac Mortality”, the authors analyzed National Cancer Database (NCDB) data from 344,831 patients diagnosed with breast cancer between 1998 and 2006. The NCDB database includes histopathologic data and specific treatment information such as sequencing of therapies, dose, technique and target.
All of the patients analyzed suffered from ductal carcinoma in situ (DCIS) or invasive carcinoma of any histologic subtype, and received external beam radiation therapy after breast-conserving surgery.
Data showed that 50.7% of women had left breast tumors, while 49.3% had right breast tumors.
After adjusting for age, grade, estrogen receptor status, tumor size, number of positive nodes, receipt of chemotherapy and receipt of endocrine therapy, the results showed that at 5 and 10 years of follow-up, both left and right-sided patients had an overall survival (OS) of 92% and 78%, respectively, suggesting that OS is independent of tumor laterality.
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“The delivery of radiation therapy for breast cancer is markedly different today than it was several decades ago when the association between breast radiation, cardiac disease and cardiac death was observed. Treatment planning and more advanced treatment techniques and technologies have reduced the risk to the heart,” Charles E. Rutter, MD, lead author of the study and a fourth-year resident in the Department of Therapeutic Radiology at Yale School of Medicine in New Haven, Connecticut, said in an ASTRO press release. “This study demonstrates that the advances in breast radiation oncology have made treatment safer, and should reduce patients’ fears of cardiac risk and impact on their overall health after they complete their cancer treatment.”
