Radiation Therapy for Breast Cancer: Three New Studies

What's new in breast cancer radiation therapy news? Last week we added three studies on radiation to the LATESTBreastCancer.com database and website. Topics include postmastectomy radiation, radiation of the axilla and heart related side-effects.

Radiation after mastectomy reduces recurrence rates in women with large breast tumors

An August 20 study from MD Anderson in the International Journal of Radiation Oncology, Biology Physics examined recurrence rates of 162 patients with clinically T3N0 tumors who were treated with neoadjuvant (before surgery) chemotherapy and mastectomy. 'T3' means the tumors were larger than 5 cm. 'N0' means there was no lymph node involvement. (For some of the patients, pathological evaluation later revealed lymph node involvement.)

The study revealed that women who also received postmastectomy radiation were less likely to experience a local-regional recurrence (LRR) than those who did not receive radiation. Postmastectomy radiation reduced recurrence rates in women with and without lymph node involvement. Accordingly, the authors suggested that postmastectomy radiation be considered for women with T3N0 breast cancer.

Whole breast radiation is sufficient to prevent lymph node recurrence after sentinel lymph node procedure

An August 31 study in Cancer from the Memorial Sloan-Kettering Cancer Center evaluated the effectiveness of whole breast irradiation in preventing lymph node recurrence in 326 women with positive sentinel lymph nodes (SLNs) who did not undergo axillary lymph node dissection. Instead of removing all lymph nodes in the axilla area, only the sentinel lymph nodes were removed. 93% received some sort of radiation therapy.

After 4 years, 3 of the 326 women experienced a lymph node recurrence. Two of them received radiation in the standard supine (face-up) position. One did not receive radiation at all. There was no lymph node recurrence among the 66 who received radiation in the prone (face-down) position.

The authors concluded that regional control was high (99% at 4 years) in women with low-volume sentinel lymph node disease, "regardless of whether the axilla was irradiated." They noted,

"Whole-breast radiation alone, including in the prone position, is sufficient treatment after breast-conserving surgery for select patients with tumor-containing SLNs who omit axillary dissection."

Risk of cardiovascular disease after radiation is greater in older women with left-side breast cancer

An August 30 study in Cancer Epidemiology, Biomarkers & Prevention evaluated the risk of cardiovascular disease in 806 women over 65 with early stage breast cancer.

As a group, radiotherapy was not associated with a greater risk of cardiovascular disease. However, among women who received radiation, those who were treated for cancer of the left breast had a significantly increased risk of cardiovascular disease compared to those with right-side breast cancer.

The authors concluded that laterality (the side of treatment) "is critical to understanding the effect of" radiotherapy on cardiovascular disease. "As some irradiation to the heart is unavoidable, . . . continued effort is required to minimize such exposures, especially in older women with left-sided tumors."

To see all the latest news and research on radiation therapy for breast cancer, please visit the LATESTBreastCancer.com website. Click on the "Treatments" tab and search for "radiation" or "postmastectomy".