Research by investigators at The Cancer Institute of New Jersey suggests post-mastectomy radiation therapy may not have a significant effect on disease recurrence or mortality rates in early-stage breast cancer patients with one to three cancerous lymph nodes.

The results are part of a presentation given in early May at the 13th annual meeting of the American Society of Breast Surgeons, in Phoenix.

CINJ is a part of the University of Medicine and Dentistry of New Jersey-Robert Wood Johnson Medical School. Its network is comprised of hospitals throughout the state.

Disease staging for breast cancer is dependent on whether axillary lymph nodes—located in the armpit—are involved, and node status, positive or negative, is considered a valuable prognostic indicator in the management and treatment of breast cancer. The role that radiation therapy plays remains a matter of controversy when it involves women who have had a mastectomy after early-stage breast cancer (classified as T1 or T2 disease; not having spread to other organs) and one to three cancerous axillary lymph nodes.

As suggested by National Comprehensive Cancer Network guidelines, treatment discussion is encouraged on a case-by-case basis for patients in this group, as specific treatment recommendations are unclear. Investigators at CINJ examined the effect of post-mastectomy radiation as it relates to recurrence rate and mortality.

The study used data from a retrospective review of patient charts from 1986 to 2004, focusing on those patients with breast cancer who had either T1 or T2 disease and between one and three positive axillary lymph nodes. In this group, 83 patients were identified and divided into two groups: 38 women who received post-mastectomy radiation and 45 who didn't. Patient and tumor-related characteristics were examined.

The groups were similar with respect to age at diagnosis and estrogen receptor status. Differences were found in the groups with regard to number of positive lymph nodes, which in turn led to more patients receiving post-mastectomy radiation treatment.

In the group that underwent post-mastectomy radiation, 11 of 38 (29 percent) had disease recurrence with a median time to recurrence of 49.6 months. In the group that didn't receive radiation following mastectomy, 10 of 45 (22 percent) had a recurrence, with a median time to recurrence of 46.8 months. Investigators determined there was no statistically significant difference in recurrence rates between the two groups. Additionally, there was no significant difference in the site of recurrence, with distant recurrence being the most common in six of 11 patients who received radiation and in seven of 10 patients who didn't.

The research also shows no statistically significant difference with regard to mortality rate between the two groups. There were nine deaths among the 38 patients (24 percent) that were treated with post-mastectomy radiation and nine deaths among the 45 patients (20 percent) in the group that didn't receive radiation.

Dr. Archit Naik, breast surgery fellow at CINJ and the medical school, is the lead researcher on the study.

"With no standard approach to treating patients within these particular subcategories, it is important to explore the effects of current therapies so that we can continue to tailor treatments to a patient's specific cancer and hopefully improve outcomes," Naik says.

Naik and colleagues further note that given the small number of subjects and other potential variables, future studies with larger groups are needed.