Novel imaging technique may reduce lymphedema in breast cancer patients

With guidance from a specialized scan, radiation oncologists at Mayo Clinic (http://www.mayoclinic.org/) were able to reduce by 55 percent the number of lymph nodes critical for removing fluid from the arm that received damaging radiation doses.

VIDEO ALERT: Additional audio and video resources, including excerpts from an interview with Dr. Andrea Cheville and other researchers presenting at San Antonio Breast Cancer Symposium, are available on the Mayo Clinic News Blog (http://newsblog.mayoclinic.org/2010/12/06/lymphedema-study/). These materials also are subject to embargo, but may be accessed in advance by journalists for incorporation into stories. The password is sanantonio1.

The researchers report that integrating single photon emission computed tomography (SPECT) with the computerized tomography (CT) scans utilized for breast cancer radiotherapy planning may offer patients substantial protection against lymphedema, an incurable, chronic swelling of tissue that results from damage to lymph nodes sustained during breast cancer radiation. The SPECT-CT scan pinpoints the precise locations of the lymph nodes that are critical for removing fluid from the arm, allowing physicians to block them, as much as possible, from X-ray beams delivered to the chest.

These findings were presented at the 33rd Annual CTRC-AACR San Antonio Breast Cancer Symposium.

"In an effort to deliver therapeutic doses of radiation to the breast, lymph nodes under the arm are innocent bystanders that often are irrevocably harmed. Minimizing harm to these nodes during breast cancer treatment is the most effective way we have seen to reduce women's risk of developing lymphedema," says the study's lead investigator, Andrea Cheville, M.D., a consultant in Physical Medicine and Rehabilitation at Mayo Clinic in Rochester, Minn. (http://www.mayoclinic.org/rochester/), who specializes in lymphedema management.

"Lymphedema is a critical concern of breast cancer survivors, so developing a more individualized approach to irradiation is greatly needed," she adds.

This ongoing prospective cohort study includes 30 women with early-stage, low-risk breast cancer who had completed surgery to remove tumors and were scheduled for radiotherapy to the affected breast. These patients either had no lymph nodes that were known to be positive (meaning the cancer had not spread to these sites), or had only micrometastasis to lymph nodes. Thus, radiation to the lymph nodes in the armpit was not warranted in these patients.

The technique the researchers developed to shield lymph nodes from radiation involved merging SPECT scans with the CT images utilized in radiation treatment planning.

"We can know exactly where the critical lymph nodes are under the armpit," Dr. Cheville says, adding that critical nodes are the ones that drain the arm. "While a person can have as many as 62 lymph nodes under the arm, only a few are responsible for that function."