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Release: Sept. 21, 1999

Analysis suggests women treated for breast cancer do better with axillary node dissection

IOWA CITY, Iowa -- The good news: The rate of breast-conserving surgery to treat breast cancer has increased steadily since the mid 1980s. The potential bad news: Many women with early stages of the disease do not receive axillary node dissections as part of this treatment, which could mean a lower chance of survival after 10 years, according to a University of Iowa-led analysis.

"It's hard to say in a study like this exactly why there is a survival rate difference because you can't go back and actually find out all the relevant facts," said Carol Scott-Conner, M.D., Ph.D., UI professor and head of surgery. "But the data did show that the women who did not have the dissections had worse survival rates than those who did."

Breast-conserving surgery involves removing just the cancerous tumor without taking the entire breast. Axillary nodes are lymph nodes found under the arm. Axillary node dissections involve taking out roughly 15 of the innumerable lymph nodes through a small incision under the arm.

Originally physicians thought that cancer spread from the local site to the regional lymph nodes and then to the rest of the body. By removing the lymph nodes, a surgeon might prevent the cancer from spreading. However, about 15 years ago, physicians started to believe that cancer spread systemically from the very beginning. The doctors thought that removing the lymph nodes just provided information about how bad the tumor was and didn't actually prevent the cancer from spreading. As a result, many physicians likely decided to forgo dissection.

"People started to think of it as more of a diagnostic procedure instead of something that might actually help to improve survival," Scott-Conner said.

Using National Cancer Data Base information on 547,847 women, Scott-Conner and collaborators at other universities found that surgeons were more likely to forgo axillary node dissection on women with Stage I breast cancer than women with Stage II disease (14.5 percent versus 5.5 percent). The researchers also found that the 10-year relative survival for Stage I women treated with partial mastectomy and axillary node dissection was 85 percent versus 66 percent for comparable women in whom the node removal was omitted.

"We are concerned about the numbers because it really hasn't been proven for breast cancer that you should forgo the axillary node dissection," Scott-Conner said. "Our results were fairly striking. The survival was significantly worse for patients who did not have the dissection.

"If this had been the only study, then I would say, 'Well, we need to get more information.' But there was a similar study from the Rhode Island Tumor Registry. Because it was a smaller group within a single state, they were able to do much more careful analysis of the data. Their results were very similar. I just don't think we have enough information right now to make the leap and say that we can omit doing dissections."

The next step in the dissection debate is to study sentinel node biopsies, Scott-Conner said. This investigation is under way and should be completed in a couple of years. The sentinel node is the lymph node to which the tumor would spread first. There are a couple of ways of figuring out which is the sentinel node, Scott-Conner said. After injecting a dye around the tumor or using a radioactive tracer, cancer specialists can then look for the lymph node that has the marker concentration. This technique has proven useful for detecting melanoma.

"The idea is if you take out the sentinel lymph node and tests indicate it is not cancerous then you shouldn't have to dissect the other nodes," Scott-Conner said. "If it tests positive, you probably ought to remove more lymph nodes because they might also be cancerous."

Scott-Conner's analysis of axillary node dissections appeared in a recent issue of the Journal of the American College of Surgeons and was subsequently abstracted in the Journal of the American Medical Association. The work was supported by the American College of Surgeons and the American Cancer Society.

NOTE TO EDITORS: A videotaped interview with Dr. Carol Scott-Conner is available upon request. Please contact Tom Moore at (319) 356-3945.