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Key Words: breast cancer, lumpectomy, mastectomy, radiation therapy. (Definitions of many terms related to cancer can be found in the Cancer.gov Dictionary ².)

Women with relatively small breast cancers who were treated with breast-conserving surgery plus radiation therapy were as likely to be alive and disease-free 20 years later as women treated with mastectomy (surgery to remove the affected breast), two groups of researchers report in separate studies published in the October 17, 2002, issue of the New England Journal of Medicine.

These results should lay to rest the long-running debate over whether mastectomy is better than breast-conserving surgery, comments Monica Morrow, M.D., of Northwestern University Feinberg School of Medicine, in an accompanying editorial.

“The failure to observe a survival advantage of mastectomy after 20 years should convince even the most determined skeptics that mastectomy is not superior to breast conservation for the treatment of breast cancer,” Morrow writes.

Jeff Abrams, M.D., of the National Cancer Institute’s Cancer Therapy Evaluation Program agrees. “We now have results from two studies showing that long-term survival is identical with breast-conserving surgery and radiation therapy, compared with mastectomy,” he says.

The two studies report the results of a 20-year follow-up of women who took part in two clinical trials comparing mastectomy with breast-conserving surgery in the 1970s and 1980s. One trial, involving 1,851 women, was conducted in the United States. The second trial, with 701 patients, took place in Italy. (See the journal abstracts: Fisher et al. and Veronesi et al.)

In the U.S. trial, women were randomly assigned to be treated with mastectomy, lumpectomy (removal of the tumor and some surrounding tissue) alone, or lumpectomy plus radiation therapy. Underarm lymph nodes were removed in all participants. All women enrolled in this trial had tumors no larger than 4 centimeters (about 1.5 inches) in diameter. About 40 percent of the participants had cancer that had spread to lymph nodes in the armpit. Most women were aged 50 or older when they enrolled in the trial.

In the Italian trial, participants received either radical mastectomy (a more extensive operation that removes muscle tissue and lymph nodes as well as the breast) or a breast-conserving procedure called “quadrantectomy” (similar to but more extensive than lumpectomy in which the underarm lymph nodes are removed) plus radiation therapy. All women enrolled in this trial were under age 70 and had tumors no larger than 2 centimeters (less than 1 inch) in diameter; most had no cancerous lymph nodes.

Twenty years later, 681 women (37 percent) who took part in the U.S. trial were alive and cancer-free. Survival rates were not significantly different in the three treatment groups. In the Italian trial, 393 women (56 percent) were alive 20 years later. As in the U.S. trial, survival rates did not differ according to the treatment the women received.

The differences in survival between the two trials reflect the fact that women with larger tumors were permitted to enter the U.S. trial, and these tumors are known to spread beyond the breast more frequently.

In the U.S. trial, 14 percent of women treated with lumpectomy plus radiation therapy had a recurrence of cancer in the same breast, compared with 39 percent of women who received lumpectomy alone. Lumpectomy plus radiation therapy and surgical removal of affected lymph nodes is now the standard of care for women with breast tumors up to 5 centimeters, according to Abrams. In the Italian trial, 9 percent of women who had breast-conserving surgery plus radiation therapy had a recurrence of cancer in the same breast, compared with 2 percent of those treated with radical mastectomy.

“Both of these studies show that local recurrences in women treated with conservative surgery and radiation can be effectively treated when they recur, as proven by the absence of a difference in survival compared with women who received a mastectomy,” said Abrams. “Most women are effectively treated with lumpectomy and radiation, and do not need a mastectomy. It is preferable to treat with mastectomy only those women who have a local recurrence after lumpectomy.”

Quadrantectomy, the breast-conserving procedure used in the Italian trial, is not used frequently in the United States but is necessary in some cases to remove a somewhat larger tumor, Abrams said. Radical mastectomy is rarely performed any more.

Glossary Terms

Surgery to remove abnormal tissue or cancer from the breast and a small amount of normal tissue around it. It is a type of breast-sparing surgery.

Surgery to remove the breast (or as much of the breast tissue as possible).

The use of high-energy radiation from x-rays, gamma rays, neutrons, protons, and other sources to kill cancer cells and shrink tumors. Radiation may come from a machine outside the body (external-beam radiation therapy), or it may come from radioactive material placed in the body near cancer cells (internal radiation therapy). Systemic radiation therapy uses a radioactive substance, such as a radiolabeled monoclonal antibody, that travels in the blood to tissues throughout the body. Also called irradiation and radiotherapy.

A study in which the participants are assigned by chance to separate groups that compare different treatments; neither the researchers nor the participants can choose which group. Using chance to assign people to groups means that the groups will be similar and that the treatments they receive can be compared objectively. At the time of the trial, it is not known which treatment is best. It is the patient's choice to be in a randomized trial.

The percentage of people in a study or treatment group who are alive for a certain period of time after they were diagnosed with or treated for a disease, such as cancer. The survival rate is often stated as a five-year survival rate, which is the percentage of people in a study or treatment group who are alive five years after diagnosis or treatment. Also called overall survival rate.