Area Around Breast Tumor Can Predict Recurrence

A key to predicting whether a certain type of breast cancer will return after surgery lies in the tissue surrounding the tumor. If a large enough margin of neighboring tissue is free from any residual cancer cells after the surgery, a new study reports, the chances are smaller that the cancer will come back.

The study, recently published in the journal Cancer, adds to a growing body of evidence showing that the cells found in the margin of tissue surrounding the tumor can act as a major predictor of whether the disease will recur after the operation.

Although the finding is not new, it does confirm several earlier studies showing that the larger the margin of normal tissue around a breast cancer—and the smaller the cancer itself—the less chance that residual cells are left behind after surgery. And that means less chance the cancer will recur.

"It's the margin that determines the likelihood of residual tumor being found in the breast," says study author Dr. Andrew Neuschatz, a radiologist at the New England Medical Center in Boston.

The study also suggests that women who have a low risk of residual disease may be able to skip the radiation therapy that usually follows surgery. However, other researchers who have conducted similar studies say women should not jump to that conclusion just yet.

"The margin width is the most important thing—and there are a subgroup of women in whom you might be able to skip radiation—but this study hasn't shown that yet," says Dr. Jeanne Petrek, director of surgery at Memorial-Sloan Kettering's Evelyn Lauder Breast Center in New York City. "It merely suggests that this idea be looked at in a future study."

The findings pertain to a specific type of non-invasive breast cancer known as ductal carcinoma in situ (DCIS). This involves cancerous changes in cells lining the breast ducts that carry milk to the nipple. DCIS makes up between 5 percent and 10 percent of all breast cancers, and is unlikely to invade other areas of the breast. Currently, the most common method of treatment is a lumpectomy or a modified radical mastectomy—a decision that is often based on the size of the lump and the size of the breast.

"If the tumor is large and the breast is small, it would require removing so much tissue a woman might be better off cosmetically having a mastectomy," says Petrek.

If a lumpectomy is performed, experts say the goal is to remove the cancer and at least some surrounding tissue, known as the "margin." If examination of that surrounding tissue finds it free of cancer cells, it is thought to be a "negative margin." If cancer cells are found, it is a "positive margin."

Previously, physicians believed that cancer recurrence could be influenced not only by the margin status, but also the age of the patient, the size of the original cancer, and how far advanced it was at the time of removal—a classification known as staging.

Based on the new study, however, researchers say the only factor that really matters in predicting future disease is whether there is a wide enough margin of "negative," cancer-free cells removed from the tumor site.

"DCIS lesions with negative margins, or even minimally positive margins, have a fairly low likelihood of containing residual tumor in the breast as shown on re-excision," says Neuschatz. And that, he says, is usually indicative that a cancer won't recur.

Always consult your physician for more information.

To become better informed about cancer risks and early detection, contact your nearest Sisters of Mercy Health System hospital or clinic.