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Examining Cells Removed During Breast Cancer Surgery May Predict Recurrence (dateline May 2, 2000)

A new study published in the May 2000 issue of the Journal of Clinical Oncology investigates the link between breast cancer recurrence and a protein found on some breast cancer tumors called the p53 tumor suppressor. Up until recently, little has been known about the p53 protein except that, when mutated, p53 can increase a woman’s risk of developing breast cancer. Now researchers from the University of Texas Health Science Center at San Antonio have discovered that if accumulations of the p53 protein are found in cells removed during breast cancer surgery (mastectomy), the patient may be twice as likely to experience a recurrence (return) of breast cancer later in life.

The researchers say a p53 mutation is the most common gene mutation found in breast cancer tumors. When functioning normally, the p53 protein helps to suppress tumors so cancer will not grow and spread. However, when the p53 protein is mutated, it accumulates within the cancer cells. These accumulations of p53 proteins, researchers say, increase the likelihood that breast cancer will return after treatment.

In the study, researchers examined 1,530 women with breast cancer who underwent mastectomies  (breast removal) with or without radiation therapy . The breast cancer cells removed by surgery were analyzed for accumulations of the p53 protein. Among those women who had a mastectomy alone, 17% with p53 accumulations in their cells experienced a return of breast cancer. By comparison, only 9% of the women without p53 accumulations developed breast cancer within five years of their initial treatment.

Among the women who were treated with radiation in addition to mastectomy, 22% of those with p53 accumulations experienced a return of breast cancer while only 9% of women without p53 accumulations developed breast cancer again. The researchers conclude that women with p53 protein accumulations in their breast cancer cells are 50% more likely to experience a recurrence of breast cancer.

Researchers did not investigate why women who had mastectomies followed by radiation therapy had a higher rate of breast cancer recurrence. However, Richard Elledge, MD, director of the Breast Cancer Center at Baylor College of Medicine, does not believe the slightly increased risk of recurrence seen after radiation therapy is significant. Dr. Elledge said that the women treated with radiation therapy typically already had a higher risk of breast cancer recurrence.

Researchers are not certain at this time whether the presence of p53 protein accumulations in cancer cells should influence a patient’s course of treatment. Presently, breast cancer treatment is based on several factors, including tumor size, grade, and the extent to which the cancer has spread. According to the researchers, larger studies of the p53 protein need to be conducted before any alterations in treatment can be suggested.