Genetic 'Signature' Predicts Breast Cancer Recurrence

Technique also works for prostate, lung and brain cancer, study says

WEDNESDAY, Jan. 17, 2007 (HealthDay News) -- A genetic "signature" that consists of 186 genes combined together can predict the risk of breast cancer recurrence in women with the disease, a new study found.

And the same set of genes also predicts the recurrence of prostate cancer, lung cancer and medulloblastoma, the most common form of childhood brain cancer, the researchers said.

"This is very impressive data that will hopefully be able to predict which patients can benefit or not benefit from certain types of treatment," said Dr. Jay Brooks, chairman of hematology/oncology at Ochsner Health System in Baton Rouge, La., who was not involved with the study. "Whether this can be taken into the direct clinical arena will remain to be seen."

The authors of the study, from Stanford University and the University of Michigan, said they're already working to make the findings available to doctors and their patients. The findings are published in the Jan. 18 issue of the New England Journal of Medicine.

A small number of cells within breast cancer are believed to be the ones that actually cause the cancer to grow. These "cancer stem cells" were first identified in 2003.

The authors of the new study compared the gene expression profile of breast cancer stem cells with that of normal breast cells. From that data, the researchers culled a list of 186 genes that comprised an "invasiveness" gene signature. This signature was then evaluated to see how it related to overall survival as well as metastasis-free (no cancer spread) survival in patients.

As it turned out, there was a strong correlation between the gene signature and both overall and metastasis-free survival, the researchers said.

The gene signature was then combined with prognostic criteria from the National Institutes of Health to classify patients into those with a "good" or "poor" prognosis. Those with a good prognosis had a 10-year rate of metastasis-free survival of 81 percent, while those with a poor prognosis had a rate of 57 percent.

And when the gene signature was combined with a second group of genes previously identified by researchers, the signature's predictive value was even more accurate, the researchers said.

A second study in the same issue of the journal found that denser breasts were associated with a higher risk of breast cancer, and the risk was elevated in cancers found both at screenings and in the period between screenings. The study's lead author is Dr. Norman Boyd, a senior scientist with The Campbell Family Institute for Breast Cancer Research at Princess Margaret Hospital, in Toronto.

Women with breast density in 75 percent or more of their baseline mammogram had about a five times greater risk of breast cancer, compared with women who only had density in 10 percent of their first-ever mammogram. The findings held true after adjusting for all known risk factors for the disease.

These findings confirm previous research, but they use more modern technology, Boyd said. "We wanted to see whether we would see similar messages with modern mammography, and we did," he said. "We also wanted long-term observation."

"Women should understand that this [breast density] is indeed a risk factor with the same kind of awareness they might accept knowing that some of their relatives have breast cancer," Boyd said. "If they know they have dense breast [tissue] and something changes, they may report it more promptly."

And women on hormone replacement therapy, which can increase breast density, should talk with their doctor about what they should do, he said.

More information

For more on breast cancer, visit the American Cancer Society.

SOURCES: Norman F. Boyd M.D., D.Sc., senior scientist, The Campbell Family Institute for Breast Cancer Research, Princess Margaret Hospital, Toronto; Jay Brooks, chairman of hematology/oncology, Ochsner Health System, Baton Rouge, La.; Jan. 18, 2007, New England Journal of Medicine
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