Gene Finding Presents "Signature" for Breast Cancer
Researchers report they have found a pattern of 76 genes, something geneticists call a "signature," that can predict the return of breast cancer, says a report in the medical journal The Lancet.
Experts say the findings could one day spare many women the painful side effects that accompany chemotherapy.
About 60 percent to 70 percent of women with lymph-node-negative breast cancer are cured by surgery and radiation therapy.
However, guidelines recommend that 85 percent to 90 percent of these women receive chemotherapy to make sure the disease is eradicated.
Knowing which women are unlikely to face a recurrence of cancer could help avoid unnecessary treatments, the researchers explain.
But experts caution this latest gene signature might not be the final answer to predicting the path a breast cancer will take, and other genetic factors may still figure into the recurrence equation.
In the Dutch study, John Foekens, and his colleagues at Erasmus Medical Center in Rotterdam, looked at gene patterns in samples of 286 breast cancer tumors. These samples came from 209 women whose breast cancer had not spread to their lymph nodes, and who had not received hormone therapy or chemotherapy.
During a follow-up of eight years, 93 of the women developed recurrent cancer that had spread beyond the breast to other parts of the body. From these women, the researchers examined 115 tumors.
Based upon their analysis, they identified a 76-gene signature that appears to predict cancer recurrence.
To test their findings, the research team looked for this gene signature in 171 women with lymph-node-negative breast cancer.
They found the gene signature could predict cancer recurrence within five years with 93 percent accuracy. However, it was less predictive in women whose cancer returned after five years, showing a 48 percent accuracy rate.
"Since only 30 to 40 percent of untreated lymph node-negative patients develop tumor recurrence, our prognostic signature could provide a powerful tool to identify those patients at low risk, preventing over-treatment in substantial numbers of patients," says Foekens.
"If confirmed in subsequent studies, the recommendation of adjuvant systemic therapy in patients with lymph-node-negative primary breast cancer could be guided by this prognostic signature," he concludes.
While the author of an accompanying commentary thinks the study is important, he notes that the signature is not the whole story in predicting cancer recurrence.
"This particular gene signature might not be the only one that is important," says Tor-Kristian Jenssen, from PubGene AS, in Oslo, Norway. He noted that other studies have found gene signatures related to prognosis, and the varying results are conflicting.
"In a complex disease like breast cancer, there are many factors and there could be different processes going on in different patient groups," Jenssen says. "That's why this is not the final answer."
"I agree with the commentary," says Debbie Saslow, director of breast and gynecologic cancer at the American Cancer Society. "These papers come out, and they look very promising, and there is a lot of excitement for the potential for this technology, but we're not at a point yet where we feel that it's ready to use."
Saslow does think the problem the researchers are tackling is very important.
"There are a whole lot of women who get diagnosed with breast cancer who don't need aggressive treatment," she says. "We are treating almost all of them, and there is a huge need to identify which ones would truly benefit, so that we can spare the others the side effects.
"So, the problem is extremely important and I hope this pans out, but at this point we have to wait and see," Saslow says.
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