Genes Predict Breast Cancer Outcome
Findings Could Affect Whether Chemotherapy Is Prescribed
Dec. 18, 2002 -- We've heard about BRCA1 and BRCA2 gene mutations linked with inherited breast cancer. Researchers are now taking a closer look at genes related to a patient's outcome. A new study shows that genes can help predict which women have a better chance of surviving breast cancer -- even if the cancer has advanced to their lymph nodes.
The findings may also help doctors determine which patients could benefit best from chemotherapy -- sparing patients with poor prognosis from having unnecessary treatments, writes Marc J. Van de Vijver, MD, an oncologist at the Netherlands Cancer Institute in Amsterdam.
His study appears in the Dec. 19 edition of TheNew England Journal of Medicine.
Selecting patients for chemotherapy is a big problem for oncologists, writes Anne Kallioniemi, MD, PhD, a researcher with the University of Tampere in Finland, in an accompanying editorial.
Right now, oncologists base their decision on the patient's age, the size of the tumor, whether lymph nodes show cancer cells, stage of the tumor, and whether the tumor is hormone-receptor positive or negative, she writes.
However, these criteria have not been a fail-safe predictor of how well breast cancer patients will fare. "That uncertainty means that some patients who need chemotherapy do not receive it, whereas others are unnecessarily treated," Kallioniemi writes.
The Dutch study "is an excellent starting point," she writes.
In their study, the Dutch researchers took a closer look at 70 genes they have linked with breast cancer and matched them with tissue from breast cancer tumors in 295 women under age 53, all with early-stage cancer; 144 had cancer cells in their lymph nodes while 151 did not.
In analyzing cells in the women's breast tumors, researchers found that 180 had genes indicating poor prognosis while 115 had genes indicating good prognosis.
Overall survival after 10 years was almost 55% in the poor-prognosis group and almost 85% for the good-prognosis group.
The risk of cancer spreading beyond the breast was five times higher for women who had a poor prognosis profile.
The findings can help doctors identify those breast cancer patients who -- even though they have cancer in the lymph nodes -- might have "an unexpectedly good prognosis," writes Kallioniemi.
It remains to be seen whether genetic tests can accurately identify those patients who will eventually develop metastatic cancer, she writes. Also, further studies are needed to determine whether the genetic profile applies to a broader group of women -- and how treatment will affect disease outcome.
However, the findings do indicate that -- early on -- tumors already have a "genetic code" to metastasize or not, writes van de Vijver. This means that early genetic testing could help doctors determine the best course of action -- and who could benefit from chemotherapy.
They conclude by writing that the gene expression profile method was a more accurate predictor of outcome in this group of women than the currently used criteria, such as lymph node involvement of the tumor.
SOURCE: The New England Journal of Medicine, Dec. 19, 2002.