A new testing method that analyzes the genetic signature of breast cancer tumors may be better than the methods doctors now use to predict whether the cancer will spread, and whether a woman needs chemotherapy, according to researchers.

Dutch researchers said the genetic signature -- the activity of a collection of 70 genes — appears to predict the likely progression of breast cancer better than such measures as the size of the tumor when it is discovered, or whether cancer has spread to a woman's lymph nodes.

In their study of 295 patients reported in the New England Journal of Medicine, the researchers said that 45 percent of those found to have a "poor prognosis" genetic signature died within a decade, compared to only 5.5 percent of women whose cancers had a "good prognosis" genetic signature.

"The gene-expression profile we studied is a more powerful predictor of the outcome of disease in young patients with breast cancer than standard systems based on clinical and histologic criteria," the researchers reported.

While the test is still regarded as experimental, researchers hope that a genetic test of this type may someday spare women with a "good prognosis" the ordeal of chemotherapy with its side effects of nausea, fatigue and hair loss.

Dr. Anne Kallioniemi of the University of Tampere in Finland, in an accompanying editorial, called the study"an excellent starting point" but noted that more trials are needed on patients of different ages and different breast cancer stages.

She pointed out that researchers also need to determine whether this genetic profile is the last word "or whether there will be a need to refine or expand this list of genes."

Other sources: New England Journal of Medicine