Research
by Sparano et al published in the NEJM
suggests that the gene test known as Oncotype
DX may help women with early stage breast cancer avoid chemotherapy.
The authors performed a prospective
trial involving women with hormone-receptor–positive, HER2–negative, axillary
node–negative breast cancer with tumors of 1.1 to 5.0 cm in the greatest
dimension (or 0.6 to 1.0 cm in the greatest dimension and intermediate or high
tumor grade). The Oncotype DX assay
of 21 genes was performed on the tumor tissue, and the results were used to
calculate a score indicating the risk of breast-cancer recurrence; patients
were assigned to receive endocrine therapy without chemotherapy if they had a
recurrence score of 0 to 10 on a scale 1 to 100, indicating a very low risk of
recurrence.
Of the 10,253 eligible women
enrolled, 1626 women (15.9%) who had a recurrence score of 0 to 10 were
assigned to receive endocrine therapy alone without chemotherapy. At 5 years,
in this patient population, the rate of invasive disease–free survival was
93.8%, the lack of metastasis at a distant site was 99.3%, and the rate of
overall survival was 98.0%.
The authors concluded that patients
with hormone-receptor–positive, HER2-negative, axillary node–negative breast
cancer, those with tumors that had a favorable gene-expression profile the test
accurately identified the group of women whose cancers are likely to
respond to hormone-blocking drugs and adding chemo would do little if any good
while exposing them to side effects and other health risks. The researchers found that patients who
skipped chemo based on the test had a small chance of cancer recurrence at 5 years with endocrine therapy alone.
