Clinical Utility of the 70-gene MammaPrint Profile in a Japanese Population

Objective: van't Veer and colleagues developed a 70-gene prognosis profile known as MammaPrint to identify breast cancer patients who were at low risk of developing metastases. We evaluated the prognostic value of the 70-gene MammaPrint profile in Japanese women with node-negative breast cancer.

Methods: Frozen tumour samples from 102 eligible node-negative breast cancer patients aged 70 or younger were characterized with the MammaPrint array. The patients were treated with breast-conserving therapy or mastectomy with axillary lymph node dissection between December 1998 and August 2001. About 73 percent received adjuvant hormonal therapy and 28 percent received adjuvant chemotherapy. The gene expression profiles obtained by MammaPrint classified the patients as high- or low-genomic risk. The median follow-up was 7.1 years.

Results: Among the 102 patients, 20 (20%) were classified as low-genomic risk and 82 (80%) were classified as high-genomic risk. The probability of distant metastasis-free survival at five years was 100% for the low-risk group and 94% for the high-risk group.

Conclusions: The 70-gene MammaPrint prognosis profile accurately identified Japanese breast cancer patients at low risk of developing recurrences. In fact, 100% of the individuals in the low-risk category remained metastasis-free for the duration of the observation period.