Verification of a prolonged untreated natural history of breast cancer by the multigene assay.

Individualization of therapy for breast cancer patients has progressed significantly over the last 5 years. A 54-year-old female went over 2 years after her diagnosis of breast cancer with no treatment. The pathologic size, however, indicated that the tumor may not have progressed from diagnosis to operation. Due to the apparent lack of progression over 2 years without treatment, a multigene assay was ordered. The recurrence score was 15, indicating a less than 10% risk of distant recurrence at 10 years. The recurrence score also falls into the "low risk" category. The prolonged natural history of this breast cancer patient suggested an indolent cancer. The "low risk" recurrence score confirmed this history and indicated that adjuvant chemotherapy is probably not beneficial to this patient.