The 70-Gene Profile (MammaPrintTM) Is an Independent Predictor of Breast Cancer Specific Survival for Women 65 Years of Age or Older.

Abstract

Abstract Background: One-half of all new breast cancer diagnoses occur in women age 65 years or older. In this age group, the use of adjuvant chemotherapy is largely influenced by co-morbidity and little is known about the applicability of prognostic multi-gene assays. The 70-gene profile (MammaPrint) is an independent prognostic indicator in early breast cancer, however, its performance in women with breast cancer 65 years or older has not been systematically studied.Methods: Women 65 years or older who were diagnosed at the Jules Bordet Institute and the Netherlands Cancer Institute between 1987 and 2003 with primary breast cancer with 0-3 involved lymph nodes who received either no adjuvant systemic therapy or adjuvant hormonal therapy alone were selected. MammaPrint test results were compared with clinical-pathological risk assessment using Adjuvant!Online.Results: Of 204 women aged 65 years or older (median age 70 years), 129 (63.2%) were classified as genomic low risk and 75 (36.8%) as genomic high risk. After a median follow-up of 8.6 years (range 0.3-17.9), the 5- and 10-year breast cancer specific survival (BCSS) for the genomic low risk group was 96% (SE 2%) and 86% (SE 4%) versus 82% (SE 4%) and 66% (SE 6%) for the genomic high risk group (log-rank p=0.001). In univariate analysis, MammaPrint was prognostic for 5-year BCSS (HR=5.0, 95%CI 1.8-14.1, p=0.002) and 10-year BCSS (HR=3.1, 95%CI 1.6-6.0, p=0.001). In a multivariate model adjusted for 10-year risk predicted by Adjuvant!Online, MammaPrint was independently prognostic for 5-year BCSS (HR=4.4, 95%CI 1.6-12.7, p=0.005) and 10-year BCSS (HR=2.5, 95%CI 1.3-5.0, p=0.009). As in prior validation series, the performance of MammaPrint was time dependent, with improved prognostication for early BCSS (≤5 years).Conclusion: Although a smaller proportion of breast cancers diagnosed in women 65 years or older are classified as high-risk by MammaPrint, it is an independent prognostic indicator that may be useful to select patients that can safely forego adjuvant chemotherapy. Additional data from patients over 70 years of age will be available at the time of the meeting. If these data are confirmatory, the ongoing prospective MINDACT trial will be amended to include older women. Citation Information: Cancer Res 2009;69(24 Suppl):Abstract nr 4049.