Clinicopathologic, molecular subtype, and survival prognostic features in premenopausal breast cancer patients by age at diagnosis.

Abstract

653 Background: Studies show that breast cancer patients younger than 35 at diagnosis differ from older patients in terms of cancer size, survival, and recurrence risks. We analyzed patients according to age at diagnosis (<35 and ≥35 years). Methods: We reviewed 518 cases of operable and premenopausal breast cancer patients diagnosed between 2000 and 2002 at the Instituto Nacional de Enfermedades Neopláasicas (Lima, Peru). We compared overall survival (OS) and disease-free survival (DFS) by age at diagnosis, according to clinicopathologic and molecular subtype: luminal A (ER+ and/or PR+, HER2−) luminal B (ER+ and/or PR+, HER2+); triple-negative (ER−, PR−, HER2−), and HER2 (ER−, PR−, HER2+). We used univariate and multivariate analyses with Kaplan-Meier and Cox regression. Results: Median follow-up was 7.4 years. There was significant difference (p=0.023) between molecular subtype by age group, in the 6-year DFS (57.8% vs. 79.5%, p<0.001), in the 6-year OS (65.1% vs. 84.3%, p<0.001). Patients were analyzed according to node status; there was significant difference in DFS in the metastatic node group (49.5% vs. 76.4%, p<0.001) and negative- node group (71.2% vs. 87.0%, p=0.028) for patients <35 and ≥35 years, respectively. Patients were thus analyzed by molecular subtype; there was significant difference in SLE (p<0.001) in patients <35 versus ≥35 years. Multivariate analysis showed that in patients <35, molecular subtype (HER2 and triple-negative) and node metastases were risk factors for disease recurrence. When molecular subtype and subtype luminal A (reference group) were compared, the HER2 group had a hazard ratio (HR) =1.7 (95%CI 1.1−2.7) and triple-negative subtype HR=2.4 (95%CI 1.5−3.8). Conclusions: Premenopausal patients <35 years with metastatic nodes, luminal A, and triple-negative molecular subtypes have a higher risk of recurrence than those ≥35 years. Molecular subtype and DFS N pt P (chi-squared test) 6-year DFS (%) P value <35 years ≥35 years <35 years ≥35 years Luminal A 36 (47.8%) 207 (42.4%) 55.6 85.8 <0.001 Luminal B 9 (18.2%) 79 (10.6%) 56.0 77.0 0.09 HER2 28 (19.0%) 82 (32.9%) 70.5 74.0 0.69 Triple-negative 12 (15.0%) 65 (14.1%) 0.023 37.0 70.0 0.03 Total 85 433 No significant financial relationships to disclose.