Differential Expression of Prognostic Factors and Effect on Survival in Young (≤40) Breast Cancer Patients: A Case-Control Study

Abstract

The belief that young women develop more aggressive forms of breast cancer than other women is controversial. The purpose of this study was to determine if women 40 years of age and under with breast cancer have more negative prognostic indicators and a higher 5-year mortality than those women over 40 years of age. From January 1998-December 2002, all women with breast cancer were identified from our tumor registry. Women with metastatic disease at presentation were excluded from our study. The women were divided into two groups, women under 40 (cases) and women 40 and over (controls). Seventy-eight cases were identified and matched to 228 controls. These cohorts were matched 3:1 (cases:controls) based on tumor staging. The data collected on each patient included prognostic factors such as tumor size, tumor type, estrogen and progesterone receptors, Her2/neu, and Ki-67. Information on surgical procedure, postoperative therapy, recurrence, and mortality was also gathered. The mean ages for cases and controls were 35 and 59 years, respectively. The rates of modified radical mastectomy were similar in the two groups, but young women were more likely to have breast reconstruction (33.7% vs 9.8%). The rates of breast conservation therapy were actually lower in the group under 40 (32.5% vs 37.6%). Tumors in the 40 and under group were more frequently estrogen receptor negative (33.8% vs 21.9%: P = 0.046) and progesterone receptor negative (50.0% vs 35.5%: P = 0.033). Younger women also experienced a greater prevalence of Ki-67 (P < 0.001) and higher levels of Her2/neu overexpression (P = 0.013). Women over 40 were more likely to receive hormonal therapy (39.7% vs 36.1%). Women over 40 had a lower overall rate of recurrence. A difference in overall survival does exist between these two groups of women, which trends toward significance. The women 40 and under had a lower overall 5-year survival. The reason for this difference remains unclear. Although we demonstrate a higher percentage of younger women with negative biochemical markers, the only factors independently and significantly related to higher mortality were estrogen receptor negativity and tumor stage at presentation.