Reproductive factors and prognostic risk stratification in breast cancer: A single-centre study from Kerala with the PC-RISK-5 scoring system

Abstract

To examine the associations between reproductive factors — parity, lactation duration, and menopausal age — and tumour characteristics, molecular subtype, and PC-RISK-5 prognostic scores in women with breast cancer from a tertiary centre in Kerala, India. This retrospective cohort study included 221 women with invasive breast carcinoma diagnosed between January 2015 and June 2016 at a tertiary centre in Kerala, India. Molecular subtyping followed the St Gallen 2013 framework (Luminal A defined as Ki-67 <20%; HER2 3+ only). The PC-RISK-5 score assigned one point each for age >60 years, Ki-67 >30%, histological grade ≥II, lymph node positivity, and HER2 (IHC 2+/3+). Patients were stratified into three age bands (≤39, 40–65, >65 years). Associations were assessed using chi-squared, Kruskal–Wallis, and Mann–Whitney tests. Overall survival was analysed using Kaplan–Meier estimates with log-rank comparison. A two-sided p < 0.05 was considered statistically significant. Among 221 women (mean age 55.7 years), invasive ductal carcinoma predominated (93.7%). Later menopausal age was associated with higher PC-RISK-5 scores (mean 2.27, 2.86, and 3.00 across <42, 42–50, and >50 years; p = 0.028) and with greater nodal positivity (19%, 46%, and 57%; p = 0.041). PC-RISK-5 scores differed significantly across molecular subtypes ( p = 0.0003), being highest in HER2-driven tumours. Lactation duration showed a non-significant trend toward lower triple-negative proportion with longer duration (25.9% to 14.9%; p = 0.32). Parity, age at first childbirth, and reproductive factors overall showed no significant association with molecular subtype, grade, or survival. In this Kerala cohort, most reproductive factors were not significantly associated with tumour biology or outcome. Later menopausal age was the notable exception, associated with higher prognostic risk and nodal involvement, consistent with prolonged oestrogen exposure. PC-RISK-5 scores varied with molecular subtype, although this partly reflects shared components.