Comparison of Clinicopathological Features and Treatments between Young (≤40 Years) and Older (>40 Years) Female Breast Cancer Patients in West China: A Retrospective, Epidemiological, Multicenter, Case Only Study.

Ke Wang,Yu Ren,Qilun Liu,Ke Zheng,Wei Wei,Jianghua Ou,Ling Wang,Ling Wang,Jianjun He,Hui Li,Guosheng Ren,Guosheng Ren,Ke Zheng,Jun Jiang,Tianning Zou,Binlin Ma,Binlin Ma,Hongyuan Li,Hongyuan Li,Yves St-Pierre

doi:10.1371/journal.pone.0152312

Abstract

The incidence of young cases of breast cancer is higher in China compared to the western world. We aimed to explore differences in risk factors, clinicopathological features and treatment modes of young female breast cancer compared to older patients in West China. We collected clinical information from 12,209 female breast cancer patients in West China, including risk factors, clinicopathological features and treatment modes, from January 2010 to December 2012. Chi-square tests and the multivariate logistic regression analysis were applied for statistical analysis. There were 2,682 young (≤40 years) cases and 9,527 older cases at the time of breast cancer diagnosis. Young patients had a greater tumor diameter at diagnosis, and a higher probability of axillary lymph node and distant metastasis (P < 0.05). The progesterone receptor positive expression rate, estrogen receptor/progesterone receptor double positive expression rate, and human epidermal growth factor receptor 2 (HER2) negative expression rate was higher in young patients compared to older patients (P < 0.05). For young patients, the age at menarche was earlier, they had lower marriage rates, fewer pregnancies and births, and a lower breastfeeding rate (P < 0.05). A higher proportion of young patients underwent advanced operations, neoadjuvant and adjuvant chemotherapy, radiotherapy, and endocrine therapy compared to older patients (P < 0.05). We found significant differences in the clinicopathological features, risk factors and treatment modes between young (≤40 years) and older (>40 years) female breast cancer patients in West China. As some of these results differ from those found in the western female population, it is likely that the mechanism of tumorigenesis of young female breast cancer patients in West China may differ from that in western developed countries. Further investigation into the regional differences in breast cancer tumorigenesis is warranted.

Highlights

Differences in the clinical and biological characteristics between young and older breast cancer patients have been observed
We found significant differences in the clinicopathological features, risk factors and treatment modes between young (40 years) and older (>40 years) female breast cancer patients in West China
As some of these results differ from those found in the western female population, it is likely that the mechanism of tumorigenesis of young female breast cancer patients in West China may differ from that in western developed countries

Summary

Introduction

Differences in the clinical and biological characteristics between young and older breast cancer patients have been observed. In 2010, the crude incidence rate of female breast cancer patients were 32.43 per 100,000 and the estimated number of death was about 55,500 in China.[4] Several studies have shown that young patients (40 years) accounted for about 20% of the total breast cancer cases in China [5, 6], which is significantly higher than that of western population (i.e., around 5%) [7, 8]. This suggests the possibility that certain differences in the pathogenesis of breast cancer may exist between young Chinese women and women in the western population

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