Tumour biology and survival outcomes in young women with breast cancer: single-centre retrospective analysis.

Introduction: Breast cancer is the most common malignancy worldwide. The disease is more severe in younger women and often confers a poorer prognosis. This study aimed to profile a cohort of young women with breast cancer and address whether aspects of their tumour biology were related to their long-term outcomes.

Methods: The records of consecutive women aged 40 and under with a diagnosis of breast cancer at a single centre between 1 January 2010 and 30 December 2015 were analysed and a profile was created. They were followed up until 19 July 2023 (median 112 months, range 4-161), and the impact of oestrogen positivity (ER+), human epidermal growth factor 2 positivity (HER2+), tumour grade, axillary lymph node metastases and Ki67 value on overall survival and disease-free interval (DFI) was investigated.

Results: One hundred and sixty-four patients were included. Younger patients typically presented with large, high-grade tumours with axillary lymph node metastases, and 83.2% of the cohort were alive at 5 years. ER+ tumours appeared to have a better 5-year survival: ER+/HER2- 86.3%, ER+/HER2+ 88.5%, ER-/HER2+ 71.4%, and triple-negative (ER-/HER2-) 70.8%. However, neither the log-rank test nor the Cox regression model found a significant effect of ER status and long-term survival (P = 0.485 and P = 0.158 respectively).

Discussion: Young patients with breast cancer have a lower 5-year survival than the UK average for all ages, and patients in this single-centre study with ER+ tumours appeared to have better short-term but similar longer-term outcomes compared to ER- breast cancer.