Defining clinicopathological and radiological features of breast cancer in women under the age of 35: an epidemiological study.

Introduction: Breast cancer is the most commonly diagnosed female cancer. Diagnosis in younger women (under 35 years) is different to their older counterparts, and mammography is not considered as sensitive in this cohort. Consequentially, younger patients may present later with more advanced disease.

Methods: This is a retrospective analysis of a prospectively updated database containing consecutive patients who presented to the symptomatic breast unit of Galway University Hospital between 2009 and 2015. Patient clinicopathologic factors, clinical examination features, diagnostic radiological modalities and Bi-RADS score were all assessed. Data was analysed using Statistical Package for the Social Sciences version 25.

Results: One thousand eight hundred thirty-six patients were diagnosed with breast cancer, and of these, 51 (2.8%) patients were < 35 years. Invasive ductal carcinoma made up 90% of diagnosis, and 42% had an associated ductal carcinoma in situ. Fifty-four percent were high-grade tumours and 52% presented with stage III disease or greater. The main radiological tool used was ultrasound, which had a sensitivity of 87.50% (95% confidence interval [CI] 74.75 to 95.27%). Mammogram sensitivity was 86.84% (95% CI 71.91 to 95.59%). Magnetic resonance imaging was used in 29% of cases, with a sensitivity of 100.00% (95% CI 78.20 to 100.00%).

Conclusion: Females under 35 tend to be diagnosed with aggressive, advanced stage tumours. Ultrasound remains the radiological test of choice, although diagnosis using mammography demonstrated a relatively high sensitivity compared with previous reports. This study emphasises the varying epidemiology of breast cancer in younger patients and the potential role of mammography in making radiological diagnosis in those who are symptomatic.