Why do large breast cancers still present in a population offered screening?

Area of Science:

• Epidemiology
• Oncology
• Public Health

Background:

• Mammography screening aims to reduce large breast cancer rates.
• Despite screening, women still present with large invasive breast cancers.
• Understanding factors associated with large tumor size is crucial for prevention and early detection strategies.

Purpose of the Study:

• To investigate the epidemiological factors associated with large invasive breast cancer size at diagnosis.
• To identify correlates of breast cancer size, particularly in relation to detection method.

Main Methods:

• Population-based epidemiological study of 1,459 women diagnosed with invasive breast cancer in Australia (2002-2003).
• Data collected via interviews on personal, mammogram, and breast histories.
• Tumor biological characteristics and mammogram dates obtained from medical records.

Main Results:

• Detection by screening mammogram was strongly associated with smaller cancer size (OR=0.27).
• Higher Body Mass Index (BMI), higher cancer grade, and lobular tumor type were independent correlates of larger tumors (> or =2 cm).
• Hormone Replacement Therapy (HRT) use reduced odds of large tumors only when detected symptomatically.

Conclusions:

• Lack of mammogram detection, elevated BMI, and higher cancer grade are significant contributors to large breast cancers in the population.
• These factors, particularly lack of mammogram detection and BMI, are amenable to public health interventions.
• Screening mammography remains a critical tool for detecting breast cancer at earlier, smaller stages.