In which quadrant are most breast cancers located?

In which quadrant are most breast cancers located?

• A. Upper outer
• B. Upper inner
• C. Lower outer
• D. Lower inner

Answer: (A)

Most breast cancers occur in the upper outer quadrant because this area contains the greatest amount of breast tissue and ducts, plus it includes the tail of Spence extending toward the axilla. That larger tissue volume means more cells at risk for malignant change, so this quadrant is the most common site. Cancers can arise in other quadrants, but they are less frequent due to having less tissue and ductal density in those regions. In practice, this is why the upper outer quadrant is emphasized during palpation and targeted imaging.

Most breast cancers occur in the upper outer quadrant because this area contains the greatest amount of breast tissue and ducts, plus it includes the tail of Spence extending toward the axilla. That larger tissue volume means more cells at risk for malignant change, so this quadrant is the most common site. Cancers can arise in other quadrants, but they are less frequent due to having less tissue and ductal density in those regions. In practice, this is why the upper outer quadrant is emphasized during palpation and targeted imaging.