Which of the following is NOT a recognized breast cancer risk factor?

• A. Regular physical activity
• B. Early menarche
• C. BRCA1/2 mutations
• D. Dense breasts

Answer: (A)

Regular physical activity is not a breast cancer risk factor; it actually lowers risk through multiple mechanisms, such as better weight management, improved insulin sensitivity, reduced inflammation, and a favorable hormonal milieu. The question asks you to pick factors associated with higher risk. Early menarche lengthens lifetime estrogen exposure, which increases risk. BRCA1/2 gene mutations markedly raise lifetime risk due to impaired DNA repair. Dense breast tissue is also linked to higher risk and, at the same time, can make cancers harder to detect on screening. So, the statement that regular physical activity is not a risk factor is correct, while the other options are recognized risk factors.