Which of the following is likely to decrease the risk of breast cancer?

• A. Pregnancy after age 35 years
• B. Late onset of menarche
• C. Early onset of menarche
• D. Regular physical activity

Answer: (D)

Regular physical activity is associated with a reduced risk of breast cancer due to several mechanisms. Engaging in consistent exercise can help maintain a healthy body weight and regulate hormone levels in the body, particularly estrogen. Since higher levels of estrogen have been linked to an increased risk of breast cancer, regular physical activity can mitigate this risk by promoting hormonal balance and reducing overall body fat, which is a source of estrogen.

Additionally, physical activity may enhance immune function and improve metabolic health, which can further contribute to cancer risk reduction. Studies have shown that women who are physically active throughout their lives tend to have a lower incidence of breast cancer compared to those who are sedentary.

Factors such as late onset of menarche and pregnancy after age 35 can influence breast cancer risk but are not as robust in their protective role as regular exercise. Early onset of menarche is typically associated with an increased risk due to longer exposure to estrogen. In contrast, regular physical activity acts as a proactive measure for reducing breast cancer risk through lifestyle and health improvements.