What factor significantly increases the risk for breast cancer in women?

A family history of breast cancer significantly increases the risk for women because genetic predispositions play a crucial role in the development of the disease. If a woman has first-degree relatives, such as a mother, sister, or daughter, who have been diagnosed with breast cancer, her risk is notably higher due to inherited mutations in genes such as BRCA1 and BRCA2. These genes are linked to a much greater likelihood of developing breast and ovarian cancers.

In contrast, while low physical activity could influence overall cancer risk, it is not as directly correlated with breast cancer as a family history is. High caffeine intake has not been conclusively linked to an increased risk of breast cancer, and maintaining a normal body weight is generally associated with a reduced risk of various cancers, including breast cancer. Hence, understanding familial patterns of breast cancer is essential for risk assessment and guiding screening strategies.