Which factor significantly increases the risk of developing breast cancer in clients?

The factor that significantly increases the risk of developing breast cancer is menopausal obesity. Weight gain during menopause is associated with higher levels of estrogen in the body, which is known to promote the growth of hormone-sensitive tumors, including many types of breast cancer. Excess body fat can lead to increased circulating estrogen levels due to the conversion of androgens to estrogens in adipose tissue, exacerbating the risk.

Maintaining a healthy weight, especially following menopause, is crucial for minimizing this risk. Other lifestyle factors, such as regular exercise and a low-fat diet, can contribute to overall health and may help reduce the risk of various cancers, including breast cancer, but they do not carry the same level of risk as obesity during menopause. Family history of cancer can also indicate risk, but the direct impact of menopausal obesity on hormone levels and tumor growth makes it a significant contributing factor.