| Age is likely the most important overall factor | | | | to shorter women (5' 3" or shorter). A person's |
| associated with breast cancer risk. This cancer risk | | | | height is determined by the interaction of genetics |
| increases in the older post-menopausal population. For | | | | and nutrition. How height might affect this cancer risk |
| this reason, all cancer screening recommendations are | | | | is unclear. |
| based primarily on age. Obesity, however, may be | | | | Breast Size: There is a popular belief that small |
| the single most preventable risk factor associated | | | | breasts are at lower risk of breast cancer. This |
| with this disease. With the dramatic increase in | | | | theory has been used to explain why women with |
| obesity in the U.S., this may be the number one | | | | breast implants have a smaller risk of this cancer. |
| reason for a persistently high incidence in breast | | | | However, most studies have found no association |
| cancer. Other physical factors also play some roles in | | | | between breast size and tumor risk. One study, |
| this cancer risk. These include height, body shape, | | | | however, did find an increase in the risk of |
| breast size, and mammographic density. These | | | | malignancy among lean women with larger breasts. In |
| physical factors are summarized below. | | | | this study, more than 4,000 women were grouped |
| Body Weight: A woman's body weight does affect | | | | according to their bra size before childbirth. Women |
| her risk of breast cancer but the effect is different | | | | who were lean (chest size less than 34 inches) and |
| for premenopausal and postmenopausal malignancies. | | | | had larger breasts (size B, C or larger cups) were at |
| Most studies have found that heavier women | | | | higher risk of post menopausal breast cancer relative |
| (weighing more than 175 pounds) have a lower risk | | | | to women of the same chest size with an A or |
| of this cancer before menopause and higher risk of | | | | smaller cup size. Women with other chest sizes had |
| this cancer after menopause, compared to thinner | | | | no association between breast cup size and cancer |
| women (weighing less than 130 pounds). Since 80% | | | | risk. More studies are needed to confirm these |
| of breast cancers occur after menopause, the | | | | results. |
| negative effects of obesity far outweigh the | | | | Mammographic density: Numerous epidemiological |
| beneficial effects. The results are the same whether | | | | studies have shown that breast density as measured |
| body weight is examined directly or if body mass | | | | on mammograms is a significant risk factor for breast |
| index is used to adjust for the effects of height on | | | | cancer. The risk of cancer associated with the |
| body weight. | | | | highest category of density has been estimated to |
| Body Shape: Several human studies have found that | | | | be much greater than in the lowest density category. |
| women who carry more of their body fat on their | | | | Mammographic density appears to be predictive for |
| stomach (apple shaped) have higher rates of | | | | developing invasive cancer after DCIS (ductal |
| postmenopausal breast cancer compared to women | | | | carcinoma in situ). Increasing density is associated |
| with more of their body fat around their hips (pear | | | | with increasing breast cancer risk in both |
| shaped). This seems to be true regardless of | | | | premenopausal and postmenopausal women, with the |
| women's body weight. The relationship of the location | | | | effect persisting for ten years after mammography. |
| of fat on the body and premenopausal cancer risk | | | | Mammographic density has also been shown to be a |
| has not been clearly determined | | | | risk factor for this cancer in women with a family |
| Height : A woman's height has been associated with | | | | history of the disease. Mammographic density is |
| breast cancer risk in many studies. Taller women (5' | | | | probably important even in patients who are BRCA |
| 9" or taller) have a small increase in risk of both | | | | gene positive. In fact, mammographic density may |
| premenopausal and postmenopausal cancer compared | | | | actually have a substantial heritable component. |