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Mammographic density and breast cancer. J Watch General. 2007;1-1.

It has been known for some time that breast cancer is harder to detect in women with dense breasts than it is in women with fattier breasts. However, two recent reports suggest that breast density is also an actual risk factor for breast cancer, regardless of the woman's age.

The researchers measured the percentage of breast density in the participants' baseline mammograms, and then associated this data with risk of breast cancer according to the cancer detection method used, age, and elapsed time since initial screening. The results showed that women who had a breast density of 75% or more had a much increased risk of cancer than those women with a breast density of less than 10%. Additionally, the report shows that the increased risk continued for more than 8 years after the beginning of the study and was greater in younger, rather than older women. The researchers concluded that breast density is responsible for a significant percentage of breast cancer risk.

Since most cases of breast cancer and breast cancer deaths occur in postmenopausal women, women under 40 years of age are not screened as often as they should be. They also have fewer treatment options. More studies of breast cancer in younger women need to be conducted to further support these findings and make the necessary changes to the screening process of younger women.