I had a screening mammogram an it came back negative but report says heterogeneously dense breast, what does this mean and how accurate are the result?

Normal finding: Dense breasts on mammogram are usually seen in younger women with fuller breasts. I wonder why you would be getting a screening mammogram at age 35? Do you have a family history of breast cancer?

Dense breasts: "Dense" breasts are normal, but decrease the sensitivity of the mammo for detecting cancers. Some studies show that the sensitivity of mammography in this setting can decrease to as low as 50%. Also, dense breasts are an independent risk factor for developing breast cancer, and cancers discovered in women with dense breasts tend to be more advanced.