But it is generally true, she said, that breast density decreases with increasing age, body weight and the number of children.

They looked for correlations in the degree of breast density within pairs of twins.

Identical twins have identical genes, so that any differences in breast density between them would most likely be because of environmental factors or measurement error.

High breast density is associated with low sensitivity.

At all ages, regardless of hormone therapy (HT), high breast density is associated with 10% to 29% lower sensitivity.

Other risk assessment models incorporating breast density have been developed but are not ready for clinical use.

Among those caught a year or less after the mammogram, 68% were because of breast density.

Among those caught 24 months later, 38% were because of breast density; 31% were linked with faster growing tumors.

Daily estrogen-progestin increased breast density compared with estrogen alone or placebo.

Part of the difficulty in interpreting mammograms in younger women stems from breast density.