Dense breast tissue appears white on a mammogram, and cancer also appears white, so it can be very difficult to see the cancer, Simitian said.
Senate Bill 791 requires that following a mammogram, patients with dense breast tissue be informed that they have dense breast tissue; that dense breast tissue can obscure abnormalities such as cancer on a mammogram; and that the patient may wish to discuss the potential value of additional screenings with their doctors.
A January 2011 study by the Mayo Clinic found that in women with dense breast tissue 75 percent of cancer is missed by mammography.
The National Cancer Institute estimates that one in eight women will develop breast cancer. More than half of all women have dense breast tissue, and risk among that group is five times greater than for women without dense tissue.
Senate Bill 791 requires that, for patients with dense breast tissue, two additional sentences be included in the federally required letter that a radiologist must send a patient after performing a mammogram.
"Because your mammogram demonstrates that you have dense breast tissue, which could hide small abnormalities, you might benefit from supplementary screening tests, depending on your individual risk factors. A report of your mammography results, which contains information about your breast density, has been sent to your physician's office and you should contact your physician if you have any questions or concerns about this notice."
The bill will now go to Gov. Jerry Brown. Simitian represents the 11th state Senate district, which will include Mountain View in next year's election.
Simitian said he introduced the bill because he thinks the "two-sentence notice can save thousands of lives. The bil1 will also save money, because treating cancer in its early stages is far less expensive than battling advanced cancer," he said.
"When it comes to your health, ignorance is not bliss," Simitian said. "This bill is about giving patients the information they need to make informed decisions about their own bodies and their own health."
Soquel resident Amy Colton, a registered nurse and a cancer survivor, suggested the bill in Simitian's annual "There Oughta Be A Law" contest. Colton was never informed of her breast density during years of routine mammograms. She only discovered that she had dense breast tissue after completion of her treatment for breast cancer, which her mammograms had failed to detect over several years, according to Simitian's office.