Women with dense breast tissue would have to be notified about the need for additional screenings at their mammograms under legislation passed by the Missouri Senate.
The measure was passed 32-0 by senators on Thursday and it now heads to the House.
Sponsoring Republican Sen. Dan Brown, of Rolla, says mammograms might not pick up cancer if a woman has dense tissue. He says his wife was diagnosed with breast cancer only after a biopsy was taken after several mammograms turned up negative.
Starting in 2015, the bill would require facilities that perform mammograms to notify patients that if they have dense breast tissue that additional tests might be required to detect cancer.