There were two schools of thought, which made it confusing for primary physicians, but this is from one website at Harvard.edu. You can see the inconsistency:
"The U.S. Preventive Services Task Force recommends mammograms every other year for women ages 50 to 74, but says there's not enough evidence to recommend regular mammogram screenings in women ages 75 and older.
Because the frequency and age ranges for testing vary by organization, it can be hard to know which recommendation to follow. Dr. Smith goes by the American Cancer Society guidelines, advising all of her female patients age 40 and older to have annual mammograms.
Should you stop having mammograms after age 75, as the U.S. Preventive Services Task Force recommends? "If anything, the risk of breast cancer goes up every year a woman is alive," Dr. Smith says. "To say that you stop checking at 75, when the average life expectancy of a woman in this country is in the mid-80s, doesn't make sense to me." As long as you're healthy enough to tolerate a lumpectomy under local anesthesia—should you need it—Dr. Smith recommends that you continue to get annual mammograms in your 70s and beyond."