The need for yearly mammograms is one of those ongoing debates that can be hard to keep up with. Breast cancer screening for older women is even more confusing.

The American Cancer Society recommends annual mammograms for women age 75 who are in good health, while the US Preventive Services task force cites a lack of evidence to evaluate the harms and benefits of mammography screening.

Once you are 75 and older, there is not much in the way of breast density, so it's actually a perfect age to get screened.

Now comes a new study from American researchers to add to the picture. The findings suggest that mammography does benefit healthy women who are over 75 and who have a reasonable life expectancy. That's because by increasing the detection rate of early-stage cancers, which are easier to treat, a mammogram can help keep older women alive.

Judith Malmgren, lead author on the study, told TheDoctor that if a woman is reasonably healthy and has no other life-threatening health issues, a mammogram is a valuable and worthwhile health maintenance procedure.

A healthy woman who has reached 75 has a life of expectancy of about 13 years in the U.S., said Malmgren. “You get your teeth cleaned every six months, you get your cholesterol checked yearly, you get your blood pressure checked. Why in heaven’s name would you not get a mammogram?”

The researchers analyzed data from over 1100 patients aged 75 years and older who had been diagnosed with primary breast cancer during a 21-year period. They found that the percentage of breast cancers detected by mammography increased over that time from 49 percent to 70 percent.

Compared to physician- or patient-detected cancers, which were more likely to be invasive cancers, cancers detected via mammography were more likely to be at the earlier stage, either stage I or 0 breast cancer.

Over the 21-year duration of the study, the number of stage II and stage III cancers decreased, but the number of stage 0 cancers — non-invasive breast cancers — increased.

Invasive breast cancers detected via mammography were more likely than those detected by a physician or a patient to be treated with lumpectomy and radiation. Physician- and patient-detected cancers were more likely to be treated with chemotherapy, which is not well tolerated in older persons, and mastectomy, according to Malmgren, an affiliate assistant professor at the University of Washington School of Public Health and Community Medicine. So catching possibly invasive cancers early was a benefit to older women.

Cancer detected by mammography was associated with significantly better five-year survival for invasive breast cancer, compared to physician detection or patient detection.

“I am not sure that all docs understand that older women are at higher risk for breast cancer, or that breast cancer risk goes up with age,” said Malmgren. If you are over age 75 and your doctor doesn’t recommend that you get a mammogram, you should ask for one, or at least broach the subject, she recommended.

“Once you are 75 and older, there is not much in the way of breast density, so it's actually a perfect age to get screened,” she said.

The study was published online recently in the journal Radiology.