And as far preventing deaths goes, Wender said that one trial has shown that annual screening can lower the risk of dying from breast cancer, versus biennial screening — in women younger than 50.
“Given all of these findings,” Wender said, “ACS recommended that annual screening is the best interval for all premenopausal women.”
At age 55 — a proxy for menopause — women can either stick with yearly mammograms or switch to every other year, the ACS says.
“We do think the data are quite supportive that on a population level, screening every other year is optimal [for postmenopausal women],” Wender said.
But for individual women, he added, there are other factors they can consider and discuss with their doctor: If they have had an abnormal mammogram in the past, yearly screening might be wise. The same may be true if they have “dense” breasts with less fatty tissue — which can make it harder to interpret the mammogram.
The current findings were based on 232 women, ages 40 to 82, who were diagnosed with breast cancer in 2016 or 2017. The vast majority, 200, had undergone yearly screening, while 32 women had been screened every two years.
On average, women in the biennial group had slightly larger tumors, and were less likely to be diagnosed in the earliest stages. In addition, 38% needed chemotherapy as part of their treatment, versus 28% of women in the annual-screening group; however, that difference was not significant in statistical terms.
According to Moorman, there were no clear differences between the two groups as far as age, race, family history of breast cancer, or the number who were “high-risk.”
She will present the findings next week at the annual meeting of the Radiological Society of North America, in Chicago. Studies reported at meetings are generally considered preliminary until they are published in medical journal.
Wender said that screening guidelines will keep evolving as more research evidence comes in.
What’s most important, he said, is that all eligible women get mammograms “at least every other year” — with annual screenings being “ideal” for younger women.
Right now, Wender added, that’s not the reality: Only about two-thirds of U.S. women in the screening age range get mammograms every other year.