The study by Emory University internist Dr. Sara Turbow with officials at the U.S. Centers for Disease Control and Prevention (CDC), found breast cancer incidence of 442.7 per 100,000 women between the ages of 75 and 79. That compares with 417.7 per 100,000 in the 65-69 age bracket.
Furthermore, an analysis of survey data showed that nearly half -- 46.8% -- of women age 77 or older reported that they had received a screening mammogram within the last two years, though this is not recommended by the USPSTF.
The study was conducted to provide recent incidence figures for breast cancer in older women and to assess use of screening mammography, given the conflicting recommendations on the appropriate age for stopping screening. The USPSTF guidelines, which were last updated in 2016, advise that evidence is insufficient to assess the benefits and harms in screening for women over age 75, mainly because women this old were not included in randomized controlled trials of breast screening.
However, the American Cancer Society advises that older women should continue if they are in good health. Other groups also have guidelines that consider a woman's health status in decision-making about when to stop screening.
For the current study, breast cancer incidence rates were derived from the CDC's U.S. Cancer Statistics dataset for 2016 and screening mammography use was based on survey data from women aged 65 and up responding to the agency's 2018 National Health Interview Survey.
Researchers found the highest incidence of breast cancer in women between the ages of 70 and 74 -- at 458.3 cancers per 100,000 women -- and the lowest in women over the age of 85, at 295.2 per 100,000 (see table).
"The complexity of decisions around breast cancer screening in older women is compounded by the fact that breast cancer incidence is high in this age group and the highest breast cancer mortality rates occur among women aged ≥ 75 years," Turbow and colleagues reported.
The likelihood of having distant metastases at the time of diagnosis increased along with rising age.
"Findings of high breast cancer incidence rates and increased risk of advanced disease at diagnosis for some after age 74 years may suggest a potential benefit from continued screening for some older women," the authors wrote.
|Invasive breast cancer incidence rates, by age
|Age group, years
|Incidence per 100,000 women
|Disease localized at diagnosis
|Distant metastases present at time of diagnosis
The survey data show that screening is common among older women, with more than half between 77 and 84 years of age and 26% over the age of 85 reporting having had a mammogram within the prior two years. Those with a better health status and ability to engage in activities of daily living were significantly more likely to have recently undergone screening mammography beyond the age limit advised by the USPSTF, but many in fair or poor health also reported having had recent mammograms, they reported.
In addition to the data for women above 77 years of age, the authors flagged room for improvement in those between 65 and 74 years, as approximately one-quarter did not report having a recent mammogram in the past two years, even though routine screening in this age group is recommended by multiple expert organizations, the authors wrote.
The study data come at a crucial time -- as the USPSTF is reviewing its recommendations for screening mammography this year. In emailed comment to Auntminnie.com, Turbow said that she was surprised at just how many women over the age of 77 -- nearly half -- had a recent mammogram.
The findings add to the broader conversation about considerations for stopping breast cancer screening by showing that many women continue to be screened past the USPSTF recommended upper age limit for screening and that breast cancer incidence is high among older women, Turbow said.
"As USPSTF and others weigh whether age, life expectancy, or other factors should drive decisions about when to stop screening mammograms, this analysis can inform them about how recommendations for screening for breast cancer with mammography are applied in this population," she said.
A lot of research around how to incorporate life expectancy and comorbidities into screening decisions is ongoing.
"Next steps could include investigating the systemic reasons why older women are or are not screened, and whether we should have different approaches to stopping screening for women who may not have received regular mammograms when they were within the recommended age group for screening for breast cancer," Turbow said.
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