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Study results do not support age cutoff for mammography
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Mammography screening decisions among older women should be based upon individual patient values, comorbidities and health status rather than age, according to study results.
Within the past decade, debate has intensified about the risks and benefits of mammography screening due to different interpretations of evidence on outcomes. Moreover, women aged 75 years and older have been excluded from randomized controlled trials, limiting available evidence to small observational studies.
Consequently, uncertainty exists about when to stop mammography screening.
Cindy Lee, MD, assistant professor in residence in the breast imaging section at University of California, San Francisco, and colleagues used the National Mammography Database to review data on more than 5.5 million screening mammograms performed on more than 2.5 million women between January 2008 and December 2014.
Researchers assessed the association between patient age and screening mammography performance metrics in women aged 40 years and older.
Results showed the overall mean cancer detection rate was 3.74 (95% CI, 3.69-3.79) per 1,000 screening exams, and the recall rate was 10% (95% CI, 10-10). The positive predictive value for biopsy recommended was 20% (95% CI, 20-21) and the positive predictive value for biopsy performed was 29% (95% CI, 28-29).
HemOnc Today spoke with Lee about the study findings and their potential clinical implications.
Question: What prompted you and colleagues to conduct this study?
Answer: I am a breast imager. I see patients who come in for their screening mammograms and I get asked frequently if patients aged 75 years and older should continue screening. There is not enough evidence to determine how breast cancer screening benefits women older than 75. In fact, all previously randomized trials of screening mammography excluded people older than 75 years. Unfortunately, age is the biggest risk factor for breast cancer, so as patients get older, they have a higher risk for breast cancer. It is, therefore, important to know how well screening mammography works in these patients.
Q: What did the main findings suggest?
A: We found encouraging results for screening older women. Screening mammography performs better when the patient is older. We relied on four measurements to evaluate how well screening works. The first measure was recall rate, which is a hot ‘buzz word.’ Whenever people think of screening, they want to know how many women have been called back for additional imaging because recall rate is directly proportional to the rate of false positives. A second measure was the cancer detection rate, or the number of cancers found per 1,000 screening exams. The third and fourth measures used in this study were the positive predictive values for biopsy recommended and for biopsy performed. These two positive predictive values explained how many cancers were found among cases recommended for biopsy and among biopsied cases. A good screening exam should have a low recall rate, high cancer detection rate and positive predictive values — fewer false positives while catching more cancers. We found that, with increasing age, cancer detection rate and the positive predictive value are both going significantly up. At the same time, the recall rate is going significantly down until about age 90 years. So, screening mammography works better in older women.
Q: Were you surprised by these findings?
A: We were surprised by how well screening works in older people. Knowing before we started that this disease affects older individuals, we expected to see more screening-detected cancers in older women. We were surprised that the recall rate and the number of false positives, equating to unnecessary workup, both decreased in older women. The difference is statistically significant and shows us that screening should not stop cold at age 75. Our results suggest we should continue screening as long as the person can live another 7 to 10 years, and as long as the person would desire treatment if cancer was found.
Q: Can you describe the clinical implications of these data?
A: Our data support continued screening mammography in women aged older than 75 years, and they do not support a clear age cutoff. There is no magic age to stop screening mammography because the benefits appeared to continue to age 90. Decisions to stop screening should be based on a discussion between each woman and her physician, because the individual patient preferences, comorbidities and health status are unique. We are promoting an individualized decision with screening in older women, and it really does require a patient-centered approach to care.
Q: Breast cancer detection and positive predictive values of mammography continued among women aged 75 to 90 years. What does this mean for the clinical community going forward?
A: This study is the largest on the topic of screening in older woman. Our results support a patient-centered approach to screening mammography. If a patient is older than 75 years old, healthy, has more than 5 to 7 years of life expectancy, and desires treatment for breast cancer if diagnosed, she should have access to a screening mammogram. On the other hand, if the patient has limited life expectancy or does not desire breast cancer treatment, then it is appropriate to stop screening. All of this taken together tells us we need to discuss with our patients their needs and preferences before making a personalized recommendation on breast cancer screening.
Q: Is there anything else you would like to mention?
A: The database we used, the National Mammography Database, is more than a research tool. It is designed as a practical quality improvement tool that any U.S. breast imaging facility can join to get periodic performance feedbacks with comparison to national benchmarks and its peers. Many facilities can now join the database for free at: www.acr.org/Quality-Safety/National-Radiology-Data-Registry/National-Mammography-DB. My hope is for more radiologists and more radiology facilities to take advantage of this, because the database will help them see how they compare with their peers as a facility and also as a physician in reading mammograms. It is a powerful tool that I hope more physicians will use. – by Jennifer Southall
References:
Lee CS, et al. Abstract #RC215-15. Presented at: Annual Meeting of the Radiological Society of North America; Nov. 27-Dec. 2, 2016; Chicago.
Lee CS, et al. Am J Roentgenol. 2016;206:883-890.
For more information:
Cindy Lee, MD, can be reached at University of California, San Francisco, Department of Radiology & Biomedical Imaging, 505 Parnassus Ave., M-391, San Francisco, CA 94143-0628; email: cindy.lee3@ucsf.edu.
Disclosure: Lee reports no relevant financial disclosures.