Mammography data are ‘practice-changing’ in US for older women with breast cancer
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Key takeaways:
- Researchers noted similar efficacy results between study arms for breast cancer-specific survival and OS.
- Study findings found less frequent mammograms to yield similar outcomes as annual mammograms.
SAN ANTONIO — Women aged 50 years or older who de-escalated to less-frequent mammography 3 years after curative surgery for early-stage breast cancer had similar outcomes to women who received annual mammography.
The findings, presented at San Antonio Breast Cancer Symposium, provide data indicating less frequent mammographic surveillance may be best practice for this specific patient population to reduce stress associated with treatment, while also reducing the burden on the health care system, according to researchers.
“We were a bit disappointed with the compliance that we received — we thought that could have been higher — but that honestly ended up being OK because the preplanned subset analysis of the protocol didn’t make a difference,” Janet A. Dunn, PhD, head of clinical trials at University of Warwick, U.K., told Healio. “We were delighted that we didn’t see any differences all the way through across the two treatment arms. We also did a whole load of subgroup analyses and forest plots, and there were still no differences.”
Background and methodology
The widespread practice of annual surveillance mammograms for an unspecified period of time after treatment for early breast cancer poses a significant health care cost in both the United States and across Europe. Current U.K. guidelines recommend annual mammograms up to 5 years before reverting to 3-year screening without specified risk stratification.
Researchers conducted the multicenter phase 3 Mammo-50 trial to assess annual mammography vs. twice a year for conservation surgery and three times a year for patients receiving mastectomy up to 9 years.
They randomly assigned 5,235 women (2,618 received annual mammograms, 2,617 received less frequent mammograms; 83% women aged 55-75 years; 87% had invasive disease) between the two cohorts. Eligibility criteria pertained to women over the age of 50 that who had received previous treatment with curative intent for invasive or noninvasive breast cancer that were 3 years post curative surgery.
Breast cancer-specific survival and cost effectiveness served as the primary study outcomes, whereas secondary outcomes included recurrence-free interval and OS.
Results, next steps
Researchers observed similar efficacy outcomes with respect to breast cancer-specific survival, 5-year recurrence-free interval and OS between the two cohorts.
Upon analysis, researchers noted a breast cancer-specific survival at 5 years of 98.1% among patients in the annual cohort and 98.3% among patients in the less frequent cohort (HR = 0.92; 95% CI, 6.4-1.32).
Researchers also noted 5-year recurrence free interval rates of 94.1% for the annual arm and 94.5% among patients in the less frequent arm (HR = 1; 95% CI, 0.81-1.24).
Among the 5,235 women in the study, with a median follow-up of 5.4 years (interquartile range, 4.6-5.9), researchers reported 319 women died (104 of breast cancer; 53 from the annual arm and 51 from the less frequent arm).
A total of 15,967 mammograms occurred in the annual arm with 8,662 mammograms received in the less frequent arm; 83% of women in the annual arm complied with the allocated mammogram schedule, compared with 69% of women in the less frequent arm.
Researchers noted that the COVID-19 pandemic affected compliance, with approximately 160 of the 452 women (35%) missing mammograms being attributed to the pandemic.
“The big thing is that you have to be over 50 years old at diagnosis and get to that 3-year mark post diagnosis, and at that time we’re only getting very few events, so it is rather limited to the older population,” Dunn told Healio. “People can go through these less frequent mammograms — it doesn’t have to be annual anymore, it’s just as safe.
“I think we do need to re-stratify though ... when we do these de-escalation studies, certainly in the U.K., oncologists seem to be able to predict the lower risk patients to put in that can be de-escalated. So, we do need to look at the risk profile.”
Perspective
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Richard J. Bleicher, MD, FACS
This study was an interesting study from the UK that evaluated annual mammography after breast cancer treatment vs. less frequent mammography, finding that the women who had less frequent mammograms did just as well. The study is thought-provoking but at this point still exploratory and should not change practice, especially as their follow up was short at 5.7 years. The two groups having different frequencies of mammography after treatment were not risk-adjusted, it seems, as the presenter noted that the authors have collected a lot of data, but did not have that data analyzed or available at this point. For example, the presenter noted in response to questions that they did not yet have the differences between the stage and extent of diagnoses between the original tumors in the two arms, nor the specifics of the recurrences that occurred in each arm. There also was no information yet on treatment differences between the two arms, or in presentation of the tumors between the two arms, nor compliance with treatments. Thus the differences between the two arms cannot be discerned. This is important because if the group that had less frequent mammography, for instance, had less aggressive tumors or more rigorous therapy, that might compensate for less frequent mammography in outcomes. The concept is interesting and the specifics of how to screen should be further evaluated, but annual post-treatment mammography should definitely not be abandoned at this time.Perspective
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Virginia Kaklamani, MD
We have this question asked all the time and patients think that the minute they get breast cancer that they will get screened more intensely. Now we’re going to say maybe you need even less intense screening, and I have to explain that it doesn’t make a difference whether they have a 6-month mammogram or a 1-year mammogram. These results are really good, especially since our patients are living longer and longer. We have patients in their 70s with a 20-year history of breast cancer getting annual screenings. I, personally, will incorporate this into my practice. I think this will be practice changing in the U.S.
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Dunn JA, et al. Abstract GS03-02. Presented at: San Antonio Breast Cancer Symposium; Dec. 5-9, 2023; San Antonio.
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