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Screen-detected breast cancers persist without treatment
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Screen-detected breast cancers that went untreated remained visible and suspicious for malignancy at next mammography, according to a prospective cohort study published in Journal of the American College of Radiology.
“Invasive breast cancer does not disappear without treatment,” Debra L. Monticciolo, MD, FACR, section chief of breast imaging at Baylor Scott & White Health and professor of radiology at Texas A&M Health Science Center College of Medicine, told HemOnc Today. “Others have suggested that this is the case and that this leads to overdiagnosis. Our results show that this is untrue.”
Previous literature suggested that some screen-detected breast cancers stopped growing or regressed. To address that assessment, researchers surveyed 42 fellows of the Society of Breast Imaging to determine the natural histories of untreated, screen-detected, biopsy-proven breast cancers.
“Those who work with breast cancer directly know this to be a false claim but that has not stopped it from being claimed by some who use this to discourage screening,” Monticciolo said. “We decided to study the question scientifically.”
Among all practices, reports included 25,281 screen-detected invasive breast cancers and 9,360 screen-detected cases of ductal carcinoma in situ (DCIS) from 2006 to 2016.
Of those, 240 cases of invasive breast cancer and 239 cases of DCIS went untreated for a variety reasons, including patient contraindications to surgery, chemotherapy, hormonal therapy, radiation or individual preference. None of the untreated screen-detected breast cancers spontaneously disappeared or regressed at next mammography.
The findings provided “direct evidence to the contrary” that some breast cancers regress, according to researchers.
The analysis did not include data regarding patient demographics, tumor histology, or clinical progression of the disease, nor did researchers determine exact reasons why some patients had no treatment.
The U.S. Preventive Services Task Force (USPSTF) recommends biennial screening mammography for women aged 50 to 74 years and suggests the decision to start screening before age 50 years should be an individual one.
“The most important takeaway clinically is that concerns of overdiagnosis should not delay the start of screening nor inform the interval,” Monticciolo said. “That is, the USPSTF states that they recommend waiting until 50 years of age to start screening and recommend screening biennially because it will decrease overdiagnosis. Our work shows that this is false. Cancers, even the small number that are ‘overdiagnosed,’ will all still look suspicious on screening whether the woman with that cancer starts screening when aged 40, 45 or 50 years. The amount of ‘overdiagnosis’ will be unchanged; screening later or at longer intervals will only delay the diagnosis. It will, of course, delay the diagnosis of nonoverdiagnosed cancers, which is nearly all of them.”
Women who want to maximize the benefits of screening, including better treatment options for those diagnosed with breast cancer, should begin annual screening at age 40 years, Monticciolo said.
“It is the best way to detect cancer early, which saves lives,” she said. – by Chuck Gormley
For more information:
Debra L. Monticciolo, MD, FACR, can be reached at Department of Radiology, Scott & White Medical Cetner, 2401 South 31st St., MS-01-W256, Temple, TX 76508; email: debra.monticciolo@bswhealth.org.
Disclosure: The researchers report no relevant financial disclosures.
Perspective
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The study by Arleo and colleagues reports on a survey of members of the Society of Breast Imaging. A minority (39%) responded over a 2-week period of time to a 14-question survey. Given “no review of individual patient records,” institutional board approval did not apply. The participants reportedly reviewed 6,865,324 screening mammograms over the 10 years that constituted the timeframe of the study. Physicians received instructions to complete the survey “on the basis of their practice’s audit information, if accessible; if not, they were asked to complete the survey questions on the basis of their best estimates.” They reported 240 patients with untreated screen-detected breast cancer and 239 cases of untreated screen-detected ductal carcinoma in situ. They stated that “zero were reported to have spontaneously disappeared or regressed at next mammography.”
This study must not be misconstrued as a prospective study, let alone a randomized trial. This collection of anecdotes provides no analysis of anything other than serial images. The ability to collect these 479 cases out of 6,865,324 mammograms over a 2-week period of time and assure the reader that no patient received any additional interventions without reviewing any of the individual records severely limits the ability to draw any meaningful conclusions. Further, there is no data whatsoever on patient characteristics or their outcomes.
Drawing conclusions based on survey collection is hazardous at best and potentially very misleading. To state that “our results show that all untreated, screen-detected cancers persist” and imply this as universal biologic fact constitutes a gross overreach based on a survey study. Further, to make a take-home point that “starting screening at a later age … and increasing the screening interval … will simply delay the timing of overdiagnosis but will not decrease the frequency of overdiagnosis,” while possibly true, is again an overreach if based on this report. Finally, to conclude that the survey proves that “overdiagnosis is not mitigated by less screening” is similarly not supported by this report.
It bears repeating that finding an abnormality on a mammogram is not the endpoint of significance. What really matters to the patient are outcomes: death from disease, DFS and local recurrence. These outcomes, those that are meaningful to the patient, are in no way addressed by this paper.
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