The following is the view of two researchers regarding the long-term contribution of suspending cancer screening, to the advancement of cancer knowledge.
Gilbert Welch (Centre for Surgery and Public Health at Brigham and Women's Hospital and author of "Less Medicine, More Health")
And Vinay Prasad (oncologist, Associate Professor of Medicine in Oregon Health and Science University et auteur de "Malignant: How Bad Policy and Bad Medicine Harm People With Cancer")
Synthesis by Cécile Bour, MD, 28/05/2020
We had already recently reported the views of Judith Garber, a political and health policy scientist at the Lown Institute, and also whose of Susan Bewley, Professor Emeritus of Obstetrics and Women's Health at King's College London and President of HealthWatch.
According to the authors, due to the fact that medical care services were overwhelmed by the epidemic, some patients certainly suffered harm on their health.
For others, though, the two authors suggest that the delay may have been beneficial.
In addition to the effect of the decrease in surgical interventions, emergency room admissions, requests for additional biological and radiological examinations, and the increase in telemedicine, the two researchers review the impact of suspending cancer screening.
Previous research on the global effects of physician strikes has suggested a decrease in mortality concomitant with reduced medical consumption. It therefore seems relevant to carefully study mortality trends in 2020 and to disentangle Covid-related deaths from other causes of death. It would be just as important to look at inequalities according to socio-economic background: the interruption of medical care may reduce mortality among the over-medicated wealthy, but the opposite phenomenon is feared among the poorest.
The screening area
Suspending cancer screening is one of the areas to be studied according to Welsch and Prasad. For them, there is no doubt that the decline in mammography will lead to a decrease in the number of breast cancers diagnosed. But is this a bad or a good thing?
This is a good opportunity to study what will happen in American cancer statistics when screening resumes, in the opinion of these authors.
They expect one of two observations:
- Breast cancer rates might "catch up" with the delay in diagnosis, meaning the deficit in cancer diagnoses during the pandemic would be matched for by a surplus of cancers in subsequent years. In other words, any cancers not detected in patients during the pandemic would eventually be found afterwards.
- The alternative would be that breast cancer diagnoses would never catch up…
Years ago, researchers observed this phenomenon in Norway. Welsch and Prasad refer here to the famous Oslo Institute study of 2008: in a group, women aged 50-64 years had three mammograms in six years, and at the end of six years it turned out that they had more invasive breast cancers detected than women in the comparison group, who had only one mammogram after six years. If all breast cancers were expected to become symptomatic, there would have been as many in both groups. There is no reason why there should be fewer in the group that was not regularly screened, except that breast tumors that never expressed themselves and even regressed spontaneously were detected in excess in the group that had more frequently mammography. This study was at the origin of the demonstration and quantification of overdiagnosis. (See our brochure).
A mammographic procedure done later and less frequently therefore leads to fewer breast cancer diagnoses. It could be argued that this deficit eventually manifests itself in undetected tumors appearing within a longer time frame, around 5, 10 or 25 years. However, this is not the case; this deficit is never caught up even after 25 years of follow-up, as Miller's study shows.
The results of the 2008 Oslo study suggest that some small cancers regress on their own. Question: could this be happening now during the Covid-19 pandemic? And could it be highlighted?
In the article the authors also look at the decline in heart attacks and strokes observed during this period. These diseases were either under-diagnosed or there were actually fewer of them?
Who benefited from this period of less medicalization, and who lost?
Conclusion of the authors
We won't find the benefits unless we look for them, say Prasad and Welsch. We need physician-researchers who are willing to ask hard questions about the services they provide - questions that may threaten their own professional/financial interests.
Covid-19 provides a once in a lifetime opportunity to study what happens when the well-oiled machine of medical care downshifts from high to low volume in order to focus on acutely ill patients. It will be comfortable for physician researchers to study what was lost. It will be courageous for them to study what was gained.
Here, the two researchers present and highlight the question of overdiagnosis and discuss its causes (spontaneous regression of a slow-growing/null tumor), rather than trying to quantify it.
Indeed, the period of suspending screening is likely to be too short for examining its impact reliably. For that it would require that the interruption last two or three years or more (as in the Oslo study comparison group, where the time period for mammography non-examination in the comparison group was 6 years), and that this interruption concerns people who would have been eligible within that time period, according to the initial schedule, as well as that there be no attempt to catch up with the delay.
In our situation, only a few months of over-diagnosed cancers will disappear.
Already in our country the INCa has been rushing, although the epidemic is not yet totally behind us, to send a note to the ARSs (Regional Health Agency) asking to set up a timetable to catch up with the screenings not carried out! (Page 2)
"A plan to catch up on screening not carried out will be established by each CRCDC (regional coordination centers for cancer screening), depending on the estimated number of screenings not carried out and on the epidemiological situation in the territories, its own resources and the methods for resuming activity".
It should be noted that there is an obsessively technocratic concern about the activity indicators of the screening centers, there is no question of reflecting on the possibility of a study based on the data collected during the suspension of screening period, no, it is a question of catching up on indicators that would have lagged behind schedule for the last three months.
A Danish physician colleague confirms that in Denmark, as well, the reactivation has also taken place, and it is not lagging behind….
Another reflection is that if we will find only a slight reduction in incidence due to the short duration of suspending cancer screening, it will be very difficult to detect reliably the eventual compensatory increase mentioned by the authors, or on the contrary the absence of a compensatory increase, not to mention the fact that tumors that disappear by themselves (the over-diagnosed) need nevertheless at least several months, if not years, to disappear.