Screening by mammography over a 24-year period in women aged 50 to 74 years has had little effect in reducing rates of advanced bad cancer or bad cancer mortality in the Netherlands, according to a new investigation.
dramatically increase the detection of early-stage bad cancer, both ductal carcinoma in situ (DCIS) and stage I and, in doing so, contribute to an increase in the rate of overdiagnosis, which is defined as the detection of tumors in the detection that would never lead to clinical symptoms in a woman's life.
The study, published in BMJ concludes that screening would be badociated with zero to 5% reductions in bad cancer mortality in women aged 50 years or older, while improved treatments will be badociated with a 28% reduction in mortality.
In addition, screening mammography was badociated with a 32% increase in overdiagnosis, an increase driven by the advent of digital mammography and the extension of screening to women aged 70 to 75 years, the authors write.
"The primary goal of cancer screening is to detect cancer at an early stage before it becomes metastatic disease," lead author, Philippe Autier, MD, of the Institute of Global Public Health at the University of Strathclyde, Lyon , France, Medscape Medical News .
"If screening works, then we should observe a lower incidence in the burden of advanced cancer of poor prognosis in the population. While we have seen decreases in the incidence rate of advanced cervical and colorectal cancer, the same has not happened with bad cancer, "said Dr. Autier.
"Everyone expected, including myself, that the same would be true for mammography screening, but unfortunately, after years and years of detection, we are realizing that we are not seeing reductions in advanced bad cancer. This is something that is being observed not only in the Netherlands, but in all countries where there are many screening tests, including the United States, "he said.
Results from the Netherlands
Since 1989, women aged 50 to 69 in the Netherlands have been invited to a screening mammogram every 2 years. In 1997, screening was expanded to include women aged 70 to 75 years.
Digital mammography was available in the Netherlands in 2006.
Dr. Autier and her group studied trends in bad cancer incidence adjusted for age and specific stage among women who participated in the national bad screening program from 1989 to 2012.
They found that the incidence of bad cancer in Stage II to IV in women 50 years or older was 168 per 100,000 in 1989 and 166 per 100,000 in 2012.
They also discovered that, after deducting clinical cancers from the time of anticipation, 32% of the cancers found in the women who were examined in 2010 to 2012 they were diagnosed in excess, and also that 59% of the cancers detected on the screen would be overdiagnosed.
Women aged 70 to 74 years were particularly prone to overdiagnosis. In that age group, the overdiagnosis of stage I cancers was approximately twice as high as in women 50 to 69.
"These observations are in line with other data showing that the replacement of film-based mammography by Digital mammography has substantially increases the burden of bad tumors in situ without decreasing the rates of interval cancer, "said Dr. Autier.
"Strongly suggests that the advent of digital technologies has probably worsened the problem of overdiagnosis without clear evidence of improvements in detection capacity to curb the risk of death from bad cancer," he said.
Taking a radiologist
Approached for a reaction to new findings from the Netherlands,
Stamatia Destounis, MD, clinical professor, School of Medicine, University of Rochester, New York, said ] Medscape Medical News: "I think they're misinterpreting their data."
"They are making badumptions here that are not compatible, for example, t The rate of invasive cancers before screening mammography had been increasing, so the fact that this rate remained stable during the study represents a decrease and shows that there is a benefit to detection, "said Dr Destounis.
Dr Destounis also opposes the combination of DCIS and stage I bad cancer as a single entity, which she says confuses the problem of overdiagnosis.
"There are some legitimate problems with DCIS with respect to overdiagnosis, but combining the two [DCIS and stage I] complicates their badysis.The benefit of the test, whether for the bad, the colon or any part of the body is to find invasive cancer small that does not become stage II, "he said.
Although some in situ cancers may be indolent and not become invasive cancer, there is currently no way to know what they are, said Dr. Destounis.  "Our job as radiologists is to detect every new abnormality, and that's what mammography exams do.There may be room to change our position after the pathologist interprets the screen as a very early low-grade DCIS, and I believe that there are changes that are occurring now in the US with respect to what to do with very early in situ tumors, but the authors have done a poor service by grouping the DCIS and stage I, "he said.
"The way in which the authors badyzed their data is defective The goal of screening mammography is to find those stage I cancers and obviously we are doing a good job of doing so." Even his own badysis shows that we are doing a good work to find these tumors in stage I, and in all age groups, "he added.
Call the benefits of the screening in question
However, a public health expert who has raised questions about the benefits of periodic mammography exams for many women says that the new results from the Netherlands claim others findings
"This study in the Netherlands basically reproduces the image in the United States," H. Gilbert Welch, MD, MPH, professor of medicine, Dartmouth Institute for Health Policy and Clinical Practice, Lebanon, New Hampshire, said Medscape Medical News .
"The generalized introduction of mammography is badociated with a dramatic increase in the early detection of bad cancer stage, but the concomitant decrease in the rate at which women present with late stage bad cancer. The combination suggests that screening mammography has little effect on mortality from bad cancer and that the decrease in mortality we have seen in the last 20 years is largely the result of better treatment, "said Dr. Welch.
Dr. Welch co-authored a 2012 study with Archie Bleyer, MD, Oregon Health and Science University, Portland, which showed similar results, including a 30% increase in overdiagnosis rates and only a small effect on the rate of cancer death. mom. That study was published in the New England Journal of Medicine .
"An important message is that it does not solve the problem by throwing more technology on it, adding an ultrasound, adding an MRI and adding a digital mammogram only makes the problem of overdiagnosis worse. probabilities of having an overdiagnosis problem, "said Dr. Welch.
"We have been putting too much pressure on screening mammography, we have totally overstated its benefits and underestimated its damage, it can lead a woman to be treated for bad cancer that she would never otherwise need to know about," she said.
Older people in particular should be cautious about having cancer screenings, he said.
"When you start getting older, you do not want to do any type of cancer screening, you create more problems than you solve, you take many more procedures, you end up getting medicalized and some people undergo surgery. principle that people with limited life expectancy should not be screened for prostate cancer [as] only bad things can happen as a result of that.I think the general story is that we have gone a little bit overboard in our I want to find cancer early, "said Dr. Welch.
"Women between the ages of 70 and 75 are the ones who really have an outbreak of incidence when they start screening, most of the cancers that are found are not relevant and, for those who are, the majority can be I know it's a counterculture message, but I think it's the truth, "he said.
Mortality from bad cancer is declining, not because of screening but because treatments have improved, Dr. Welch said.
"That's the good news that a lot of strange people are much better at treating bad cancer than 20 years ago." Ironically, the better we become at treating bad cancer, the less important screening is ", he added.
The study was supported by the International Prevention Research Institute. Dr. Autier, Dr. Welch and Dr. Destounis have revealed no relevant financial relationships.
BMJ 2017; 359: j5224. Full text
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