Breast-Cancer Tumor Size, Overdiagnosis, and Mammography Screening Effectiveness

NEJM Screening Mammograms, Analysis by Dr. H. Gilbert Welch

Dr. H. Gilbert Welch gives us a brief explanation of the findings of the New England Journal of Medicine article “Breast Cancer Tumor Size, Overdiagnosis, and Mammography Screening Effectiveness“, October 13, 2016.

Study Abstract

BACKGROUND
The goal of screening mammography is to detect small malignant tumors before they grow large enough to cause symptoms. Effective screening should therefore lead to the detection of a greater number of small tumors, followed by fewer large tumors over time.

METHODS
We used data from the Surveillance, Epidemiology, and End Results (SEER) program, 1975 through 2012, to calculate the tumor-size distribution and size-specific incidence of breast cancer among women 40 years of age or older. We then calculated the size-specific cancer case fatality rate for two time periods: a baseline period before the implementation of widespread screening mammography (1975 through 1979) and a period encompassing the most recent years for which 10 years of follow-up data were available (2000 through 2002).

RESULTS
After the advent of screening mammography, the proportion of detected breast tumors that were small (invasive tumors measuring

CONCLUSIONS
Although the rate of detection of large tumors fell after the introduction of screening mammography, the more favorable size distribution was primarily the result of the additional detection of small tumors. Women were more likely to have breast cancer that was overdiagnosed than to have earlier detection of a tumor that was destined to become large. The reduction in breast cancer mortality after the implementation of screening mammography was predominantly the result of improved systemic therapy.

If screening had been a drug, it would have been withdrawn from the market

Which country will be first to stop mammography screening?

Key points

  • Screening with mammography does not reduce the occurrence of advanced cancers.
  • Rigorous observational studies in Europe have failed to find an effect of mammography screening.
  • Mammography screening produces patients with breast cancer from among healthy women and increases the number of mastectomies performed.
  • The most effective method we have to reduce the occurrence of breast cancer is to stop screening.

Time to stop mammography screening?

The Canadian Task Force on Preventive Health Care should be congratulated for its new recommendations on screening for breast cancer in women at average risk aged 40–74 years. These guidelines are more balanced and more in accordance with the evidence than any previous recommendations.

The recommendations against routine clinical breast examinations, breast self-examinations and magnetic resonance imaging to screen for breast cancer in this age and risk group are all straightforward.

The recommendations on mammography screening are even more conservative than the change in policy suggested by the US Preventive Services Task Force in 2009, which created an uproar in the United States from people interested in maintaining the status quo. The new Canadian guidelines are appropriately cautious, advising against routinely screening women aged 40–49 years. The task force recommends screening women aged 50–69 years every two to three years, although it admits that this is a weak recommendation based on moderate-quality evidence, and screening women aged 70–74 years on the same schedule based on low-quality evidence. The task force also suggests that women who do not place a high value on a small reduction in breast cancer mortality, and who are concerned with false-positive results on mammography and overdiagnosis, may decline screening.

These guidelines are an important step in the right direction, away from the prevailing attitude that a woman who does not undergo screening is irresponsible. Recent research even suggests that it may be most wise to avoid screening altogether, at any age, as outlined below.

The Canadian Task Force on Preventive Health Care decided not to include observational studies in its systematic review unless they were needed to elucidate the harms of screening or the values and preferences of patients. However, important observational studies have been published in recent years, without which a systematic review would be incomplete. These observational studies have been discussed elsewhere and have also been included in an update (currently submitted for publication) of our 2009 Cochrane review of mammography screening.

Doubtful effect of screening

Time to stop mammography screening?; National Institutes of Health PMC3225414 183(17): 1957–1958, Nov 22 2011.

Programming a latest-gen mammography station, nicoyogui.

If screening does not reduce the occurrence of advanced cancers, it does not work. A systematic review of studies from seven countries showed that, on average, the rate of malignant tumours larger than 20 millimetres was not affected by screening. Because the size of a tumour is linearly correlated to the risk of metastasis, this result is evidence against an effect of screening.

Denmark has a unique control group within its population — only 20% of its population was screened during a 17-year period. The annual decrease in breast cancer mortality in the relevant age group (55–74 years) and period was 1% in the areas with screening and 2% in the non-screened areas.Among women who were too young to benefit from screening, the decreases were larger (5% for screened areas, 6% for unscreened areas). Similar results have been reported from the United Kingdom, Sweden and Norway.

A study involving women from 30 European countries showed that the mean decrease in breast cancer mortality between 1989 and 2005 among women less than 50 years of age was 37%; the corresponding decrease was 21% among women aged 50–69 years. The declines began before the start of organized screening programs in many countries and are more likely explained by the introduction of tamoxifen. The introduction of tamoxifen could explain the larger decline seen among young women who often have estrogen-sensitive tumours.

Another study compared three pairs of similar neighbouring countries that had introduced screening 10–15 years apart. The pairs were Northern Ireland and the Republic of Ireland, the Netherlands and Belgium, and Sweden and Norway. There was no relation between start of screening and the reduction in breast cancer mortality.The fall in breast cancer mortality was about the same in all countries. Furthermore, the decline was also about the same as that seen in the United States, where screening started as early as in Sweden.

Screening seems to be ineffective in today’s world for two reasons. First, adjuvant therapy, such as tamoxifen and chemotherapy, is highly effective (even when the cancer has metastasized) but was not often used at the time of the old trials. Second, public awareness of breast cancer has increased, and women tend to see a doctor much earlier today when they have noticed something unusual in their breast. In Denmark, the average size of a tumour decreased by nine millimetres from 1979 to 1989, a reduction that occurred before screening started. In addition, this decrease was larger than the average difference in tumour size seen between screened and control groups in trials (5 mm), despite the tendency for small, overdiagnosed tumours to spuriously exaggerate the difference.

It has often been claimed that mammography screening reduces breast cancer mortality by 30%. However, thorough systematic reviews have estimated only a 15% reduction, and data on tumour size from the trials are compatible with only a 12% effect.This effect is similar to the results seen in the most reliable studies, which showed a 10% effect after 13 years.

Overdiagnosis

Any possible effect of screening on breast cancer mortality must be marginal and could be counteracted by the life-shortening effect that radio-therapy and chemotherapy have when used in healthy women in whom breast cancer has been overdiagnosed (i.e., a diagnosis of breast cancer that would not have been made in the woman’s remaining life had she not undergone screening). The main effect of screening is to produce patients with breast cancer from among healthy women who would have remained free of breast disease for the rest of their lives had they not undergone screening. Compelling data from the US, Norway and Sweden show that most overdiagnosed tumours would have regressed spontaneously without treatment.  In addition, screening substantially increases the number of mastectomies performed, despite routine claims to the contrary by advocates of screening.

The best method we have to reduce the risk of breast cancer is to stop the screening program. This could reduce the risk by one-third in the screened age group, as the level of overdiagnosis in countries with organized screening programs is about 50%.

If screening had been a drug, it would have been withdrawn from the market. Thus, which country will be first to stop mammography screening?

Peter Gøtzsche, MD, 2011.

Drawing the Line between Health and Disease: Who and How to Define Disease?

New way to define disease is needed to reduce overdiagnosis

Abstract

A new process is needed for defining diseases that takes account of the potential risks of overdiagnosis and overtreatment as well as the benefits of appropriate diagnosis and care, researchers, policymakers, and consumer groups agreed at an international congress this week.

“The problem at the moment is that we don’t have an internationally agreed process,”

said Paul Glasziou, professor of evidence based practice at Bond University, Robina, Queensland.

“Disease definitions are developed on a very ad hoc basis, often by guideline panels making recommendations about tests and treatments who, along the way, incidentally change the definition of a disease,”

he told the Preventing Overdiagnosis conference, co-sponsored by The BMJ and held on 20-22 September in Barcelona.

“We have a clear, internationally agreed process on what evidence is needed to recommend a particular treatment. But there has been a neglect of the fundamental issue that comes before that, which is the definition of disease.”

… continue reading on The BMJ 2016;354:i5082, 21 September 2016. Image Sergio Terrasa at #PODC2016.

Overdiagnosis and Overtreatment in Cancer

An Opportunity for Improvement

Abstract

Over the past 30 years, awareness and screening have led to an emphasis on early diagnosis of cancer.

Although the goals of these efforts were to reduce the rate of late-stage disease and decrease cancer mortality, secular trends and clinical trials suggest that these goals have not been met; national data demonstrate significant increases in early-stage disease, without a proportional decline in later-stage disease.

Unbelievable scam of cancer industry blown wide open: $100 billion a year spent on toxic chemotherapy for many FAKE diagnoses… National Cancer Institute’s shocking admission affects millions of patients, natural news, October 08, 2015.

What has emerged has been an appreciation of the complexity of the pathologic condition called cancer. The word “cancer” often invokes the specter of an inexorably lethal process; however, cancers are heterogeneous and can follow multiple paths, not all of which progress to metastases and death, and include indolent disease that causes no harm during the patient’s lifetime.

Overdiagnosis and Overtreatment in Cancer, An Opportunity for Improvement, JAMA, August 28, 2013.

Image thirteenofclubs.

Better biology alone can explain better outcomes. Although this complexity complicates the goal of early diagnosis, its recognition provides an opportunity to adapt cancer screening with a focus on identifying and treating those conditions most likely associated with morbidity and mortality.

Au nom de tous les seins

Incertain dépistage organisé

Porté par des enjeux humains et de santé publique, le documentaire suit le parcours de quatre femmes confrontées, un jour, à la peur du cancer du sein. Leurs histoires sont le point de départ d’une enquête scientifique qui bouscule nos certitudes..

Tous les ans au mois d’octobre, la campagne pour le dépistage bat son plein. Mais depuis quelques années, la controverse monte:

En savoir plus

Could our relentless pursuit of good health be making us sick?

Too many treatments can be harmful,
Too much medicine can cause angst, confusion and harm

Video published on 27 Oct 2015
by ABCTVCatalyst

Advances in medicine have propelled health care to new heights and a vast array of diagnostic tests and drug therapies is now available. But are we getting too much of a good thing?

More info and videos
  • An increasing number of doctors now say that sometimes, “less is more” when it comes to medical interventions. Some doctors are concerned that resources are being wasted on the “worried well” and that the ever-expanding definition of how we define “disease” has been influenced by vested interests. Could excessive medical interventions be causing more harm than good?
  • Find more overdiagnosis, overtreatment videos on our YT channel.

Choose wisely when it comes to taking more screening tests

Do More Screening Tests Lead to Better Health?

Choosing Wisely Canada is a campaign to help physicians and patients engage in conversations about unnecessary tests, treatments and procedures.

More info and videos

Overuse of medical care, overdiagnosis and overtreatment questioned

Astounding Number of Medical Procedures Have No Benefit, Even Harm

A concerning new review published in the Journal of the American Medical Association online ahead of print on the topic of overuse of medical care, i.e., health care for which “risk of harm exceeds its potential for benefit,” finds that many commonly employed medical procedures, to which millions are subjected to each year, are based on questionable if not also, in some cases, non-existent evidence.

2015 Study Abstract

IMPORTANCE:
Overuse of medical care, consisting primarily of overdiagnosis and overtreatment, is a common clinical problem.

OBJECTIVES:
To identify and highlight articles published in 2014 that are most likely to influence medical overuse, organized into the categories of overdiagnosis, overtreatment, and methods to avoid overuse, and to review these articles and interpret them for their importance to clinical medicine.

EVIDENCE REVIEW:
A structured review of English-language articles in PubMed published in 2014 and a review of tables of contents of relevant journals to identify potential articles that related to medical overuse in adults.

FINDINGS:
We reviewed 910 articles, of which 440 addressed medical overuse. Of these, 104 were deemed most relevant based on the presentation of original data, quality of methods, magnitude of clinical effect, and number of patients potentially affected. The 10 most influential articles were selected by author consensus using the same criteria. Findings included

  • lack of benefit for screening pelvic examinations (positive predictive value <5%),
  • carotid artery screening (no reduction in stroke),
  • and thyroid ultrasonography (15-fold increase in thyroid cancer).
  • The harms of cancer screening included
    • unnecessary surgery
    • and complications.
  • Head computed tomography was an overused diagnostic test (clinically significant findings in 4% [7 of 172] of head computed tomographic scans).
  • Overtreatment included
    • acetaminophen for low back pain,
    • perioperative aspirin use,
    • medications to increase high-density lipoprotein cholesterol level,
    • stenting for renal artery stenosis,
    • and prolonged opioid use after surgery (use >90 days in 3% [1229 of 39 140] of patients).

CONCLUSIONS AND RELEVANCE:
Many common medical practices should be reconsidered. It is anticipated that our review will promote reflection on these 10 articles and lead to questioning of other non-evidence-based practices.

Sources and more information
  • Update on Medical Practices That Should Be Questioned in 2015, JAMA Internal Medicine, doi:10.1001/jamainternmed.2015.5614, November 09, 2015.
  • Astounding Number of Medical Procedures Have No Benefit, Even Harm, greenmedinfo, November 10th 2015.

Mammography Screening SlideShare Presentation

Why was screening implemented? What is overdiagnosis?

  • Why was screening implemented?
  • What is overdiagnosis?
  • The evidence for overdiagnosis
  • Available data
  • Facts from recent studies
  • Risks of screening
  • The illusion of early detection
  • Harms due to overdiagnosis
  • Benefit-risk balance
  • So, what to do?
Sources:

The American Health Care Paradox

A challenge to American doctors…

A challenge to American doctors…

Why Spending More is Getting Us Less

For decades, experts have puzzled over why the US spends more on health care but suffers poorer outcomes than other industrialized nations. Now Elizabeth H. Bradley and Lauren A. Taylor marshal extensive research, including a comparative study of health care data from thirty countries, and get to the root of this paradox: We’ve left out of our tally the most impactful expenditures countries make to improve the health of their populations—investments in social services.

In The American Health Care Paradox, Bradley and Taylor illuminate how narrow definitions of “health care” archaic divisions in the distribution of health and social services, and our allergy to government programs combine to create needless suffering in individual lives, even as health care spending continues to soar. They show us how and why the US health care “system” developed as it did; examine the constraints on, and possibilities for, reform; and profile inspiring new initiatives from around the world.

Offering a unique and clarifying perspective on the problems the Affordable Care Act won’t solve, this book also points a new way forward.

More information