What is an effective screening ?

What is an effective screening?

An effective screening involves two criteria:

  • important reduction in mortality
  • reduction in the incidence of advanced cancers

Example of a screening that meets these criteria, cervical screening, images from a presentation by Pr P.Autier

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What about breast cancer? Is screening for breast cancer effective?

1°Criterion, mortality

Since 1996, there have been approximately 11,000 to 12,000 deaths from breast cancer per year. We are therefore not seeing the massive and drastic reduction that we observe in medicine when strategies really work. (The discovery of tuberculosis antibiotic therapy led to the closure of the sanatoriums within two years, the sterilization of the scissors used to cut the umbilical cords has effectively eliminated mortality from neonatal infections).
Furthermore, it is misleading to come up with figures for specific mortality (mortality from disease, here breast cancer) without giving figures for overall mortality (all-causes mortality).
Deaths due to the consequences of breast cancer diagnosis and subsequently due to surgical or anaesthetic accidents, complications of chemotherapy and radiotherapy such as cardio-vascular damages and radiation-induced cancers are not included in breast cancer mortality.
To date, there are no clear signs of a decrease in overall mortality from mammography screening.

As far as the specific mortality from breast cancer is concerned, we can see that it has been decreasing since 1993. However, this decrease occurred before the generalization of screening in France (in 2004) and cannot be attributed to it. In the United Kingdom, the decline in breast cancer mortality was 11% between 1985 and 1993, while screening was only operational in 1988.
In an impact report, a comparison of eight countries in Europe and North America reveals no correlation between national screening penetration and chronology or the extent of breast cancer mortality reduction. The comparative approach in this study with 14 other types of cancer shows a similar decrease in the mortality rate of these cancers, while these other cancers are not the subject of screening campaigns.
The start of the decline in breast cancer mortality is correlated with therapeutic de-escalation at a time when there is better control of the therapies administered to women and of their adverse effects.

There is a decrease in mortality from breast cancer, on the one hand it is not correlated with the screening practice, and on the other hand, by the very confession of official authorities data, 12,000 women continue to die of breast cancer every year, not counting those who die from complications that are distant from their treatment (12 146 in 2018 in France)..
Another fact is that mortality rates and survival are the same in groups of screened women and in groups of unscreened women, at similar stage of the cancer at the time of its diagnosis, as shown by several studies, including A.Miller's in particular, with a long follow-up of the groups of women over 25 years.

2°Criterion, the rates of serious cancers

The accumulation of epidemiological data shows that in populations where mammography screening has been widely used for a long time, the incidence of advanced cancers has shown little or no decrease. Numerous studies confirm this fact [1].
A recent, large 2015 study of 16 million women in the United States corroborates this disappointing finding [2]:
- No significant reduction in mortality (red line in the graph on the left)
- No reduction in serious cancers (red line in the graph on the right)

Survival at 5 years

This data, which INCa and screening promoters often advantageously highlight, is an indicator of the lifetime of cancer and not of the effectiveness of screening.
Early cancer diagnosis gives the illusion of a longer survival.
This is an optical illusion: by anticipating the date of the occurrence of cancer, one has the impression of an extension of the life, whereas life expectancy has not improved in any way.
The prolongation of survival is the result of two phenomena: the effectiveness of therapies that prolong the life of a patient with his cancer, and screening that anticipates the date of appearance of cancer regardless of the outcome of the disease.
Survival is increased all the more as the over-diagnosis is greater. Indeed, by definition, all over-diagnoses cure!

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A good counter-example is the cervical cancer: its 5-year survival is very poor, but mortality from this cancer has fallen dramatically.

Comparison of 6 different screenings

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While the incidence increases without any impact on serious cancers or significant reduction in mortality due to screening, this increase is then the direct effect of medical intervention which over-detects lesions, which is of no use to people's health.

For one cancer, we see that the contract is being fulfilled: this is the cervical cancer. Anticipating precancerous lesions means that the incidence of this cancer, the rate of severe forms as well as its mortality decrease perceptibly and is relatively well correlated with the introduction of screening.
However for the breast, prostate and thyroid, the situation is much more disappointing, with an unresolved problem: increasing overdiagnosis, without a satisfactory decrease in serious cancers or a reduction in treatment.
For colon cancer, it is currently recommended that screening be reserved for high risk individuals.

Bibliography

[1].Autier P, Boniol M, Koechlin A, Pizot C, Boniol M. Effectiveness of and overdiagnosis from mammography screening in the Netherlands: population based study. BMJ 2017;359:j5224.

Autier, M. Boniol, R. Middleton, JF Dore, C. Héry, T. Zheng et al. Advanced breast cancer incidence following population-based mammographic screening Ann Oncol, 22 (8) (2011), p. 1726-1735

Bleyer, HG Welch Effect of Three Decades of Screening Mammography on Breast-Cancer Incidence N Engl J Med, 367 (21) (2012), pp. 1998-2005

NA de Glas, AJ de Craen, E. Bastiaannet, EG Op ‘t Land, M. Kiderlen, W. van de Water, et al. Effect of implementation of the mass breast cancer screening programme in older women in the Netherlands: population based study.


Autier, M. Boniol, The incidence of advanced breast cancer in the West Midlands United Kingdom, Eur J Cancer Prev, 21 (3) (2012), pp. 217-221


Nederend, LE Duijm, AC Voogd, JH Groenewoud, FH Jansen, MW Louwman Trends in incidence and detection of advanced breast cancer at biennial screening mammography in The Netherlands: a population based study. Breast Cancer Res, 14 (1) (2012), p. R10


ML Lousdal, IS Kristiansen, B. Moller, H. Stovring, Trends in breast cancer stage distribution before, during and after introduction of a screening programme in Norway Eur J Public Health, 24 (6) (2014), pp. 1017-1022


RH Johnson, FL Chien, A. Bleyer Incidence of breast cancer with distant involvement among women in the United States, 1976 to 2009 JAm Med Assoc, 309 (8) (2013), pp. 800-805


Laura Esserman, Yiwey Shieh, Ian Thompson, Rethinking screening for breast cancer and prostate cancer, Jama, 302 (15) (2009), pp. 1685-1692


Jorgensen, PC Gøtzsche, M. Kalager, P. Zahl Breast Cancer Screening in Denmark
A Cohort Study of Tumor Size and Overdiagnosis, 166 (5) (7 mars 2017), pp. 313-323

HG Welch, DH Gorski, PC Albertsen Trends in Metastatic Breast and Prostate Cancer, N. Engl JMed, 373 (18) (2015), pp. 1685-1687

Di Meglio, RA Freedman, NU Lin, WT Barry, O. Metzger-Filho, NL Keating, et al. Time trends in incidence rates and survival of newly diagnosed stage IV breast cancer by tumor histology: a population-based analysis Breast Cancer Res Treat, 157 (3) (2016), p. 587-596`

[2] « Breast Cancer Screening, Incidence, and Mortality Across US Counties »
Auteurs : Harding C, Pompei F., Burmistrov D., et al. JAMA Intern Med. Published online July 06, 2015. doi:10.1001/jamainternmed.2015.3043

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