About usefulness of early detectors

When one claim to design an early detector of some illness, it is important to think about early detection in healthcare in general, what are the benefits, inefficiencies and the new problems it creates.

As a personal anecdote about usefulness of early detectors, I had a skin carcinoma, that two doctors (the family and the company MDs) saw without reacting for years, one of them even asked me what it was. At the end it was a cardiologist who told me it was probably a carcinoma and that I had to consult quickly a specialist.
MDs have to know what to make of the tests results of those devices. For example some medical organizations start to provide free kit for genetic screening for some conditions [0], as we know some drugs work well for some genomes but less for others, which is a concept a bit weird in itself but very fashionable at the moment.
But those kits do not work the same way, so their results are not comparable with each others, some may analyze the DNA in blood, while others may take a sample with a biopsy needle. Neither can claim to capture the full picture of the tumor’s mutations. In addition tumors’ genome evolves very quickly and is not homogeneous, it is as if many mutations are branching out quickly from a common ancestor cell. At some time later a tumor is the site of several unrelated mutations.
Some tests sometimes provide conflicting or overlapping results from the same patient. Researchers at the University of California, San Diego, published a 168-patient study on discordance in early 2016 that shows there are overlap as well as differences, between DNA analyses from biopsies of tissue and blood samples.
Some tests even make suggestions for drugs, studies have shown that different commercial solutions may in some cases suggest different drugs, or do not suggest drugs that a MD would have prescribed. Those commercial products need to improve, and doctors’ professional bodies need to develop guidelines to teach how to cope with those new tools.

Another thing is the false negative, the press reported recently an unfortunate case where a women felt something was wrong with her baby, in the last months of her pregnancy. She then used a fetal Doppler and found an heart beat, unfortunately the baby was stillborn. It is possible that if she had not used her fetal Doppler, she would have gone immediately to her hospital which may have saved the baby.
False positive are another problem, as an older man I am regularly reminded to check for PSA by the state health insurance, PSA (prostate-specific antigen) is a marker of prostate cancer. I am aware of the risk of cancer, but two large studies, one in US and two in Europe told that for a thousand people screened positively, one man will probably be saved, but several dozens will suffer severe degradation in their life quality and health in general.

The testing process may also induce traveling cost for the patient, lost of time and revenues, incomfort or even suffering, especially in women healthcare. Unnecessary biopsies and other medical procedures for people who are wrongly diagnosed or whose cancer might never have spread, can also hasten health problems.
While early detectors might seem a good idea in general, one problem is the anxiety they generate, for example even if everything is right, it does not mean everything will stay right in the future so there is a constant urge to re-check. Even medical doctors could succumb to cognitive bias, when they find “something” in mammography, then ask for more tests which are negative but nevertheless urge to have more frequent testing in the future, creating unnecessary anxiety for the patient[1].

What does all this mean for a designer of an early detector of heart failure? Certainly that there is a need to not make big unwise claims. There is also a need to collaborate with real doctors, not only scientists.
At the same time how to attract attention of people to make them use it and finance R&D ?

[0] http://www.xconomy.com/national/2017/05/31/in-maine-making-cancer-dna-tests-free-and-asking-tough-questions/
[1] https://blogs.scientificamerican.com/cross-check/why-we-overrate-the-lifesaving-power-of-cancer-tests/


2 thoughts on “About usefulness of early detectors

  1. My post about early detectors was spot on time.
    Please check out the new challenge by the Bonnie J. Addario Lung Cancer Foundation to help radiologists detect lung cancer earlier without so much false positive.
    They want to understand and improve the best submissions to the last Data Science Bowl challenge of Kaggle which was about lung cancer detection.

    Please contribute by grabbing an issue from the project’s GitHub repository and submitting a PR!



    1. Another excellent article in the New Yorker, tells the story of Thyroid cancer detection in South Korea 15 years ago. Many people were found having this kind of cancer, because of a new ultrasound device. By 2014, thyroid-cancer incidence was fifteen times what it was in 1993, making it the most commonly diagnosed cancer in the country. Yet the rate at which people died from thyroid cancer remained unchanged [0].
      This add another type in my typology above, the true positive that is useless, worse than useless in fact as many people received surgery that was unnecessary.
      The article main point is to go beyond oncology’s obsession with the cellular automaton and its genes.
      You can inject the same virus into different hosts and get vastly different responses. It’s the host tissue and cancer cells relationship in a complex assemblage of factors. that determines the nature of the illness. There isn’t one factor but a series of factors that determined how and why the cancer took hold.
      A beautiful article.

      [0] https://www.newyorker.com/magazine/2017/09/11/cancers-invasion-equation


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