With the odds of about 1 in 2 people getting cancer at some point in their lives, why isn’t it protocol for everybody to get screened for cancer of all types more often? Like maybe every few years starting at the age of twenty? It seems most times it get caught is when somebody is complaining of a symptom, often times too late.
In: Biology
Too expensive for insurance companies. You can pay out of pocket for whatever you want but companies don’t care abt you
screening the general population at large is more likely to find harmless things than it is to find cancer. this is called an “incidentaloma”.
these likely harmless abnormalities still require workup including biopsies or surgeries to make sure they aren’t cancer. In addition to the harm from all of these extra procedures, there’s a huge amount of anxiety and suffering around these false positive results.
the best cancer screenings are done in populations at an elevated risk using modalities that can help determine the risk of malignany and minimizes false positives
Some cancers don’t have any screening and those are included in the 1/2. Many cancers still will get missed even if you start screening decades earlier because they simply don’t occur until later in life. Most importantly, cancer screening is not perfect. When something has a low probability event, the odds of false positives increase especially when it is more important to catch all cases rather than miss a diagnosis. It’s a delicate balance though because cancer screening tests are not diagnostic and require more invasive (i.e. more dangerous) follow-up tests, or sometimes, the screening itself isn’t completely benign (e.g. anesthesia + risks of perforation from colonoscopy). If your false positive screening rate is too high, you end up causing *more* harm to the population than if you did nothing.
I also would venture there’s a major reporting bias amongst people. It is much more likely that you are seeing stories about people who were diagnosed with cancer than all the people who had screening tests catch pre-cancerous lesions. I know I’ve never seen anyone post about their parents’ or grandparents’ recent colon polyps or negative low dose CT scan or normal PSA. Honestly even a lot of stage I curative cancers are kept secret still.
That’s just not practical, financially sensible, safe for patients, or even medically necessary. We regularly screen for cancers that it makes sense to screen for. For example, women get regular mammograms for breast cancer, men get regular prostate screenings for prostate cancer, older people get regularly colonoscopies for colon cancer, and people can get regular skin checks for skin cancer. We screen for those cancers because they’re the most common. People at higher risk for other types of cancers can get screened on an as-needed basis.
There are hundreds of other types of cancers, some more common and some very rare. It doesn’t make sense to be screening people for every possible type of cancer, especially ones that are rare or uncommon in that particular group of people.
Even if it did, it’s literally impossible. There simply isn’t enough medical equipment in the world to be doing all of those screenings. Every MRI and CT machine in existence would just be doing nonstop cancer imaging and nothing else. The healthcare system would grind to a halt because all we’d be doing is looking for cancer. There’d be no time or resources left to do any other kind of healthcare.
Even if the above weren’t true, it’s not safe to be doing all of that. Many types of cancers can’t be diagnosed without biopsies or CT scans. You can’t just be taking bits out of all of your organs all the time on the off chance you might have cancer. It’s also very unsafe to be subjecting people to all the radiation from CT scans. All that radiation exposure could actually *cause* cancer.
And even if all of the above were not true, it would be financially disastrous. Even if you propose that the government pay for all these screenings or that doctors must provide them free of charge, they money has to come from *somewhere.*
We have to be selective with our limited resources and personnel, this is achieved by focusing on specific high risk groups or testing based on symptoms. More important reasons to follow regularly with a primary care doctor who can pick up on more subtle signs of potential cancer
We are getting very close to the point where we can do this both inexpensively and easily. I’d say within the next 10 years a monthly blood test for cancer will be widespread and affordable.
source: My master’s degree dissertation into cancer diagnostics
– Because not every kind of cancer has a good screening test. Read about the statistical concepts of sensitivity and specificity.
– Because not every person is equally likely to get any (or all) cancers. Read about pre-test probability.
– Because not every screening test is equally valid for every person. Read about positive and negative predictive value.
In order for a screening test to be useful, it has to have a reasonable chance of catching real cases (minimizing false negatives) while ignoring healthy people (minimizing false positives). The statistical concepts I mentioned above all build on each other to determine how useful a test will be for any specific group of people. All cancers are different, so the inputs required to make a screening test valid for any particular cancer are also different. Applying all screening tests to all people (even those very unlikely to have a particular type of cancer) would increase the number of false positives and false negatives found. How would we figure out which people that tested positive were actually positive? And how would we sort through the negatives to determine which people had falsely tested negative and actually needed treatment?
The costs of a false positive or false negative screening test can be vast and not limited to financial costs. What if a screening test tells you that you have a type of cancer, but it’s a false positive? What if you undergo chemo, or radiation, or surgery because of a positive test, and permanently alter your future health trajectory unnecessarily? What if your mental health or relationships are affected? What if you found out after everything that your test was incorrect, and you never had cancer to begin with?
1) Not all cancers will kill you.
2) Some cancers could kill you, but probably won’t get that far before you die of something else.
3) Unnecessary screenings can actually harm patients by misidentifying benign processes that then get further worked up (tests, biopsies, stress, cost, possible surgeries) before realizing they’re not an actual problem.
4) We don’t have effective, affordable screenings for all cancers.
There are hundreds of types of cancer and many are very difficult to detect until they’ve advanced. Some of the most exciting developments in cancer treatment aren’t actually the treatment, theyre methods of detecting it early enough that its treatable with current methods.
They do watch for warning signs of common ones but regularly screening is not technologically feasible, much less financially so.
The dangers of false positives can often outweigh the chances of getting the cancer. Some screening makes sense but if you are giving random scans which provide radiation or lead to unnecessary biopsies, you are also doing harm
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