In medical school, one of my mother's classes had an exercise one day which took this form:
Here are a bunch of slides of prostate samples. Find the cancerous one.
This led to the teacher getting so many questions about whether the slide someone was currently looking at was the cancerous one that he was forced to interrupt the class to make this more general announcement:
There's a bit of cancer in everyone's prostate. Find the slide with obvious cancer.
I'm not a doctor, but my understanding has been that we all have cancer cells at any given point in time. Consider how many cells inside you are undergoing cell division; errors in cell division are where cancer cells come from.
The question is whether your body sees and kills the cancer cells; most of the time it does, which is why most of us can live pleasantly for most of our lives despite errors cropping up silently. What we term cancer are the cancer cells that slipped past our body's defences, growing into masses that cause no end of grief.
To put it in computer terms, it's like error correction in HDDs and SSDs and ethernet connections. Errors are inevitably going to occur while data is in transit, but they are of no concern so long as error correction and other such mechanisms can correct and recover. The errors do become a concern when they start slipping past such mechanisms, however.
This is my understanding as well and my favorite protein, p53 [1], is responsible for hunting down cancerous cells. From what I remember reading in Robins Basic Pathology, it takes many steps for a cell to evolve into cancer and our body has ways to reduce the probability at each step. The most fascinating topic to me is how someone's lifestyle and environment affect their body's natural cancer defence mechanisms. We can do many things to stack the odds in our favour, but sometimes the odds are still not in our favour. Should we strive to minimize the chance by adjusting our lifestyle and changing the environment, or strive for some kind of balance?
Elephants have 100x as many cells as a human does, live about as long, but have about 1/2 the chance of dying of cancer. Why? A big part is that each elephant cell has ~40 copies of the p53 gene.
>Should we strive to minimize the chance by adjusting our lifestyle and changing the environment, or strive for some kind of balance?
That is as much a philosophical question as it is biological, and one where the answer will vary by who is asked.
Personally, I will say this: If you're miserable while endeavouring to prevent cancer (or any other disease), that's putting the cart before the horse. The goal is, presumably after all, to live happily.
That's my understanding too. But we're talking about cancer that can be observed on a slide. At that point, that's beyond the error correction mechanisms AFAIK.
You're probably correct as to babies. But the prostate gland is extremely cancerous and my assumption would be that that tendency begins at either birth or puberty. The exponential function spends the entire infinite length of the negative x-axis rising from 0 to 1; think about the growth of cancer in your prostate gland that way.
I would not expect a man in his late 20s to fall into the category "men of an advanced age". But I would be unsurprised to learn that there was visible protocancer in a sample of his prostate.
Someone I knew had the slow-growing case for quite some time. Then, it abruptly without warning turned into the aggressive form and killed him. Makes it very difficult to know what to expect. I guess frequent checks are necessary, because once its evident, you're already in a world of trouble...
The stats are still pretty bad. Prostate cancer kills more people than breast cancer (though it's usually men in their 80s, so the QALYS is not as bad). A prostate cancer diagnosis is not terrible (since it's so damn common) and aggressive treatment and overly-aggressive screening might be a bad idea in most cases (since it's often best to not worry too much - over-treatment and even over-testing has its costs) but there's certainly a need for better treatment in cases where it does get bad (which is a very sizable number of older men).
Doctors don't try to do the test on every man over 55 without a good reason.
Not sure where you're getting your stats from. In both US and Canada this isn't true.
There are an estimated 43,780 deaths attributable to breast cancer and 34,500 to prostate cancer in the US for 2022[0] and 5555 vs 4600 respectively in Canada. This is spite of aggressive screening and early treatment vs not really for prostate cancer.
But, curiously, they stop testing at 70 (or was it 72?). That's what my urologist told me last year when I had my exam. Ever since my father had prostate cancer, I've had a yearly PSA and exam by a urologist (thinking that a urologist will be better at detecting tumors than a GP/PCP).
There is weak evidence to support testing over 70 due to increasing risks of biopsy/treatment and no evidence to support improved overall mortality.
Some guidelines suggest that it's reasonable to continue in patients with >10-15 year life expectancy if the patient desires, but there is no strong recommendation or evidence to support this recommendation or screening in this age group.
Some guidelines actually have a strong recommendation to stop screening men with < 15 year life expectancy.
Even less evidence for a DRE. PSA by a GP is sufficient if you desire screening.
> Even less evidence for a DRE. PSA by a GP is sufficient if you desire screening.
I believe my father's prostate cancer was found via DRE and not PSA. That is, PSA was in the normal range. That is what made me get a DRE from a urologist once a year (since then).
It’s hard to comment accurately as prostate cancer isn’t a single disease.
PSA cutoff trades sensitivity and specificity. It isn’t a binary positive/negative.
There are certain highly aggressive but very rare subtypes (e.g. neuroendocrine) that will present with low PSA levels. Rarely an aggressive adenocarcinoma (Gleason 8+) will present with low PSA. Screen detected prostate cancers with low PSA are most likely clinically insignificant [0].
If you are known to have a first degree relative with a rare subtype then routine screening guidelines don’t apply to your circumstance.
Important points to keep in mind:
Just because a prostate cancer is “found” it doesn’t mean it needs to be treated.
There is no survival benefit when comparing treating early prostate adenocarcinoma (conventional and most common type representing 99% of prostate cancers) at very low PSA vs using 4ng/mL as a cutoff.
There are verifiable and proven harms with over treatment of low grade prostate cancer, workup of a “nodule” felt on DRE in the context of normal PSA is more likely to harm a patient than benefit them even if cancerous which forms the basis of current guidelines.
All forms of cancer screening will have edge cases that are missed. Even in your father’s case only the peripheral zone is palpable by DRE (would miss transitional zone or 20% of cancers). When considering recommendations to make at a population level harms vs benefits have to be carefully weighed, in the case of prostate the evidence strongly suggests against DRE, and weakly against prostate cancer screening in general.
Looking towards the future, there is probably a role for prostate MRI somewhere which is good at detecting clinically significant (Gleason 7+) cancers but this is still being actively studied and we don’t have enough evidence at this time to support screening.
Yes, cancer is never good but for most men prostate cancer develops late and is usually growing very slowly and doesn't spread.