Hacker News Board Hacker News, browsed like a classic message board
Live data from Hacker News

Are we screening too much for skin cancer? It's complicated

undark.org

Post reply on HN
Print view View original

51–60 of 70 posts

Re: Are we screening too much for skin cancer? It's complicated

#51

Post by rscho »

taneq wrote: post #28
throwlotterywon wrote: post #13

Recently, I had a mole on the top of my foot about an inch or two from my toes that grew from a normal size small dot to bigger than a pencil eraser in the span of two months. I went to the doctor, not suspecting any cancer, but because it was ANNOYINGLY itchy and started to grow a red ring around it. For context, I'm a nerdy software engineer who RARELY ventures outside of an air conditioned room, obviously no tanni…

I'm surprised he only took a sample. Where I live, anything suspected of being melanoma gets removed immediately, it's still sent off for testing to see whether it was cancerous or not but if you're taking a biopsy might as well just take it out entirely.

> I'm surprised he only took a sample.

The lesion was likely too big to comfortably remove in-office.

Re: Are we screening too much for skin cancer? It's complicated

#52

Post by LorenPechtel »

bricemo wrote: post #3

This is a complicated space to get right. Prostate cancer is the opposite: The government used to screen for it (PSA blood test) and so people would see their doctor at stage 1 or 2 cancer, when it can be easily tested. But the problem was that the positivity rate was about 45:1, and the test is too expensive at that scale. So now PSA tests are not routine. As a result, people are now coming in to their doctors with…

The reason they quit screening for it is that prostate cancer screening was found to have zero benefit on the number that really matters: how many die.

The thing is prostate cancer is usually a very slow cancer. Very often the proper response to a diagnosis of prostate cancer is keep an eye on it. Being aggressive about going after prostate cancer means more patients harmed by treatment (can you say "erectile dysfunction") but no lives saved. The few saved from cancer are offset by those who die from treatment.

There are basically three types of cancers and note that other than by observing what happens over time the doctors can't tell them apart:

Aggressive cancers. You're dead. The doctors putting you through hell might buy you a bit more time, but that's it.

Slow cancers. In most patients you'll die with the cancer, not of it. Prostate cancer tends to fall into this category.

Middle of the road cancers. These are the only ones where treatment is actually of much benefit to the patient. Found early enough you might even get a cure.

Re: Are we screening too much for skin cancer? It's complicated

#53

Post by LorenPechtel »

aeternum wrote: post #16
jedberg wrote: post #14

This sounds like the same arguments as whether mammograms should start at 40 or 50 years old. Apparently a lot of the cancers they catch during screenings at 40 would go away on their own, so now they only recommend mammograms before 50 if cancer runs in your family, to avoid unnecessary biopsies and other surgeries.

I've never understood this argument, more information should always be better. The real problem seems to be the knee-jerk biopsy/surgery. If a QA engineer points out a potential bug, it's foolish immediately/blindly delete chunk of code containing the bug. It's just as foolish to say we're randomly deleting too much good code, so let's fire the QA engineers.

The problem is that information comes with risk.

And I don't understand your comment about knee-jerk biopsy--if you're not going to do the biopsy why did you even bother with the mammogram??? My wife has been through that: Routine mammogram--it got read while she was still there. The radiologist didn't like a spot. Ultrasound. They still didn't like the spot. An hour of sitting around while they get authorization, then they do a biopsy there in the radiology facility.

That came back abnormal but not cancer. At that point the urgency was over, she was referred to a surgeon who removed what pathology said was a precancerous lump.

Re: Are we screening too much for skin cancer? It's complicated

#54

Post by thaumasiotes »

throwlotterywon wrote: post #13

Recently, I had a mole on the top of my foot about an inch or two from my toes that grew from a normal size small dot to bigger than a pencil eraser in the span of two months. I went to the doctor, not suspecting any cancer, but because it was ANNOYINGLY itchy and started to grow a red ring around it. For context, I'm a nerdy software engineer who RARELY ventures outside of an air conditioned room, obviously no tanni…

> "We'll call you if there's any problems, if you don't get a phone call, nothing is wrong. See you at your next appointment!"

This is definitely the wrong way to do it. If nothing's wrong, I want to hear about it.

Re: Are we screening too much for skin cancer? It's complicated

#55

Post by aeternum »

ejolto wrote: post #25
tasty_freeze wrote: post #23

Earlier quoted context omitted.

An under 3-minute video by a funny and informative doctor explaining this (youtube handle "medlife crisis"): https://www.youtube.com/watch?v=7kQk9-KLPfU

This one is even more relevant as he talks about dangers of over screening for beast cancer, and side effects of mastectomy+chemo: https://youtu.be/yNzQ_sLGIuA

Even in his examples, the screening itself does not seem to be the problem. It's relatively cheap and quick.

The problem was the decision to undergo treatment when the complications outweighed the benefit. What if we did more screening but also less treatment?

Re: Are we screening too much for skin cancer? It's complicated

#56

Post by aeternum »

fifteenforty wrote: post #37
aeternum wrote: post #16

Earlier quoted context omitted.

I've never understood this argument, more information should always be better. The real problem seems to be the knee-jerk biopsy/surgery. If a QA engineer points out a potential bug, it's foolish immediately/blindly delete chunk of code containing the bug. It's just as foolish to say we're randomly deleting too much good code, so let's fire the QA engineers.

All tests have false positives and false negatives. Whether we explicitly say it or not, most clinical decision making algorithms are based on a Bayesian approach. If you have next to no risk of a disease, don’t get tested for it. You might get treated for it!

>If you have next to no risk of a disease, don’t get tested for it. You might get treated for it!

If this is true, then clinical decision makers don't understand or are not correctly applying Bayesian priors.

Re: Are we screening too much for skin cancer? It's complicated

#57

Post by allturtles »

aeternum wrote: post #55
ejolto wrote: post #25

Earlier quoted context omitted.

This one is even more relevant as he talks about dangers of over screening for beast cancer, and side effects of mastectomy+chemo: https://youtu.be/yNzQ_sLGIuA

Even in his examples, the screening itself does not seem to be the problem. It's relatively cheap and quick. The problem was the decision to undergo treatment when the complications outweighed the benefit. What if we did more screening but also less treatment?

Unfortunately you can't know the benefit in advance. It's not generally possible to tell from a MRI/CT that detects a tumor if it will kill you soon if not treated, if it will kill you no matter what you do, or if it will just sit there for a decade and do nothing.

Re: Are we screening too much for skin cancer? It's complicated

#58

Post by aeternum »

allturtles wrote: post #57
aeternum wrote: post #55

Earlier quoted context omitted.

Even in his examples, the screening itself does not seem to be the problem. It's relatively cheap and quick. The problem was the decision to undergo treatment when the complications outweighed the benefit. What if we did more screening but also less treatment?

Unfortunately you can't know the benefit in advance. It's not generally possible to tell from a MRI/CT that detects a tumor if it will kill you soon if not treated, if it will kill you no matter what you do, or if it will just sit there for a decade and do nothing.

The only way we will figure that out is to collect lots of data on it. Perhaps there are correlations in the MRI/CT that determine lethality/malignancy.

Even if we perform zero treatment, this data argument should be sufficient reason to increase rather than decrease the number of MRIs we do. CT is different since there is some radiation exposure risk that must be considered.

Re: Are we screening too much for skin cancer? It's complicated

#59

Post by jedberg »

aeternum wrote: post #58
allturtles wrote: post #57

Earlier quoted context omitted.

Unfortunately you can't know the benefit in advance. It's not generally possible to tell from a MRI/CT that detects a tumor if it will kill you soon if not treated, if it will kill you no matter what you do, or if it will just sit there for a decade and do nothing.

The only way we will figure that out is to collect lots of data on it. Perhaps there are correlations in the MRI/CT that determine lethality/malignancy. Even if we perform zero treatment, this data argument should be sufficient reason to increase rather than decrease the number of MRIs we do. CT is different since there is some radiation exposure risk that must be considered.

If you do a screening and find something that might be cancer and do nothing about it, you've committed a major ethical violation. If you tell the patient "we found something that might be cancer but we suggest you don't do anything about it so we can get more data on whether it ends up killing you", well, the patient will probably see another doctor.

Re: Are we screening too much for skin cancer? It's complicated

#60

Post by google234123 »

edmundsauto wrote: post #49
cycomanic wrote: post #24

Earlier quoted context omitted.

I don't think it's as easy as "let the patient decide". First, probabilities are very abstract concepts for people, that's why people respond very differently to the dangers of things when given the probability. Some people are scared if there is a 1:1000 chance of something happening, others are reassured, but both might have very similar reactions if they actually get hit by the chance event. Secondly, also there i…

Yes, patients should be making all decisions regarding their own health. Am I misreading you? Are you really suggesting they shouldn’t have these options because they might make a bad decision?

This article is about screening which is a public health policy. Policies shouldn't promote things that are not effective.

Anyway, patients can't make all decisions regarding their own health since most drugs need a medical prescription. And doctors won't just do any procedure that you ask them to.

Post reply on HN