"The other" drug resistance problem

This is what annoys me when people continue to trot out that saying "The cure for cancer." Scientists have known for years that there will never be a "cure" for cancer. Somehow, though, I can't get people to understand why there will never be a cure for cancer - cancer is simply evolution in action; an evolution that you can't stop without killing the patient.

I have never thought of cancer as an evolution more like wearing out. The more replications of the cell the more likely it will mutate. However that it doesn't explain cancer in the young or resistance to cancer drugs. I am curious are they finding resistance to Tamoxifen?

There definitely is Tamoxifen resistance. As far as the evolution and mutation, remember that there will be huge selection pressures when exposed to drugs, and that mutations that confer even partial resistance will quickly be selected for. Really, cancer cells are quite similar to a bacterial population. Some cells will have an intrinsic drug resistance; in other populations, one will develop following exposure.

I have no background in this area, so I hope this isn't a completely stupid question.

Bacteria that are exposed to anti-biotics gain resistance, reproduce and go on to infect other hosts. The first dose of anti-biotics in these further hosts is therefore ineffective. As a result, some anti-biotics totally lose their value.
Cancer cells, to my knowledge, do not pass to new hosts, and therefore cancer treatments should remain effective when used on a new host. Treatments may be ineffective on patients who have already received that treatment, but should continue to be effective for new patients.
As far as I understand, the worry with bacterial resistance is that we will have an outbreak of a deadly disease that is resistant to all of the available anti-biotics. It seems that this problem will not happen with cancer.
If I am correct about this, then it would seem that bacterial resistance is a much bigger problem than cancer resistance. Is this correct, or am I missing something?

If I am correct about this, then it would seem that bacterial resistance is a much bigger problem than cancer resistance.

Overall, I agree. It's much like the difference between public health and personal medicine. Antibiotic resistance is a public health problem, because what one individual does in regard to how they manage their treatment can affect us all. With cancer, this isn't the case--their own cancer cells may become resistant to a drug, but it won't affect their neighbor's cancer treatment.

"Cancer cells, to my knowledge, do not pass to new hosts"

That's not entirely true. There's a type of cancer in Tasmanian devils that is passed on when they bite each other (physically, the cells are passed to a new organism). However, for the vast, vast, vast majority of cancers, no, they can't be passed on.

Resistance to cancer medications is an entirely expected consequence of taking them. It's only a large problem because, since the cancer cells are *your* cells and function in almost the same way, finding treatments is much more difficult than it is for bacterial infections. Also, for the same reason (the similarity of cancerous/normal cells), cancer treatments are less likely to clear the body of the "infection" than are antibiotics. So cancer treatments wind up being taken chronically, which increases the chances for resistance. It's like HIV medications - they don't clear the body of the virus, so they must be taken chronically, so the virus tends to evolve resistance. Which is why multiple anti-retrovirals are usually used as treatment.

Thanks for the explanations, that helps a lot.

Very interesting. Do you know what kind of cancer can be transmitted in Tasmanian devils? Is it spread through saliva to the blood stream via the bite or just from cell to cell?

I think I found the cancer Devil Facial Tumour Disease. I wonder if it is possible that a pathogen such as a virus could be involved? It just seems strange that a cancer could spread like that.

Hey Brian, do you have a blog? If not, you should! Great information - I'm a cancer pharmacologist and never knew about the Tasmanian devils.

Afarensis blogged about the Tasmanian devils over here; indeed, fascinating stuff.