Science Forums 2

[maikeru]

Originally Posted by DanielZKlein

Stumbling over a news story on animal testing (which I whole-heartedly endorse, not that anyone cares ;P) I was wondering this: if you want to test cancer treatments on rats, first you have to have rats with cancer. How do scientists go about this?

It depends on the type of cancer(s) the scientists or researchers want to induce and study in the rats. Different types of exposure to toxins, carcinogens, or radiative forms of energy (UV, x rays, gamma rays, etc.) induce different types of cancers or multiple cancers. Say I want to study a skin cancer, like melanoma, in rats. First, I might shave a selected area on the rats, like their backs, or pick a hairless rat strain, and simply expose them to large amounts of UV radiation from a UV lamp. Of course, they need to be divided into proper control and experimental groups and the usual considerations when designing a good experiment.

Do they just screen large rat populations and pick out those specimens that naturally developed cancer?

Usually not. Sometimes certain carcinogenic or teratogenic chemicals or methods are included to increase DNA damage, mutation, or transformation of desired cells into cancer. One example might be rubbing benzene, a known and highly toxic carcinogen, onto a rat's skin and then exposing it to UV rays afterward. While benzene can and probably will induce cell transformation on its own, combining it with UV will make the effect much more potent, and resultant damage to cells much, much worse, leading to a higher (and probably guaranteed) rate of cell transformation in the test animals.

Do they have some ways of inducing cancer in rats? Radiation? Do they make the rats smoke a lot? ;P

Rats prefer Cuban cigars to be honest. Anyway, depends on what kind and how you want to induce what cancer. Cancer is a broad term for a spectrum of diseases that involve aberrant and usually immortal, malignant body cells. It can be caused by DNA damage, faulty enzymes or proteins, faulty control of enzymes or certain proteins, faulty DNA controls but little or no damage to the actual DNA (like improper methylation or silencing of critical genes), or improper stimulus to certain cells so that they grow and do not die when they should.

I googled a little, but with no results. I'm very curious about this--does anyone know?

If you have any more questions, feel free to ask.