why are epithelial cells more likely to become cancerous?

Answer 1

1. They divide more frequently than other cells as they are sloughed off and replaced, increasing the likelihood for errors in division and other mutations.
2. They are exposed to more mutagens and in more concentrated form --
from the outside such as UV light, chemicals.

Answer 2

Epithelial cells also have a higher rate of cell division than most other cell types. A cell that rarely or never divides will have a very low frequency of becoming cancerous.

For the same reason, retroviruses that cause cancer by activating downstream proto-oncogenes cannot integrate into non-replicating cells.

The other answers so far are also correct.

Answer 3

Epithelials are the cells surrounding organs. I am guessing they maybe more susseptable to carcinogens (either "passing by" in body fluids (eg in the digestive system..carcinogenic compounds going through) and have greater contact with them or they are close to the surface ie to UV or gamma and x-rays and are more greatly affected than those underneath).

Answer 4

Short answer:

Epithelial cells are exposed to more toxins. Smoking=lung cancer, mouth cancer; bad diet=colon cancer; excess sunlight=skin cancer, etc.

Brain cells are less exposed to this kind of stuff, which is why brain cancer is much less common than skin cancer.