Question

what makes some genes responsible for an increased risk of certain cancers?

Answer 1

Damage to the gene on the chromosome...Could be due to UV radiation, alteration to the the DNA structure such as alkylation, depurination from chemicals & smoke for example. This will change the the structure of the gene sometimes allowing it to cause cancer. A lot of factors are environmental factors such as diet.

Humans are susceptible to cancer if certain important genes such as "RAS" "p53", and "RB" are damaged or disrupted due to chemicals or random unlucky mutations(rare), they will promote cell division and will not be able to stop, or they won't know when there are too many cells and keep allowing cells to divide. Hence the formation of tumors and eventually metastases.
Source(s):
Biology Student

hope that helps :D