I just finished the cancer biography "The Emperor of All Maladies" today, and it goes into molecular medicine in the final part. It's a quick read (or else I was particularly interested and read it fast). I highly recommend it in general:

https://www.amazon.com/Emperor-All-Maladies-Biography-Cancer...

You can also think of cancer as a consequence of multicellularity.

Multicellular organisms need checks on how often and by how much a group of their cells can multiply. A liver must contain a specific amount of liver cells, and cancer occurs when these cells are able to continually divide and eventually activate non liver specific genes.

The cells of a multicellular organism become highly altruistic because each cell of the organism gives up its ability to reproduce in order to provide a chance for the organism's gametes to produce a new living organism.

So wyldfire's original comment on Cancer being a 'feature' is not necessarily incorrect, however the explanation is.

Cancer occurs when the contract that states that the Liver cells, who cannot reproduce, become able to continually divide without checks and balances. You can also almost think of Cancer as Cellular natural selection and evolution within the body. Cancer is a feature and consequence of multicellularity and likely not adaptive in any way such as sickle cell anemia and malaria resistance.

An awesome book which touches on this in addition to other history or cancer is The Emperor of all Maladies http://www.amazon.com/Emperor-All-Maladies-Biography-Cancer/...

Here's a great PBS series to watch if you want to learn more about cancer.

http://www.pbs.org/show/story-cancer-emperor-all-maladies/

It's based on this book, which I have not read: http://www.amazon.com/The-Emperor-All-Maladies-Biography/dp/...

The book is excellent as well

http://www.amazon.com/Emperor-All-Maladies-Biography-Cancer/...