Professor Byock says the excavation team has gained insight into the Viking Age settlement in Mosfellsdal The excavation has unveiled information on the health conditions of the people - cancer and tuberculosis were prevalent - as well as other aspects of the cultural make up. (A.D.~900)
http://www.freerepublic.com/focus/f-news/1466181/posts
But it depends on the kinds of cancer. Some have been with us forever, but other kinds of cancer that are now common used to be quite rare. Certain aspects of our modern diet and the chemicals we are exposed to contribute to this. Other diseases such as hypertension and diabetes are also largely modern phenomenons. The diets and activity levels of our ancestors prevented them from occuring.