A related misconception arises from stories that sometimes appear in the news suggesting that we are now experiencing a cancer "epidemic." It is true that a person's chance of developing cancer within his or her lifetime is almost twice as great today as it was a half century ago, which means that doctors are seeing more cases of cancer than they did in the past. However, this increase is caused largely by the facts that people are living longer and cancer is more prevalent in older people.

When corrected for the increasing average age of the population, cancer rates in the United States have actually been stable or even falling slightly in the past several years. Much of the rise prior to that was due to cigarette smoking, a well established and avoidable cause of cancer.

Source: http://resources.purematters.com/prevention/cancer-prevention/understanding-cancer