There's also confirmation bias. Any year, some people will have individual reasons for saying that about—I lost my mother-in-law to cancer in February, and roadnotes to cancer in October—so I've said things like "I'm glad 2014 is over" and "I hope the new year is better." 2013 wasn't that shape of bad for me, so I didn't post something like that, but I also didn't post "2013 was wonderful, can we keep it longer?" My friends who have wonderful years may say things like "this past year was great, I really like my life" when their birthdays come along: but it doesn't seem to go with end-of-year stuff.

So, rationally, I don't think the U.S. cancer rate has suddenly gone up; it's a random artifact of the particular people I know, and the way we divide time. (My mother-in-law was diagnosed in 2013; another friend, being treated now, was diagnosed several weeks back. But I associate both those with 2014.)