I've got your citations.. right here

Among Caucasians in the United States, cancer mortality for several prominent cancers, including cancer of the breast, prostate, and colon, shows a striking latitudinal gradient, with increased mortality rates among individuals residing in the northern states compared with individuals residing the southern states.

Devesa SS, Grauman MA, Blot, WJ, Pennello GA. Hoover RN, Fraumeni JF. Atlas of cancer mortality in the United States: 1950 to 1994. NIH Publication No. 99–4564, 1999.

This whole article is worth reading, and has a number of counter-intuitive findings.