Wanted to write about an interesting article which I read in the student BMJ, 'Shift Work and Cancer'. I had no idea before reading this that research has been published claiming to show a link between the two. Some of the underlying reasons cited include suppression of melatonin, sleep pattern disruption of the hypothalamic-pituitary axis and decreased vitamin D production.
Fritschi L. Shift Work and Cancer. BMJ. 2009 Jul 15;339:b2653. doi: 10.1136/bmj.b2653.