From this article on food and weight loss myths:
Myth: Avoid coffee (and caffeine) because it contributes to illness, including cancer.
Fact: For most people who drink coffee in moderation, it's benign, even beneficial, says Harvard's Willett. True, too much coffee can cause insomnia, anxiety, irritability and headache, but coffee drinkers have fewer kidney stones and gallstones and a 50% lower suicide rate than non-coffee drinkers. And coffee isn't linked to cancer.