NEW YORK (Reuters Health) - Thousands of cases of breast and colon cancers might be averted each year if people in colder climates raised their vitamin D levels, researchers estimate in a new report.A number of studies have suggested that vitamin D may be important in cancer risk. Much of this research is based on cancer rates at different latitudes of the globe; rates of breast, colon and ovarian cancer, for example, are lower in sunnier regions of the world than in Northern climates where cold winters limit people’s sun exposure.