evidence: When selecting a sunscreen, MD Anderson dermatologists recommend choosing a broad-spectrum product with at least sun protection factor (SPF) 30. 'Broad spectrum' means the product protects from both UVA and UVB rays which can lead to sun damage and skin cancer. SPF refers to the amount of UVB rays it blocks. [...] Myth 3: Sunscreen causes cancer. False. There is no medical evidence that sunscreen causes cancer. However, there is a lot of evidence that UV rays from the sun and tanning beds do.