What causes cancer to appear in some places more frequently than others?

Unknown: From your question, i believe that you are asking why cancers seem to arise in certain tissues. The common areas include breast, colon, prostate, lung, skin. This is likely because the cells in these regions are more prone to mutation either because they are bombarded by mutagens (ie. U.V. Radiation for the skin, smoking for the lungs) more readily or inherently the dna is more susceptible.