It seems possible. When I had Hodgkins, they fed me chemicals that went to the cancerous nodes, so they could get better CAT scans of them before and during treatment. This way, instead of taking a CAT scan, you zap the nodes.
That chemical - radioactively tagged glucose for a PET scan, for instance - is used by all cells, but consumed at slightly higher rates by more rapidly growing cells - such as tumors.
It is preferentially absorbed by tumors because of its chemical properties as a natural energy source for metabolic functions, and the slightly higher rate of consumption of tumors due to their higher growth rate. However, mucous membranes, hair and nails, and blood cells also absorb at a higher rate.