<prompt> Beta 2 microglobulin is a tumour marker for:Multiple myelomaLung cancerColonic neoplasmChoriocarcinoma  <response>: Increased levels of microglobulin are seen in the urine and serum of patients with multiple myeloma. Serum beta 2 microglobulin is the single most powerful predictor of survival and can substitute for staging. ref Harsh mohan 6th383,Robbins 9th 