In the same context that hydronephrosis induces increased urinary B2-MG (21), a higher tumor burden or mass effect (large size) (4.23 ± 3.34 vs 3.23 ± 1.96, p=0.002) resulting in ipsilateral urinary stasis may also induce kidney tubular damage and increase B2-MG excretion. This evidence concerns the gene MGAM and neoplasm.