Metastasis of urothelial tumors of the bladder: correlation between sites and number of organs involved.

Urothelial tumors of the bladder in 2,561 autopsy cases were classified according to the number of organs involved in metastasis, and a comparison was made concerning the frequency of the metastases in various organs. In cases with single organ metastasis, lymph node and lung involvement was low (20% and 14% respectively), but it increased as the number of metastatically involved organs increased. The frequency varied depending on the number of organs involved. Three basic types of metastases were established. Type 1: An increase in metastases was seen rectilinearly in accordance with the number of organs involved. Metastases to the lymph nodes (overall), lungs, liver, bones (overall), rectum and retroperitoneal lymph nodes belonged to this group. Type 2: The frequency was low in cases with metastasis to one or two organs, but markedly increased when three or more organs were involved. Metastases to the adrenals, kidneys and pancreas belonged to this group. Type 3: The frequency was almost unchanged, regardless of the number of organs involved. Metastases to the prostate and perivesical lymph nodes belonged to this group. The number of metastatically involved organs is useful in analyzing the mode of metastasis.