Metastatic patterns of prostate cancer: An autopsy study of 1,589 patients

The prognosis of prostate cancer is mainly determined by the presence or ab sence of metastases. Nevertheless, the metastatic pathways in prostate canc er are not entirely understood. Among 19,316 routine autopsies performed fr om 1967 to 1995 on men older than 40 years of age, the reports from those 1 ,589 (8.2%) with prostate cancer were analyzed. Hematogeneous metastases we re present in 35% of 1,589 patients with prostate cancer, with most frequen t involvement being bone (90%), lung (46%), liver (25%), pleura (21%), and adrenals (13%). Several lines of evidence suggested the existence of a back ward metastatic pathway through veins from the prostate to the spine in add ition to classical hematogeneous tumor spread via the vena cava. First, the re was an inverse relationship between spine and lung metastases, suggestin g that metastasis to the spine is independent of lung metastasis. Second, t he maximum frequency of spine involvement occurred in smaller tumors (4 to 6 cm) as compared with the maximum spread to lung (6 to 8 cm) and liver (>8 cm), suggesting that spine metastases precede lung and liver metastases in many prostate cancers. Third, there was a gradual decrease in spine involv ement from the lumbar to the cervical level (97% v 38%), which is consisten t with a subsequent upward metastatic spread along spinal veins after initi al lumbar metastasis. The results of this study show that bone, lung, and l iver are the most frequent sites of distant prostate cancer metastases, Bes ides the cava-type of metastasis through lung passage, there are strong arg uments for the existence and clinical significance of a backward venous spr ead to the spine, which is likely to occur early in the metastatic process. Copyright (C) 2000 by W.B. Saunders Company.