Ca prostate commonly metastasises to the veebrae:
Prostate cancer homing to the lumbar spine mediated by the connection of the Batson's periprostatic venous vessel to the veebral venous plexus. Ref: The Biology of Skeletal Metastases: Volume 118, 2004, Page 292; bailey and Love's Sho Practice of Surgery, 23rd Edition, Page 1250; Clinical Surgery By S. Das, Page 196.
Because valveless communication exist with Batson's periprostatic plexus.
Via drainage to Sacral lymph node
Of direct Spread
None of the above