Lymphatic drainage and CTV in carcinoma of the prostate.

The prostate lymphatics drain into the periprostatic subcapsular network, from which 3 groups of ducts originate: the ascending ducts from the cranial prostate draining into the external iliac lymph nodes, the lateral ducts running to the hypogastric lymph nodes and the posterior ducts draining from the caudal prostate to the subaortic sacral lymph nodes of the promontory. Internal, external iliac and obturator lymph nodes are the most frequently involved by prostate carcinoma. Metastases to presacral and common iliac lymph nodes are rare. For the limited staging accuracy, present indications for seminal vesicle irradiation and pelvic node prohylactic irradiation are essentially based on risk categories and estimation algorithms; the latter while are widely used in international studies are not free of limitations as stressed since they were introduced. A method to deliver high doses to the tumor while limiting the irradiation of critical organs might be the delivery of a boost to the tumor only. This approach could become increasingly feasible with the diffusion of imaging procedures able to better define tumor extension.