What is a pelvic lymph node dissection and why is this necessary?

One of the first areas of spread of prostate cancer is often the lymph nones near the prostate. Our bodies have thousands of lymph nodes that act a guardians of our bodies. Lymph nodes are involved with fighting infections (the tonsils area actually an example of lymph nodes) as well as cancer. Certain lymph nodes located near the prostate are often the first landing site for cancer that has spread outside of the prostate. Depending on the aggressiveness of the cancer, these lymph nodes are removed at the time of surgical removal of the prostate. It provides important mictroscopic information on the spread of prostate cancer.