Tracing the Path of Prostate Cancer Spread

Bertram Yuh, MD

Assistant Clinical Professor

Urology and Urologic Oncology

City of Hope

When prostate cancer metastasizes, the propensity is for the disease to follow the drainage of the prostate through pelvic lymphatic channels. Unfortunately, the pelvic lymphatics on an individual basis are variable, and radiographic imaging and functional tests have yet to show significant sensitivity for detecting lymph node disease. As such, current surgical practice is to perform lymph node dissection (LND) in patients who are at higher risk of harboring disease in the lymph nodes.

The past decade has demonstrated a movement toward more extensive LND in order to sample and remove more lymph nodes. Studies have shown that a limited LND overlooks a large number of nodes, and the European Association of Urology and National Comprehensive Cancer Network guidelines suggest performing an extended LND if an LND is to be done at all. The enthusiasm for a more aggressive extended LND needs to be balanced against possible risks, in order to avoid harm to the patient. The number of lymph nodes removed has been used as a surrogate for LND quality, though the actual template followed is likely of more significance. Experienced surgeons are more likely to perform extended LND, as this involves delicate dissection around major pelvic blood vessels.

Recent regulatory recommendations have advocated against PSA screening to reduce overdiagnosis and overtreatment, and has been a topic of major debate. However, a product of reduction in the use of PSA screening may be a stage migration toward more patients presenting with locally advanced and/or metastatic disease. The main advantage of extended LND is in staging these patients. As lymph nodes can be positive in >30% of high-risk individuals, the earlier detection of patients with N+ disease can allow for administration of adjuvant therapies, better assessment of prognosis, and enhanced ability for patient counseling. The ability to accurately assess the lymph node status at the time of surgery is an advantage of surgery compared to radiation treatment.

Another benefit of extended LND is the removal of micrometastatic disease that may in turn impact survival. In other malignancies, LND has been shown to confer a survival advantage. Using another urologic pelvic malignancy as an example, in bladder cancer the evidence for a survival advantage with extended LND is stronger. The oncologic benefit of extended LND in prostate cancer is unproven; however, several retrospective studies have shown an advantage to biochemical recurrence-free survival and cancer- specific survival.

At City of Hope, the urologic oncology team has 5 years of experience in robot-assisted extended pelvic LND at the time of prostatectomy, having performed the procedure in over 1,000 patients. The technique has continued to progress and is proven to be safe. We’ve demonstrated in several publications that the lymph node yield is increased compared to limited LND (from 7 to 22), nodal disease detection is improved (from 4% to 12%), and patients do not experience more complications. We have cared for patients with early lymphatic spread of cancer that remain cancer- free for a prolonged period of time after extended LND and no further therapy. Current and future enhancements will focus on refining dissection mapping using novel fluorescent and antibody- labeled techniques. In this way, we aim to discover which patients would benefit most, which patients may be spared LND, and which patients need a deliberately more thorough LND.

Extended LND removes more cancerous lymph nodes and optimizes the staging ability of prostatectomy. Patients may have one treatment opportunity to have these lymph nodes removed, and surgical treatment at a center with expertise in this procedure can offer that chance.