Indigo Overview
Indigo is prostate cancer that has relapsed after a previous attempt at curative treatment (surgery, radiation, HIFU, laser, electroporation or cryotherapy) but without detectable cancer that has advanced into areas of the body distant to the pelvic lymph nodes. Over 50,000 men relapse after treatment every year in the United States. Often the relapses are localized to the pelvis and the possibility of cure still exists. Also, some of these “relapses” are so minor it is possible to watch them and forgo immediate treatment. When the cancer spreads beyond the pelvic lymph nodes, the stage becomes Royal, not Indigo. Therefore, Indigo represents residual cancer in the previously treated prostate gland, in the prostate fossa (the area where the prostate gland was located prior to surgical removal of the gland), or in the pelvic lymph nodes. Metastases detected in the pelvic bones is Royal, not Indigo.
Indigo falls into three categories: Low, Basic, and High
Low-Indigo is cancer confined to the prostate or the prostate fossa. This can occur when there is residual disease after surgery noted in a pathology report, such as a positive margin or seminal vesicle invasion. Low Indigo also occurs when there is residual disease after radiation or cryotherapy is detected in the prostate by imaging or biopsy.
Basic-Indigo is a rising PSA after treatment, a clear PSMA scan and a PSA doubling time greater than 9 months.
High-Indigo is a PSA doubling time 9 months or less or surgically detected or scan-detected cancer in the pelvic nodes.
The traditional approach to Low-Indigo in younger men utilizes a sequential, one-treatment-at-a-time policy with salvage treatment administered to the prostate gland or prostate fossa alone. Men with High-Indigo will often be managed with a multimodality approach using extended radiation fields and supplemental TIP to improve cure rates. In men with Basic Indigo treatment can be withheld while undergoing periodic PSA testing and scanning with PSMA Pet scans. A less aggressive treatment stance may be more appropriate as men get older.
ABOUT THE AUTHOR
Mark Scholz, MD is the Executive Director of the Prostate Cancer Research Institute. He is also the Medical Director of Prostate Oncology Specialists Inc. He received his medical degree from Creighton University in Omaha, NE. Dr. Scholz completed his Internal Medicine internship and Medical Oncology fellowship at University of Southern California Medical Center. He is co-author of Invasion of the Prostate Snatchers. He has authored over 20 scientific publications related to the treatment of prostate cancer.