USPIO Imaging - Detecting Prostate Cancer Cells

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Someone once said, build a better mouse-trap and the world will beat a path to your door. If the mouse is prostate cancer, we’ve been working on that trap for many years, making slow but significant progress.

Many of the advances of the past decade, perhaps most importantly the evolution of DART (dynamic adaptive radiotherapy), have allowed thousands of men to be treated non-surgically with every expectation of surviving with high quality of life for many years, without experiencing a biological recurrence. I like to remind men that the newest longevity tables are very encouraging: a man who is 65 today is predicted to live an average of 18 more years, if he is 70 that prediction is 15 years, and if he is 75 the prediction is 12 more years.

Men who have chosen a treatment other than our combination protocol, especially those having a robotic procedure, may face a different future. In our practice we are seeing alarming numbers of post-robotic patients coming to us for salvage radiation as soon as 6-10 months after their robotic experience. Recurrence, or better “persistence,” of disease is obvious when the PSA fails to fall, or if it falls but soon begins to rise again. In these cases, prostate cancer had probably already broken through the capsule, or more than likely the robotic procedure was not successful in removing all the active cells within the gland.

Among our own patients, even though their PSA reached an appropriate nadir, some are seeing a slow rise of PSA many years after their initial treatment, indicating that some few cells must have escaped the original radiation assault. (We have addressed this potentiality in recent years by adding a third part to treatment – radiation to the lymph nodes of the pelvis and abdomen, as they are the usual route of escape.)

Fortunately, diagnostic advances have kept pace with our treatment improvements and one bright star in that realm is the USPIO (Ultra-small Super-Paramagnetic Iron Oxide) imaging. This IV infusion of the nanoparticle Ferumoxytal (Feraheme) makes possible a very revealing picture of where active prostate cancer cells have traveled through the lymph system. While the process is not currently FDA approved, it is on a fast track to gain approval. Last fall, Dr. Stephen Bravo, Dr. Charles Myers and I, along with two other physicians, submitted a scientific presentation to the annual meeting of the Radiologic Society of North America (the largest meeting of its kind) with the first data gleaned from this promising procedure.

In brief, 16 patients with suspected biochemical recurrence (evidenced by rising PSAs) underwent the USPIO test. The tests for twelve of these men demonstrated positive pelvic lymph nodes, 2 had positive retroperitoneal lymph nodes, 1 had positive mediastinal lymph nodes, and 1 had a positive left supraclavicular lymph node. A total of 29 identified nodes were subsequently biopsied using image-guided technology.

Biopsies confirmed 25 lymph nodes with metastatic prostate cancer; two lymph nodes revealed lymphoma and 2 lymph nodes proved normal.

The clinical relevance of USPIO was reported to have “the potential to identify neoplastic nodes down to a resolution of 3- mm, thereby markedly improving the detection of metastatic lymph node disease.” (We have actually seen the USPIO reveal nodes down to a resolution of 1.3 mm.)

A larger study was presented at the CIRT (Cancer Imaging and Radiation Therapy) meeting in Orlando in February 2013. The meeting was a joint presentation of RSNA (Radiologic Sciences of North America) and ASCO (American Society of Clinical Oncology).

This is, indeed, good news for men who post-treatment experience an otherwise unexplained rise in PSA.

(The complete report is available through our office. Just give Ginya a call.)

Michael Dattoli, MD