The annual Genitourinary Cancers Symposium is a three day professional meeting on cancers related to the prostate, bladder, kidneys, and other organ systems related to urinary and sexual function. Prostate cancer has an entire poster section devoted just to this disease. At the Feb. 26-28, 2015 symposium on Orlando, one of the general presentation sessions included papers on the use of new imaging technologies to detect and identify early metastatic cancers. For example, let’s imagine a prostate cancer patient who had a robotic prostatectomy, and the surgical margins were clear except for one very small spot where his tumor had penetrated the capsule. This is called a positive surgical margin, or PSM, which is often associated with future recurrence. In this case, our patient’s PSA goes from zero to 0.2 within 18 months; six months later it has risen again to 0.4. He is assumed to have biochemical recurrence because rising PSA after prostatectomy is a prostate cancer-specific biomarker. It means his prostate cancer had already started spreading microscopically at the time of surgery. Now the detective work begins: Where is the new cancer growth? How extensive is it? How aggressive is it? Treatment choices depend on the answers.
During the Symposium session on imaging advances, Dr. Peter Pinto (Senior Investigator, Urologic Oncology Branch, National Cancer Institute) spoke on promising imaging modalities that are in development and/or clinical testing. He stated that current patient testing such as bone scans and CT scans to explore for recurrence are in many cases inadequate for truly effective clinical management. I want to recap his remarks and include links to articles or blogs I have written on some of the same advances.
- 18-F Sodium Flouride PET/CT scans may replace conventional bone scans because they are more sensitive and specific for prostate cancer that has metastasized to the bone. The scan itself takes less time, and was approved for coverage by Medicare in 2011. See how PET scans use radioactive tracers to detect the cancer at https://sperlingprostatecenter.com/introduction-positron-emission-tomography-imaging-pet-scans/. Also read how [18F]-fluorocholine compares with 3T mpMRI at https://sperlingprostatecenter.com/2149-2/.
- Choline is a lipid metabolism transport tracer (C-11) that bonds with prostate cancer cells and then “lights up” on PET/CT scans to reveal early metastatic cancer. In some studies, it appears to indicate the aggressiveness of the tumor, possibly providing information to direct treatment decisions. However, C-11 decays quickly (short half-life) so the imaging center has to have an onsite cyclotron to produce it so it can rapidly be brought to administer to the patient for scanning. Dr. Pinto said that an alternative, F-18, has a half-life five times longer, and is used in Europe but is not yet available in the U.S. See more on choline at https://sperlingprostatecenter.com/choline-c-11-pet-scans-prostate-cancer/
- According to Dr. Pinto, “C-11 acetateoffers similar utility as choline. It is lipid-membrane incorporated with excretion in the pancreas. Acetate may provide good-quality imaging of the lymph nodes around the kidney, ureter, or bladder. For this tracer, however, at this time there is a scant body of literature to support its use.”[i] My article on how this scan can help treatment planning is at https://sperlingprostatecenter.com/c-11-acetate-petct-scan-helps-prostate-cancer-treatment-planning/.
The National Cancer Institute/National Institutes of Health conducts ongoing research into the use of breakthrough imaging modalities to detect and diagnose localized and advance prostate cancer. Dr. Pinto and his group are not only identifying very early prostate cancer tumors, but they are also conducting what will be the longest-term study on focal laser ablation when results are announced, which is expected as early as next month. Stay tuned for breaking news!
[i] Pinto, Peter. #GU15 – Novel imaging modalities boost detection of early metastatic disease in prostate cancer. Session 2: Clinical Context: Using New Imaging Modalities To Identify Early Metastatic Disease. GU Cancers Symposium, Orlando, FL Feb. 26-28, 2015.