ASCO 2018: Lifting the Veil on Micrometastatic Disease: Emerging Imaging Strategies in Biochemical Recurrence
Dr. Norris then moved on to discuss some currently used imaging modalities. He began with the Hydroxyapatite-based imaging: Tc-99 MDP vs. NaF. NaF has greater sensitivity and specificity than Tc-99 MPD. However, NaF does not image local or distant soft tissue disease, and still does not directly image the tumor. The ideal imaging modality sould allow us to image the tumor itself, identify bone and soft tissue disease deposits, whether local or distant, and enable early detection of disease that doesn’t rely on compartment based changes.
Due to our lack of highly specific and sensitive imaging modalities, we wrongfully categorize a certain percentage of patients as high risk patients with local disease, or as patients who are defined as having only BCR without the development of metastasis. Using an ideal imaging modality would allow us to categorize patients correctly, and improve the prognosis of patients rightfully categorized has having high risk localized disease or BCR.
Geography, financial resources, what type of scan is ordered, and the disease biology, all affect if patients are being diagnosed with BCR or with metastatic disease. The reimbursement for different imaging modalities across the US varies by the state where the imaging is performed. Local Medicare administrative contractors may determine coverage within their respective jurisdictions for different positron emission tomography (PET).
Determining which scan to order is also not a simple task. Studies have shown improvement of specificity and sensitivity of different PET scans, with F-18 Fluciclovine shown to be better than C-11-Choline, and PSMA scans demonstrated to be even better than the rest of available PET scans.
Lastly, disease biology is a determinant of disease detection. The biology of the disease determines it distribution and grade. The detection rate is affected by the growth pathway, by the presence of neuroendocrine disease, degree of prior therapy, and by genetic determinants.
Dr. Norris concluded his great talk, reiterating that disease detection is based on region/financial barriers, the imaging modality ordered, and the disease biology. It is most likely, that usage of multimodality imaging will provide the most complete disease detection rate. Using the improved and better imaging modalities will result in a need to update our prognostic models predicting metastatic disease. Unfortunately, the best practice based on these variables has yet to be determined.
Presented by: Michael Norris, Memorial Sloan Kettering Cancer Center, New York, USA
Written by: Hanan Goldberg, MD, Urologic Oncology Fellow (SUO), University of Toronto, Princess Margaret Cancer Centre, Twitter:@GoldbergHanan at the 2018 ASCO Annual Meeting - June 1-5, 2018 – Chicago, IL USA