Oncology

Prostate Cancer

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Advanced Imaging Techniques and Future Directions for the Oligometastatic Disease State

clinical topic updates by William K. Oh, MD

Overview

Advanced imaging techniques that offer a favorable combination of sensitivity and specificity may facilitate the detection of occult metastases that are unidentifiable on conventional imaging, particularly small-volume lesions, micrometastases, or oligometastatic disease.

Expert Commentary

William K. Oh, MD

Chief Medical Science Officer, Sema4
Clinical Professor of Medicine
Division of Hematology and Medical Oncology
Icahn School of Medicine at Mount Sinai
New York, NY

“Over time, the next-generation imaging techniques are expected to improve our ability to provide personalized therapy to patients with smaller and smaller volumes of disease.”

William K. Oh, MD

In the context of rising prostate-specific antigen (PSA) after definitive prostatectomy and/or radiation, nonmetastatic disease is essentially an entity that exists only because we are unable to identify the metastatic or micrometastatic sites. Conceptually, oligometastatic disease describes the cases in which metastases are present but are relatively small, few, and/or less aggressive in nature, so as to be potentially amenable to treatments that may slow or halt progression. Oligometastatic disease is less well characterized in prostate cancer than in other cancers such as colon cancer. Current research efforts are focused on developing and adapting next-generation imaging to better characterize both nonmetastatic disease (including in both hormone-sensitive and castration-resistant prostate cancer) and oligometastatic prostate cancer. 

We had an important advance in molecular imaging with the US Food and Drug Administration approval of 18F-fluciclovine for the detection of microscopic metastatic disease in patients with rising PSA after surgery and/or radiation. This was important because it has improved our ability to detect minimal amounts of disease in those who received definitive local therapy. However, more sensitive and specific imaging techniques are continually being pursued. Prostate-specific membrane antigen (PSMA) is a transmembrane protein expressed in all types of prostatic tissue, and its expression is increased in metastatic tissue. 68Ga-PSMA positron emission tomography has a favorable combination of specificity and sensitivity in patients with advanced or oligometastatic prostate cancer. Although it is commercially available in many parts of the world, it has not yet been widely available in the United States, where it is considered investigational. The real issue with advanced imaging techniques is determining how to best treat the patients in the stages of disease that they reveal. For example, will targeting the oligometastatic sites with radiation or surgery increase survival or improve quality of life? Traditionally, if a patient has a rising PSA after surgery, we would radiate that individual postoperatively without knowing whether they had any persistent disease in their pelvis or prostate bed. Over time, I think that the next-generation imaging techniques will improve our ability to provide personalized therapy to patients with smaller and smaller volumes of disease (ie, micrometastasis and oligometastasis).

References

Calais J, Czernin J, Fendler WP, Elashoff D, Nickols NG. Randomized prospective phase III trial of 68Ga-PSMA-11 PET/CT molecular imaging for prostate cancer salvage radiotherapy planning [PSMA-SRT] [published correction appears in BMC Cancer. 2019;19(1):97]. BMC Cancer. 2019;19(1):18.

Crawford ED, Koo PJ, Shore N, et al; RADAR III Group. A clinician's guide to next generation imaging in patients with advanced prostate cancer (RADAR III). J Urol. 2019;201(4):682-692.

Deek MP, Yu C, Phillips R, et al. Radiotherapy in the definitive management of oligometastatic prostate cancer: the Johns Hopkins experience. Int J Radiat Oncol Biol Phys. 2019 Aug 13. pii: S0360-3016(19)33641-7. doi: 10.1016/j.ijrobp.2019.08.008. [Epub ahead of print]

Fendler WP, Calais J, Eiber M, et al. Assessment of 68Ga-PSMA-11 PET Accuracy in localizing recurrent prostate cancer: a prospective single-arm clinical trial. JAMA Oncol. 2019;5(6):856-863.

Perera M, Papa N, Roberts M, et al. Gallium-68 prostate-specific membrane antigen positron emission tomography in advanced prostate cancer-updated diagnostic utility, sensitivity, specificity, and distribution of prostate-specific membrane antigen-avid lesions: a systematic review and meta-analysis. Eur Urol. 2019 Feb 14. pii: S0302-2838(19)30095-8. doi: 10.1016/j.eururo.2019.01.049. [Epub ahead of print]

Perez-Lopez R, Tunariu N, Padhani AR, et al. Imaging diagnosis and follow-up of advanced prostate cancer: clinical perspectives and state of the art. Radiology. 2019;292(2):273-286.

William K. Oh, MD

Chief Medical Science Officer, Sema4
Clinical Professor of Medicine
Division of Hematology and Medical Oncology
Icahn School of Medicine at Mount Sinai
New York, NY

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