CUA 2017: Chemotherapy and Novel Hormones in “Low Volume” Hormone-Sensitive Metastatic Prostate Cancer

Toronto, Ontario ( Dr. Oliver Sartor from Tulane University provided a comprehensive talk today during the CUA-CUOG Multidisciplinary GU cancer meeting at the CUA 2017 annual meeting. According to Dr. Sartor, the definition of metastatic prostate cancer disease is imaging dependent, as CT and bone scan are limited to detecting 1cc lesions (or 1 billion cells). How do we improve detection of disease compared to CT and bone scan?

When assessing bone and soft tissue there are a number of modalities, including PSMA-PET, choline-PET, F18-PET, and diffusion weighted PET. Further, when assessing lymph nodes only, superparamagnetic nanoparticles + MRI is an option, as is NaF PET when only bone metastases are involved. However, Dr. Sartor notes that localization of the disease is only the beginning and not the end of imaging, since there are opportunities to see more than just location, including disease phenotype (adenocarcinoma, anaplastic, neuroendocrine, small cell) and assessment of the disease microenvironment (ie. immune markers, hypoxia). 

Given the recently reported LATITUDE and STAMPEDE trials1,2 earlier this month at ASCO 2017, there has been much discussion regarding how to best treat men with metastatic/locally advanced hormone-naïve prostate cancer. Dr. Sartor provides an excellent summary of the current landscape:

Dr. Sartor notes that,  LATITUDE nor STAMPEDED did not explicitly assess a “low volume” disease subset. But Dr. Sartor states that “does it really matter? How important is “low volume” in assessing the risks and benefits of abiraterone activity?” 

We know the biology of oligometastatic disease varies substantially with marked heterogeneity. There are a number of ways that we can treat oligometastatic disease in today’s landscape: radiation to the metastatic site (and potentially delay systemic therapy), use the ‘old’ ADT regimen, use the ‘new’ post-LATITUDE/STAMPEDE ADT regimen, ADT + radiation to the metastatic lesion, potentially adding docetaxel, or doing nothing since most patients have no symptoms. Dr. Sartor notes that there is “something for everyone….a true ‘dealer’s choice’”. Importantly, there are ongoing RCTs of local therapy in the metastatic setting, including (i) STAMPEDE, (ii) HORRAD, (iii) an MD Anderson lead initiative, and (iv) the TRoMbone trial: Testing Radical prostatectomy in men with prostate cancer and OligoMetastases of BONE. 

In summary, Dr. Sartor notes that low volume metastatic disease is likely to be treated with ADT + abiraterone/prednisone. The value of adding surgery or radiation to ADT is not clear, however SBRT can likely delay time to ADT in the oligometastatic setting. Determining clinical benefit is the next critical step and “it would be good to get away from castration”!

Speaker: A. Oliver Sartor, MD, Tulane University, New Orleans, LA, USA

Written By: Zachary Klaassen, MD, Urologic Oncology Fellow, University of Toronto, Princess Margaret Cancer Centre  Twitter: @zklaassen_md at the  72nd Canadian Urological Association Annual Meeting - June 24 - 27, 2017 - Toronto, Ontario, Canada

1. Fizazi K, Tran N, Fein L, et al. Abiraterone plus Prednisone in Metastatic, Castration-Sensitive Prostate Cancer. N Engl J Med 2017 Jun 4 [Epub ahead of print].

2. James ND, de Bono JS, Spears MR, et al. Abiraterone for Prostate Cancer Not Previously Treated with Hormone Therapy. N Engl J Med 2017 Jun 3 [Epub ahead of print].

More on LATITUDE from ASCO 2017