The usage of AS for low risk prostate cancer had increased from less than 10% in 2010 to approximately 40% nowadays.2 However, it is important we differentiate correctly between different disease states and know the right patients to allocate to AS. Genomic testing such as the Oncotype GPS test, helps identify heterogeneity within risk groups, and could help to use AS for the right patients. GPS results combined with NCCN designation yields a more complete risk profile.
Histopathologic differentiation is also extremely important. When dealing with Gleason 4 disease, it is prudent to remember that Gleason 4 encompasses a whole range of different histopathologic subtypes. These include poorly formed glands, fused glands, glomeruloid glands and cribriform glands. These different subtypes have different prognostic significance. It has been shown that absence of cribriform and intraductal carcinoma in patients with Gleason 3+4 disease have a similar prognosis to those with Gleason 3+3 disease, and these patients are appropriate candidates for AS. 3
When comparing genomic testing to multiparametric MRI (mpMRI), one should note that MRI is only as valuable as the tissue it allows one to obtain, and it has marginal independent prognostic significance. Genomic testing can predict a high risk of adverse pathology at a very early stage, despite other diagnostic tests, such as mpMRI, being completely normal.
Stephenson concluded his talk with a few important key points. For low and very low risk prostate cancer, AS should be the default treatment. Genomic testing distinguishes important biological differences among Gleason 3+4 disease. Furthermore, histologic subtypes may also have an important role. When assessing the role of mpMRI, there is concern about under-grading, especially when features such as high PSA, high PSA density, few positive cores, and high-volume Gleason 6 disease exist.
1. Anna Bill-Axelson et al. Radical Prostatectomy or Watchful Waiting in Early Prostate Cancer. March 6, 2014, N Engl J Med 2014; 370:932-942 DOI: 10.1056/NEJMoa1311593
2. Cooperberg MR, Carroll PR. Trends in Management for Patients With Localized Prostate Cancer, 1990-2013. JAMA. 2015 Jul 7;314(1):80-2. doi: 10.1001/jama.2015.6036.
3. Kweldam CF et al. Disease-specific survival of patients with invasive cribriform and intraductal prostate cancer at diagnostic biopsy. Mod Pathol. 2016 Jun;29(6):630-6. doi: 10.1038/modpathol.2016.49. Epub 2016 Mar 4.
Presented by: Andrew Stephenson, MD, Cleveland Clinic
Written by: Hanan Goldberg, MD, Urologic Oncology Fellow (SUO), University of Toronto, Princess Margaret Cancer Centre @GoldbergHanan at the 2018 AUA Annual Meeting - May 18 - 21, 2018 – San Francisco, CA USA