Active surveillance has been increasingly adopted as a standard approach for men with Gleason score ≤ 6 localized prostate cancer, with major guidelines and consensus statements encouraging this approach,1 including a recently published guideline from Cancer Care Ontario (CCO),2 and endorsement of the CCO guideline by ASCO, led by Ron Chen, MD, and Suneil Jain, MD, PhD.3 The ASCO endorsement of the CCO guideline is summarized in this issue of The ASCO Post.
Limited Evidence
The supporting evidence consists of noncomparative studies in which very few men are observed to die from prostate cancer during participation in active surveillance programs. The available trials vary in length of follow-up, with some being longer-term studies, although most are still relatively immature in follow-up time.2,4,5 There are no randomized trial data, although it has been argued that given the low event rate, comparative studies are impractical and unnecessary. This is a case in which, ultimately, consensus based on best available evidence plus clinical judgment has prevailed, balancing potential benefits and harms.
Ethan Basch, MD
Efforts reflected in the CCO guideline and ASCO endorsement are laudable, since it is challenging to change practice patterns in the face of limited evidence, particularly when the practice pattern involves an intervention that is believed to “cure” a patient. When practices come into common use in the absence of clear evidence of benefits—take, for example, prostate-specific antigen (PSA) screening—it is challenging both to study and to pull back on use. So regardless of one’s position on the evidence for active surveillance, it is indisputably a triumph when clinicians recommend holding off on potentially unhelpful or net harmful interventions.
The approach to Gleason 3+4=7 prostate cancer is a bit less clear-cut. In the CCO guideline and ASCO endorsement, active surveillance is considered an option if disease volume is small, but otherwise a definitive intervention such as prostatectomy or radiotherapy is recommended.
Key Recommendations
A useful component of the CCO guideline is a specific recommended approach to active surveillance, including:
- PSA testing every 3 to 6 months (although PSA kinetics do not reliably predict disease stability or reclassification to a higher-risk status and do not serve as a basis for treatment)
- Digital rectal exam every year
- A 12- to 14-core confirmatory transrectal ultrasound biopsy (including anterior directed cores) within 6 to 12 months of starting surveillance, then serial biopsy a minimum of every 3 to 5 years thereafter
- Optionally, a multiparametric magnetic resonance imaging (MRI) scan when a patient’s clinical findings are discordant with pathologic findings and would be useful for identifying occult cancers or evidence of progression
During surveillance, if a patient is reclassified in a higher-risk category (defined by repeat biopsy showing Gleason score > 7 and/or increases in the volume of tumor), then consideration should be given to definitive therapy (eg, prostatectomy or radiotherapy). Again, these recommendations are based largely on limited and extrapolated data and rely on clinical judgment.
The Path Forward
A question remains: How will patients actually be discovered to have a Gleason 6 prostate cancer, given controversies regarding recommended approaches to prostate cancer screening?6 Screening recommendations remain variable, with some guidelines recommending against PSA screening altogether, while others suggest a risk-stratified approach employing shared decision-making.
One rationale for pulling back on PSA screening has been a sense of the inevitability of potentially harmful and unnecessary interventions if a low-risk or indolent cancer is discovered through screening. The new CCO guideline and ASCO endorsement provide some reassurance that there is growing consensus to follow these cancers expectantly rather than to intervene immediately. Putting the pieces together, using a risk-stratified approach for both screening and intervention may ultimately yield benefit for higher-risk men while avoiding unnecessary harm to those at low risk.■
Disclosure: Dr. Basch reported no potential conflicts of interest.
Dr. Basch is Associate Professor of Medicine, Urology, and Public Health, Director of Cancer Outcomes Research, University of North Carolina, Chapel Hill.
