I agree with you that a confirmatory biopsy within a year of the first biopsy should be a requirement for active surveillance programs. Random biopsies will miss higher grade PC about
a third of the time. And a negative mpMRI is a "false negative," about
10-20% of the time. See, for example, this recent study:
pubs.rsna.org/doi/10.1148/radiol.2017152877I also understand why your doctor disagrees. He authored a study last year that showed that at MSK, only 11% of AS patients were found to have higher grade cancer on confirmatory biopsy, and their mpMRI "false negative" rate was only 7%, both far surpassing what is normally achieved in usual clinical practice. Based on their extraordinarily good outcomes, they developed a model using PSA density, MRI results, and initial biopsy results to predict whether a confirmatory biopsy is needed:
/www.ncbi.nlm.nih.gov/pmc/articles/PMC4840176/I would point out two small problems with their model: it is based on retrospective data and it has not yet been validated at any other institution. In other words, all the patients had already had confirmatory biopsies, and MSK did not look at what happens when patients do not have confirmatory biopsies (they only looked at what
would have happened). I don't doubt that their clinicians are among the best in the world, which is why their results are superior and probably not generalizable - only external validation could show that.
So that leaves the ball in your court -- if you believe their model is truly predictive for you specifically, you can forgo the confirmatory biopsy. If you have misgivings, you may want to look elsewhere. Sticking with AS is all about
maintaining reasonable confidence in the protocol.