Ask the Experts – R Jeffrey Karnes

Question 1. Should biomarker assays be an integral part of prostate cancer patient management? Do they have a role in every step along the continuum of care?

Answer
They should be an integral part of care, but that’s not to say they should be applied in every step of patient management. There are biomarkers for the initial assessment, such as deciding whether or not to perform a biopsy, as well as biomarkers that are useful in deciding when a man should undergo rebiopsy following a previous negative biopsy.

Examples include phi, 4Kscore, prostate cancer antigen 3 (PCA3), and perhaps the most utilized biomarker, multiparametric magnetic resonance imaging (mpMRI). Other available biomarker assays (eg, Prolaris®, Oncotype DX® genomic prostate score, Decipher®, ProMark®) are useful following positive biopsies and can help in deciding whether a patient might benefit from active treatment vs surveillance. And specifically in the postoperative setting, the Decipher GRID program can help weigh in on adjuvant therapy following primary treatment for the at-risk patient.

Question 2.  Which biomarker assays have you found to be the most useful in clinical decision-making?

Answer
I do not routinely use prebiopsy serum markers, partly because the patients I see are referrals. For initial assessments, I typically do not use serum markers other than free prostate-specific antigen (PSA) on occasion. I am using mpMRI more frequently for the man with elevated PSA and with a previous negative biopsy.

In the postoperative setting, I have had the most experience with Decipher. I have found it to be the most helpful biomarker assay in various stages of prostate cancer management, such as deciding how to proceed in cases of PSA recurrence or whether a patient should be placed on active monitoring with early salvage therapy or undergo adjuvant therapy.

Question 3. Do the results of biomarker tests help in patient counseling?

Answer
I think there is information we can provide patients that better informs them of their risk and even their potential benefit from primary or secondary treatment. The key is to make sure the stage is set with the patient by using baseline clinicopathologic parameters. Biomarker assays can add to prognostic information but not by a large degree. When deciding on active therapy or active surveillance for a patient who has a 30% risk of having a higher-grade lesion, then a supplemental biomarker test may indicate that the risk is a little bit higher or lower. However, for the majority of patients, there is not going to be big swings in the risk.

Question 4. Is there a benefit to using biomarker assays in combination? Have you found any combinations to be especially helpful?

Answer
There is a benefit to using combination biomarker assays. However, I do not think we have seen high-level evidence that using biomarker assays in combination ultimately changes outcomes. But this is evolving.

Question 5. Are there any biomarkers now in the early stages of development that have the potential to be a game changer with respect to risk stratification?

Answer
I am seeing more biomarkers that are predictive in nature rather than purely prognostic even in the advanced cancer setting, which can help to tailor a therapy that is more “precise” to that individual.