To achieve the goal of personalized medicine it is necessary not only to have agents with defined molecular specificities, but to have minimally invasive biomarker and imaging tests that will identify which patients have the target in their tumor and the patient’s pharmacogenotype. A related objective is to have a way to measure the effect of a drug on its molecular target in the tumor to be able to answer important questions, such as how much drug is required to inhibit the target in a tumor and is there is a benefit to giving more drug or will this only increase toxicity.
As a prostate cancer researcher, I consider the role of genetic biomarkers to stratify patients according to risk of progression, to select those who need treatment and those who can safely undergo active surveillance, and to spare the latter patients the morbidity of biopsy and/or treatment. Oncotype DX and others require biopsy tissue, so the issue of sepsis from trans rectal TRUS biopsy remains. Multi-parametric MRI shows considerable promise in identifying higher risk prostate cancer but misses most low risk diagnoses. Transperineal template mapping biopsies of the prostate have virtually no risk of infection and exhaustively sample the prostate about as well as pathology on a surgically excised prostate. Attached is a review paper by Sartori and Chan on various prostate biomarkers that you may find useful.
Genomic tests such as Oncotype DX provide prognostic information - hopefully adding to existing prognostic features such as clinical stage, biopsy grade and PSA level. Their role in clinical practice is still being evaluated - and in my view they should still be considered investigational. If they are confirmed to be reliable in further prospective studies, and can add more prognostic precision than existing prognostic models/nomograms, they may help select appropriate treatment for men e.g. intervention vs surveillance for low-risk cancers.
In terms of diagnosis of prostate cancer, as Dr Wayne rightly says, the choice of biopsy approach is in evolution, particularly in response to the risk of multi-resistant gram-negative sepsis after TRUS biopsy. In addition to its advantage in terms of reduced risk of infections, transperineal biopsy also allows a more thorough sampling of the prostate (although cancer pick-up rates seem comparable to TRUS biopsy, and I am not sure it is as good a sampling as a radical prostatectomy specimen).
mpMRI is also emerging as a useful diagnostic modality - and again I agree with Dr Wayne that it demonstrates significant & not indolent disease, thus potentially reducing over-diagnosis. However, at present, biopsy confirmation is still undertaken for for those with a lesion on mpMRI, and the exact follow-up for men with abnormal PSA but normal mpMRI is not clear.
The Oncotype DX portfolio of breast, colon, and prostate cancer tests applies advanced genomic science to reveal the unique biology of a tumor in order to optimize cancer treatment decisions. In breast cancer, the Oncotype DX Breast Recurrence Score test is the only test that has been shown to predict the likelihood of chemotherapy benefit as well as recurrence in invasive breast cancer. Additionally, the Oncotype DX Breast DCIS Score test predicts the likelihood of recurrence in a pre-invasive form of breast cancer called DCIS. In prostate cancer, the Oncotype DX Genomic Prostate Score® test predicts disease aggressiveness and further clarifies the current and future risk of cancer prior to treatment intervention.
https://www.exactsciences.com/newsroom/published/2021/03/10/09/00/new-data-highlight-role-of-oncotype-dx-breast-recurrence-score-test-in-shaping-clinical-practice
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