OMPRN is delighted to welcome Dr. Ju-Yoon Yoon, a surgical and molecular pathologist at Unity Health Toronto, where he works behind the scenes to help diagnose and guide treatment decisions for people with cancer.
In this interview, Dr. Yoon explains the role of molecular pathology, the tools used to uncover insights hidden in tumour tissue, and how his work supports personalized cancer care.
Interview conducted over Zoom by Kyster Nanan on 29 September 2023.
How do molecular pathologists help diagnose and treat cancer?
Surgical pathologists deal with tissues, so the tissues come to the laboratories, and we are medical doctors who look at the tissue, mostly under the microscope to make a diagnosis. Often those tissues will require further work-up to identify which treatments may work best for you. Those can involve things such as immunostains or molecular assays.
In the current state of things, a lot of molecular assays generally focus on nucleic acids which may be both DNA or RNA. We have various assays that look at the sequence of the DNA or RNA and we can interpret the results and try to package the findings in a way that is suitable for your treatment team. Your treatment team would include a medical oncologist, surgical oncologist and a radiational oncologist to ensure the best treatment for you.
If you would like to know more about some of the roles certain professionals play in your cancer care, consult our ‘support professionals in cancer care’ infographic.
“Think of us as molecular doctors for your tumour’s DNA and RNA—we perform a kind of molecular autopsy to figure out what’s driving the tumour and how we can use that information for treatment.”
What is the difference between a “medical oncologist” and a “molecular pathologist”?
You have probably met your medical oncologist already if you have happened to be diagnosed with a cancer, of course these are key members of your treatment team that oversees systemic therapy. You probably have not met your molecular pathologist; we are behind the scenes. Think of us as molecular doctors for your tumours DNA and RNA and we in a way perform molecular autopsy on the tumour. We figure out what is driving the tumour and what can we leverage in terms of molecular findings for your treatment purposes.
In what ways do pathologists and molecular pathologists work together?
We generally work in the same department and work very closely with one another. The surgical pathologists look at the tissue under the microscope and work with us, the molecular pathologists, to identify the appropriate tests and from there we work with them to ensure that the appropriate tests is done for the tumour. This is to identify the best molecular targets that can be useful for treatment purposes.
What kind of interaction do you have with patients?
It is highly unlikely that you have met your molecular pathologist, and we work behind the scenes to ensure that the best molecular assays and tests have been performed to best guide the treatment team. In that sense, our interactions are always indirect, we look at your tumour and I, as a surgical pathologist look at your tumour under a microscope and look at the DNA and RNA profiles of your tumour and we issue a report to summarize our findings.
Generally, the audience is your treatment team and the recommendation is that you go through the reports with your treatment team to best understand the report. So, we don’t get to meet with you, but certainly we are behind the scenes, hoping for the best results for you.
How often do you see patients?
There is a potential chance that you have met a colleague of mine, a pseudo-pathologist who my be doing a fine needle aspiration in a clinic. Sometimes what they would do is see you, explain the procedure and do a needle biopsy. This is a very fine needle aspiration trying to get samples from superficial lesions that they would assess on the spot to see what is adequate for diagnosis.
What are some common techniques used in molecular pathology?
We generally focus on nucleic acids and molecular labs, this includes DNA and/or RNA extracted from your tumour generally, and we are looking into ways. One is looking at the polymerase chain reaction or PCR that amplify the little bits of DNA usually in a sequence- specific manner. This is used to see if you have a specific variant that we can detect using these PCR assays.
Secondly, we look at something named Next generation sequencing, which describes a certain way of sequencing an assay with respect to DNA or RNA. Another way to describe it, is called mass parallel sequencing and that’s quite descriptive in a sense that rather than sequencing little bits at a time we have a whole bunch of parallel reactions that are happening at the same time. All this reaction data are then demultiplexed and teased out to find out what is happening at different areas within the genomes of the tumour.
For more information on molecular pathology, consult our ‘what is molecular pathology’ infographic.
What do you find most challenging about molecular pathology?
One challenge is that we infer what is happening to the tumour based on something that can almost be biologically removed. If you think about the molecular dogma, we have DNA that encodes RNA, then the RNA encodes proteins. The proteins are the molecules that carry out certain functions that have an impact. We are looking at the DNA level and trying to infer what is happening at protein level, then to the cell level and ultimately the tumour. This type of extrapolation is a challenging aspect of molecular pathology.
What are some common misconceptions about molecular pathology?
I can think of 2 things, both are related to TV shows. One is, some Flag House, where a single doctor does everything on his own, that’s not how it works in the real world. I work with a team of molecular technologists, and I am mostly involved in interpretation of the results.
The second thing is speed, when you have shows like CSI, telling you that you can do all these tests in a matter of an hour or even less, it makes us look bad. We are performing our standard tests with a turn-around time of weeks, and I understand that this can be frustrating for a lot of people, but the calculus of this has to do with personnel resources with respect to batching of the assays for us to make these tests economically feasible as well as the shear amount of data we receive from these assays that we have to interpret. I can certainly understand some of the frustrations and those TV shows don’t help.
What kind of skills do you need to be a good molecular pathologist?
I think more and more, a good asset to have been to just be a good data scientist because you have to deal on a daily basis with so much data and try to incorporate and interpret all of these bits. To try to really understand what the best treatment option for a particular patient is a challenge, going forward, we are probably going to be generating more and more data, so dealing with even more data and being a good data scientist will be a good asset.
Conclusion
Molecular pathologists might never meet the patients they help, but their work is a key part of cancer care. As Dr. Yoon explains, studying the DNA and RNA of a tumour is a detailed and complex process that happens behind the scenes—but it’s crucial for finding the best treatment. As science continues to uncover more about how cancer works at the molecular level, the role of molecular pathologists keeps growing, helping to make cancer treatments more accurate and more effective for each person.
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