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Cancer Surgery/Cancer Radiotherapy/Cancer Drug Treatment in EPISODE table


I am trying to figure out how to use the Treatment episodes for modeling cancer registry data, specifically the Cancer Radiotherapy, Cancer Surgery and Cancer Drug Treatment episodes. From the documentation online I understand that high level/composite treatments end up in EPISODE and low level/individual treatments in standard OMOP (PROCEDURE_OCCURRENCE, DRUG_EXPOSURE). How does that work for the three episodes:

Cancer Surgery:
Most, if not all, surgeries in the cancer registry can be modelled as procedures in PROCEDURE_OCCURRENCE. Does that mean most patients will not have a Cancer surgery episode? Or is it desirable to add a high level surgery for all those patients as a Cancer surgery episode, for example “Excison of neoplasm”? If surgeries should be added to EPISODE only if they are high level/composite then what is an example of such a surgery?

Cancer Drug Treatment:
How is this episode different from a Treatment Regimen episode? episode_object_concept_id comes from the Procedure or Regimen domain so it seems Cancer Drug Treatment will also be a Regimen. Or should Cancer Drug Treatment be seen as an indicator that the patient received chemotherapy and is Treatment Regimen meant to specify what regimen(s)? (And if so, is that the same for Cancer Surgery and Cancer Radiotherapy?)

Cancer Radiotherapy:
Is the Cancer Radiotherapy episode meant to model the full (multi-week) radiotherapy treatment while the individual (daily) treatments are in PROCEDURE_OCCURRENCE?

Thanks for your help!


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Hi @peter.prinsen ,
just making sure that you have read the documentation in the OncoWG Wiki, also the ETL part? I just realized that the “NAACCR Treatment Episode” link is empty, only the general Treatment Episode is a valid one and covers the Antineoplastic Drugs with Regimen Finder. Maybe @agolozar can point us into a better direction?
From what I understood, the EPISODE table was primarily meant for the overall disease episodes and its use was extended to also cover particular treatment episodes. As the CDM definition says, I would use a Cancer Surgery episode to aggregate all procedure occurences during a period of time that has semantic congruence (e.g. excision of primary and LN metastases vs. excision of distant metastases 3 years later). Excision of neoplasm sounds like a valid match for episode_object_concept_id, though you might want to be a bit more specific if possible. But I understand high level is what is required here. I don’t think it makes sense to just use the EPISODE table and NOT create respective event table entries, though. The respective procedure entries should be present and linked by EPISODE_EVENT.
Your question about Drug Treatment and Regimen is a valid one. I understand there is a parent-child relationship possible between these, maybe also including the Treatment Cycle concept, like to show multi level dependencies. Again, I would assume, Asieh can provide more insights.

Hi @mik ,

Thanks! Yes, I checked all the documentation but I think a lot of it is relatively old and still pertains to the “older” episode model from early 2020. I understood that the WG is planning to update the documentation this year so I think things will become clearer.

We will follow your suggestion and make sure all the relevant event tables are filled (PROCEDURE_OCCURRENCE, DRUG_EXPOSURE, etc.). It does indeed make sense to fill those, next to the EPISODE table.

@agolozar, is there already documentation that answers my question that I overlooked?