Should we establish 'extension' and 'invasion' hierarchies with Cancer Modifier?

[rtmill]

Extension and Invasion concepts exist within Cancer Modifier but have no linkages - neither mappings nor hierarchically.

Extension example: https://athena.ohdsi.org/search-terms/terms/36769838

Invasion example: https://athena.ohdsi.org/search-terms/terms/36769449

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Alternatively, SNOMED has hierarchies we may be able to leverage rather than creating our own new hierarchies. They both fall under the "tumor finding" hierarchy.

SNOMED Invasion hierarchy : https://athena.ohdsi.org/search-terms/terms/4159956

SNOMED Extension hierarchy: https://athena.ohdsi.org/search-terms/terms/4300153

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Option A) Rebuild our own hierarchies within Cancer Modifier
Option B) Leverage SNOMED instead and de-standardize extension/invasion concepts in Cancer Modifier
Option C) Something else