The Tumor Satellite profile currently reads:

The ‘Tumor Satellite’ observation may contain a reference to the index tumor observation.
The ‘Tumor Satellite’ observation may contain a distance to the index tumor.

It would be clearer for the reader if the location of these concepts were explicitly defined. Perhaps:

The ‘Tumor Satellite’ observation may contain a reference to the index tumor observation in Observation.derivedFrom.
The ‘Tumor Satellite’ observation may contain a distance to the index tumor in Observation.value[x].

As well, changing the derivedFrom:observation description from "Tumor Observation reference." to "Index tumor observation reference" would be helpful.