Assertion: serotonin | /r/AtLocation | excess amounts
Facets:
value: by cancers
type: OTHER
value: by certain tumors
type: OTHER
value: sometimes
type: TEMPORAL
Source sentences:
text: Serotonin and 5-HIAA are sometimes produced in excess amounts by certain tumors or cancers, and levels of these substances may be measured in the urine to test for these tumors.