A prerequisite for patient-friendly personal health records (PHR) is their ability to allow seamless integration of patient terminology with professional terminologies. In this work, we mapped a set of symptoms/ problems from the self-assessment component of a cancer patient support system to concepts in the Unified Medical Language System (UMLS) Metathesaurus. Our objective was to learn how the UMLS can be used as a tool to connect patient terminology with professional vocabularies. The mapping to UMLS was done with the help of ten expert cancer nurses who evaluated concepts, their synonyms and placement in the source vocabulary hierarchical structure. The UMLS concepts were also compared with terms and phrases found in patient medical records that addressed the same set of symptoms. In this study we observed several problems related to the use of the UMLS Metathesaurus as a tool to connect from patient-level expressions to professional-level classification systems. More work is needed to increase interoperability between layperson health applications and clinical systems.