Background
The use of open-ended questions supplementing static questionnaires with closed questions may facilitate the recognition of symptoms and toxicities. The open-ended ‘Write In three Symptoms/Problems (WISP)’ instrument permits patients to report additional symptoms/problems not covered by selected EORTC questionnaires. We evaluated the acceptability and usefulness of WISP with cancer patients receiving active and palliative care/treatment in Austria, Chile, France, Jordan, the Netherlands, Norway, Spain and the United Kingdom.

Methods
We conducted a literature search on validated instruments for cancer patients including open-ended questions and analyzing their responses. WISP was translated into eight languages and pilot tested. WISP translations were pre-tested together with EORTC QLQ-C30, QLQ-C15-PAL and relevant modules, followed by patient interviews to evaluate their understanding about WISP. Proportions were used to summarize patient responses obtained from interviews and WISP.

Results
From the seven instruments identified in the literature, only the free text collected from the PRO-CTAE has been analyzed previously. In our study, 161 cancer patients participated in the pre-testing and interviews (50% in active treatment). Qualitative interviews showed high acceptability of WISP. Among the 295 symptoms/problems reported using WISP, skin problems, sore mouth and bleeding were more prevalent in patients in active treatment, whereas numbness/tingling, dry mouth and existential problems were more prevalent in patients in palliative care/treatment.

Conclusions
The EORTC WISP instrument was found to be acceptable and useful for symptom assessment in cancer patients. WISP improves the identification of symptoms/problems not assessed by cancer-generic questionnaires and therefore, we recommend its use alongside the EORTC questionnaires.