Taste and smell disturbances in patients with gastrointestinal stromal tumors using tyrosine-kinase inhibitors.

This study will be conducted at the University Medical Center Groningen (UMCG). Patients who are currently treated with a TKI for a GIST and understand spoken and written Dutch will be included. Fifty eligible patients will be asked to participate. At this moment, around fifty patients are currently treated with TKIs for a GIST at the UMCG. Based on a recent study on taste alterations in oncological patients receiving systemic therapy, it is expected that this number is sufficient to provide meaningful data. The potential participants are derived from the patient database of the Dutch GIST registry that is open for all patients diagnosed with a GIST. Potential participants will be screened in the objection registry of the UMCG. Patients who are registered will not be invited to participate in this study. Patients who are not registered will be send a letter that explains the study design and mentions that they will receive a telephone call. The potential participants will be asked to answer questions regarding taste disturbances by phone. This call will last approximately fifteen minutes. At any moment, they can decide to withdraw from the study. When patients pick up the phone, they will be asked explicitly for consent to participate. If consents is given, participants will answer the questionnaire.
The questionnaire that is used in this study (see supplement) is based on two previously used questionnaires which, respectively, were designed 1) to study metallic taste in patients who undergo systemic cancer therapy and 2) to study the impact of taste and smell alterations on the liking of specific nutritional supplements during systemic anti-cancer therapy. Information about the medical history of the patients and their current use of TKIs will be collected from the patients electronic file after the phone call and will not be part of the questionnaire.
The primary outcome of this questionnaire will be the proportion of patients reporting taste and smell alterations. The secondary outcome will be data on the type of taste disturbances and in particular alterations of bitter, sweet, salt, sour, metallic and a continuous taste. Furthermore, insight in the relation with the impact on daily life and QoL of the participants will be provided.

It is hypothesized that taste and smell disturbances are common among GIST patients using TKIs.

Start July 15, finish December 1 - 2019

Patients will be interviewed by phone about taste alterations. Information about the background of the patients, including gender, age and type and treatment of the GIST, will be collected from the patients electronic file.