QoLIDia: Quality of Life in Cancer Patients With Diabetes During Immunotherapy

The goal of this observational study is to see how type 2 diabetes affects quality of life in cancer patients receiving immunotherapy. We want to know if patients with diabetes have a greater decline in quality of life over six months compared to those without. The main question we aim to answer is: \- How does quality of life change over six months in patients with versus without diabetes? Participants will complete quality-of-life surveys at the start, then at 3 and 6 months. This will help us see if diabetes adds extra challenges during cancer treatment

Inclusion Criteria: * Age ≥18 years. * Histologically confirmed solid malignant tumor. * Planned treatment with ICI monotherapy or dual-ICI combination therapy (metastatic, adjuvant, or neo-adjuvant settings). * Previous systemic anticancer therapy other than ICI is allowed. * Ability and willingness to provide written informed consent and to complete HRQoL questionnaires. * Sufficient Danish language proficiency to read, and complete study questionnaires. Exclusion Criteria: * Previous ICI treatment within 6 months. * Concurrent systemic anticancer therapy other than ICI. * Declines or does not provide informed consent. * Cognitive or physical impairment preventing valid consent or completion of patient-reported outcomes.