SPAINTRK aims to be the first trial in Spain to systematically collect data on outcomes of Spanish patients with solid neoplasms treated with Larotrectinib through the compassionate drug use program, during the time elapsed between the indication approval and the drug commercialization. This will contribute to selection of the best treatment for cancer patients with NTRK fusions, such as Trk inhibitors like Larotrectinib. Since the FDA and the EMA approved the use of Trk inhibitors, like Larotrectinib, there is a new and effective option of treatment for patients with NTRK fusions in solid neoplasms. This observational retrospective study will allow to analyze data of patients treated with Larotrectinib across the country and increase the knowledge on response to rare and different cancers Main objective is describe the effectiveness of Larotrectinib treatment in tumors with NTRK fusion in Spanish patients as a clinical series. This is an observational retrospective study including thyroid cancer patients with solid neoplasms with NTRK fusions. The study will use secondary data retrieved from medical records from each patient. The medical records include all the clinical variables defined in order to perform the analysis and it is not necessary to access additional sources.In total, 19 patients diagnosed with solid neoplasms that have been confirmed to bear NTRK fusions in their tumors will be included in the study. It is known that these patients have received the treatment with Larotrectinib in 14 centers in Spain, prior to treatment reimbursement in Spain.