# GUIDELINE OBJECTIVES
The objective of this guideline is to determine the most effective therapy for patients with thymic epithelial tumours.

# TARGET POPULATION
The target population are adult patients with thymic epithelial tumours, including thymoma, thymic carcinoma, and thymic neuroendocrine tumours (NETs).

# INTENDED USERS
The intended users of this guideline are all healthcare professionals managing patients with thymic epithelial tumours.
Complete resection -refers to an R0 resection of the tumour or resection with negative margins Total resection -refers to resection of the entire thymus (including all mediastinal tissues anterior to the pericardium, aorta, and superior vena cava from phrenic nerve to phrenic nerve laterally and from the diaphragm inferiorly to the level of the thyroid gland superiorly, including the upper poles of the thymus), the tumour, and any involved structures Partial resection -refers to resection of less than the entire thymus, but includes the tumour and any involved structures
The staging system for patients with thymic epithelial tumours has recently changed to a TNM staging system. The evidence used to support these recommendations was mainly from observational studies that used the prior Masaoka and Masaoka-Koga staging systems. Given the lack of randomized trials, the Working Group endorsed most of the consensus-based recommendations from the previous version of this guideline  (see Appendix 1). For patients with thymic NETS, recommendations were endorsed from the National Comprehensive Cancer Network (NCCN) Version 1.2021 Neuroendocrine and Adrenal Tumors Guideline.
General Principles 1. The aim of surgery in all cases is to achieve a complete resection. 2. The TNM staging system should be used for all patients. 3. Discussion of all patients at multidisciplinary cancer conference (MCC) is strongly recommended, not just at local MCC but also with higher-volume centres. Presentation at the International Thymic Malignancies Interest Group tumour board should be considered. 

# PATIENTS WITH

# IMPLEMENTATION CONSIDERATIONS
The Working Group members believed that patients in rural areas or patients who are disadvantaged may find it more challenging to attend daily PORT treatments or treatments in high-volume centres since they may live further away from these centres in Ontario or may have difficulty in acquiring transportation for daily treatments than patients in urban areas or patients who are less disadvantaged. Also, peptide receptor radionuclide therapy has not been approved for patients with thymic epithelial tumours in Ontario.

# FURTHER RESEARCH
Larger, collaborative, international prospective trials that control for confounders are needed to provide a greater degree of certainty in the evidence to inform recommendations.

# GUIDELINE LIMITATIONS
The Working Group for this guideline did not include patient representatives. Thus, when developing recommendations, input from patients about their values and preferences was not sought and a systematic review for this information was not performed. Working Group members used their prior clinical experiences with patients with thymic epithelial tumours to assume their relevant values and preferences.