## 1 Introduction  
Lung cancer accounted for 12% of all newly diagnosed cancers and 19% of all cancer-related deaths worldwide in 2022 [1]. With 5203 incident cases and 4125 deaths in 2022 in Austria, lung cancer accounted for 12% of new cancer diagnoses and 20% of cancer deaths, making it the leading cause of cancer-related deaths [2]. Non-small cell lung cancer (NSCLC) accounts for the majority of lung cancer diagnoses (80-90%) [3; 4]. Approximately half of NSCLC patients in Europe [5; 6; 7; 8; 9; 10], including Austria [11], are diagnosed with stage IV disease. This is important considering that 5-year overall survival (OS) is estimated at \(\leq\)10% in metastatic patients [4; 12]. In addition, based on literature that precedes the introduction of immune checkpoint inhibitors (ICIs) and targeted therapy (TT) options in the non-metastatic setting [13], both resected and unresected patients with early-stage NSCLC (ES-NSCLC) experience frequent recurrence [14; 15; 16; 17]. The 5-year OS rates range from 92% to 13% across Stage IA1 to IIIC NSCLC [12]. Although prognosis of lung cancer patients in Austria has shown improvements over the years, the last estimated 1-, 3- and 5-year age-standardized net survival was 52% (2015-2017), 30% (2014-2018) and 20% (2010-2015), respectively [18; 19]. Furthermore, though trends are not unanimous, some studies in Europe and the US have shown that delays in lung cancer management are associated with poorer prognosis [20; 21; 22; 23]. Altogether these observations highlight the need for improvements in clinical care. Surgical tumour resection is the principal treatment option for patients with stage I-II NSCLC, followed by adjuvant treatment, if indicated [24; 25]. For locally advanced (LA) NSCLC, which encompasses both resectable and unresectable cases, treatment may involve a combination of surgery, systemic therapy (ST) and/or radiotherapy (RT) [24; 25]. For patients with metastatic NSCLC, non-surgical ST is the preferred option [26; 27]. Platinum-based chemotherapy (ChT) was the standard ST option for first-line (1L) treatment of metastatic NSCLC without actionable oncogenic driver mutations up until European Medicines Agency (EMA)-approval of the first ICI in the 1L setting in 2016 [28; 29]. Since then, owing to better treatment outcomes, ICIs (as monotherapy or chemoinmunotherapy) have gradually become a big part of the standard of care for 1L treatment [18; 26; 28; 29]. For oncogene-addicted NSCLC, effective options include TTs, such as tyrosine kinase inhibitors (TKIs) targeting EGFR or ALK [18; 27]. The advent of ICIs is also expanding the treatment armamentarium of ES-NSCLC (stage I-III), with first EMA approval in 2018 granted for durvalumab as consolidation therapy for chemoradiotherapy (CRT)-treated unresected stage III NSCLC [30; 31]. From 2021 onwards, the indication of multiple pre-existing molecules has been extended to the (neo)adjuvant setting; these include three ICIs for patients with high risk of recurrence [13; 32; 33; 34; 35; 36; 37; 38] and one TKI for patients with EGFR-mutated NSCLC [13; 39]. Further expansion of indications is awaited [13; 40; 41; 42; 43]. As the treatment paradigm for ES-NSCLC is changing, it is imperative to understand real-world (RW) management practices in order to better inform future healthcare decision-making and optimize oncology care, especially in the setting of ES-NSCLC which requires multidisciplinary collaborations. However, Austria lacks a national lung cancer registry [18], while observational studies on local epidemiology are scarce and outdated [11; 44]. Thus, the PRATER retrospective study was primarily designed to characterize the profile, therapeutic strategies and journey of patients diagnosed with ES-NSCLC during 2018-2021 using RW data from leading hospital institutions in Austria.