## 3 Results
### Exploratory Part: Aggregate Data for Patients Initially Diagnosed with Stage I-IV NSCLC  
During the entire 4-year index period (2018-2021), 7846 patients were newly diagnosed with NSCLC at any stage at the 14 participating sites. The majority of patients (67.9%; 5326/7846) were under the care of hospital sites located outside Vienna, while 56.4% (4429/7846) received care by non-academic institutions. An even distribution of NSCLC diagnoses was observed throughout the years, with 24.5% (1921/7846), 24.8% (1949/7846), 24.0% (1883/7846) and 26.7% (2093/7846) being diagnosed in years 2018, 2019, 2020 and 2021, respectively. The number of new NSCLC diagnoses at the study sites did not significantly differ (\(p\) = 0.231) between the pre-COVID-19 and COVID-19 periods (3870 and 3976 diagnoses, respectively; representing a relative increase of 2.7%). Throughout the index period, most frequent disease stage at diagnosis was Stage IV (43.3%), followed by Stage III (24.9%), Stage I (22.0%) and Stage II (9.9%) (Figure 4A). Patient distribution by institution location and type is presented in Figure S4. The number of patients diagnosed with NSCLC across the different stages per year is depicted in Figure 4B. The distribution of new Stage II, III and IV NSCLC diagnoses changed slightly but did not statistically significantly differ between the pre-COVID-19 and COVID-19 periods, whereas the proportion of Stage I patients significantly increased during the pandemic (n = 920; 23.1%) compared to the pre-pandemic period (n = 805; 20.8%) (\(p\) = 0.012; increase by 14.3%) (Figure 4C). Overall, 2.3% (40/1725), 3.2% (25/775), 5.5% (108/1950), and 12.9% (439/3396) of Stage I, II, III and IV patients, respectively, did not receive any therapy as part of ITS. Among Stage I-II NSCLC patients, 78.4% (1959/2500) underwent surgery and 19.5% (487/2500) received RT (without surgery), as part of ITS. Surgery was coupled with (neo)adjuvant RT or ST in a higher percentage of resected Stage II (54.2%; 325/600) than Stage I patients (6.6%; 90/1359). Among the unresected RT-treated patients, ST was administered in a slightly higher percentage of Stage II (34.7%; 43/124) than Stage I patients (23.7%; 86/363). ST-alone was administered in 3.8% (96/2500) of Stage I-II patients; of the latter, 45.8% (44/96) received investigational ST, 24.0% (23/96) ICI \(\pm\) ChT, 22.9% (22/96) ChT-alone, and 7.3% (7/96) TT \(\pm\) ChT. Compared with earlier stages, surgery rates were notably lower among Stage III NSCLC patients (40.6%; 792/1950), while adjuvant treatment rates among resected patients were higher: 78.9% (625/792) in Stage III versus 5.2% (71/1359) in Stage I and 46.7% (280/600) in Stage II. Adjuvant treatment among resected Stage III patients comprised (C)RT in 78.2% (489/625) of cases, ICI in 18.2% (114/625), and TT in 3.5% (22/625). RT (without surgery) was more frequent among Stage III NSCLC patients (28.4%; 554/1950) compared with earlier stages, and was part of CRT in 77.8% (431/554) of these cases. A fourth (25.6%; 499/1950) of Stage III NSCLC patients received ST-alone, mainly comprising ChT-alone (36.1%; 180/499) or ICI \(\pm\) ChT (33.5%; 167/499). Figure 4: Results based on aggregate high-level data for patients initially diagnosed with stage I-IV NSCLC: (**A**) NSCLC stage distribution; (**B**) Number of patients newly diagnosed with NSCLC per stage and year of diagnosis; (**C**) percent change in number of patients newly diagnosed with NSCLC between COVID-19 (2020/21) and pre-COVID-19 (2018/19) periods; and (**D**) Type of initial therapeutic strategy, per NSCLC stage at initial diagnosis. \({}^{\dagger}\) Asterisk (\({}^{\star}\)) indicates statistically significant difference of \(p\leq 0.05\). \({}^{\ddagger}\) Statistical differences are shown with asterisks: * \(p\leq 0.05\), *** \(p\leq 0.001\). \({}^{\lx@sectionsign}\) Any adjuvant treatment (including ChT, TT, ICI alone or in combination). \({}^{\ddagger}\) Any additional treatment (including concurrent or sequential CRT).