Introduction: Lung cancer is one of the most common cancers in the world. Mortality due to lung cancer remains high, accounting for 18% of all cancer-related deaths annually. Its most common form is non-small cell lung cancer, for which treatment with immune checkpoint inhibitors (ICIs) has been introduced in 2015, significantly improving patient survival.
Methods: We conducted a systematic review of observational studies describing the outcomes of non-small cell lung cancer patients, treated with ICIs in monotherapy (mono-IT) or in combination with chemotherapy (CT-IT) in the first-line setting. The literature review was performed following the PRISMA 2020 guidelines. We searched the Medline database using the PubMed search engine, for which we developed a search profile. We searched for studies conducted between the year 2015 and August 31, 2022. Studies were selected based on inclusion and exclusion criteria and categorized according to the type of treatment used. For the included studies, we extracted baseline patients' characteristics and treatment's effectiveness, which were further statistically evaluated using the R software. The effectiveness results were also statistically compared with those of registrational randomized controlled trials (RCT).
Results: We included 49 observational studies on mono-IT and 7 observational studies on CT-IT treatment. Patients' characteristics in observational studies differed from RCTs primarily in the proportion of patients with performance status ⡥2 (18,9% in mono-IT treatment and 8,9% in CT-IT treatment) because these patients were excluded from RCTs, and the proportion of included non-smokers (10,6% compared to 8,1% in mono-IT, 22,9% compared to 13,1% in CT-IT). Patients in mono-IT treatment were older than those in RCTs (median age 70 compared to 63). In observational studies of mono-IT treatment, the pooled median overall survival (OS) was 17.07 months, pooled median progression-free survival (PFS) was 7.44 months, pooled overall response rate (ORR) was 44%, and pooled 1-year OS was 59%. In observational studies of CT-IT treatment, the pooled median OS was 20.36 months, pooled median PFS was 8.26 months, and pooled ORR was 52%. The efficacy data are highly heterogeneous for observational studies, and the included patients also differ in characteristics from the patients included in RCTs. However, the treatment efficacy did not statistically significantly differ between observational studies and registrational RCTs for PFS and ORR in mono-IT or KT-IT treatment, and also OS in KT-IT treatment. The difference was statistically significant for OS in mono-IT treatment, but because of the small sample of included RCT studies, the conclusion cannot be drawn.
|