Background: Lung cancer treatment has rapidly advanced, particularly with immune checkpoint inhibitors (ICIs) targeting PD‐1 and PD‐L1. However, there are variable responses, such as immune‐related adverse events. Several factors predicting the prognosis of lung cancer ICI treatment have been studied so far, but they have limitations, leaving an unmet need. This study aims to investigate delta‐He, a novel marker reflecting the iron availability and inflammation through the difference in hemoglobin content between reticulocytes and erythrocytes, as a potential prognostic factor in patients with NSCLC undergoing PD‐1/PD‐L1 inhibitor therapy.Methods: This research was conducted at Chungnam National University Hospital, analyzing 79 advanced NSCLC patients treated with PD‐1/PD‐L1 inhibitors. The study population had a mean age of 70 years, with the majority being male (82.3%) and former or current smokers (84.8%). Blood samples collected before therapy initiation were examined for hematological parameters, including delta‐He, using Sysmex XN‐550 and XN‐20 analyzers. The study employed receiver operating characteristic (ROC) curves and Kaplan–Meier curves for the statistical analysis, using SPSS version 26 (IBM Corp., USA) and MedCalc version 22 (MedCalc Software Ltd., Belgium) to evaluate the sensitivity and specificity of delta‐He, and to analyze progression‐free survival (PFS) and overall survival (OS).Results: The study revealed that delta‐He is a significant prognostic marker in patients with NSCLC treated with PD‐1/PD‐L1 inhibitors. A delta‐He cutoff value of 3.3 pg was identified based on ROC analysis. Patients with high delta‐He values (> 3.3 pg) showed significantly longer median PFS (9.6 vs. 3.0 months, p = 0.024) and OS (not reached vs. 12.2 months, p = 0.010) than those with low values. The high delta‐He group also had higher objective response rate (41.4% vs. 26.0%) and disease control rate (86.2% vs. 52.0%). Multivariate analysis highlighted higher delta‐He (> 3.3 pg), along with other factors such as FEV1 and smoking status, as important predictors of survival, underscoring its potential role in guiding therapeutic decisions of ICIs in NSCLC (PFS: HR 0.874, 95% CI 0.264‐0.874, p = 0.016; OS: HR 0.327, 95% CI 0.150‐0.715, p = 0.005).Conclusion: Our study shows delta‐He as a promising prognostic biomarker for lung cancer patients treated with PD‐1/PD‐L1 inhibitors, highlighting its potential to guide therapeutic decisions and improve patient management in a non‐invasive manner. Further research is necessary to validate delta‐He's predictive and prognostic value across broader populations and in combination with other biomarkers, emphasizing its role in advancing personalized oncology.

Pulmonary large cell neuroendocrine carcinoma (LCNEC) is a rare and aggressive subtype of non-small cell lung cancer with a poor prognosis. Spontaneous regression, that is, partial or complete disappearance of a malignancy without medical intervention, is extremely rare in LCNEC. Herein, we present a case of spontaneous complete regression in a 71-year-old male patient with recurrent LCNEC after surgical resection. The patient was diagnosed with stage IB LCNEC and underwent surgical resection. At 1-year follow-up, chest computed tomography revealed a recurrent lesion next to the stump site and enlargement of lymph nodes 4R and 7; recurrent LCNEC was confirmed. The patient declined chemoradiation therapy. One year after recurrence, the patient experienced severe multifocal necrotizing pneumonia and was treated with antibiotics, resulting in a gradual decrease in the size of the recurrent lesion. Five years after the initial diagnosis, positron emission tomography/computed tomography revealed no hypermetabolic lesions, indicating the spontaneous complete regression of LCNEC.

An older age is associated with severe progression and poor prognosis in coronavirus disease 2019 (COVID-19), and mechanical ventilation is often required. The specific characteristics of older patients undergoing mechanical ventilation and their prognostic factors are largely unknown. We aimed to identify potential prognostic factors in this group to inform treatment decisions. This retrospective cohort study collected data from patients with COVID-19 at 22 medical centers. Univariate and multivariate Cox regression analyses were performed to assess factors that influence mortality. We allocated 434 patients in geriatric (≥80 years) and elderly (65–79 years) groups. The former group scored significantly higher than the elderly group in the clinical frailty scale and sequential organ failure assessment, indicating more severe organ dysfunction. Significantly lower administration rates of tocilizumab and extracorporeal membrane oxygenation and higher intensive care unit (ICU) and in-hospital mortality were noted in the geriatric group. The factors associated with ICU and in-hospital mortality included high creatinine levels, the use of continuous renal replacement therapy, prone positioning, and the administration of life-sustaining treatments. These results highlight significant age-related differences in the management and prognosis of critically ill older patients with COVID-19. Increased mortality rates and organ dysfunction in geriatric patients undergoing mechanical ventilation necessitate age-appropriate treatment strategies to improve their prognoses.

Cytomegalovirus (CMV) commonly infects immunocompromised individuals, such as cancer patients. We present a case involving a 60‐year‐old male with Stage 3A lung adenocarcinoma and chronic obstructive pulmonary disease (COPD) diagnosed with CMV tracheobronchitis, initially suspected as cancer progression. Treatment with ganciclovir led to partial improvement in symptoms of shortness of breath and cough, as well as bronchoscopic findings. However, due to ganciclovir‐induced neutropenia, the therapy was switched to foscarnet. Distinguishing between cancer progression and infectious tracheobronchitis through physical examination and chest CT scans remains challenging. In lung cancer patients presenting with airway and bronchial narrowing along with ulcerative mucosal lesions, CMV infection should be considered. A bronchoscopic biopsy is crucial for accurate diagnosis and determining the appropriate treatment in these patients.

During chemotherapy, certain cancer cells undergo cell death, which alters the properties of remaining cells and leads to numerous changes in the constituent cells of lung cancer. Immunotherapy has been used as neoadjuvant therapy, and several studies have reported changes in lung cancer tissue following treatment with immuno-anticancer drugs in early stage disease. However, no research has currently discussed the pathological and PD-L1 expression changes in metastatic lung cancer. Here, we describe a patient with lung adenocarcinoma and multiple metastases who achieved complete remission after receiving initial carboplatin/pemetrexed followed by pembrolizumab treatment for 2-years. The initial biopsy revealed adenocarcinoma with high PD-L1 expression, and next-generation sequencing (NGS) identified KRAS, RBM10, and STAG2 mutations. After 2-years of treatment with pembrolizumab, the patient achieved complete response (CR). The patient underwent first salvage surgery for the oligo-relapse lesion, and the pathology result showed a large cell neuroendocrine tumor (NET) with adenocarcinoma and no PD-L1 expression. NGS revealed KRAS and TP53 mutations. After one year, a chest computed tomography (CT) scan revealed a small nodule in the right lower lobe, and the patient underwent second salvage surgery. Pathology results showed minimally invasive adenocarcinoma with no PD-L1 expression and no significant genetic mutations. This case report demonstrates the dynamic changes cancer cells undergo following pembrolizumab treatment and salvage surgeries and is the first report to compare pathological changes after immunotherapy and two subsequent salvage surgeries in metastatic lung adenocarcinoma. Clinicians must remain vigilant to these dynamic changes throughout treatment and consider salvage surgery for oligo-relapse lesions. By understanding these changes, new strategies can be developed to improve the long-term efficacy of immunotherapy.

Introduction: Home-based spirometry has emerged as a potential component of decentralized clinical trials (DCTs) in respiratory medicine, but its real-world feasibility in patients with chronic obstructive pulmonary disease (COPD) and other respiratory diseases remains insufficiently characterized. This study evaluated the feasibility of remote pulmonary function monitoring using a portable spirometer and mobile application in adults with COPD or other respiratory diseases. Methods: This exploratory single-arm study enrolled adults aged 19 years or older with COPD or other respiratory diseases. Participants were asked to perform home-based spirometry at six prespecified time points (Days 15, 29, 43, 57, 71, and 85). Feasibility was assessed using visit-level and participant-level adherence, spirometry quality grades, and patient-reported usability and satisfaction. Participants completing at least 5 of 6 scheduled measurements were classified as the high-adherence group; this cut-off was an operational, study-specific definition. Results: A total of 30 participants were enrolled (19 with chronic obstructive pulmonary disease, 5 with asthma, 2 with asthma–COPD overlap, and 4 with other respiratory conditions), and 23 completed the study. Visit-level completion rates declined over time, from 88.5% on Day 15 to 47.8% on Day 71 and 56.5% on Day 85. Nine participants completed all six measurements, while 13 completed at least five. Portable spirometry quality showed variability across visits, with both high-quality and low-quality measurements observed. Compared with the low-adherence group, the high-adherence group reported significantly higher scores for convenience, communication with the research team, overall satisfaction, willingness to participate in future telemedicine-based trials, device training adequacy, ease of device use, and application usability. Conclusions: Home-based spirometry may be a useful decentralized trial component in patients with COPD and other respiratory diseases; however, the decline in adherence over time and the variability in measurement quality indicate that substantial operational refinement is needed before broader implementation. Because no feasibility threshold was prespecified, no concurrent laboratory spirometry comparison was performed, and the study population was diagnostically heterogeneous, these findings are exploratory and address operational feasibility rather than measurement validity.