Restrictive ventilation impairment is a common comorbidity of lung cancer, and their interaction poses significant clinical challenges. Patients with restrictive ventilation impairment are three to six times more likely to develop lung cancer than those with normal lung function. The prognosis of lung cancer positively correlates with the severity of chronic obstructive pulmonary disease; therefore, attention needs to be paid to the progression and decline of lung function. In this retrospective study, we found a significant association between lung function impairment and early-stage lung adenocarcinoma invasion: 38.72% of patients with stage I lung adenocarcinoma have different types of lung dysfunction. This study demonstrated that obstructive ventilation, restrictive ventilation, mixed ventilation, preserved ratio impaired spirometry, and diffusion capacity impairment were associated with a higher risk of lung cancer invasion and highlighted the effects of PFTs in predicting lung cancer invasion. Our prediction model for lung cancer invasion included age, tumor size, lung function, basophil count, and direct bilirubin level and showed good discrimination and calibration in both the training and validation sets. To the best of our knowledge, this is the first study to discuss the connection between various forms of lung function impairment and invasion in LUAD. These good predictive performances increase the clinical capacity to identify AIS/MIA from IAD.
Increasing research has elucidated the substantial correlation between the development of lung cancer and the decline of lung function [24]. A large study reported that FEV1 < 80% in the presence of airway obstruction was a risk factor independent of lung cancer development [25]. The performance of a lung cancer prediction model for individuals who had never smoked was improved with the addition of lung function as a covariable [26]. A cohort study conducted in South Korea revealed that even slight and moderate impairments in lung function are associated with a higher chance of developing lung cancer and a significant attributable risk [12]. The shared mechanisms for lung function impairment and lung cancer development include significant carcinogenic exposure, chronic inflammation-induced remodeling and thickening of the bronchiolar wall, production of genotoxic reactive oxygen species, and inflammatory gene variation in the inflammation-cancer transition [27]. Several supplementary pathological characteristics, including secondary histological patterns [28], nuclear grade [29], mitotic grade [30], presence of dissemination across air gaps [31], and necrosis [32], have been demonstrated to possess predictive significance. As the evolution of airway function and pathology may be related, it may be feasible to evaluate airway function using PFTs to predict lung cancer invasion, even when it is difficult to evaluate lung cancer invasion by microcosmic means.
Numerous studies have explored the clinical and pathologic features of AIS and MIA [33, 34], with a focus on 5-year recurrence-free survival after resection [35, 36]. Due to the increasing prevalence of screening using low-dose CT, early-stage tumors should be detected more frequently. The histological features of tumors are the gold standard for determining tumor type and invasion. However, the power of histological characteristics of tumors for prognosis prediction is limited [37]. Additionally, the identification of histological features is dependent on pathologists, whose assessment varies according to their experience and specialization. Therefore, the reproducibility of histologic pattern assessments can be challenging [38]. Supplementing the preliminary evaluation and prediction of lung cancer invasion with a nomogram model before surgery will help achieve better postoperative management and treatment for LUAD. Patients may benefit from the changing landscape of emerging management and optional treatment options. Our study provides a landmark for performing preoperative PFTs to predict LUAD invasion, and our nomogram had an area under the curve of 0.82 in the internal training set.
Since LE can reduce morbidity and improve patient outcomes when compared to pneumonectomy, it has become the standard surgical approach for lung cancer. SE has become more popular for AIS/MIA as it has the advantage of preserving more lung parenchyma; however, SE is generally only indicated for patients with small tumors and no lymph node invasion [39]. Although several studies have shown contradictory findings about the relationship between the extent of lung tissue removed and the decline of lung function, some have reported that SE offers preservation of PF compared with open LE [40]. A large retrospective observational study that included 1284 patients demonstrated that the decline in pulmonary function was significantly more pronounced following LE compared to SE [41]. Harada et al. reported that patients with non-small cell lung cancer who underwent SE had significantly better functional preservation than those who underwent LE, and the extent of removed lung parenchyma was strongly related to the decline of FVC and FEV1 at follow-up [42]. Preoperative pulmonary function may be associated with invasive lung cancer, and surgical methods may further increase loss of lung function. Once the patient is on the operating table, the surgical method has already been decided based on the intraoperative pathological examination. Therefore, adequate evaluation of lung cancer invasion before surgery will help with treatment decisions, allowing for the optimal surgical type and thereby improving patient outcomes.
An important finding of our study was establishing a quick and easy prediction model that provides a new supplement for the preliminary evaluation of pulmonary adenocarcinoma invasion, assisting in preoperative and postoperative management for LUAD. The present study demonstrates the role of PFTs, a noninvasive, low-cost, and rapid examination, in identifying individuals at high risk of lung cancer invasion. Radiomics technology can accurately detect early-stage lung adenocarcinomas. This method can semiautomatically and objectively discriminate the less-invasive lung adenocarcinomas suitable for sublobar resection by applying voxel-based histogram analysis to 3D-CT images [43]. The highly accurate method can assist physicians in decision-making and treatment planning. Chen et al. [44] found that tumor size and solid component size are the two most important CT factors for identifying pathological tumor invasion. Our study also demonstrated that tumor size measured by CT can independently predict lung adenocarcinoma invasion. With the increasing prevalence of screening using low-dose CT, an increasing number of early-stage tumors are being detected more frequently. Combined CT and PFT screening in this high-risk population can offer better therapy and patient management guidance.
In conclusion, this study proposed a new prediction model for IAD. The scoring methodology and practicality of the prediction model enable its rapid and simple integration into regular clinical practice since they eliminate the need for the doctor to acquire new technological skills. The model provided a new supplement for predicting pulmonary adenocarcinoma invasion and was reproducible in the training and validation sets. In clinical practice, this prediction model will provide doctors with a standard tool to utilize, and it will also help researchers assess prognostic and/or predictive indicators in early-stage adenocarcinoma. A multidimensional approach for the assessment of a higher individual risk of lung cancer invasion may improve future prevention strategies, early detection approaches, and clinical management of this lethal disease.