Globally, there are approximately 2.21 million cases of lung cancer diagnoses and 1.80 million deaths (1). Small cell lung cancer (SCLC) accounts for about 10%–15% of primary lung malignancies, characterized by rapid growth and early metastasis (2). Current guidelines recommend concurrent chemoradiotherapy (CRT) for node-positive SCLC (3–5), which has yielded 5-year survival rates of 16%–26% (6). Surgical resection, combined with CRT as part of a multidisciplinary treatment approach, is only recommended in clinical stages I and II disease (cT1-T2N0), as none of the existing large randomized controlled trials (RCT) (7, 8) or the recent Cochrane systematic review (9) demonstrated a survival benefit from surgical resection for SCLC.

In contrast, retrospective studies have suggested acceptable outcomes in surgery for early-stage disease (10–13). However, despite the barely acceptable results, the recurrence rate of surgically treated SCLC remains high. According to a retrospective study by the Mayo Clinic, the postoperative recurrence rate of the combined treatment of surgery and CRT was reported to be as high as 50% at 3 years (median RFS, 2.4 years) (14). This absence of a synergistic effect of surgery and CRT in SCLC treatment, which has also been suggested by previous RCTs (7, 8), could be at least partially due to the method of surgical resection. For instance, inappropriate surgical manipulation can theoretically dislodge tumor cells into the bloodstream and lymphatic system (15); this effect might be more significant in highly aggressive diseases, such as SCLC, thus leading to postoperative distant metastasis.

Given the limitations of contemporary SCLC resection methods and the high postoperative recurrence rates, there is an urgent need for innovative surgical techniques that ensure precise, complete resection while minimizing the risk of circulating tumor cell dissemination. Although recent advancements and a deepening understanding of VATS have shown promising results in the radical resection of SCLC, controversies still exist regarding the effectiveness of this procedure. These include limited access to mediastinal lymph nodes (16), challenges with instrument maneuverability (17), and concerns about intraoperative tumor handling (18). Given the aggressive nature of SCLC, a more refined surgical approach that enhances oncologic resection while maintaining minimal invasiveness is necessary. HilumDirect uVATS may provide advantages for SCLC management by enabling a single small-sized incision with direct access to the lung hilum. This approach facilitates improved precision, potentially reducing the risk of tumor cell dissemination and enabling more thorough lymph node clearance. By minimizing tumor manipulation, this technique could enhance local control outcomes, lower recurrence rates, and offer a promising alternative to conventional resection methods for SCLC. By comparing outcomes of HilumDirect uVATS with conventional uVATS, this study seeks to provide insights into optimizing surgical intervention for SCLC within a multimodal treatment framework.

Our study aimed to evaluate the safety, feasibility, and potential for improved outcomes of HilumDirect uniportal video-assisted thoracoscopic surgery (uVATS) in patients undergoing resection for small cell lung cancer (SCLC). Our findings indicate that HilumDirect uVATS is a safe and reliable procedure with comparable operative outcomes to conventional uVATS. Notably, we observed a numerical, though non-significant, difference favoring enhanced lymph node yield, cancer-specific survival (CSS), and recurrence-free survival (RFS). These findings emphasize the promise of precision-focused, minimally invasive surgical techniques in addressing the unique challenges presented by SCLC.

The central innovation of HilumDirect uVATS lies in its strategically designed incision, which sets it apart from conventional uVATS approaches. By shortening the operative distance to the lung hilum, main bronchus, and upper mediastinum, the incision enhances precision in tumor resection and lymphadenectomy. As Figure 1 shows, HilumDirect uVATS offers a wider intercostal space and larger instrument-to-chest wall angles, thus enabling broader and farther reach while facilitating the collaboration of surgical instruments compared to conventional uVATS. The significance of thorough lymph node dissection cannot be overstated in SCLC, where nodal involvement is strongly linked to recurrence and poor survival outcomes. In a database analysis, Cao et al. demonstrated a correlation between inadequate lymphadenectomy (<4 lymph nodes per resection) and worse outcomes (27). The lymph node yield, which currently varies significantly across institutions (28), is also recognized as an indicator of resection quality. In a multicenter retrospective study, Xu et al. highlighted the importance of adequate lymphadenectomy by comparing open and VATS surgery for SCLC, suggesting that a lower N2 lymph node yield (11.8 ± 8.2 vs. 8.4 ± 5.8, p = 0.048) correlates with a trend toward worse OS (29). In our study, the HilumDirect group exhibited a numerical difference, suggesting a potentially higher lymph node yield. Substantial evidence from large-scale research indicates a correlation between thorough lymphadenectomy and prognostic benefit. Gajra et al. have shown that extensive lymphadenectomy is associated with improved outcomes in stage I NSCLC (30). Similar correlations have been noted in other solid tumors as well (31–33). While the traditional Halsted view suggests that improved prognoses stem from clearer staging and a more exhaustive resection of tumor cells, evidence from a large-scale multicenter randomized controlled trial, i.e., Z0030, demonstrated equivalence between mediastinal lymph node sampling and systematic and thorough lymphadenectomy in presection sampling proven node-negative early-stage NSCLC (34), supporting the Cady-Fisher perspective, i.e., thorough lymphadenectomy benefits primarily through accurate staging, as cancer is a systemic disease. However, caution must be taken when interpreting our results, as a numerical but not statistical difference is insufficient for solid causal inference. Therefore, the findings of our study should be regarded as exploratory and suggestive, rather than definitive. The mechanism behind lymphadenectomy and survival remains under debate, and whether there are mechanisms other than accurate staging (35), such as reducing regional and systemic tumor burden and immunomodulation, is beyond the scope of our study.

Another theoretically plausible mechanism contributing to the observed numerical difference, which suggests possible improved survival with HilumDirect uVATS, may lie in the thermal effects of the cautery used during resection. The application of energy-based instruments could secure the resection margin by destroying residual microscopic tumor cells near the resection edge. This thermal effect was demonstrated in an ex vivo laryngeal model by Mannelli et al. (36). George et al. also suggested that coagulation diathermy could induce varying degrees of cellular damage compared to non-energetic instruments (37). This “sterilization effect” of cautery, while speculative, combined with the inherently broader effective resection range compared to non-energetic instruments, could help reduce local recurrence and complement systemic therapy. While our study was not designed to investigate underlying mechanisms, the observed numerical trends suggest hypotheses for future research. Future studies should aim to directly investigate the potential impact of cautery-based mechanisms on oncological outcomes in the surgical treatment of SCLC.

SCLC is known for its high metastatic potential and sensitivity to tumor cell dissemination during surgery. Conventional techniques, which often require significant retraction to ensure exposure due to the distance between the incision and the lung hilum, may inadvertently lead to excessive tumor manipulation, increasing the risk of circulating tumor cells (CTCs) entering the bloodstream or lymphatic system (15). Furthermore, certain orientations for exposure and division of the lung hilum may become inaccessible in cases of bulky disease. Single-directional VATS surgery developed by Liu et al. could address this issue by sequentially dissecting hilar structures using a triangle port design (38). However, this technique requires at least three ports, which may increase surgical trauma. The HilumDirect uVATS incision minimizes the need for extensive tissue retraction and manipulation by allowing an omnidirectional approach through a single port, as illustrated in the method section, potentially contributing to better control of SCLC. However, whether this theoretical advantage could translate into survival benefits still needs further investigation, as our study did not indicate a statistically significant superiority of the HilumDirect uVATS approach.

The assistant surgeon's training is crucial for adopting VATS surgery, as D'Amico et al. suggested (39). Kranenburg et al. systematically recorded and analyzed the ergonomic issues encountered during three-port VATS surgery (40), which were also present during the era of uVATS. The primary problems of VATS surgery generally stem from the discordance between the operative axis and the surgeon. As Bertolaccini et al. illustrated, transforming the rhomboid field from outside the thoracic cavity in multiport VATS to inside in uVATS enhanced the ergonomic experience for the surgeon (41). From a geometric perspective, the axis of HilumDirect uVATS, from the incision to the operative field, is more perpendicular to the chest wall than that of conventional uVATS, facilitating more comfortable positioning for both the surgeon and the camera-holding assistant alongside the axis. This design not only improves procedural efficiency but also creates a reproducible technique that can be easily taught to trainees.

Before interpreting the results, it is important to mention a significant statistical fact. Given the relatively small sample size (n = 87 total, n = 56 after matching), the study is at risk of a type II error, which may limit the detection of statistically significant differences. Future larger-scale studies are necessary to validate these findings.

As a cornerstone of modern SCLC management, chemoradiotherapy plays a crucial role in controlling tumor growth and enhancing survival. Evidence strongly suggests that treatment-naïve patients, particularly those with stage II disease, experience worse prognoses (42). However, Cox regression did not detect significant protective effects of neoadjuvant chemotherapy, adjuvant chemotherapy, or radiotherapy on CSS and RFS in either the whole cohort or the PSM cohort. This finding may be influenced by selection bias (43) and immortal time bias (44). Nonetheless, PSM effectively balanced neoadjuvant therapy proportions between groups, mitigating this concern to some extent. Given the impracticality of true randomization due to ethical constraints, future research may explore alternative methodologies, such as animal models and large-scale real-world database analysis, to better elucidate the true impact of multimodal therapy on surgical outcomes.

Due to inherent database limitations, detailed comorbidity records were unavailable for analysis. However, previous studies, such as those by Kearney et al. (45), have demonstrated that pulmonary reserve—measured by predicted postoperative FEV1—correlates strongly with the risk of postoperative complications. Moreover, ECOG performance status, a widely validated predictor of survival in lung cancer patients (46), was balanced between groups after matching, providing some assurance that baseline functional status was comparable. Nonetheless, pulmonary function and ECOG score are not perfect substitutes for comorbidity burden. The absence of detailed comorbidity data introduces a potential source of residual bias, which must be considered when interpreting our findings.

Surgical expertise is a critical determinant of operative quality, especially when evaluating an innovative surgical approach. While surgical proficiency varies among individuals (47), it is well established that operator experience influences surgical outcomes, particularly for complex resections. In this study, all HilumDirect uVATS cases were conducted by a single surgeon who pioneered this technique. However, technical innovation does not inherently translate into superior outcomes, as shown by the lack of significant differences in operative time, intraoperative blood loss, and other perioperative indicators. Despite these findings, the successful execution of radical resection via HilumDirect uVATS requires technical expertise and specialized training. Therefore, a measured and cautious approach is warranted when generalizing these results to broader clinical practice.

Ultimately, while our study focused exclusively on small-cell lung cancer, this disease context requires further elaboration. The biological aggressiveness and high recurrence rate of SCLC make it an especially rigorous testbed for evaluating the effectiveness of surgical techniques. In contrast, NSCLC, with its relatively slower progression and longer disease-free intervals, may obscure subtle yet meaningful differences between surgical approaches due to generally favorable outcomes. From this perspective, HilumDirect uVATS was intentionally applied to a high-risk population, grounded in the rationale that any oncological advantage observed in SCLC, even if modest, may support its efficacy and warrant broader investigation in more indolent thoracic malignancies.

This study has several limitations that warrant consideration. First, its retrospective design, conducted at a single center with a small sample size, limits the generalizability of our findings and increases the risk of a type II error. Although propensity score matching was employed, residual confounders may still exist. Specifically, the fact that all HilumDirect procedures were performed by a single surgeon who pioneered the technique introduces a potential performance bias. Furthermore, unmeasured confounders, such as detailed comorbidity data, which were unavailable in our database, could have influenced outcomes, although we attempted to mitigate this by matching on ECOG status and pulmonary function. Additionally, variations in surgeon expertise could introduce bias, and the relatively short follow-up period for some patients may underestimate long-term survival and recurrence outcomes. Perioperative factors such as pain scores and quality-of-life measures were not recorded, which might have provided deeper insights into the benefits of HilumDirect uVATS. Moreover, while numerical differences toward improved lymph node yield and survival were observed, they did not reach statistical significance, underscoring the need for larger, multicenter studies. Lastly, the underlying mechanisms contributing to these differences, such as reduced tumor manipulation, immune modulation, and thermal ablative effect, remain speculative and require further investigation.

Our study demonstrates that HilumDirect uVATS is a safe and feasible surgical technique for the treatment of small cell lung cancer (SCLC). It offers comparable operative outcomes and the potential for improved results compared to conventional uVATS. The innovative incision design of HilumDirect uVATS enhances surgical precision, reduces tissue manipulation, and facilitates a more comprehensive lymphadenectomy, addressing critical challenges in SCLC resection. While numerical differences suggested possible improvements in cancer-specific survival and recurrence-free survival, particularly among node-positive patients, these findings did not reach statistical significance, highlighting the need for further validation in larger, prospective, multi-center studies.