Recent Advancements in Minimally Invasive Surgery for Early Stage Non-Small Cell Lung Cancer: A Narrative Review

Introduction: Lung cancer remains a global health concern, with non-small cell lung cancer (NSCLC) comprising the majority of cases. Early detection of lung cancer has led to an increased number of cases identified in the earlier stages of NSCLC. This required the revaluation of the NSCLC treatment approaches for early stage NSCLC. Methods: We conducted a comprehensive search using multiple databases to identify relevant studies on treatment modalities for early stage NSCLC. Inclusion criteria prioritized, but were not limited to, clinical trials and meta-analyses on surgical approaches to early stage NSCLC conducted from 2021 onwards. Discussion: Minimally invasive approaches, such as VATS and RATS, along with lung resection techniques, including sublobar resection, have emerged as treatments for early stage NSCLC. Ground-glass opacities (GGOs) have shown prognostic significance, especially when analyzing the consolidation/tumor ratio (CTR). There have also been updates on managing GGOs, including the non-surgical approaches, the extent of lung resection indicated, and the level of lymphadenectomy required. Conclusions: The management of early stage NSCLC requires a further assessment of treatment strategies. This includes understanding the required extent of surgical resection, interpreting the significance of GGOs (specifically GGOs with a high CTR), and evaluating the efficacy of alternative therapies. Customized treatment involving surgical and non-surgical interventions is essential for advancing patient care.

Distinct impacts of radiological appearance on lymph node metastasis and prognosis based on solid size in clinical T1 non-small cell lung cancer

BACKGROUND

Solid nodules (SN) had more aggressive features and a poorer prognosis than part-solid nodules (PSN). This study aimed to evaluate the specific impacts of nodule radiological appearance (SN vs. PSN) on lymph node metastasis and prognosis based on solid size in cT1 non-small cell lung cancer (NSCLC).

METHODS

Patients with cT1 NSCLC who underwent anatomical resection between 2010 and 2019 were retrospectively screened. Univariable and multivariable logistic regression analyses were adopted to evaluate the associations between nodule radiological appearance and lymph node metastasis. The log-rank test and Cox regression analyses were applied for prognostic evaluation. The cumulative recurrence risk was evaluated by the competing risk model.

RESULTS

There were 958 and 665 NSCLC patients with PSN and SN. Compared to the PSN group, the SN arm had a higher overall lymph node metastasis rate (21.7% vs. 2.7%, P < 0.001), including nodal metastasis at N1 stations (17.7% vs. 2.1%), N2 stations (14.0% vs. 1.6%), and skip nodal metastasis (3.9% vs. 0.6%). However, for cT1a NSCLC, no significant difference existed between SN and PSN (0 vs. 0.4%, P = 1). In addition, the impacts of nodule radiological appearance on lymph node metastasis varied between nodal stations. Solid NSCLC had an inferior prognosis than part-solid patients (5-year disease-free survival: 79.3% vs. 96.2%, P < 0.001). The survival inferiority only existed for cT1b and cT1c NSCLC, but not for cT1a. Strikingly, even for patients with nodal involvement, SN still had a poorer disease-free survival (P = 0.048) and a higher cumulative incidence of recurrence (P < 0.001) than PSN. Specifically, SN had a higher recurrence risk than PSN at each site. Nevertheless, the distribution of recurrences between SN and PSN was similar, except that N2 lymph node recurrences were more frequent in solid NSCLC (28.21% vs. 7.69%, P = 0.041).

CONCLUSION

SN had higher risks of lymph node metastasis and poorer prognosis than PSN for cT1b and cT1c NSCLC, but not for cT1a. SN exhibited a greater proportion of N2 lymph node recurrence than PSN. SN and PSN needed distinct strategies for nodal evaluation and postoperative follow-up.

Dynamic Analysis of the Impact of Micropapillary Component on Different Recurrence Patterns of Pathological Stage IA3 Lung Adenocarcinoma: A Multicenter, Retrospective Study

BACKGROUND

This study aimed to evaluate the dynamic impact of the micropapillary (MIP) component on local recurrence (LR), distant metastasis (DM), and multiple recurrence (MR) of pathological stage IA3 lung adenocarcinoma.

METHODS

Between July 2012 and July 2020, a total of 351 patients at two medical institutions were enrolled in this study. Cumulative incidence of curves, dynamic risk curves, and time-dependent multivariate analysis was performed to evaluate the effect of the MIP component on patients.

RESULTS

The 5-year cumulative incidence of total recurrence with or without an MIP component was 34.2% and 12.3%, respectively (p = 0.001). In three recurrence patterns, our findings revealed that the 5-year cumulative incidence of LR (p = 0.048) and DM (p = 0.005) was higher in the 'MIP-present' group than in the 'MIP-absent' group. In the dynamic recurrence curve, the risk of the three recurrence patterns was different and varied over time between the two groups, especially in DM. Moreover, the dynamic cumulative event curve showed that after 1, 2, and 3 years of survival, the cumulative incidence of DM in the group with MIP continued to be higher than that in the group without MIP (all p < 0.05). Time-dependent Cox regression analysis indicated that the MIP component continued to be an independent risk factor for the cumulative incidence of DM in patients with 3-year survival.

CONCLUSIONS

Of the three recurrence patterns, the MIP component mainly aggravated the risk of DM in patients with pathological stage IA3 lung adenocarcinoma, which persisted for 3 years.

Segmentectomy for patients with early-stage pure-solid non-small cell lung cancer

For decades, lobectomy has been the recommended surgical procedure for non-small cell lung cancer (NSCLC), including for small-sized lesions. However, two recent pivotal clinical trials conducted by the Japanese Clinical Oncology Group/West Japan Oncology Group (JCOG0802/WJOG4607L) and the Cancer and Leukemia Group B (CALGB140503), which compared the survival outcomes between lobectomy and sublobar resection (the JCOG0802/WJOG4607L included only segmentectomy, not wedge resection), demonstrated the efficacy of sublobar resection in patients with early-stage peripheral lung cancer measuring ≤ 2 cm. The JCOG0802/WJOG4607L demonstrated the superiority of segmentectomy over lobectomy with respect to overall survival, implying the survival benefit conferred by preservation of the lung parenchyma. Subsequently, the JCOG1211 also demonstrated the efficacy of segmentectomy, even for NSCLC, measuring up to 3 cm with the predominant ground-glass opacity phenotype. Segmentectomy has become the standard of care for early-stage NSCLC and its indications are expected to be further expanded to include solid lung cancers > 2 cm. However, local control is still a major concern for segmentectomy for higher-grade malignant tumors. Thus, the indications of segmentectomy, especially for patients with radiologically pure-solid NSCLC, remain controversial due to the aggressive nature of the malignancy. In this study, we reviewed previous studies and discussed the efficacy of segmentectomy for patients with such tumors.

Segmentectomy for cancer control in radiologically pure-solid clinical stage IA3 lung cancer

OBJECTIVES

This study aimed to compare cancer control after segmentectomy and lobectomy in patients with radiologically pure-solid clinical stage IA3 non-small-cell lung cancer (NSCLC).

METHODS

Patients with radiologically pure-solid clinical stage IA3 NSCLC who underwent lobectomy or segmentectomy at 3 institutions between 2010 and 2019 were identified. We estimated propensity scores to adjust for confounding variables regarding tumour malignancy, including age, sex, smoking history, tumour size, maximum standardized uptake value on 18F-fluorodeoxyglucose positron emission tomography, lymph node dissection, histological type and lymphatic, vascular and pleural invasion. Cumulative incidence of recurrence (CIR) was evaluated as a primary end point.

RESULTS

Among 412 patients, postoperative recurrence occurred in 7 of 44 patients (15.9%) undergoing segmentectomy, and 71 of 368 patients (19.3%) undergoing lobectomy. CIR was comparable between patients undergoing segmentectomy (5-year rate, 21.9%) and those undergoing lobectomy (5-year rate, 20.8%; P = 0.88). Locoregional recurrence did not differ between patients undergoing segmentectomy (6.8%) and those undergoing lobectomy (9.0%). In multivariable analysis, segmentectomy (versus lobectomy) was not identified as an independent prognostic factor for CIR (hazard ratio, 1.045; 95% confidence interval, 0.475-2.298; P = 0.91). In propensity score matching of 40 pairs, CIR was not significantly different between patients undergoing segmentectomy (5-year rate, 20.7%) and those undergoing lobectomy (5-year rate, 18.4%; P = 0.81).

CONCLUSIONS

Cancer control may be comparable between segmentectomy and lobectomy in patients with radiologically pure-solid clinical stage IA3 NSCLC. Further studies are warranted to clarify the survival benefits of segmentectomy in these patients.

Segmentectomy versus lobectomy for small-sized pure solid non-small cell lung cancer

BACKGROUND

Segmentectomy has been recommended for ground glass opacity (GGO)-dominant small-sized non-small cell lung cancer (NSCLC) or those with GGO component. Pure solid NSCLC is a special sub-type and has an inferior prognosis. Whether segmentectomy could achieve comparable long-term outcomes with lobectomy for pure solid small-sized NSCLC remained controversial. This study aimed to compare the prognosis of segmentectomy and lobectomy for pure solid NSCLC.

METHODS

NSCLC patients with a pure solid nodule (≤2 cm) who received segmentectomy or lobectomy between January 2010 and June 2019 were retrospectively screened. Log-rank test, univariable, and multivariable Cox regression analyses were used for prognostic comparison. Further, the propensity score matching analysis was adopted to yield a matched cohort.

RESULTS

After screening, 344 pure solid NSCLC patients with a median follow-up time of 56 months were reserved. Among them, 98 patients underwent segmentectomy and the other 246 subjects received lobectomy. The lobectomy group had a larger tumor size, a higher rate of lymph node metastasis than the segmentectomy arm. Generally, patients with segmentectomy had a better disease-free survival (DFS) (p = 0.011) and overall survival (OS) (p = 0.028) than those with lobectomy. However, the multivariable Cox regression analysis indicated that no significant survival difference existed between segmentectomy and lobectomy after adjusting the potential confounding factors (DFS: hazard ratio [HR], 0.72; 95% confidence interval [CI], 0.30-1.77, p = 0.476; OS: HR, 0.36; 95% CI, 0.08-1.59, p = 0.178). Consistently, in the propensity score matched cohort, segmentectomy (n = 74) yielded similar DFS (p = 0.960) and OS (p = 0.320) with lobectomy (n = 74).

CONCLUSIONS

Segmentectomy could achieve comparable oncological outcomes with lobectomy for pure solid small-sized NSCLC.

Preoperative prognostic prediction for stage I lung adenocarcinomas: Impact of the computed tomography features associated with the new histological grading system

Objectives

This study aimed to identify the computed tomography (CT) features associated with the new International Association for the Study of Lung Cancer (IASLC) three-tiered grading system to improve the preoperative prediction of disease-free survival of stage I lung adenocarcinoma patients.

Methods

The study included 379 patients. Ordinal logistic regression analysis was used to identify the independent predictors of IASLC grades. The first multivariate Cox regression model (Model 1) was based on the significant factors from the univariate analysis. The second multivariate model (Model 2) excluded the histologic grade and based only on preoperative factors.

Results

Larger consolidation tumor ratio (OR=2.15, P<.001), whole tumor size (OR=1.74, P=.002), and higher CT value (OR=3.77, P=.001) were independent predictors of higher IASLC grade. Sixty patients experienced recurrences after 70.4 months of follow-up. Model 1 consisted of age (HR:1.05, P=.003), clinical T stage (HR:2.32, P<.001), histologic grade (HR:4.31, P<.001), and burrs sign (HR:5.96, P<.001). Model 2 consisted of age (HR,1.04; P=.015), clinical T stage (HR:2.49, P<.001), consolidation tumor ratio (HR:2.49, P=.016), whole tumor size (HR:2.81, P=.022), and the burrs sign (HR:4.55, P=.002). Model 1 had the best prognostic predictive performance, followed by Model 2, clinical T stage, and histologic grade.

Conclusion

CTR (cut-off values of <25% and ≥75%) and whole tumor size (cut-off value of 17 mm) could stratify patients into different prognosis and be used as preoperative surrogates for the IASLC grading system. Integrating these CT features with clinical T staging can improve the preoperative prognostic prediction for stage I lung adenocarcinoma patients.

Wedge resection is an acceptable treatment option for radiologically low-grade lung cancer with solid predominance

OBJECTIVES

This study aimed to determine the clinical characteristics for predicting low-grade cancer in radiologically solid predominant non-small-cell lung cancer (NSCLC) and compare the survival outcomes of wedge resection with those of anatomical resection for patients with and without these characteristics.

METHODS

Consecutive patients with clinical stages IA1-IA2 NSCLC showing radiologically solid predominance ≤2 cm at 3 institutions were retrospectively evaluated. Low-grade cancer was defined as the absence of nodal involvement and blood vessel, lymphatic and pleural invasion. The predictive criteria for low-grade cancer were established by multivariable analysis. The prognosis of wedge resection was compared with that of anatomical resection for patients who met the criteria, using the propensity score-matched analysis.

RESULTS

Among 669 patients, multivariable analysis showed that ground-glass opacity (GGO) (P < 0.001) on thin-section computed tomography and an increased maximum standardized uptake value on 18-fluoro-2-deoxyglucose positron emission tomography/computed tomography (P < 0.001) were independent predictors of low-grade cancer. The predictive criteria were defined as GGO presence and maximum standardized uptake value ≤1.1 (specificity: 97.8%, sensitivity: 21.4%). In the propensity score-matched pairs (n = 189), overall survival (P = 0.41) and relapse-free survival (P = 0.18) were not significantly different between patients who underwent wedge resection and anatomical resection among those who fulfilled the criteria.

CONCLUSIONS

The radiologic criteria for GGO and a low maximum standardized uptake value could predict low-grade cancer, even in solid-dominant NSCLC sized ≤2 cm. Wedge resection could be an acceptable surgical option for patients with radiologically predicted indolent NSCLC showing a solid-dominant appearance.

Tumor size, but not consolidation-to-tumor ratio, is an independent prognostic factor for part-solid clinical T1 non-small cell lung cancer

BACKGROUND

Tumor size and consolidation-to-tumor ratio (CTR) are crucial for non-small cell lung cancer (NSCLC) prognosis. However, the optimal CTR cutoff remains unclear. Whether tumor size and CTR are independent prognostic factors for part-solid NSCLC is under debate. Here, we aimed to evaluate the prognostic impacts of CTR and tumor size on NSCLC, especially on part-solid NSCLC.

METHODS

We reviewed 1366 clinical T1 NSCLC patients who underwent surgical treatment. Log-rank test and Cox regression analyses were adopted for prognostic evaluation. The "surv_cutpoint" function was used to identify the optimal CTR and tumor size cutoff values.

RESULTS

There were 416, 510, and 440 subjects with pure ground-glass opacity (pGGO), part-solid, and pure solid nodules. The 5-year overall survival (disease-free survival) for patients with pGGO, part-solid, and pure solid nodules were 99.5% (99.5%), 97.3% (95.8%), and 90.4% (78.9%), respectively. Multivariate Cox regression analysis indicated that CTR was an independent prognostic factor for the whole patients, and the optimal CTR cutoff was 0.99. However, for part-solid NSCLC, CTR was not independently associated with survival, even if categorized by the optimal cutoffs. The predicted optimal cutoffs of total tumor size and solid component size were 2.4 and 1.4 cm for part-solid NSCLC. Total tumor size (HR = 6.21, 95% CI: 1.58-24.34, p = 0.009) and solid component size (HR = 2.27, 95% CI: 1.04-5.92, p = 0.045) grouped by the cutoffs were significantly associated with part-solid NSCLC prognosis.

CONCLUSIONS

CTR was an independent prognostic factor for the whole NSCLC, but not for the part-solid NSCLC. Tumor size was still meaningful for part-solid NSCLC.