Prognostic significance of spread through air spaces in pulmonary metastases from colorectal cancer

STAS: New explorations and challenges for thoracic surgeons

Spread through air spaces (STAS) represents a relatively novel concept in the pathology of lung cancer, and it specifically refers to the dissemination of tumour cells into the parenchymal air spaces adjacent to the primary tumour. In 2015, the World Health Organization (WHO) classified STAS as a new invasive form of lung adenocarcinoma (LUAD). Many studies investigated the role of STAS and revealed its association with the prognosis of LUAD and its influence on the outcomes of other malignant pulmonary neoplasms. Additionally, the underlying mechanisms and predictive models of STAS have received considerable attention in recent years. This paper provides a comprehensive overview of the research advancements and prospects of STAS by examining it from multiple perspectives.

Analysis of recurrence in lung adenocarcinoma with spread through air spaces

OBJECTIVES

Spread through air spaces is defined as tumor cells in air spaces away from the edge of tumor in lung carcinoma. It is associated with higher locoregional recurrence and lower survival in lung adenocarcinoma. The features of spread through air spaces portending worse outcomes are still under investigation. We reviewed our lung cancer experience to define potential factors related to spread through air spaces that influence recurrence and survival.

METHODS

Between January 2010 and December 2017, we identified 968 patients who underwent resection for T1-3N0M0 lung adenocarcinoma. Of these, histologic examination was possible in 787 patients. We examined the presence of spread through air spaces, spread through air spaces characteristics (micropapillary, solid nest, or single cell), average density (number per slide), and farthest distance from tumor at which spread through air spaces was detected, or maximal spread distance. Overall survival and recurrence-free survival were estimated using Kaplan-Meier curves, and differences between spread through air spaces positive versus spread through air spaces negative groups were assessed using the log-rank test.

RESULTS

Spread through air spaces was present in 389 of 787 of the reviewed cases (49.4%). Overall survival and recurrence-free survival were significantly lower in the spread through air spaces positive group over 10 years (P < .0001). The incidences of locoregional and distant recurrence were nearly doubled over 10 years in the spread through air spaces positive group compared with the spread through air spaces negative group (P = .002 and <.0001, respectively). In a multivariable Cox regression model adjusted for spread through air spaces characteristics, distance, and tumor size, lobar resection did not confer survival advantage in patients with spread through air spaces (hazard ratio of sublobar resection with respect to lobar resection, 1.44; 95% confidence interval, 0.98-2.11; P = .067). In the spread through air spaces positive group, spread through air spaces density was 2.7 ± 1.4 clusters per slide and the maximal spread distance was 2.2 ± 1.7 mm from the tumor edge. There was no observed correlation between spread through air spaces density or maximal spread distance and overall survival or recurrence.

CONCLUSIONS

We show increased distant recurrence in spread through air spaces positive lung adenocarcinoma. Quantifiable measures of spread through air spaces do not appear to correlate with recurrence or survival metrics.

Spread through Air Spaces (STAS) in Solitary Pulmonary Metastases from Colorectal Cancer (CRC)

BACKGROUND

Spread through air spaces (STAS) is a recently described route of tumor invasion associated with poor prognosis in primary lung cancer. Aim of this study was to investigate the presence of STAS and to assess its prognostic significance in patients undergoing pulmonary metastasectomy (PM) for solitary metastases from colorectal cancer (CRC).

MATERIALS AND METHODS

All 49 CRC patients (30 male and 19 female, median age 66 years) who underwent PM between January 2008 and December 2015 were retrospectively analyzed.

RESULTS

STAS was identified in 26.5% (n = 13) of resected specimens. Location of pulmonary lesions (central vs. peripheral) was assessed based on the available computed tomography imaging (n = 47, 96%). STAS was detected in all five patients with central metastases (100%) versus 7 of 42 (17%) with peripheral metastases (p = 0.0001). Locoregional recurrence occurred in STAS-positive patients (n = 4 of 13 vs. n = 0 of 36), all STAS-negative patients remained recurrence-free (p = 0.003). Median number of alveoli with STAS involvement was four (range from 2 to 9). There was statistically positive relationship between the number of alveoli invaded with STAS and locoregional recurrence of metastases (p = 0.0001). The presence of STAS is not a factor affecting the 5-year overall survival rate (p = 0.6651).

CONCLUSION

We identified STAS as a frequent finding in resected CRC lung metastases and found insignificant association with outcome.

Spread through air spaces is a powerful prognostic predictor in patients with completely resected pathological stage I lung adenocarcinoma

PURPOSE

To evaluate the frequency of spread through air spaces (STAS) in patients with early-stage primary lung cancer and to elucidate the association between STAS and various clinicopathological factors.

METHODS

We retrospectively reviewed data from a total of 265 consecutive patients who underwent lobectomy and mediastinal lymph node dissection (172 patients) or sublobar resection (93 patients) for completely resected pathological stage I lung adenocarcinoma. We evaluated clinical variables, including the preoperative serum carcinoembryonic antigen (CEA) level, tumour size, consolidation tumour ratio (CTR), maximum standardized uptake value (SUVmax) on FDG-PET, histological results, presence of STAS and vascular and lymphatic invasion.

RESULTS

The median follow-up time after surgery was 49 months. Eighty-seven patients (32.8 %) had STAS. The overall survival rates of patients in the STAS-positive and STAS-negative groups were 92.7 % and 97.1 % at 3 years, respectively (p = 0.1255), and the recurrence-free survival rates were 82.1 % and 95.9 % at 3 years, respectively (p = 0.0001). STAS was found in 73 patients (42.4 %) in the lobectomy group, which was a significantly higher proportion than the 14 patients (15.1 %) in the sublobar resection group. The STAS-positive group had significantly larger areas of invasion, higher CTRs, preoperative CEA and SUVmax levels, and more lymphatic and vascular invasion. STAS also correlated significantly with large consolidation sizes, larger invasive size, higher CTRs and the presence of a micropapillary pattern. Cox regression analysis after adjustment for important prognostic factors revealed that the presence of STAS was an independent predictor associated with postoperative recurrence, most of which was observed locoregionally.

CONCLUSIONS

STAS was an independent factor associated with postoperative recurrence after lung resection for stage I lung adenocarcinoma. Among stage IA patients, the postoperative outcomes of STAS-positive patients were worse than those of STAS-negative patients and were similar to those of stage IB patients.

Spread Through Air Spaces (STAS) Is an Independent Prognostic Factor in Resected Lung Squamous Cell Carcinoma

Objective: There is no histoprognostic grading for lung squamous cell carcinoma (LUSC). Different prognostic factors have been described in the recent literature and are not always studied in parallel. Our objective was to search for morphological histopathological prognostic factors in LUSC. Materials and Methods: In this single-center retrospective study of 241 patients, all patients with LUSC who underwent surgical excision over a 12-year period were included. The primary endpoint was 5-year overall survival. Results: STAS was present in 86 (35.7%) patients. The presence of Spread Through Air Spaces (STAS) was correlated with tumor location (p < 0.001), pathological stage (p = 0.039), tumor differentiation (p = 0.029), percentage of necrosis (p = 0.004), presence of vascular and/or lymphatic emboli, budding (p = 0.02), single cell invasion (p = 0.002) and tumor nest size (p = 0.005). The percentage of tumor necrosis was correlated with the overall survival at 5 years: 44.6% of patients were alive when the percentage of necrosis was ≥50%, whereas 68.5% were alive at 5 years when the necrosis was <30% (p < 0.001). When vasculolymphatic emboli were present, the percentage of survival at 5 years was 42.5% compared to 65.5% when they were absent (p = 0.002). The presence of isolated cell invasion was correlated with a lower 5-year survival rate: 51.1% in the case of presence, versus 66% in the case of absence (p = 0.02). In univariate analysis, performance status, pathological stage pT or pN, pleural invasion, histopathological subtype, percentage of tumor necrosis, vasculolymphatic invasion, single-cell invasion, budding and tumor nest size correlated with the percentage of survival at 5 years. On multivariate analysis, only STAS > 3 alveoli (HR, 2.74; 95% CI, 1.18−6.33) was related to overall survival. Conclusion: In conclusion, extensive STAS is an independent factor of poor prognosis in LUSC. STAS is correlated with the presence of other poor prognostic factors such as emboli and pleural invasion and would reflect greater tumor aggressiveness.

Spread through air spaces is a common phenomenon of pulmonary metastasized tumours regardless of origins

OBJECTIVES

Spread through air spaces (STAS) is a unique pattern of invasion in primary lung cancers. However, little is known about STAS in pulmonary metastases (PMs). This study was to investigate the incidence of STAS among PMs and the association between STAS and clinicopathological characteristics of PMs.

METHODS

A total of 127 patients who underwent metastasectomy at our institution from June 2009 to December 2019 were retrospectively analysed. Survival analysis was performed in 40 patients with PM from colorectal cancer (CRC).

RESULTS

STAS was identified in 33.1% of patients (42 of 127) with PMs. STAS was found in PMs of various primary cancers, including CRC, breast cancer, renal cell carcinoma, cholangiocarcinoma and osteogenic and soft tissue sarcoma, but the incidence varies. PMs originating from epithelial tissue showed higher incidence of STAS than those from mesenchymal tissue (45% vs 11%, P < 0.001). Elder age (P = 0.006) and primary sites (P < 0.001) were significantly correlated with STAS. In patients with PMs from CRC, the presence of STAS was an independent predictor of shorter recurrence-free survival (hazard ratio = 10.25, P = 0.002) and poor overall survival (hazard ratio = 4.75, P = 0.047) by multivariable analysis.

CONCLUSIONS

STAS might be a lung-specific tumour invasion pattern and STAS is commonly observed in PMs of different origins. The incidence of STAS was significantly higher in PMs originating from epithelial tissues than those from mesenchymal tissues. Presence of STAS was an independent predictor of poor prognosis in patients with PM from CRC.