Surgery or stereotactic body radiotherapy for metachronous primary lung cancer? A propensity score matching analysis

Stereotactic Body Radiation Therapy for Primary Lung Cancer and Metastases: A Case-Based Discussion on Challenging Cases

PURPOSE

Data informing the safety, efficacy, treatment logistics, and dosimetry of stereotactic body radiation therapy (SBRT) for lung tumors has primarily been derived from patients with favorably located solitary tumors. SBRT is now considered a standard-of-care treatment for inoperable early-stage non-small cell lung cancer and lung metastases, and therefore extrapolation beyond this limited foundational patient population remains an active source of interest.

METHODS AND MATERIALS

This case-based discussion provides a practical framework for delivering SBRT to challenging, yet frequently encountered, cases in radiation oncology. The cases highlighted herein include the use of SBRT for ultracentral tumors, multiple tumors, and reirradiation. Patient characteristics, fractionation, prescription dose, treatment technique, and dose constraints are discussed. Relevant literature to these cases is summarized to provide a framework for the treatment of similar patients.

RESULTS

Treatment of challenging cases with lung SBRT requires many considerations, including treatment intent, fractionation selection, tumor localization, and plan optimization. In such scenarios, patient selection is critical to understanding the risk-benefit profile of an SBRT approach despite significant advances in delivery techniques and safety.

CONCLUSIONS

A case-based discussion was developed by the Radiosurgery Society to provide a practical guide to the common challenging scenarios noted above affecting patients with lung tumors. A multidisciplinary approach should guide the treatment of such cases to maximize the therapeutic window.

Prognostic analysis of helical tomotherapy stereotactic body radiotherapy in multiple primary or second primary lung cancers

PURPOSE

To evaluate the safety and efficacy of Helical Tomotherapy stereotactic body radiotherapy (HT-SBRT) in treating multiple primary lung cancers (MPLCs) and second primary lung cancer (SPLC).

METHODS

From January 2010 to September 2023, 106 MPLCs and SPLC (T1-3N0M0) underwent HT-SBRT. The cumulative incidence for local recurrence (LR) was calculated using the competing risk approach and compared using Gray's test. Cancer-specific survival (CSS) and progression-free survival (PFS) were assessed using Kaplan-Meier analysis and log-rank tests.

RESULTS

After adjusting for competing risks, the LR rates for all lesions (n = 150) was 15.3%, with 2- and 4-year rates of 7.5% and 11.4%. For second primary lung nodules post-surgery, the cumulative incidence of LR was 16.1%, with 2- and 4-year rates of 6.9% and 8.7%. In MPLCs treated with HT-SBRT, the cumulative incidence of LR was 14.3%, with 2- and 4-year rates of 8.2% and 14.3%. In patients with MPLCs treated with HT-SBRT (n = 27), the CSS rates at 2, 4, and 10 years were 90.5%, 78.6%, and 53.6%, respectively, and the PFS rates were 59.5%, 32.8%, and 24.6%. In patients with SPLC who received HT-SBRT after surgery (n = 79), the CSS rates at 2, 4, and 10 years were 90.9%, 81.7%, and 61.0%, respectively, while the PFS rates were 75.4%, 64.4%, and 58.5%. Additionally, 0.9% of patients experienced grade 3 acute radiation pneumonitis, and no severe (grade 4-5) toxicities were reported.

CONCLUSIONS

HT-SBRT may be a safe and effective treatment for MPLCs and SPLC, though prospective studies are needed to confirm its efficacy.

Real-World Survival Comparisons Between Radiotherapy and Surgery for Metachronous Second Primary Lung Cancer and Predictions of Lung Cancer-Specific Outcomes Using Machine Learning: Population-Based Study

BACKGROUND

Metachronous second primary lung cancer (MSPLC) is not that rare but is seldom studied.

OBJECTIVE

We aim to compare real-world survival outcomes between different surgery strategies and radiotherapy for MSPLC.

METHODS

This retrospective study analyzed data collected from patients with MSPLC between 1988 and 2012 in the Surveillance, Epidemiology, and End Results (SEER) database. Propensity score matching (PSM) analyses and machine learning were performed to compare variables between patients with MSPLC. Survival curves were plotted using the Kaplan-Meier method and were compared using log-rank tests.

RESULTS

A total of 2451 MSPLC patients were categorized into the following treatment groups: 864 (35.3%) received radiotherapy, 759 (31%) underwent surgery, 89 (3.6%) had surgery plus radiotherapy, and 739 (30.2%) had neither treatment. After PSM, 470 pairs each for radiotherapy and surgery were generated. The surgery group had significantly better survival than the radiotherapy group (P<.001) and the untreated group (563 pairs; P<.001). Further analysis revealed that both wedge resection (85 pairs; P=.004) and lobectomy (71 pairs; P=.002) outperformed radiotherapy in overall survival for MSPLC patients. Machine learning models (extreme gradient boosting, random forest classifier, adaptive boosting) demonstrated high predictive performance based on area under the curve (AUC) values. Least absolute shrinkage and selection operator (LASSO) regression analysis identified 9 significant variables impacting cancer-specific survival, emphasizing surgery's consistent influence across 1 year to 10 years. These variables encompassed age at diagnosis, sex, year of diagnosis, radiotherapy of initial primary lung cancer (IPLC), primary site, histology, surgery, chemotherapy, and radiotherapy of MPSLC. Competing risk analysis highlighted lower mortality for female MPSLC patients (hazard ratio [HR]=0.79, 95% CI 0.71-0.87) and recent IPLC diagnoses (HR=0.79, 95% CI 0.73-0.85), while radiotherapy for IPLC increased mortality (HR=1.31, 95% CI 1.16-1.50). Surgery alone had the lowest cancer-specific mortality (HR=0.83, 95% CI 0.81-0.85), with sublevel resection having the lowest mortality rate among the surgical approaches (HR=0.26, 95% CI 0.21-0.31). The findings provide valuable insights into the factors that influence cumulative cancer-specific mortality.

CONCLUSIONS

Surgical resections such as wedge resection and lobectomy confer better survival than radiation therapy for MSPLC, but radiation can be a valid alternative for the treatment of MSPLC.

Progress in genome-inspired treatment decisions for multifocal lung adenocarcinoma

INTRODUCTION

Multifocal lung adenocarcinoma (MFLA) is becoming increasingly recognized as a distinct subset of lung cancer, with unique biology, disease course, and treatment outcomes. While definitions remain controversial, MFLA is characterized by the development and concurrent presence of multiple independent (non-metastatic) lesions on the lung adenocarcinoma spectrum. Disease progression typically follows an indolent course measured in years, with a lower propensity for nodal and distant metastases than other more common forms of non-small cell lung cancer.

AREAS COVERED

Traditional imaging and histopathological analyses of tumor biopsies are frequently unable to fully characterize the disease, prompting interest in molecular diagnosis. We highlight some of the key questions in the field, including accurate definitions to identify and stage MLFA, molecular tests to stratify patients and treatment decisions, and the lack of clinical trial data to delineate best management for this poorly understood subset of lung cancer patients. We review the existing literature and progress toward a genomic diagnosis for this unique disease entity.

EXPERT OPINION

Multifocal lung adenocarcinoma behaves differently than other forms of non-small cell lung cancer. Progress in molecular diagnosis may enhance potential for accurate definition, diagnosis, and optimizing treatment approach.

Recent Advances in the Diagnosis and Management of Multiple Primary Lung Cancer

With the wide application of computed tomography in lung cancer screening, the incidence of multiple primary lung cancer (MPLC) has been increasingly reported. Despite the established criteria, the differentiation between MPLC and intrapulmonary metastasis remains challenging. Although histologic features are helpful in some circumstances, a molecular analysis is often needed. The application of next-generation sequencing could aid in distinguishing MPLCs from intrapulmonary metastasis, decreasing ambiguity. For MPLC management, surgery with lobectomy is the main operation method. Limited resection does not appear to negatively affect survival, and it is a reasonable alternative. Stereotactic ablative radiotherapy (SABR) has become a standard of care for patients refusing surgery or for those with medically inoperable early-stage lung cancer. However, the efficacy of SABR in MPLC management could only be found in retrospective series. Other local ablation techniques are an emerging alternative for the control of residual lesions. Furthermore, systemic therapies, such as targeted therapy for oncogene-addicted patients, and immunotherapy have shown promising results in MPLC management after resection. In this paper, the recent advances in the diagnosis and management of MPLC are reviewed.

Multiple Primary Lung Cancers: A New Challenge in the Era of Precision Medicine

With the widespread implementation of lung cancer screening, more and more patients are being diagnosed with multiple primary lung cancers (MPLCs). In the era of precision medicine, many controversies remain in differentiating MPLCs from intrapulmonary metastasis and the optimum treatment choice, especially in patients exhibiting similar histology. In this review, we summarize common diagnostic criteria and novel discrimination methods with a special emphasis on the emerging value of broad panel next-generation sequencing (NGS) for the diagnosis of MPLCs. We then discuss current advances regarding therapeutic approaches for MPLCs. Radical surgery is the main treatment modality, while stereotactic body radiotherapy (SBRT) is safe and feasible for early-stage MPLC patients with inoperable tumors. In addition, immunotherapy and targeted therapy, particularly epidermal growth factor receptor-tyrosine kinase inhibitors, are emerging therapeutic strategies that are still in their infancy. Characteristics of both genomic profiles and tumor microenvironment are currently being evaluated but warrant further exploration to facilitate the application of targeted systematic therapies in MPLC patients.