Tumor Control and Overall Survival after Stereotactic Body Radiotherapy for Pulmonary Oligometastases from Colorectal Cancer: A Meta-Analysis

Stereotactic body radiation therapy and thermal ablation for treatment of patients with pulmonary metastases: a systematic literature review and meta-analysis

OBJECTIVE

To compare local tumor progression (LTP) and overall survival (OS) after image-guided thermal ablation (IGTA; microwave/radiofrequency ablation) versus stereotactic body radiation therapy (SBRT) in patients with pulmonary metastases.

METHODS

A systematic literature review was performed to capture studies that used IGTA or SBRT for patients with pulmonary metastases and studies that reported one, two, and threeyear LTP/OS were included. Patients with pulmonary metastases, and a subgroup with metastases from colorectal or renal cell carcinoma, or sarcoma (termed subgroup) which are considered more radioresistant, were analyzed. Single-arm pooled analyses, univariable, and multivariable random-effects meta-regressions were conducted to compare LTP and OS between IGTA and SBRT treated patients.

RESULTS

Analyses included 3,264 IGTA and 5,486 SBRT patients. IGTA patients with pulmonary metastases had higher LTP than SBRT patients at one year, 13% and 9% respectively. At two years, the LTP for IGTA patients was 14% compared to 16% for SBRT patients. Three-year LTP remained lower for IGTA patients compared to SBRT patients (14% and 22% respectively). In the subgroup, SBRT patients had higher LTP than IGTA patients across all timepoints. OS was similar across analyses/subgroups in the single-arm pooled analyses. The multivariable analyses showed that SBRT was associated with significantly lower OS at one year; however nonsignificant differences were observed at years two and three.

CONCLUSIONS

In patients with pulmonary metastases, IGTA had lower LTP than SBRT at later timepoints. In patients with colorectal, renal cell carcinoma, or sarcoma pulmonary metastases, LTP was similar to overall LTP for IGTA, while it was higher for SBRT.

Treatment of Colorectal Lung Metastases: Two Centers Retrospective Study

INTRODUCTION

Clear guidelines for colorectal lung metastasis (LM) treatment are not available. This study aimed to provide insight into the treatment strategies and efficacy of local and systemic therapy in patients with LM eligible for (potentially) curative treatment.

METHODS

This was a retrospective study of patients with ≤5 LM discussed in two tertiary referral centers. Patient and tumor characteristics were compared between treatment groups. Treatment strategies were compared between centers and survival data between treatment groups, local treatment modalities, and treating centers.

RESULTS

Ninety-two patients (median 2 LMs) were included. Seventy-one (77%) patients underwent local treatment (17 surgery, 13 ablation, 38 radiotherapy, 3 combination of local treatments) and 21 (23%) with systemic therapy alone. The latter group more frequently had extrapulmonary metastases (81.0% vs. 26.8%, p < 0.001) and synchronous presentation of LM (23.8% vs. 7.0%, p = 0.045). Choice of local versus systemic therapy and time to start treatment after diagnosis (median 109 days, IQR 44-240 vs. 88 days, IQR 53-168) were comparable between centers. Three-year survival rates did not differ between treatment groups, local treatment modalities, or treating centers.

CONCLUSION

Treatment strategies and oncological outcomes were rather similar between centers. Survival outcomes were not different between locally and systemically treated patients.

A retrospective study comparing the efficacy of microwave ablation and stereotactic body radiotherapy in colorectal cancer lung metastases

The purpose of the present study was to assess and compare the efficacy of microwave ablation (MWA) and stereotactic body radiotherapy (SBRT) in the treatment of lung metastases from patients with colorectal cancer (CRC) and to identify the preferable treatment modality based on patient and tumor characteristics. Records of 118 patients with CRC with a total of 307 lung metastases who underwent SBRT or MWA between January 2015 and December 2022 were retrospectively analyzed, including the essential clinicopathological information on patients (age, sex and underlying diseases), diagnosis and treatment information [primary tumor site, levels of carcinoembryonic antigen (CEA) and carbohydrate antigen 19-9], imaging data [diameter of lung metastasis, location of the metastasis (i.e., whether or not the tumor was adjacent to the vessel or bronchus) and internal features] and follow-up data (postoperative therapy, complications or adverse effects and survival outcomes). For statistical analysis of the local tumor progression (LTP), disease-free survival and overall survival (OS) rates, Cox regression analysis, along with the Kaplan-Meier method adjusted using inverse probability of treatment weighting (IPTW), were performed. The median follow-up duration in the present study was 31.5 months. Multivariable Cox regression analysis revealed that the CEA level, metastasis diameter and internal features were independent predictors of OS. In the IPTW-adjusted analysis, no significant difference in the 1-year OS rate was observed between the SBRT and MWA groups (92.9 vs. 93.9%; P=0.483); however, a notable discrepancy in the treatment modalities was noted, leading to significant differences in the 2- and 3-year OS rates (65.9 vs. 57.6%, P=0.001, and 44.7 vs. 36.4%, P<0.001, respectively). A significant interaction effect for the treatment modality was observed for LTP (P=0.021). In conclusion, the present study revealed that SBRT and MWA have similar therapeutic effects in terms of prolonging the survival of patients with CRC with lung metastases; however, regarding the local control of lung metastases, MWA is associated with a number of significant advantages.

Comprehensive analysis of Japanese nationwide cohort data of particle beam therapy for pulmonary, liver and lymph node oligometastases: particle beam therapy versus high-precision X-ray radiotherapy

Japanese national oncological experts convened to evaluate the efficacy and safety of particle beam therapy (PT) for pulmonary, liver and lymph node oligometastases (P-OM, L-OM and LN-OM, respectively) and to conduct a statistically comparative analysis of the local control (LC) rate and overall survival (OS) rate of PT versus those of X-ray stereotactic body radiotherapy (X-SBRT) and X-ray intensity-modulated radiotherapy (X-IMRT). They conducted [1] an analysis of the efficacy and safety of metastasis-directed therapy with PT for P-OM, L-OM and LN-OM using a Japanese nationwide multi-institutional cohort study data set; [2] a systematic review of X-ray high-precision radiotherapy (i.e. X-SBRT/X-IMRT) and PT for P-OM, L-OM and LN-OM; and [3] a statistical comparison between LC and OS of the cohort data set in PT and that of the extracted historical data set in X-SBRT/X-IMRT from the preceding systematic review. Safety was evaluated as the incidence of grade ≥ 3 adverse events, while statistical comparisons of LC and OS were conducted by estimating the incidence rate ratios (IRR) for local progression and mortality, respectively. This study demonstrated that PT provided durable LC (3-year LC rate: 72.8-83.2%) with acceptable OS (3-year OS rate: 38.5-68.1%) and risk of severe toxicity incidence of 0.8-3.5% in radical metastasis-directed therapy for P-OM, L-OM and LN-OM. Compared to LC with X-SBRT or X-IMRT, LC with PT was potentially superior for P-OM; superior for L-OM; and equivalent for LN-OM. In particular, this study demonstrated that PT may be a new treatment option for L-OM tumors measuring > 5 cm.

Clinical outcomes and lung toxicities after lung SABR using dynamic conformal arc therapy: a single-institution cohort study

BACKGROUND

Stereotactic ablative radiotherapy (SABR) is a validated treatment for early stage lung cancer and pulmonary metastases. It provides a high local control rate with low symptomatic toxicities. Recently, Dynamic Conformal Arc Therapy (DCAT), a delivery option that differs from conventional DCA, has been implemented in the Monaco Treatment Planning System for SABR. The aim of the study was to report clinical outcomes and toxicities for patients treated for lung SABR with this new technique.

METHODS

We retrospectively identified adult patients treated for primary or secondary lung tumors with DCAT-SABR and reported their clinical, radiological, histological characteristics and dosimetric parameters. Total dose was delivered in 3 or 5 fractions for 95% of patients and prescribed on the 80% isodose line to the PTV periphery.

RESULTS

145 patients met inclusion criteria for a total of 152 lesions with a median follow up of 12 months. Local control for the irradiated site was 96.7% at 1 year. Overall survival was 93.1% at 1 year. Mean prescription dose in BED₁₀ was 110 Gy. 92% of patients had a prescribed dose superior to 100 Gy BED₁₀. Mean PTV coverage was 95.1%. There were 66 cases of grade 1 radiation pneumonitis (RP) (43%) and only 7 cases of symptomatic grade 2 RP (4.6%).

CONCLUSION

Lung SABR for primary or metastatic lung tumors using dynamic conformal arc therapy provides efficient results of local control and low lung toxicities, similar to other SABR techniques.

ADVANCES IN KNOWLEDGE

SABR using DCAT is a safe technique to treat lung lesions, allowing intra-fraction motion limitation, potentially higher OARs protection and a shortened beam delivery.

Role of surgical resection and its alternative local therapy for pulmonary metastasis of colorectal cancer

We reviewed surgical and alternative treatments for pulmonary metastasis of colorectal cancer, focusing on recent reports. The standard treatment for pulmonary metastasis of colorectal cancer is pulmonary resection, if resectable, despite the fact that the metastasis is hematogenous to distant organs. Guidelines in several countries, including Japan, have described pulmonary resection as a useful option because of the favorable long-term prognosis reported in various studies pertaining to pulmonary resection. The indications for pulmonary resection have been reviewed in several studies; additionally, the number of metastases, pretreatment carcinoembryonic antigen value, and disease-free interval from the primary resection to pulmonary recurrence have been proposed. However, no consensus has been reached to date. Contrastingly, recent advances in chemotherapy have remarkably improved the outcome of distant metastases, indicating that it is time to reconsider the significance of local treatment, including pulmonary resection. In addition to surgical resection, minimally invasive therapies, such as stereotactic body radiation therapy and radiofrequency ablation have been developed as local treatments for pulmonary metastases, and their long-term results have been reported. Prospective controlled trials and large-scale data analyses are needed to determine the best local treatment for pulmonary metastases and to find the appropriate indication for each treatment.

Knowing When to Use Stereotactic Ablative Radiation Therapy in Oligometastatic Cancer

Oligometastatic patients are a heterogeneous and yet not well-defined population. The actual definition identifies as oligometastatic, patients with 1-5 metastases in 1-3 different organs. However, only a proportion of these patients are "true" oligometastatic and therefore derive some kinds of benefit from local ablative approaches like stereotactic ablative radiation therapy (SABR). Since SABR is an easily accessible, effective and well-tolerated treatment, it is widely employed in the oligometastatic scenarios, without a particular focus on selection criteria. However, it should be crucial to identify predictive and prognostic features that could be clinically implemented. Therefore, we conducted this narrative review of the available literature to summarize all clinical, radiomic, genetic and epigenetic features found to be predictive of overall survival, progression-free survival or local control of oligometastatic patients treated with SABR.