Surgery versus stereotactic radiotherapy for treatment of pulmonary metastases. A systematic review of literature

Impact on survival without chemotherapy of local treatments of lung metastasis of colorectal cancers: Analysis on REPULCO cohort

BACKGROUND

The impact of local management of pulmonary metastases on the disease course of patients with metastatic colorectal cancer is poorly assessed.

METHODS

REPULCO database was a retrospective cohort on 18 years that included all patients treated for lung metastases from colorectal cancer who received local and/or systemic treatments.

AIMS

Primary objective was overall survival, secondary were progression-free survival and survival without chemotherapy.

RESULTS

Three hundred and fifteen patients were analyzed, 157 with only systemic treatments, 78 with only local treatments, and 80 with local and systemic treatments. Overall survival at 5 years was 26.9% (IC95%: [17.7-36.9]) for systemic treatments only, 61.0% (IC95%: [40.8-76.1]) for local treatments only, and 77.8% (IC95%: [60.1-88.3]) for local and systemic treatments. Progression-free survival at 2 years was 4.8% (IC95%: [2.1-9.2]) for systemic treatment only, 28.3% (IC95%: [17.7-39.9]) for local treatments only, and 21.8% (IC95%: [13.1-31.9]) for local and systemic treatments. Median survival without chemotherapy was 2.99 months (IC95%: [2.33-3.68]) for systemic treatments, 33.97 months (IC95%: [19.06-NA]) for local treatments, and 12.85 months (IC95%: [8.18-21.06]) for local and systemic treatments.

CONCLUSION

Local treatments of lung metastasis led to prolonged survival and allowed long periods of time without chemotherapy in this cohort.

Comparison of Metastasectomy and Stereotactic Body Radiation Therapy for Pulmonary Oligometastasis From Hepatocellular Carcinoma: A Propensity Score-Weighted Analysis

PURPOSE

Although there is a growing role for local therapy in patients with hepatocellular carcinoma (HCC) and pulmonary oligometastasis, it remains unclear whether metastatectomy or stereotactic body radiation therapy (SBRT) is the more effective treatment for these patients. We aimed to compare the oncologic outcomes of metastasectomy and SBRT for HCC with pulmonary oligometastasis.

METHODS AND MATERIALS

We retrospectively analyzed 209 patients with HCC with 322 metastatic lung lesions who underwent either metastasectomy (150 patients with 241 lesions) or SBRT (59 patients with 81 lesions) between January 2008 and December 2018. Propensity score-based inverse probability of treatment weighting was used to minimize potential bias between the 2 groups.

RESULTS

The median follow-up duration was 39.8 months (range, 2.3-166.9 months). The 2-year rate of freedom from local progression was 98.2% in the metastasectomy group and 97.0% in the SBRT group (P = .197). The 2-year rates of overt systemic progression-free survival (PFS) (51.0% vs 46.1%; P = .274), PFS (26.3% vs 9.1%; P = .074), and overall survival (OS, 74.0% vs 57.6%; P = .006) were higher in the metastasectomy group. After the probability of treatment weighting adjustment, the 2-year rates of overt systemic PFS (50.8% vs 52.7%; P = .396), PFS (23.0% vs 24.7%; P = .478), and OS (72.6% vs 83.0%, P = .428) were not significantly different between the 2 groups. In multivariate analysis, viable intrahepatic lesions and the number of prior liver-directed therapies were found to be significant prognostic factors for OS and PFS. The time interval between HCC diagnosis and the development of pulmonary metastases was also significantly associated with OS.

CONCLUSIONS

Both metastasectomy and SBRT demonstrated excellent local control and comparable oncologic outcomes in patients with pulmonary oligometastasis from HCC. The treatment modality for these patients could be determined based on the individual patient's condition and intrahepatic disease status.

Comparison of the Long-term Survival Outcome of Surgery versus Stereotactic Body Radiation Therapy as Initial Local Treatment for Pulmonary Oligometastases from Colorectal Cancer: A Propensity Score Analysis

PURPOSE

Optimal local treatment for pulmonary oligometastases from colorectal cancer (CRC) remains unclear. We aimed to compare the long-term survival outcomes between surgery and stereotactic body radiation therapy (SBRT) as the initial local treatment for CRC pulmonary oligometastases.

MATERIALS AND METHODS

We retrospectively reviewed 335 consecutive patients who initially underwent surgery or SBRT for CRC pulmonary metastases from 2011 to 2022, and 251 patients (173 surgery and 78 SBRT) were ultimately included. Freedom from intrathoracic progression (FFIP), progression-free survival (PFS), and overall survival (OS) were compared using stabilized inverse probability of treatment weighting (sIPTW) analysis. In addition, patterns of intrathoracic progression and subsequent treatment were analyzed.

RESULTS

Median follow-up was 61.6 months for surgery and 54.4 months for SBRT. After sIPTW adjustment, significant differences emerged in both FFIP and PFS between surgery and SBRT (FFIP: hazard ratio [HR] = 0.50, 95% confidence interval [CI], 0.31-0.79; PFS: HR = 0.56, 95% CI, 0.36-0.87). The 3- and 5-year FFIP rates were 58.6% and 54.8%, respectively, after surgery, and 34.6% and 31.3%, respectively, after SBRT (P = .006). The 3- and 5-year PFS rates were 49.4% and 45.2%, respectively, after surgery, and 28.8% and 26.1%, respectively, after SBRT (P = .010). However, OS was not significantly affected by treatment approach (HR = 0.93, 95% CI, 0.49-1.76). The 3- and 5-year OS rates were 85.9% and 73.1%, respectively, after surgery, and 78.9% and 68.7%, respectively, after SBRT (P = .849). Recurrence at the treated site was more prevalent after SBRT than after surgery (33.3% vs 16.9%), whereas new intrathoracic tumors occurred more frequently after surgery than after SBRT (71.8% vs 43.1%). Both groups chose radiation therapy as the primary local salvage treatment.

CONCLUSIONS

Notwithstanding the significant differences in FFIP and PFS between surgery and SBRT, the long-term survival of patients with CRC pulmonary oligometastases did not depend on the initial choice of the local treatment approach.

[Local Therapy in Stage IV Lung Cancer with Oligopersistent or Oligoprogessive Disease]

Oligopersistent and oligoprogressive disease are defined as distinct situations of metastastatic lung cancer. Oligopersistence describes a situation in which a limited number of metastases remain following effective systemic therapy. Oligoprogression represents a largely controlled tumour disease with a few metastases showing significant progression. In the oligopersistence, treatment aims to establish complete tumour control with subsequent improvement of the prognosis by means of additional local ablative treatment of all remaining lesions. In the oligoprogressive situation, local ablative treatment aims to reestablish complete tumour control while continuing systemic therapy. The concepts are based on ideas that were introduced in oncology more than 30 years ago by Hellman and Weichselbaum by using the term oligometastases. Multimodal therapy concepts have gained importance in the situation of oligopersistence and oligoprogression, particularly due to molecular targeted therapies for oncogene-driven lung cancer and chemo-immunotherapy regimes with high response rates and long response duration. The available evidence will be presented and explained by case studies.

Integrating cine EPID, dynamic delivery, and the off-axis Winston-Lutz test to enhance quality control in multiple brain metastasis stereotactic radiotherapy

PURPOSE

Stereotactic radiotherapy (SRT) has transformed cancer treatment, especially for brain metastases. Ensuring accurate SRT delivery is crucial, with the Winston-Lutz test being an important quality control tool. Off-axis Winston-Lutz (OAWL) tests are designed for accuracy assessment, but most are limited to fixed angles and hampered by local-field shifts caused by suboptimal Multi-Leaf Collimator (MLC) positioning. This study introduces a new OAWL approach for quality control in multi-brain-metastasis SRT. Utilizing cine Electronic Portal Imaging Device (EPID) images, it can be used with dynamic conformal arc (DCA) therapy. However, dynamic OAWL (DOAWL) is prone to more local-field shifts due to dynamic MLC movements. A two-step DOAWL is proposed: step 1 calculates local-field shifts using dynamic MLC movements in the beam-eye view data from the Treatment Planning System (TPS), while step 2 processes cine EPID images with an OAWL algorithm to isolate true deviations.

METHODS

Validation involved an anthropomorphic head phantom with metallic ball-bearings, Varian TrueBeam STx accelerator delivering six coplanar/non-coplanar DCA beams, cine EPID, and ImageJ's OAWL analysis algorithm.

RESULTS

Inherent local-field shifts ranged from 0.11 to 0.49 mm; corrected mean/max EPID-measured displacement was 0.34/1.03 mm. Few points exceeded 0.75/1.0-mm thresholds.

CONCLUSIONS

This two-step DOAWL test merges cine-EPID acquisitions, DCA, OAWL, and advanced analysis and offers effective quality control for multi-brain-metastasis SRT. Its routine implementation may also improve physicist knowledge of the treatment precision of their machines.

Proton Beam Therapy for Lung Oligometastatic Recurrence in Patients With Esophageal Cancer

Local treatment of oligometastatic esophagogastric cancer has been reported to improve overall survival (OS) compared to systemic therapy alone. This study evaluated the feasibility and safety of proton beam therapy (PBT) for the treatment of lung oligometastatic recurrence in esophageal cancer patients. This single-center historical cohort study enrolled 11 patients who underwent PBT for lung oligometastasis from esophageal cancer between 2010 and 2019. The selection criteria were that the primary esophageal cancer was controlled and no more than three lung metastases without outside lung tumors were present. OS, progression-free survival (PFS), and local control (LC) rates and adverse events (AEs) were assessed. Factors that may be related to OS were also investigated. The median follow-up period was 27.8 months (8.8-141.3 months). The one-, two-, and three-year OS rates were 81.8%, 72.7%, and 51.9%, respectively (median OS time: 43.7 months); PFS rates were 45.5%, 27.3%, and 27.3%, respectively (median PFS time: 8.8 months); and LC rates were 92.3%, 72.7%, and 72.7%, respectively. The eighth edition of tumor-node-metastasis (TNM) classification for esophageal cancer was the only significant OS-related factor (p = 0.0309). No grade ≥ 3 AEs were observed. Based on the low incidence of AEs and acceptable LC rate, PBT is a feasible option for the treatment of lung oligometastasis in esophageal cancer patients.

Stereotactic Body Radiotherapy for Management of Pulmonary Oligometastases in Stage IV Colorectal Cancer: A Perspective

In pulmonary oligometastases from colorectal cancer (POM-CRC), metastasectomy is the primarily recommended treatment. Stereotactic body radiotherapy (SBRT) has been suggested as a viable alternative therapy. SBRT efficacy for POM-CRC is poorly delineated compared to selected non-CRC primaries. This perspective article aims to critically summarize the existing evidence regarding efficacy of SBRT in terms of overall survival (OS) and local control (LC), and factors modulating this, in the treatment of POM-CRC. Overall, reasonable LC and OS rates were observed. The wide range of expansions in planning target volume margins introduced variation in pretreatment protocols. Dose-fractionation schedules varied according to patient and tumor characteristics, though leverage of BED10 in select studies enabled standardization. An association between SBRT dose and improved OS and LC was observed across multiple studies. Prognostic factors that were associated with improved LC included: fewer oligometastases, absence of extra-pulmonary metastases, primary tumor histology, and smaller gross tumor volume. Differences in SBRT modality and techniques over time further confounded results. Many studies included patients receiving additional systemic therapies; preprotocol and adjuvant chemotherapies were identified as prognostic factors for LC. SBRT compared with metastasectomy showed no differences in short-term OS and LC outcomes. In conclusion, SBRT is an efficacious treatment for POM-CRC, in terms of OS and LC. Heterogeneity in study design, particularly pertaining to dose protocols, patient selection, and additional therapies should be controlled for future randomized studies to further validate SBRT efficacy.

Pulmonary metastasectomy is associated with survival after lung-only recurrence in pancreatic cancer

BACKGROUND

After surgical resection of pancreatic ductal adenocarcinoma, 14% of patients have lung-only recurrence. We hypothesize that in patients with isolated lung metastases from pancreatic ductal adenocarcinoma, pulmonary metastasectomy offers a survival benefit with minimal additional morbidity after resection.

METHODS

This was a single-institution, retrospective study of patients who underwent definitive resection of pancreatic ductal adenocarcinoma and later developed isolated lung metastases between 2009 and 2021. Patients were included if they carried a diagnosis of pancreatic ductal adenocarcinoma, underwent pancreatic resection with curative intent, and subsequently developed lung metastases. Patients were excluded if they developed multiple sites of recurrence.

RESULTS

We identified 39 patients with pancreatic ductal adenocarcinoma and isolated lung metastases, 14 of whom underwent pulmonary metastasectomy. During the study period, 31 (79%) patients died. Across all patients, there was an overall survival of 45.9 months, a disease-free interval of 22.8 months, and survival after recurrence of 22.5 months. Survival after recurrence was significantly longer in patients who underwent pulmonary metastasectomy than those who did not (30.8 months vs 18.6 months, P < .01). There was no difference in overall survival between groups. However, patients who underwent pulmonary metastasectomy were significantly more likely to be alive 3 years after their diagnosis (100.0% vs 64%, P = .02) and 2 years after recurrence (79% vs 32%, P < .01) than those in who did not undergo pulmonary metastasectomy. No mortalities occurred related to pulmonary metastasectomy, and procedure-related morbidity was 7%.

CONCLUSION

Patients who underwent pulmonary metastasectomy for isolated pulmonary pancreatic ductal adenocarcinoma metastases had significantly longer survival after recurrence and clinically meaningful survival benefit with minimal additional morbidity after pulmonary resection.

Stereotactic Body Radiotherapy versus Surgery for Lung Metastases from Colorectal Cancer: Single-Institution Results

BACKGROUND

Surgery and stereotactic body radiotherapy (SBRT) are two of the options available as local treatments for pulmonary oligometastases from colorectal cancer (CRC). We hypothesized that SBRT would have, at least, a similar local control rate to surgery.

METHODS

We identified an initial cohort of 100 patients with CRC who received SBRT or surgery for lung metastases. This was then narrowed down to 75 patients: those who underwent surgery (n = 50) or SBRT (n = 25) as their first local thoracic treatment between 1 January 2004 and 29 December 2017. The Kaplan-Meier method was used to calculate lung-progression-free survival (L-PFS) and overall survival (OS).

RESULTS

The 1 and 2-year L-PFS was 85% and 70% in the surgical group and 87% and 71% in the SBRT group, respectively (p = 0.809). No significant differences were found between the two groups in terms of OS. The biologically effective dose (BED), age and initial CRC stage did not have a significant effect on local control or survival. No grade 3 or above acute- or late-toxicity events were reported.

CONCLUSIONS

These results add retrospective evidence that SBRT and surgery have similar results in terms of OS and local control in patients with lung oligometastases from CRC.

Implementation of advanced radiotherapy techniques: stereotactic body radiotherapy (SBRT) for oligometastatic patients with lung metastasis - a single institution experience

Background and aims

The treatment of oligometastatic disease has become common practice as advanced radiotherapy techniques became more available. Lung is one of the main metastatic sites for a majority of cancers and many of these patients present with a limited metastatic disease burden. For these patients, SBRT (Stereotactic Body Radiation Therapy) represents a non-invasive treatment alternative. In this report we present our experience with our first series of patients with limited metastatic disease treated with lung SBRT. The purpose of this paper is to provide a qualitative and quantitative assessment of the lung SBRT treatment process and algorithm leading up to treatment delivery in a community-based radiotherapy department.

Methods

We have retrospectively reviewed our first series of 41 patients with lung oligometastases from various malignancies, treated using SBRT between March 2019 and December 2020. Demographic, technical and outcome data were analyzed.

Results

A number of 45 lung metastases (in 41 patients) were treated with SBRT during the specified time period. The median age was 65.7 years old (range 33-83). 16 patients (39%) were treated for multiple lesions and the mean number of treated lesions was 1 (range1-3). Median dose prescribed was 50 Gy /5 fractions (median BED₁₀ =77 Gy). The median intra-fraction displacements were: Vertical (0.23cm), Longitudinal (-0.27 cm), Lateral (-0.1 cm), Pitch [0.22°], Roll [0.15°], Rotation [0.32°]. The median session time was 40 minutes. All patients completed the prescribed course of treatment.Preliminary clinical data were recorded. With a median follow-up of 9 months, local control was recorded in all but one patient. At the last known follow-up, local control was recorded for 39 (85%) out of 45 treated lesions.

Conclusion

For lung SBRT, the required corrections at the time of treatment delivery are small, as long as strict protocols are implemented. Preliminary data for lung metastasis in oligometastatic patients support SBRT as a viable method of achieving high rates of early local control. These results need to be further confirmed in a larger cohort of patients with longer follow-up.

A critical review on oligometastatic disease: a radiation oncologist's perspective

Since the first definition by Hellman and Weichselbaum in 1995, the concept of OligoMetastatic Disease (OMD) is a growing oncology field. It was hypothesized that OMD is a clinical temporal window between localized primary tumor and widespread metastases deserving of potentially curative treatment. In real-world clinical practice, OMD is a "spectrum of disease" that includes a highly heterogeneous population of patients with different prognosis. Metastasis directed therapy with local ablative treatment have proved to be a valid alternative to surgical approach. Stereotactic body radiation therapy demonstrated high local control rate and increased survival outcomes in this setting with a low rate of toxicity. However, there is a lack of consensus regarding many clinical, therapeutic, and prognostic aspects of this disease entity. In this review, we try to summarize the major critical features that could drive radiation oncologists toward a better selection of patients, treatments, and study endpoints. With the help of a set of practical questions, we aim to integrate the literature discussion.

Predicting the benefit of stereotactic body radiotherapy of colorectal cancer metastases

•

Predicting the benefit from Stereotactic body radiotherapy (SBRT) of colorectal cancer metastases.

•

CLInical Categorical Algorithm (CLICAL©) – a predictive algorithm applied to SBRT.

•

The benefit from SBRT varies among patients with metastatic colorectal cancer.

•

CLICAL© may be used as a screening tool for SBRT referrals.

Aim

Methods

Results

Conclusion

Outcomes of SBRT for lung oligo-recurrence of non-small cell lung cancer: a retrospective analysis

The benefit of local ablative therapy (LAT) for oligo-recurrence has been investigated and integrated into the treatment framework. In recent decades, stereotactic body radiation therapy (SBRT) has been increasingly used to eliminate metastasis owing to its high rate of local control and low toxicity. This study aimed to investigate the outcomes of SBRT for patients with lung oligo-recurrence of non-small cell lung cancer (NSCLC) from our therapeutic center. Patients with lung oligo-recurrence of NSCLC treated with SBRT between December 2011 and October 2018 at Cancer Hospital of the University of Chinese Academy of Sciences (Zhejiang Cancer Hospital) were reviewed. The characteristics, treatment-related outcomes, and toxicities of the patients were analyzed. Univariable and multivariable Cox regression were performed to identify the factors associated with survival. A total of 50 patients with lung oligo-recurrence of NSCLC were enrolled. The median follow-up period was 23.6 months. The 3-year local progression-free survival (LPFS), progression-free survival (PFS) and overall survival (OS) after SBRT were 80.2%, 21.9% and 45.3%, respectively. Patients in the subgroup with LAT to all residual diseases showed significantly improved OS and PFS. No treatment-related death occurred after SBRT. SBRT is a feasible option to treat patients with lung oligo-recurrence of NSCLC, with high rates of local control and low toxicity. LAT to all residual diseases was associated with better survival outcomes. Future prospective randomized clinical trials should evaluate SBRT strategies for such patients.

Single-fraction stereotactic ablative body radiation therapy for primary and metastasic lung tumor: A new paradigm?

Stereotactic ablative body radiotherapy (SABR) is an effective technique comparable to surgery in terms of local control and efficacy in early stages of non-small cell lung cancer (NSCLC) and pulmonary metastasis. Several fractionation schemes have proven to be safe and effective, including the single fraction (SF) scheme. SF is an option cost-effectiveness, more convenience and comfortable for the patient and flexible in terms of its management combined with systemic treatments. The outbreak of the severe acute respiratory syndrome coronavirus 2 pandemic has driven this not new but underutilized paradigm, recommending this option to minimize patients' visits to hospital. SF SABR already has a long experience, strong evidence and sufficient maturity to reliably evaluate outcomes in peripheral primary NSCLC and there are promising outcomes in pulmonary metastases, making it a valid treatment option; although its use in central locations, synchronous and recurrencies tumors requires more prospective safety and efficacy studies. The SABR radiobiology study, together with the combination with systemic therapies, (targeted therapies and immunotherapy) is a direction of research in both advanced disease and early stages whose future includes SF.

Managing patients with advanced soft tissue sarcoma: Evolving landscape from an Australian perspective

AIM

Despite lack of advances in the first-line systemic therapy, the overall survival (OS) has continued to improve in patients with advanced soft tissue sarcoma (STS) with the recent estimation of median OS at 20 months. Several systemic therapy options are available now for the second-line and beyond, with more treatment tailored to histology and molecular subtype. The aim of this retrospective study was to characterize current patterns of care in managing patients with advanced STS (aSTS) in Australia.

METHODS

Sarcoma databases from 7 Australian sarcoma services were accessed to identify patients diagnosed with locally advanced inoperable and/or metastatic STS between January 1, 2010 and December 31, 2015. Baseline clinicopathological factors and initial treatment patterns were descriptively analyzed. For the Victorian cohort where treatment of aSTS and follow-up details were available, further exploratory analysis was conducted to determine the impact of patient and tumor characteristics and the use of palliative-intent treatment OS.

RESULTS

Of 2261 cases of STS, 671 were deemed as aSTS. Two thirds were relapsed disease with a mean 1.9 years from initial diagnosis. Median age at diagnosis of aSTS was 59 years (18-95 years) and 56.3% was male. Histology classification revealed four main subtypes: undifferentiated pleomorphic sarcoma (UPS) (23.1%), leiomyosarcoma (18.2%), liposarcoma (12.8%), synovial sarcoma (8.2%), and other comprising 14 STS subtypes. For the Victorian cohort (N = 361), approximately 80% of patients accessed palliative-intent treatment of various modalities. Nearly 40% of patients underwent tumor-debulking surgery or metastasectomy, of which lung wedge resection was the most common (N = 83, 47.7%). A total of 438 palliative-intent radiotherapy treatments were delivered to 259 patients (71.7%), with the majority in the form of external beam radiotherapy. Palliative-intent systemic therapy was delivered to 51.5% of patients (N = 186), mostly (73%). Anthracycline-based therapy was the most commonly delivered therapy (N = 135, 72.6%). Approximately half of the patients in each line of therapy failed to proceed to the subsequent line of systemic therapy with 29.4% receiving three or more lines of therapy (N = 55). A total of 18.3% of patient (N = 34) participated in clinical trials or accessed off-label drugs. The median OS for the Victoria cohort was 15.4 months (95% confidence interval: 12.1, 18.2). The UPS histology subtype was associated with poorer OS, whereas receiving any modality of palliative-intent treatment conferred survival benefit.

CONCLUSION

In Australia, aSTS is managed with diverse treatment approaches comprising various therapy modalities. Further work is planned in describing healthcare resource utilization and estimating costs by this patient cohort.

Assessment and Prognostic Value of Immediate Changes in Post-Ablation Intratumor Density Heterogeneity of Pulmonary Tumors via Radiomics-Based Computed Tomography Features

Objectives

To retrospectively observe the instantaneous changes in intratumor density heterogeneity after microwave ablation (MWA) of lung tumors and to determine their prognostic value in predicting treatment response and local tumor progression (LTP).

Methods

Pre- and post-MWA computed tomography (CT) images of 50 patients (37-males; 13-females; mean-age 65.9 ± 9.7y, 39 primary and 11 metastasis) were analyzed to evaluate changes in intratumor density. Global, regional, and local scale radiomics features were extracted to assess intratumor density heterogeneity. In four to six weeks, chest enhanced CT was used as the baseline evaluation of treatment response. The correlations between the parametric variation immediately after ablation and the visual score of ablation response (Rvisu) were analyzed by nonparametric Spearman correlation analysis. The 1-year LTP discrimination power was assessed using the area under the receiver operating characteristic (ROC) curves. A Cox proportional hazards regression model was used to identify the independent prognostic features.

Results

Although no significant volume changes were observed after ablation, the radiomics parameters changed in different directions and degrees. The mean intensity value from baseline CT image was 30.3 ± 23.2, and the post-MWA CT image was -60.9 ± 89.8. The ratio of values change was then calculated by a unified formulation. The largest increase (522.3%) was observed for cluster prominence, while the mean CT value showed the largest decline (321.4%). The pulmonary tumors had a mean diameter of 3.4 ± 0.8 cm. Complete ablation was documented in 36 patients. Significant correlations were observed between Rvisu and quantitative features. The highest correlations were observed for changes in local features after MWA, with r ranging from 0.594 to 0.782. LTP developed in 22 patients. The Cox regression model revealed Δcontrast% and response score as independent predictors (Δcontrast%: odds ratio [OR]=5.61, p=0.001; Rvisu: OR=1.73, p=0019). ROC curve analysis showed that Δcontrast% was a better predictor of 1-year LTP. with higher sensitivity (83.5% vs. 71.2%) and specificity (87.1% vs. 76.8%) than those for Rvisu.

Conclusions

The changes in intratumor density heterogeneity after MWA could be characterized by analysis of radiomics features. Real-time density changes could predict treatment response and LTP in patients with pulmonary tumors earlier, especially for tumors with larger diameters.

Radiotherapy for oligometastatic non-small cell lung cancer: a narrative review

Preclinical and early clinical evidence suggest that radical radiotherapy of oligometastatic disease in non-small cell lung cancer (NSCLC) patients can impact outcomes with relatively limited toxicity. Whilst data from phase 2 randomized trials suggesting an improved overall survival (OS) with this treatment is promising, it has also illustrated the heterogeneity in this patient population and treatment. Oligometastatic disease in itself comprises a broad spectrum of patients, in terms of tumor load and location, stage of the disease and treatment history. This real-life variety in patient characteristics is often reflected in studies to a certain extent, hinting to the fact that all might benefit from radical radiotherapy to limited metastatic disease, yet leaving the question unanswered as to whom the ideal candidate is. Furthermore, differences between and within studies with regards to treatment modality, timing, radiation technique, and radiation dose are substantial. Also, preclinical and early clinical trials suggest that radiotherapy can work synergistically with checkpoint inhibitors by acting as an in situ cancer vaccine, therefore the combination of these two treatments in oligometastatic patients might entail the largest benefit. Ongoing randomized controlled phase 3 trials and prospective registry trials will further elucidate the true extent of benefit of this local treatment strategy and aid in identifying the ideal patient population and therapy. The current narrative review summarizes the clinical evidence on radiotherapy for oligometastatic NSCLC and highlights the remaining unknowns.

Current Evidence for Stereotactic Body Radiotherapy in Lung Metastases

Lung metastases are the second most common malignant neoplasms of the lung. It is estimated that 20–54% of cancer patients have lung metastases at some point during their disease course, and at least 50% of cancer-related deaths occur at this stage. Lung metastases are widely accepted to be oligometastatic when five lesions or less occur separately in up to three organs. Stereotactic body radiation therapy (SBRT) is a noninvasive, safe, and effective treatment for metastatic lung disease in carefully selected patients. There is no current consensus on the ideal dose and fractionation for SBRT in lung metastases, and it is the subject of study in ongoing clinical trials, which examines different locations in the lung (central and peripheral). This review discusses current indications, fractionations, challenges, and technical requirements for lung SBRT.

12 × 6 Gy stereotactic radiotherapy for lung tumors. Is there a difference in response between lung metastases and primary bronchial carcinoma?

PURPOSE

The aim of this study was to evaluate the safety and long-term tumor control after stereotactic radiotherapy (SRT) with 12 × 6 Gy of patients with primary bronchial carcinoma (BC) or with pulmonary metastases (MET) of various solid tumors. Local progression-free survival (LPFS), progression-free survival (PFS), overall survival (OS), and prognostic factors were compared.

METHODS

Between May 2012 and January 2020, 168 patients with 206 pulmonary lesions (170 MET and 36 primary BC) were treated with 12 × 6 Gy (BED₁₀ 116 Gy). The irradiated pulmonary MET were from the following cancers: 47 (27.6%) head and neck, 37 (21.8%) rectum or colon, 30 (17.6%) bronchial, 13 (7.6%) malignant melanoma, 9 (5.3%) esophageal, 9 (5.3%) sarcoma, and 25 (14.8%) other.

RESULTS

The median follow-up was 16.26 months (range: 0.46-89.34) for BC and 19.18 months (0.89-91.11) for MET. Survival rates at 3 years were: OS 43% for BC and 35% for MET; LPFS BC 96% and MET 85%; PFS BC 35% and MET 29%. The most frequently observed grade 3 adverse events (AEs) were pneumonitis (5.9% BC, 4.8% MET), pulmonary fibrosis (2.9% BC, 4% MET), and pulmonary embolism (2.9% BC, 0.8% MET). The favorable prognostic effects on overall survival of patients with MET were female gender (log-rank: p < 0.001), no systemic progression (log-rank; p = 0.048, multivariate COX regression p = 0.039), and malignant melanoma histology (log-rank; p = 0.015, multivariate COX regression p = 0.020). For patients with BC, it was tumor location within the lower lobe (vs. upper lobe, log-rank p = 0.027). LPFS of patients with metastatic disease was beneficially influenced by female gender (log-rank: p = 0.049).

CONCLUSION

The treatment concept of 12 × 6 Gy is associated with 96% local progression-free survival for BC and 85% for pulmonary metastases after 3 years. There was no difference in response after SRT of primary lung carcinoma or pulmonary metastases.

Multi-Institutional Retrospective Analysis of the Outcomes of Proton Beam Therapy for Patients With 1 to 3 Pulmonary Oligometastases From Various Primary Cancers

Purpose

Our purpose was to evaluate the efficacy of proton beam therapy (PBT) in patients with 1 to 3 pulmonary oligometastases from various primary cancers in Japan.

Methods and Materials

This multi-institutional retrospective survey included 118 patients with 141 metastatic lung tumors from miscellaneous primary cancers, across 6 Japanese institutions, and involved the analyses of local progression-free rate (LPF), distant progression-free rate, progression-free survival rate, cause-specific survival rate, and overall survival rate (OS). Treatment-induced adverse effects of grade ≥2 were evaluated according to the Common Terminology Criteria for Adverse Events (version 4.0). Cox proportional hazards regression models were used in univariable analysis and multivariable analysis (MVA) for the identification of the prognostic factors of LPF and OS.

Results

The median follow-up duration from the time of PBT was 25.5 months. The major primary disease sites included colorectal cancer (42.4%), lung cancer (11.9%), head and neck cancer (8.5%), and kidney cancer (8.5%). For years 1, 2, and 3, LPFs were 92.2%, 86.3%, and 78.4%; distant progression-free rates were 59.1%, 44.1%, and 34.0%; progression-free survival rates were 49.6%, 31.7%, and 24.2%; cause-specific survival rates were 83.4%, 72.5%, and 64.8%; and OS rates were 79.0%, 67.8%, and 59.6%, respectively. Eight patients developed acute adverse effects (grade ≥2). Ten patients developed radiation pneumonitis (grade 2) as a late adverse effect. None of the patients developed severe late toxicity (grade ≥3). Colorectal cancer as the primary disease was the only prognostic factor associated with LPF that remained independently significant in the MVAs performed using 3 sets of parameters (hazard ratio [HR], 3.31-4.76 in 3 MVA sets). In the MVA, the significant prognostic factors for OS were performance status (HR, 2.78; 95% confidence interval, 1.01-7.67) and total tumor volume (HR, 1.01; 95% confidence interval, 1.00-1.02).

Conclusions

PBT provides promising outcomes for pulmonary oligometastasis with acceptable toxicities.

Interstitial single fraction brachytherapy for malignant pulmonary tumours

PURPOSE

Interstitial brachytherapy for pulmonary tumours is an alternative to stereotactic radiotherapy, allowing high conformity despite it being an invasive technique. The aim of the study was the analysis of dose distribution, toxicity and tumour response rates.

METHODS

In the years 2014-2019, 27 patients with pulmonary tumours received 36 interstitial brachytherapies with Ir-192: 11 patients with non-small cell lung cancer, 16 patients with pulmonary metastases of other entities.

RESULTS

Patients were treated with a median (interquartile range) prescription dose of 20 (20-26) Gy in a single fraction. Mean lung dose to the ipsilateral lung was 2.8 (1.6-4.7) Gy. Maximum doses to the heart, oesophagus, thoracic wall and spinal cord were 2.4 (1.8-4.6) Gy, 2.0 (1.2-6.2) Gy, 12.6 (8.0-18.2) Gy and 1.5 (0.6-3.9) Gy. Median survival after treatment was 15 months, with a 1- and 2‑year local control of 84% and 60%. Median overall survival after initial cancer diagnosis was 94 months; 2 years following brachytherapy, 75% of patients with colorectal cancer vs. 37% with other histologies were alive; p = 0.14. In 69% (n = 25), brachytherapy could be performed without acute complications. A self-limiting bleeding occurred in 8% (n = 3), fever in 3% (n = 1), pneumothorax in 17% (n = 6), and pulmonary failure in 3% (n = 1). Patients with > 20 Gy in 95% of planning target volume had higher pneumothorax rates needing intervention (31% vs. 5%, p = 0.04).

CONCLUSIONS

Interstitial brachytherapy for pulmonary tumours is a highly conformal therapy with minimal doses to the organs at risk. For the majority of patients, treatment can be performed without relevant complications in a single fraction with a satisfactory local control.

How to handle oligometastatic disease in nonsmall cell lung cancer

Patients with nonsmall cell lung cancer and limited metastatic disease have been defined as oligometastatic if local ablative therapy of all lesions is amenable. Evidence from different clinical retrospective series suggests that this subgroup harbours better prognosis than other stage IV patients. However, most reports have included patients with inconsistent numbers of metastases in different locations treated by a variety of invasive and noninvasive therapies. As long as further results from randomised clinical trials are awaited, treatment decision follows an interdisciplinary debate in each individual case. Surgery and radiotherapy should capture a dominant role in the treatment course offering the option of a curative-intended local therapy in combination with a systemic therapy based on an interdisciplinary decision. This review summarises the current treatment standard in oligometastatic lung cancer with focus on an ablative therapy for both lung primary and distant metastases in prognostically favourable locations.