Pleural Dissemination Research Articles

Protocol summary of a randomized phase III study: comparing systemic therapy with and without debulking surgery (primary tumour resection) for clinical stage IVA (cT1-2bN0-1M1a) non-small cell lung cancer with radiologically undetermined pleural dissemination JCOG2103 (DEBULK-LUNG).

In patients with non-small cell lung cancer (NSCLC) who present with radiologically undetermined malignant pleural dissemination or incidental surgical diagnosis of the same, surgery is generally not the preferred option; systemic therapy is favoured. However, there is no consensus on incorporating primary site resection into the treatment plan. Retrospective analyses hint at potential benefits of combining systemic therapy with primary site resection, but prospective studies have yet to confirm these findings. Consequently, we have planned a multicentre, open-label, randomized controlled phase III trial to assess the efficacy of adding primary site resection to standard systemic therapy for stage IVA (cT1-2bN0-1M1a) NSCLC patients with radiologically undetermined pleural dissemination. The primary endpoint is overall survival. We aim to enroll 170 patients from 71 institutions over 5 years. This trial is registered at the Japan Registry of Clinical Trials (jRCT) under study number jRCTs031220666.

EP.06G.18 Lung Cancer with Pleural Dissemination is Potentially a Non-Shedding Tumor

EP.06G.18 Lung Cancer with Pleural Dissemination is Potentially a Non-Shedding Tumor

No survival benefit of primary tumor resection for non-small cell lung cancer patients with unexpectedly detected pleural disseminated nodules in the era of targeted therapy.

Non-small cell lung cancer (NSCLC) patients with pleural dissemination are generally contraindicated for surgery. This study aimed to investigate the survival benefits of primary tumor resection for NSCLC patients with unexpectedly detected pleural disseminated nodules during thoracotomy in the era of targeted therapy. Of the 4984 patients with NSCLC who underwent surgery without induction therapy between 2000 and 2021, we retrospectively evaluated 90 (1.8%) patients with unexpectedly detected pleural disseminated nodule. Survival analyses were performed with Kaplan-Meier methods and Cox proportional hazards regression. Among the evaluated patients, 58 were male, the median age was 67, and 77 (86%) were diagnosed with adenocarcinoma. Exploratory thoracotomy was performed in 21 (23%), and primary tumor resection was performed in 69 (77%) patients, including pneumonectomy in four, lobectomy in 39, and sublobar resection in 26. Epidermal growth factor receptor gene mutation and anaplastic lymphoma kinase rearrangement were detected in 33 (37%) and 4 (4%) cases, respectively. Among them, 31 patients received targeted therapy. The overall survival (OS) was not significantly different between patients with primary tumor resection and exploratory thoracotomy (5-year OS rate: 30.2% vs. 27.8%, p = 0.81). Multivariable analysis revealed that sex (p = 0.02) and targeted therapy (p < 0.01) were independent prognostic factors for OS. Survival outcomes in patients who received targeted therapy were significantly better regardless of primary tumor resection. Primary tumor resection might not affect the survival in NSCLC patients with unexpectedly detected pleural disseminated nodules in the era of targeted therapy.

Efficacy and survival of nivolumab treatment for recurrent/unresectable esophageal squamous-cell carcinoma: real-world clinical data from a large multi-institutional cohort

BackgroundReal-world clinical outcomes of and prognostic factors for nivolumab treatment for esophageal squamous-cell carcinoma (ESCC) remain unclear. This study aimed to evaluate real-world outcomes of nivolumab monotherapy in association with relevant clinical parameters in recurrent/unresectable advanced ESCC patients.MethodsThis population-based multicenter cohort study included a total of 282 patients from 15 institutions with recurrent/unresectable advanced ESCC who received nivolumab as a second-line or later therapy between 2014 and 2022. Data, including the best overall response, progression-free survival (PFS), and overall survival (OS), were retrospectively collected from these patients.ResultsObjective response and disease control rates were 17.0% and 47.9%, respectively. The clinical response to nivolumab treatment significantly correlated with development of overall immune-related adverse events (P < .0001), including rash (P < .0001), hypothyroidism (P = .03), and interstitial pneumonia (P = .004). Organ-specific best response rates were 20.6% in lymph nodes, 17.4% in lungs, 15.4% in pleural dissemination, and 13.6% in primary lesions. In terms of patient survival, the median OS and PFS was 10.9 and 2.4 months, respectively. Univariate analysis of OS revealed that performance status (PS; P < .0001), number of metastatic organs (P = .019), C-reactive protein-to-albumin ratio (CAR; P < .0001), neutrophil–lymphocyte ratio (P = .001), and PMI (P = .024) were significant. Multivariate analysis further identified CAR [hazard ratio (HR) = 1.61, 95% confidence interval (CI) 1.15–2.25, P = .0053)] in addition to PS (HR = 1.65, 95% CI 1.23–2.22, P = .0008) as independent prognostic parameters.ConclusionsCAR and PS before nivolumab treatment are useful in predicting long-term survival in recurrent/unresectable advanced ESCC patients with second-line or later nivolumab treatment.Trial RegistrationUMIN000040462

Pain response in single-fraction 8-Gy radiotherapy for painful non-bone-metastasis tumors: a single-center retrospective study.

The effectiveness of single-fraction 8-Gy radiotherapy for painful bone metastases has been verified in numerous randomized controlled trials. However, few reports have described the effectiveness of single-fraction 8-Gy radiotherapy in painful tumors other than bone metastases. We conducted a retrospective analysis to evaluate the pain response to single-fraction 8-Gy radiotherapy in painful non-bone-metastasis tumors. We included patients who had received single-fraction 8-Gy radiotherapy for such tumors between January 2017 and December 2022, excluding those with brain metastases, hematological tumors and those who received re-irradiation. Pain response assessment was based on the best responses documented in the medical records and conducted by two radiation oncologists. A total of 36 eligible patients were included in this study. The irradiation sites included primary lesions in eight patients, lymph node metastases in eight, muscle metastases in seven, pleural dissemination in four, skin/subcutaneous metastases in four and other sites in five. Pain response was assessed in 24 patients after radiotherapy. Pain response rate was 88% in evaluable patients; 21 of the 24 patients experienced response. The median assessment date for pain response was 37days (range: 8-156days) after radiotherapy. Re-irradiation was performed in four patients (11%). Single-fraction 8-Gy radiotherapy seemed to be a promising treatment option for painful non-bone-metastasis tumors and warrants further investigation.

Prediction of Pleural Lavage Cytology According to Thin-Section Computed Tomography in Non–Small-Cell Lung Cancer

BackgroundAlthough the positive rate of preresection pleural lavage cytology (PLC) is low, it is an important indicator of poor prognosis for non–small-cell lung cancer patients with frequent pleural dissemination (PD) recurrence. Thin-section computed tomography (TSCT) can reveal relationships between a primary tumor and the pleura at 1 to 2 mm intervals, and this is associated with visceral pleural invasion (VPI). However, its association with PLC remains unclear. Therefore, we aimed to improve PLC efficiency and predict PD recurrence by understanding the relationship between PLC and preoperative TSCT findings. Patients and MethodsBetween January 2014 and December 2018, we reviewed 978 patients with non–small-cell lung cancer who underwent PLC tests during complete resection surgery. Preoperative TSCT findings were evaluated, and factors with the highest specificity (proportion of patients with radiologically to pathologically diagnosed positive PLC) were investigated. We also evaluated their relationships with VPI and PD recurrence. ResultsPLC positive was identified in 55 (5.6%) of the 978 patients. The two TSCT findings predicting PLC results, “the absence of pleural findings,” ie, tumor not attached to pleura or without pleural tag, and “consolidation-to-tumor ratio ≤0.5”, had a specificity of 100% (95% confidence interval: 90.4%-100%); additionally, all cases with these findings were VPI negative and had no PD recurrence. And 24% of the cohort had either of these findings. ConclusionThe absence of pleural findings and/or consolidation-to-tumor ratio ≤0.5 of primary tumor on preoperative TSCT can predict PLC negativity with very high probability; therefore, PLC can be omitted for such patients.

Ovarian Cancer with TTF-1-positive Giant Pleural Dissemination.

Thyroid transcription factor 1 (TTF-1) is primarily expressed in lung and thyroid cancers, but it has also been observed in other cancers. A 60-year-old woman presented with worsening dyspnea, pleural effusion, lung metastases, a right ovarian tumor, and para-aortic intra-abdominal lymph node metastasis. Biopsies from the pleural dissemination revealed TTF-1-positive adenocarcinomas. To confirm the presence of the primary organ, biopsies were performed on a para-aortic intra-abdominal lymph node that ascended from the ovaries. An adenocarcinoma positive for TTF-1 was identified, thus confirming the diagnosis of ovarian cancer. Our findings revealed that TTF-1 positivity does not always signify a lung cancer origin.

Pleural recurrence 21 years after complete resection of thymic mucoepidermoid carcinoma: a case report

BackgroundThymic mucoepidermoid carcinomas (MECs) are extremely rare malignant neoplasms. We describe a rare case of a MEC with a high histological grade in a patient who survived for more than 20 years after the initial surgery, focusing on the clinical course and recurrence pattern.Case presentationA woman underwent surgical resection of a high-grade thymic MEC at another hospital 21 years ago. At the age of 79, she was referred to our hospital with an abnormal opacity incidentally found on her chest radiograph during a health check-up. After the percutaneous biopsy diagnosed thymic MEC, surgical resection was planned based on imaging findings, considering pulmonary metastasis. Intraoperatively, a large tumor and several nodules were detected within the parietal pleura; furthermore, pleural dissemination of the MEC was diagnosed by intraoperative rapid histological evaluation. We completed an exploratory thoracoscopic procedure without performing resection. She did not wish to undergo adjuvant therapy after surgery. Currently, the tumor is growing slowly, but the patient is asymptomatic and is being followed up without treatment intervention.ConclusionWe encountered a rare case of pleural recurrence 21 years after complete resection of thymic MEC. Whether surgical resection, including volume reduction surgery, should be used as a treatment strategy for thymic carcinoma with dissemination requires further discussion.

Clinicopathological Characteristics and Survival Outcomes in Patients with Advanced Esophageal Squamous Cell Carcinoma Who Were Intraoperatively Diagnosed Non-Curative

Introduction: Curative esophagectomy is not always possible in patients with locally advanced esophageal cancer. However, few studies have investigated patients who underwent non-curative surgery with intraoperative judgment. This study aimed to investigate patient characteristics and clinical outcomes for patients undergoing non-curative surgery and compare them between non-resectional and non-radical surgery. Methods: Among 989 consecutive patients with thoracic esophageal squamous cell carcinoma who were preoperatively expected for curative esophagectomy, 66 who were eligible for non-curative surgery were included in this study. Results: Intraoperative diagnosis of T4b accounted for 93% of the reasons for the failure of curative surgery. In those patients, esophageal cancer locally invaded into the aortobronchial constriction (70%), trachea (25%), or pulmonary vein (5%). Lymph node metastasis mainly invaded into the trachea (50%) or bronchus (28%). The overall survival of patients with non-curative surgery was 51.5%, 25.7%, and 10.4% at 6, 12, and 24 months after surgery, respectively. Although there were no differences in preoperative patient characteristics between non-resectional and non-radical surgery, distant metastasis, especially pleural dissemination, was significantly observed in T4b patients due to esophageal cancer with non-radical surgery than those with non-resectional surgery (35% vs. 15%, p = 0.002). Even in patients with non-curative surgery, R1 resection and postoperative chemoradiotherapy were identified as independent factors for survival 1 year after surgery (p = 0.047, and 0.019). Conclusions: T4b tumor located in aortobronchial constriction or trachea/bronchus makes it difficult to diagnose whether it is resectable or unresectable. Moreover, surgical procedures and perioperative treatment were deeply associated with the clinical outcomes.

ASO Visual Abstract: EGFRMutation is a Prognostic Factor in Lung Cancer Patients with Pleural Dissemination Detected During or After Surgery.

ASO Visual Abstract: EGFRMutation is a Prognostic Factor in Lung Cancer Patients with Pleural Dissemination Detected During or After Surgery.

Hyperthermic intrathoracic extracorporeal chemotherapy for secondary malignant pleural disease.

Pleural metastasis has extremely poor prognosis. Resection of pleural implants with infusion of intrathoracic hyperthermic chemotherapy may offer a survival advantage in selected patients. We evaluated the safety and efficacy of hyperthermic intrathoracic extracorporeal chemotherapy (HITEC) in patients who underwent pleurectomy/decortication (P/D) for secondary malignant pleural disease (SPD). A total of 101 patients were evaluated over 72 months, with 35 patients electing to proceed with P/D and 60 minutes of HITEC with cisplatin at 42°C. Inclusion criteria were adults 18-79 years with unilateral pleural dissemination. Exclusion criteria were patients without control of primary site, extrathoracic metastatic disease, significant comorbidities, and a history of adverse reaction to cisplatin. Median age was 56 years (36-73); 60% were women. SPD was thymoma in 13, breast cancer in 9, lung cancer in 6, colon cancer in 2, renal cell in 2, and esophageal, anal, and thymic cancers in one each. There was no operative mortality. Postoperative complications occurred in 18 patients (51%). No patient developed renal failure. Median follow-up was 24 months (4-60). The overall survival rate was 61%; 17 patients (49%) developed recurrent disease at a median of 12 months (6-36). There were no recurrences after 36 months Eleven patients (31%) died of metastatic disease at a median of 17 months (7-25). Surgical cytoreduction of SPD followed by HITEC with cisplatin was well tolerated. No patient developed cisplatin-related toxicities. Long-term follow-up is warranted to determine survival advantage and refinement of inclusion criteria.

Intraoperative rapid diagnosis of pleural lavage cytology in non-small cell lung cancer.

Positive pleural lavage cytology (PLC +) is a poor prognostic factor for non-small cell lung cancer (NSCLC). However, data on the impact of intraoperative rapid diagnosis of PLC (rPLC) are lacking. Therefore, we evaluated the efficacy of rPLC before resection during surgery. A total of 1,838 patients who underwent rPLC for NSCLC between September 2002 and December 2014 were studied retrospectively. We assessed the clinicopathological factors between rPLC findings and the impact on survival of patients with curative resection. The rPLC + status was observed in 96 (5.3%) among 1,838 patients. The rPLC + group had more unsuspected N2 (30%) than the rPLC- group (p < 0.001). The 5-year overall survival (OS) of patients who underwent lobectomy or more extensive resection with rPLC + , negative rPLC (rPLC-), and microscopic pleural dissemination (PD) and/or malignant pleural effusion (PE) were 67.3, 81.3, and 11.0%, respectively. In the rPLC + group, the prognosis of patients with pN2 was equal to that of pN0-1 (5-year OS: 77.9% vs. 63.4%, p = 0.263). Undetectable dissemination in the first evaluation immediately after starting surgery was found in 9% of rPLC + patients by additional evaluation of the thoracic cavity. Patients with rPLC + have more favorable survival than those with microscopic PD/PE after surgery. Curative resection should be performed in patients with rPLC + , even if N2 is detected during surgery. However, the rPLC + group often has N2 upstaging; therefore, systematic nodal dissection should be performed in rPLC + patients for exact staging. rPLC may contribute to preventing oversight PD by re-evaluation during surgery.

EGFR Mutation is a Prognostic Factor in Lung Cancer Patients with Pleural Dissemination Detected During or After Surgery

BackgroundPrimary lung tumors are sometimes resected when either pleural dissemination (PD) or malignant pleural effusion (MPE) exists. This study clarified the prognostic factors for non-small cell lung cancer (NSCLC) with either PD and MPE, or both, detected during or after surgery.Patients and MethodsWe examined patients with NSCLC from a multicenter database who had either PD, MPE, or both, detected during or after surgery between 2005 and 2015. Hazard ratios and 95% confidence intervals were estimated using the Cox proportional hazards model adjusted for potential confounding factors.ResultsAmong 9463 registered patients, PD, MPE, or both, were found in 114 patients with NSCLC during or after surgery. Primary tumor resection and exploratory thoracotomy were performed in 65 and 49 patients, respectively. In univariate analysis, adenocarcinoma, clinically undetected lymph node metastasis (c-N0 or unknown), EGFR mutation, and combination of chemotherapy or tyrosine kinase inhibitors after surgery were better prognostic factors for overall survival (OS), whereas in the multivariate analysis, adenocarcinoma, clinically undetected lymph node metastasis, and EGFR mutation were favorable independent prognostic factors in OS. Additionally, limited to patients with EGFR mutation, patients with primary lung tumor resection showed a significantly better 5-year OS than those with exploratory thoracotomy (86.4 vs. 44.8%; p < 0.001).ConclusionOur findings show that surgical resection of primary tumors could improve the prognosis of patients with PD, MPE, or both, detected during or after surgery when the tumors harbor an EGFR mutation.

ASO Author Reflections: Prognostic Impact of the Primary Tumor Resection for Lung Cancer Patients Diagnosed with Pleural Dissemination in the Perioperative Period-Importance of Biomarker-Based Treatment Decision Making.

ASO Author Reflections: Prognostic Impact of the Primary Tumor Resection for Lung Cancer Patients Diagnosed with Pleural Dissemination in the Perioperative Period-Importance of Biomarker-Based Treatment Decision Making.

Abstract 5838: Cancer-associated fibroblasts drive spheroid formation and pleural dissemination in non-small cell lung cancer

Abstract Introduction: Cancer-associated fibroblasts (CAFs) play an important role in cancer progression and malignant transformation by interacting with cancer cells in the tumor microenvironment. Pleural dissemination of non-small cell lung cancer (NSCLC) is a condition in which cancer cells directly spread from the primary tumor site into the extrapulmonary thoracic cavity and colonize the pleura. However, not all free detached cancer cells can survive under anchorage-independent conditions in thoracic cavity, and some important factors are assumed to be involved in the formation of pleural dissemination. In this study, we investigated the role of CAFs in the formation of pleural dissemination in NSCLC. Methods: Using in vitro co-culture models, conditioned medium, and in vivo xenograft models, we investigated CAF-induced phenotypic changes in lung cancer cell: proliferative ability, invasive ability, anchorage-independent growth ability, cell adhesion to extracellular matrix, and tumorigenicity in thoracic cavity. Next, we performed RNA sequencing analysis using 3D co-culture models of cancer cells and CAFs to explore a molecule that contributes to the formation of pleural dissemination, and then verified it using in vitro and in vivo mice models of pleural dissemination. Results: Cancer cells showed enhanced migration, anchorage-independent growth, adhesion, and invasion ability by co-culture with CAFs. In 3D co-culture model of cancer cells and CAFs, even cancer cells which did not form spheroid by themselves acquired the ability of spheroid formation surrounding the CAF core, suggesting that the interactions with CAFs promote spheroid formation. Inoculation of cancer cells together with CAFs into mouse thoracic cavity developed pleural dissemination more efficiently than inoculation of cancer cells alone. RNA sequencing analysis revealed that co-culture with CAFs upregulated the expression of Cellular Communication Network Factor 1 (CCN1), a matricellular protein, in cancer cells. We then verified that ectopically CCN1-overexpressing lung cancer cell lines increased migration and adhesion ability in vitro, and tumorigenicity in thoracic cavity in mouse pleural dissemination model. Conclusions: CAFs promote development of pleural dissemination via driving spheroid formation and upregulating CCN1 expression in NSCLC. Citation Format: Masayoshi Ohki, Naoki Matsuda, Ken Suzawa, Tomohiro Habu, Mao Yoshikawa, Kazuma Iwata, Yin Min Thu, Kazuhiko Shien, Hiromasa Yamamoto, Shinichi Toyooka. Cancer-associated fibroblasts drive spheroid formation and pleural dissemination in non-small cell lung cancer. [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2023; Part 1 (Regular and Invited Abstracts); 2023 Apr 14-19; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2023;83(7_Suppl):Abstract nr 5838.

Primary pulmonary pleomorphic liposarcoma found with a massive hemothorax

BackgroundPleomorphic liposarcoma (PLPS) is a rare and aggressive subtype of liposarcoma. Here we report the case of a 45-year-old man with PLPS in the lung, which was accompanied by a massive hemothorax.Case presentationThe patient presented to hospital with chest pain. A chest x-ray showed massive right pleural effusion. We drained the right chest cavity of 1 L of blood and enhanced computed tomography (CT) revealed a massive right hemothorax and a 78 × 70 mm mass in the right lower lung lobe. The tumor was ruptured and bleeding, so we performed right lower lobe resection. Pathological investigations revealed a PLPS. One month after surgery, positron emission tomography-CT showed considerable pleural dissemination in the right lung field. The patient died 3 months after surgery.ConclusionsPLPS of the lung is rare, but requires attention because it can cause tumor rupture and hemothorax due to rapid tumor growth, and which may make complete resection of tumor difficult or necessitate emergency surgery.

Epithelial tumors of the thymus with pleural dissemination: the potential role of surgery

Background. Pleural metastases of thymic epithelial tumors are detected in 5–7 % of patients at initial diagnosis and in 10 % of patients during a follow-up after radical surgery for the primary tumor. Partial pleuroectomy is the cornerstone of treatment strategy in this group of patients.The aim of the study was to assess the role of surgery in the treatment of patients with thymic epithelial tumors with pleural dissemination.Material and Methods. From January1, 2010 to June 30, 2021, 21 patients with thymic epithelial tumors (thymoma – 13, thymic cancer – 8) and pleural implants (stage IVA – 11, isolated pleural metastases as tumor progression after radical surgery – 10) underwent partial pleuroectomy with resection of the diaphragm and lung if necessary. Four patients underwent inthraoperative photodynamic therapy and another 4 patients received intrapleural hyperthermic chemotherapy.Results. R0 resection was performed on 12 (57.2 %) patients. Postoperative complications were observed in 6 (28.6 %) patients. The mortality rate was 7.5 %. The overall 1-, 3- and 5-year survival rates were 78 % (95 % CI 61–95), 49 % (95 % CI 23–75), and 41 % (95 % CI 15–67), respectively. The median overall survival time was 29 months (95 % CI 0–60.6). Recurrence occurred in 10 (47.6 %) cases. One-year recurrence-free survival was 60 % (95 % CI 30–90). Independent negative predictors for overall survival were: thymic cancer, incomplete resection, presence of postoperative complications and local recurrence.Conclusion. Surgery is the mainstay of treatment for patients with pleural metastases (stage IVA thymomas and recurrent thymomas). Metastasectomy of pleural implants will be suffcient to achieve a complete resection.

Efficacy of Percutaneous Direct Puncture Biopsy of Malignant Lung Tumors Contacting to the Pleura.

This is a retrospective evaluation of whether percutaneous direct puncture biopsy of lung lesions contacting to the pleura is justified. Between August 2016 and July 2021, 163 consecutive patients (100 males, 63 females with a median age of 73 years) who had malignant lung tumors measuring 0.6-12.4 cm (median, 2.9 cm) that contacted to the pleura and underwent percutaneous lung biopsy under computed tomography fluoroscopic guidance using an 18-gauge end-cut needle were examined. The trajectory was direct puncture in 80 patients (49.1%, 80/163), and trans-lung in 83 patients (50.9%, 83/163). Diagnostic yield and major adverse event rates of direct and trans-lung puncture biopsies were compared. No difference was found in diagnostic yield between direct puncture and trans-lung biopsies (93.8% vs. 98.8%, p=0.11). Major adverse events were major pneumothorax (n=13/163, 8.0%), pleural dissemination (n=18/163, 11.0%), and hemothorax requiring arterial embolization (n=1/163, 1.0%). Direct puncture caused major pneumothorax significantly less than trans-lung puncture did (0%, 0/80 vs. 15.7%, 13/83, p<0.001). No significant difference was found between the two biopsy methods regarding the incidence of pleural dissemination (11.0%, 11/80 vs. 8.4%, 7/83, p=0.32). Direct puncture biopsy of malignant lung tumors contacting to the pleura is justified.

Difference in failure patterns after stereotactic body radiotherapy for lung cancer according to clinical Tstage based on 4D computed tomography.

Stereotactic body radiotherapy (SBRT) is atreatment option for early-stage lung cancer. We aimed to examine the differences in failure patterns after SBRT according to the clinical Tstage. Atotal of 120 patients with early-stage lung cancer (T1-3N0M0) who underwent SBRT were analysed. The clinical stage in patients whose tumours were in contact with the chest wall was confirmed using four-dimensional computed tomography (4D-CT). Local failure, regional node metastasis, and distant metastasis were confirmed from clinical charts. Median follow-up time was 27.5months (range 7-122) after SBRT. Thirteen patients were restaged from clinical T2 with visceral pleural invasion to T3 with chest wall invasion using 4D-CT analysis. Thirty-seven patients developed recurrences. The median progression-free survival (PFS) and overall survival (OS) were 38.1 and 53.8months, respectively. The 3‑year PFS and OS rates were 50.7% and 60.3%, respectively. Asignificant difference was observed in PFS according to the clinical Tstage (p = 0.001). No significant differences were observed in OS according to the clinical Tstage (p = 0.213). The proportion of locoregional failures relative to distant metastasis decreased with progression from T1 to T3. The pleural dissemination rate was significantly higher in T3 tumours than in T1 and T2 tumours (p = 0.010). Clinical Tstage is associated with PFS after SBRT for lung cancer. There were differences in the failure patterns according to Tstage. 4D-CT might provide significant information for assessing chest wall invasion associated with unfavourable PFS.

AB006. Effectiveness of chemotherapy as the first-line treatment for thymic tumors with pleural dissemination

Background: Chemotherapy has been recommended to be the standard care for thymic epithelial tumors (TETs) patients with pleural dissemination. Efficacy of chemotherapy on pleural lesions is not yet assessed in large patient populations. This study aims to evaluate pleural response to chemotherapy and to analyze the related factors on patient survival to see if chemotherapy is a satisfying first-line treatment for these patients.