Lower Lobe Tumors Research Articles

525. PALLIATIVE MULTIMODALITY-THERAPY, EVEN WITH ABBREVIATED IMMUNOTHERAPY CAN MAKE CURATIVE SURGERY FOR SYNCHRONOUS LUNG AND ESOPHAGEAL CANCER POSSIBLE: A CASE REPORT

Abstract Background Synchronous lung and esophageal carcinomas are problematic. When both cancers are locally advanced, combined surgical treatment is rarely possible because of high-risk or insufficient respiratory reserve. Palliative treatment including immunotherapy can sometimes offer significant tumor response and potentially prolong survival in patients with PDL-1 tumor expression. However the place of immunotherapy for potentially rendering inoperable patients operable is still unknown. Methods Case report: A 78-year-old male with smoking history was diagnosed with synchronous locally advanced adenocarcinoma of the Gastroesophageal Junction (GEJ) cT3cN1cM0 and bilateral lung adenocarcinomas stage 4a, cT2cN1cM1a (right lower lobe 43mm confirmed by CT-guided biopsy, left upper lobe 32mm and additional S6 left lower lobe nodule). The patient was considered incurable by MDT and palliative treatment was offered as both cancers had significant PDL-1 expression (GEJ: CPS score >1, Lung: PDL-1 expression 90%). Pembrolizumab immunotherapy was started but poorly tolerated (severe myositis) and stopped again after only 6 weeks. The left-sided lung cancer had by then already regressed and stereotactic irradiation (SBRT 5x12Gy) of the right-side lung cancer was administered resulting in further local tumor control (figure). Endoscopic tumor re-evalution showed a Siewert type 2 tumor (uT3N1) similar to the initial endoscopy 15 months before. Both side lung adenocarcinomas remained regressed and the left lower lobe nodule was unchanged (6mm). Mediastinal lymph node staging by EBUS was negative. Thirteen months after initial diagnosis, 4 cycles of neo-adjuvant chemotherapy (FLOT) were administered. Combined synchronous surgery was finally done 16 months after initial diagnosis. A minimally invasive combined resection included a laparoscopic & thoracoscopic Ivor-Lewis MIE, left thoracoscopic wedge of the lower lobe nodule and a right lower lobectomy with radical lymph node dissection. Post-operative course was smooth: Clavien-Dindo score 1, hospital stay 18 days. Final pathology Distal third adenocarcinoma (1.5x1.2cm above Z-line) with major partial response ypT2N0M0, R0, 0/43 lymph nodes (subcarinal signs of nodal response), right lower lobe tumor of 60x55mm with residual 1.2mm focus of residual viable adenocarcinoma (ypTisN0M0, R0) and left lower lobe hamartoma (6mm). Follow-up showed no recurrence 9 months after surgery (25 months from initial diagnosis). Conclusions: 1) Despite much abbreviated palliative immunotherapy (6 weeks), SBRT and FLOT our patient was down-staged within 16 months from an initially palliative situation to a potential cure with complete resection of all tumors. 2) Synchronous combined radical laparoscopic & thoracoscopic Ivor-Lewis esophagectomy with lung lobectomy can be feasible after immuno-, chemo- and radiotherapy even in elderly patients.

Robot-assisted right wedge-shaped sleeve lower bilobectomy with knotless suture anastomosis: a case report

BackgroundIn bronchoplasty of wedge resections, it is necessary to transect the bronchus at a sharp angle and depth. As a result, anastomoses after wedge resections have the disadvantages of poor visibility and operability. Here, we report a case of right wedge-shaped sleeve bilobectomy that was successfully performed with continuous knotless suturing using robotic assistance.Case presentationAn 81-year-old male patient was referred for the treatment of a tumor in the right lower lobe, which protruded into the bronchus intermedius. The tumor was diagnosed as squamous cell carcinoma by transbronchial biopsy, cT1cN1M0 stage IIB carcinoma for which surgery was indicated. Because the pulmonary middle lobe artery was involved and a resection margin from the tumor protruding into the bronchial mucosal epithelium was necessary, a right wedge-shaped sleeve bilobectomy was performed. The bronchial anastomosis was performed with robotic assistance. After dissection of pulmonary vessels and interlobes, the upper lobe bronchial bifurcation was transected in a wedged shape, and a lower bilobectomy was performed. The bronchi were sutured continuously with knotless sutures. A continuous suture was performed from the ventral to the caudal side. After suturing to the dorsal side, another continuous suturing was performed from the cranial side. Continuous sutures were made until each thread passed through the other. Pericardial fat was wrapped around the anastomosis.ConclusionsA better visual field could be obtained owing to robot-assisted surgery, and robotic arms enabled an accurate and safe operation. Furthermore, continuous suturing using a knotless suture made it easier for the sutures to be handled and enabled bronchial anastomosis without assistance.

Avoiding Dosimetric Risk Factors for Complications in Neoadjuvant Chemoradiotherapy for Lung Cancer: Conventional Radiotherapy Versus Intensity-modulated Radiotherapy.

We compared three-dimensional conformal radiotherapy (3D-CRT) with intensity-modulated radiotherapy (IMRT) for avoiding dosimetric risk factors related to pulmonary complications after neoadjuvant chemoradiotherapy followed by surgery (NACRT-S) for non-small cell lung cancer (NSCLC). We performed simulations in 11 patients with dosimetric risk factors during their treatment with NACRT-S for NSCLC. Radiation treatment plans were generated using 3D-CRT and IMRT to avoid dosimetric risk factors. Regarding dose-volume histogram (DVH) parameters, we calculated the percentage of lung volume that received more than x Gy (Vx) using 1) the total lung volume minus gross tumor volume (DVHg), 2) the lung volume remaining after surgery (DVHr), and 3) the contralateral lung volume (DVHc). We analyzed the dosimetric differences between 3D-CRT and IMRT. V35g and V40g were significantly lower with IMRT than with 3D-CRT (p=0.001 each); the median V35g and V40g were 16.1% and 14.9% with 3D-CRT versus 12.0% and 9.2% with IMRT, respectively. Overall, 0% and 55% of the patients were able to avoid all dosimetric risk factors with 3D-CRT and IMRT, respectively (p=0.006). Even with IMRT, tumor location and length of the planning target volume (PTV) significantly affected the avoidance of all dosimetric risk factors (p=0.015 and 0.022, respectively). IMRT is more useful than 3D-CRT for avoiding dosimetric risk factors in NACRT-S for NSCLC. For further improvements in avoiding these factors, respiratory motion managements to reduce the length of the PTV may be required for patients with middle or lower lobe tumors.

Comparison of different approaches in complete thoracoscopic segmentectomy of lung lower lobe.

Safe and oncologically acceptable segmentectomy outcomes were reported for early-stage lung cancer. The high-resolution computed tomography allowed us to find detailed structures inside the lungs, such as the pulmonary ligaments (PLs). Hence, we have presented the relatively anatomically challenging thoracoscopic segmentectomy, for the resection of the lateral basal segment, the posterior basal segment, and both segments through the PL as a PL approach. This study aimed to retrospectively examine the lung lower lobe segmentectomy, excluding the superior and basal segments (from S7 to S10), using the PL approach as an option to treat the lower lobe tumors of the lung. We then compared the efficacy of the PL approach in terms of safety with the interlobar fissure (IF) approach. The characteristics of the patients, intra- and postoperative complications, and surgical outcomes were analyzed. Of the 510 patients who underwent segmentectomy for malignant lung tumors from February 2009 to December 2020, 85 were included in this study. Among them, 41 underwent a complete lung lower lobe thoracoscopic segmentectomy, excluding S6 and basal segments (from S7 to S10), using the PL approach, and the remaining 44 used the IF approach. The median age in 41 patients in the PL group was 64.0 years (range, 22-82), and that in 44 patients in the IF group was 66.5 years (range, 44-88), with significant differences in gender between these groups. Video-assisted thoracoscopic surgery and robot-assisted thoracoscopic surgery were performed on 37 and 4 patients in the PL group and 43 and 1 patient in the IF group, respectively. Postoperative complication frequency was not significantly different between these groups. The most common complications were the air leaks that persisted for over 7 days in 1 and 5 patients in the PL and IF groups, respectively. Complete thoracoscopic segmentectomy of the lower lobe, excluding S6 and basal segments, using the PL approach is a reasonable option for lung lower lobe tumors compared with the IF approach.

Epidemiology and survival trends of lung carcinoids in the veteran population.

e21049 Background: Lung carcinoids (LC) continue to increase in prevalence and existing data shows a female predominance of these tumors, but relevant epidemiologic data for heterogeneous populations is limited. In this study, we describe the epidemiology of LC in the United States (US) Veteran population. Methods: In this retrospective study, we searched Veteran Affairs Cancer Cube Registry (VACCR) for LC cases diagnosed between 2000 and 2017 and their baseline characteristics. Survival rates were analyzed across all baseline characteristics to identify important prognostic factors and results were compared with Surveillance, Epidemiology, and End Results cancer database (SEER). Data was analyzed via chi-square and Fischer exact probability tests (level of significance at < 0.05). Results: We identified 846 LC cases in VACCR (91% males), and 8,851 LC cases in SEER (32% males). Compared to SEER, VACCR data had more black patients (12% vs 8%), less cases with loco-regional disease (56% vs 84% in SEER) and same proportion of lower lobe tumors (40%). The annual incidence rate of LC among all lung cancers in Veterans tripled from 2000 to 2017 (0.3% to 0.9%). No racial disparities in treatment were noted among the Veterans. Male-specific 5-year survival rate was 18% lower in VACCR compared to SEER (61% vs 79%). Univariate analysis of both databases showed a statistically significant association of survival with age, primary tumor site and gender (p < 0.05 for all) (Table 1), with advanced age, upper lobe LC and male gender associated with worse survival. SEER subgroup analyses also showed lower 5-year survival rates for males across all baseline characteristics. Overall, black race appeared to be associated with worse prognosis, but the results did not reach statistical significance for VACCR data. Conclusions: Our study showed that US Veteran population, consisting of older males with more comorbidities, LC have lower survival rates than SEER population with more female LC cases. Advanced age, upper lobe predominant disease, and advanced stage were associated with worse survival. Both SEER and VACCR data suggest that male sex is a poor prognostic factor for LC. [Table: see text]

Clinical Factors That Affect Fiducial Tracking in Robotic SABR for Lung Tumors

SABR is a treatment option for patients with lung tumors that employs fiducials to track tumors during the breathing cycle. Currently, there is a paucity of data on how relative fiducial location and patient clinical characteristics affect fiducial tracking and clinical outcomes. This study aimed to identify factors that reduce the number of fiducials tracked with respiratory motion management during SABR. An institutional review board-approved retrospective review was performed of patients receiving robotic SABR for lung tumors at our institution from 2016 to 2019. Clinical data including demographics, medical history, treatment data, and follow-up were collected. Fiducial geometries were obtained with Velocity contouring software and MATLAB. Mann-Whitney U, χ2, and t tests were completed using MedCalc. A total of 73 patients with 77 treatments were identified. The χ2 analysis revealed that chronic obstructive pulmonary disease was associated with having 3 or more fiducials tracked (P=.034). Tumors in lower lobes were associated with higher rates of uncertainty errors (P=.015). The number of fiducials tracked had no effect on local tumor control or overall survival, with a median of 36 months of follow-up. A total of 28 treatments had fiducial centroid data available for geometric analysis. The most common tracking errors were rigid body error (RBE; 57%) and spacing errors (36.4%). Spacing errors had a shorter average minimum interfiducial distance than nonspacing errors (1.0 cm vs 1.7 cm, respectively; P=.017). RBE treatments had a longer average maximum distance than non-RBE treatments (4.0 cm vs 3.0 cm; P=.022). Greater motion in lower lobes can contribute to certain tracking errors that prevent more fiducials from being tracked. Maintaining interfiducial distance between experimentally determined guidelines may limit spacing errors and RBEs, the 2 most common tracking errors. An increased number of patients in a data set may result in stronger correlations between patient and tumor factors and outcomes.

Lobe-Specific Lymph Node Dissection May be Feasible for Clinical N0 Solid-Predominant Part-Solid Lung Adenocarcinoma With Solid Component Diameter ≤ 2 cm

BackgroundLymph node (LN) involvement was not rare in patients with radiological solid-predominant part-solid nodules (PSNs). The lymph node dissection (LND) strategy remained unclear. Materials and MethodsSix hundred seventy-two patients with clinical N0 solid-predominant PSNs (0.5 < consolidation-to-tumor ratio < 1) receiving systematic LND (development cohort, n = 598) or limited LND (validation cohort A, n = 74) at 2 Chinese institutions from 2008 to 2016 were collected. The development cohort was utilized to investigate the incidence and pattern of LN metastasis. Lobe-specific LN metastasis pattern was defined as superior mediastinal LN involvement from upper-lobe tumor or inferior mediastinal LN involvement from lower-lobe tumor. To further validate the LN metastasis pattern observed in the development cohort, validation cohort B consisting of 7273 patients with primary lung adenocarcinomas who received surgery from 2016 to 2021 was identified. The clinical outcomes between the development cohort and validation cohort A were compared in order to assess the feasibility of limited LND. ResultsLN involvement rate for solid-predominant PSNs was 10.0%. Larger solid component diameter (P = .005) was independently associated with increased risk of LN involvement. In upper/lower lobes solid-predominant PSNs with solid component diameter ≤ 2 cm, a lobe-specific LN involvement pattern was identified. Further validation indicated that the observed mediastinal LN involvement pattern was generalizable, and the oncologic outcomes did not vary by the extent of LND in solid-predominant PSNs with solid component diameter ≤ 2 cm. ConclusionLobe-specific LND might be feasible for solid-predominant PSNs with solid component diameter ≤ 2 cm. For other solid-predominant PSNs, systematic LND should be recommended.

Prognostic value of L4 lymph node dissection during video-assisted thoracoscopic surgery in patients with left-sided non-small cell lung cancer: a single-center, retrospective cohort study.

Lymph node dissection (LND) is crucial procedure during radical resection of non-small cell lung cancer (NSCLC), but the prognostic value of L4 LND remains elusive. To investigate the prognostic value of L4 LND in patients with left-side NSCLC who underwent video-assisted thoracoscopic surgery (VATS). Three hundred twelve patients who underwent VATS between Jan. 2007 and Dec. 2016 were reviewed. Of those, 119 underwent L4 LND (L4D+), whereas the other 193 patients did not (L4D-). The inclusion criteria were as follows: patients diagnosed with primary left-sided NSCLC who underwent VATS lobectomy combined with LND; patients subjected to R0 resection and tumor pathological stage T1-4N0-2M0. The primary endpoint was overall survival (OS). OS was calculated from the operation date to the date of death. The chi-square test was used for categorical variables, and a t test was used for continuous variables. A total of 119 patients underwent L4 LND, and the procedure was more likely to be performed on upper lobe tumors (P=0.019). Patient distributions with respect to age, gender, smoking history, clinical stage, adjuvant therapy, tumor differentiation and tumor size were well balanced between two groups. More lymph nodes (LNs) were dissected in the L4D+ group than in the L4D- group (P<0.001). The rate of metastasis to L4 lymph nodes was 9.2%, which was comparable between patients with upper and lower lobe tumors (8.9% vs. 10.0%, P=1.000). The L4D+ group exhibited a significantly better OS than the L4D- group (median OS: undefined vs. 130 months, HR 0.47; 95% CI: 0.31-0.72; P=0.002). Multivariate analysis showed that L4 LND was an independent factor for OS. However, OS did not significantly differ between the two groups of cT1aN0 and cT1bN0 patients (OS: HR 0.44; 95% CI: 0.18-1.06; P=0.12). L4 LND is recommended for patients with left-sided NSCLC as an essential component of radical resection. The role of L4 LND in cT1a-bN0 disease warrants further study.

Patterns of Postoperative Changes in Lung Volume and Perfusion Assessed by Dual-Energy CT: Comparison of Lobectomy and Limited Resection.

BACKGROUND. Pulmonary function tests (PFTs) and perfusion scintigraphy have limited utility for evaluating postoperative changes in regional pulmonary function after lung cancer resection surgery. OBJECTIVE. The purpose of this study is to compare postoperative changes in lung volume and perfusion, as assessed by dual-energy CT (DECT), between patients undergoing surgical resection of lung cancer by lobectomy versus limited resection as well as to assess associations between such changes and the lobar location of the resected tumor. METHODS. This study entailed a retrospective post hoc analysis of a prospective study that enrolled patients awaiting lung cancer resection surgery between March 2019 and February 2020. Eighty-one patients (38 men and 43 women; mean age, 60.5 ± 8.9 [SD] years), 43 of whom underwent lobectomy and 38 of whom underwent limited resection, were included. Patients underwent thoracic DECT and PFT evaluation preoperatively and at 6 months postoperatively. Pulmonary lobes were segmented. Lobar lung volume and lung perfusion ratios (both relative to whole-lung values) were computed. Perfusion measures reflected DECT-derived iodine content. Patients completed 6-month postoperative quality-of-life (QOL) questionnaires. RESULTS. Patients undergoing lobectomy, compared with those undergoing limited resection, had greater increases in the lung volume ratio of the ipsilateral nonresected lobe(s) (mean, 42.3% ± 24.2% [SD] vs 22.9% ± 13.2%, p < .001) and the contralateral lung (mean, 14.6% ± 14.0% vs 6.4% ± 6.9%, p = .002) as well as greater increases in the lung perfusion ratio of the ipsilateral nonresected lobe(s) (mean, 39.9% ± 20.7% [SD] vs 22.8% ± 17.8%, p < .001) and the contralateral lung (mean, 20.9% ± 9.4% vs 4.3% ± 5.6%, p < .001). In patients with right lower lobe tumors, the largest postoperative increases in the lung volume ratio were in the right middle lobe in those undergoing lobectomy (mean, 44.1% ± 21.0%) and limited resection (mean, 24.6% ± 14.5%), whereas the largest postoperative increase in the lung perfusion ratio was in the left lower lobe in those undergoing lobectomy (mean, 53.9% ± 8.6%) and in the right middle lobe in those undergoing limited resection (mean, 32.5% ± 24.1%). Otherwise, the largest increases in lung volume and perfusion ratios occurred in the ipsilateral nonresected lobes (vs the contra-lateral lobes), regardless of the operative approach used and the lobar location. Changes in the lung volume and perfusion ratios in the ipsilateral lobe(s) and the contralateral lung showed weak correlations with certain QOL scores (e.g., for role functioning: ρ = 0.234-0.279 [volume] and -0.233 to -0.284 [perfusion]). CONCLUSION. DECT depicts patterns of lung volume and perfusion changes after lung cancer surgery, depending on the surgical approach (lobectomy vs limited resection) used and the lobar location of the tumor. CLINICAL IMPACT. DECT-derived metrics can help understand variable physiologic impacts of lung cancer resection surgeries.

Impact of tumor location and pleural invasion on the frequency of skip hilar lymph node metastasis in lung cancer.

The appropriate extent of hilar lymph node (LN) dissection in segmentectomy for lung cancer has not yet been fully investigated. Herein, we assessed the patterns of LN metastasis using network analyses. Patients with nodal metastases of non-small-cell lung cancer measuring ≤30 mm in diameter who underwent anatomical resection were included. The assumed pathways of metastasis were visualized using Cytoscape software. Metastasis to hilar (#10) or interlobar (#11) LNs but not to more peripheral ones was defined as skip N1 metastasis. A total of 322 patients were included, with 123 of them having pleural invasive tumors and 32 having intrapulmonary metastases. There were 130 patients with pN1 disease and 192 with pN2 disease. The overall proportion of patients with skip N1 metastasis was 17%. Patients with lower lobe tumors had more frequent skip N1 metastasis than those with upper lobe tumors (31% vs. 10%, P<0.001) but had less frequent skip N2 metastasis (10% vs. 20%, P=0.02). The rates of skip metastasis to #11i in the right S6 tumor and right S9-10 tumor were unexpectedly high (22% and 17%, respectively). Similarly, skip metastasis to #11 in the left S6 tumor was relatively high (16%). There was a significant difference in the frequency of skip LN metastasis between tumors with and without pleural invasion (44% vs. 27%, P=0.001). The pattern of LN metastasis differed according to the localized segment of the tumor and the pleural invasion status.

Patient selection, inter-fraction plan robustness and reduction of toxicity risk with deep inspiration breath hold in intensity-modulated radiotherapy of locally advanced non-small cell lung cancer.

BackgroundState-of-the-art radiotherapy of locally advanced non-small cell lung cancer (LA-NSCLC) is performed with intensity-modulation during free breathing (FB). Previous studies have found encouraging geometric reproducibility and patient compliance of deep inspiration breath hold (DIBH) radiotherapy for LA-NSCLC patients. However, dosimetric comparisons of DIBH with FB are sparse, and DIBH is not routinely used for this patient group. The objective of this simulation study was therefore to compare DIBH and FB in a prospective cohort of LA-NSCLC patients treated with intensity-modulated radiotherapy (IMRT).MethodsFor 38 LA-NSCLC patients, 4DCTs and DIBH CTs were acquired for treatment planning and during the first and third week of radiotherapy treatment. Using automated planning, one FB and one DIBH IMRT plan were generated for each patient. FB and DIBH was compared in terms of dosimetric parameters and NTCP. The treatment plans were recalculated on the repeat CTs to evaluate robustness. Correlations between ΔNTCPs and patient characteristics that could potentially predict the benefit of DIBH were explored.ResultsDIBH reduced the median Dmean to the lungs and heart by 1.4 Gy and 1.1 Gy, respectively. This translated into reductions in NTCP for radiation pneumonitis grade ≥2 from 20.3% to 18.3%, and for 2-year mortality from 51.4% to 50.3%. The organ at risk sparing with DIBH remained significant in week 1 and week 3 of treatment, and the robustness of the target coverage was similar for FB and DIBH. While the risk of radiation pneumonitis was consistently reduced with DIBH regardless of patient characteristics, the ability to reduce the risk of 2-year mortality was evident among patients with upper and left lower lobe tumors but not right lower lobe tumors.ConclusionCompared to FB, DIBH allowed for smaller target volumes and similar target coverage. DIBH reduced the lung and heart dose, as well as the risk of radiation pneumonitis and 2-year mortality, for 92% and 74% of LA-NSCLC patients, respectively. However, the advantages varied considerably between patients, and the ability to reduce the risk of 2-year mortality was dependent on tumor location. Evaluation of repeat CTs showed similar robustness of the dose distributions with each technique.

Practical usefulness of partial-range 4-dimensional computed tomography in the simulation process of lung stereotactic body radiation therapy

PurposeFour-dimensional computed tomography (4DCT) scans to cover the entire lungs often fail due to changes in the patient's respiratory cycle, highlighting the need for an improved method that can facilitate successful 4DCT for lung stereotactic body radiation therapy (SBRT). This study aimed to present partial-range 4DCT (PR-4DCT) as a new simulation method to increase the success rate of 4DCT and to verify the practical usefulness of PR-4DCT. Methods & materialsWe retrospectively analyzed 230 consecutive patients (270 tumors) who underwent SBRT for primary lung cancer or pulmonary metastasis between January 2014 and December 2021. We developed a new CT simulation method (PR-4DCT) in 2019 that scans only a partial-range around the tumor. To verify the usability of PR-4DCT, CT simulation methods were compared by period. ResultsUntil 2018, before the PR-4DCT method was introduced, the rate of 4DCT implementation was less than 40%. However, the proportion has continued to increase since then, and rate of implementation of 4DCT improved to approximately 94% in 2021. Moreover, 4DCT could be performed on almost all lower-lobe tumors after the introduction of PR-4DCT. In particular, the success rate increased dramatically after using the PR-4DCT method in patients who had decided to try 4DCT, and in 2021, PR-4DCT was successful in all of these patients. ConclusionPR-4DCT is a very simple method that can be used immediately in any institution currently performing 4DCT, and it is an effective solution to increase the success rate of 4DCT in patients with an irregular respiratory cycle.

Analysis of normal lung irradiation in radiosurgery treatments: a comparison of lung optimized treatment (LOT) on cyberknife, 4D target volume on helical tomotherapy, and DIBH on linear accelerator.

Quantitative retrospective analysis of the normal lung irradiation due to the variations of the ITV volume based on the techniques used for upper lobe (UL), mid lobe (ML), and lower lobe (LL) lung tumours when used with 2-view, 1-view, 0-view based LOT technique on Cyberknife, AveIP on Helical Tomotherapy, and DIBH on VMAT systems. In the treatment of lung tumours, patients medically inoperable or those who are unwilling to undergo surgery have the option to be treated using radiation therapy. There are many motion control techniques available for the treatment of the moving target, such as movement encompassment, respiratory gating, breath-hold, motion reduction, and tumour monitoring. ITV generation is dependent on technique and hence the volume of the PTVs will differ based on the technique used. This study aimed to determine the influence of these ITVs on the irradiated normal lung volume for UL, ML, and LL lung tumours for 23 patients. The mean difference in the PTV volumes generated with the 0-view technique was significant with that of 2-view and DIBH techniques (p-value < 0.04). The mean difference in the PTV volumes generated by 2-view and DIBH was small for UL, ML, and LL tumours. V5 of the combined lung with the 0-view method was 5% compared to the 2-view method for UL tumours (p-value = 0.04) and the same was 9.5%, and 16.8% for ML and LL tumours (p-value < 0.04). In contrast to all other techniques, lung volume parameters V5, V10, V20, and V30 for the 0-view technology were consistently higher irrespective of the tumour location in the lung. The observed maximum mean lung dose (MLD) was 6.2Gy ± 2.7Gy with the 0-view technique and the minimum was 3.85Gy ± 1.75Gy with the DIBH technique. The difference in MLD between DIBH and 2-view was negligible (p-value = 0.67). The MLD increased for LL tumours from 4Gy to 6.5Gy from the 2-view to 0-view technique (p-value = 0.009). There was a significant increase in MLD for LL tumours with the 0-view technique compared to AveIP (1.9Gy, p-value = 0.04) and DIBH (2.0Gy, p-value = 0.003) technique. For ML and UL tumours, except for 0-view and 1-view, the difference in the MLD between the rest of the methods was not significant (p-value > 0.11). In the treatment of lung tumour patients with SBRT, this study has demonstrated 2-view with Cyberknife and DIBH with VMAT treatment techniques have optimal normal lung tissue sparing. There was a significant increase in the average lung volume receiving 5%,10%, 20%, and 30% dose when comparing the 1-view, 0-view, AveIP, and DIBH techniques to the 2-view technique. However, DIBH with VMAT was dosimetrically advantageous for ML and LL tumours, while providing significantly shorter treatment times than any other technique studied.

LOBE-SPECIFIC METASTASIS IN NON-SMALL CELL LUNG CANCER

Aim: to identify the pathways of lymph node metastases in non-small cell lung cancer (NSCLC).Material and Methods. The frequency of mediastinal lymph node metastases and treatment outcomes were analyzed in 327 patients with stage I–III non-small cell lung carcinoma (NSCLC), who underwent lung resection with systematic lymph node dissection (SLND) between 2007 and 2011.Results. In cases with tumor location in any lobe of the right lung, metastasis occurred in the superior and inferior mediastinal lymph nodes. In left-side tumors, the main pathways of lymphatic spread of tumors were superior and inferior mediastinal nodes as well as aortic lymph nodes. Left lower lobe tumors metastasized most often to inferior mediastinal lymph nodes. Skip metastases were observed at any location of the tumor. Routine examination of all ipsilateral mediastinal lymph nodes overstaged NSCLC in 19.5 % of cases. The overall 5-and 10-year survival rates in patients with stage I–III NSCLC with SND were 61.5 % and 49.2 %, respectively. The median survival time was 103 months.Conclusion. Despite typical metastatic patterns of mediastinal lymph nodes in patients with NSCLC, non-specific metastasis was observed at any location of the tumor, which required mandatory systematic nodal dissection.

Machine Learning Classifier Using Pretreatment Factors to Predict Radiation Pneumonitis Following Stereotactic Body Radiation Therapy for Lung Cancer

<h3>Purpose/Objective(s)</h3> Symptomatic radiation pneumonitis (RP) is a common cause of treatment related toxicity in patients receiving radiation therapy for lung cancer. Machine learning techniques have been utilized to determine predictors of RP, but most of these models have used dosimetric features to generate results. The identification of pretreatment factors related to the development of symptomatic RP and implementation of these factors into a machine learning model would be clinically useful to guide treatment decisions, risk estimation, and risk reduction of development of symptomatic RP. <h3>Materials/Methods</h3> We retrospectively reviewed data from 278 lung cancer patients that underwent stereotactic body radiation therapy (SBRT). Pretreatment factors including patient demographics, pulmonary function data, and tumor characteristics were previously analyzed for the development of symptomatic RP, defined as CTCAE v4.0 ≥ Grade 2. A programming environment was used to generate classification machine learning models based on this dataset. Models were tested for accuracy in classification, area-under-the-curve (AUC), and special attention was paid to the false negative rate. The performance of several different algorithms using various combinations of predictors was evaluated including Decision Trees, Discriminant Analysis, Logistic Regression, Naive Bayes Classifiers, Support Vector Machines, Nearest Neighbor Classifiers and Ensemble Classifiers. Each model utilized 5-fold cross-validation to prevent overfitting. <h3>Results</h3> Of the 278 patients receiving SBRT, 42 patients (15.1%) developed symptomatic RP. A RUSBoosted Trees Ensemble Classifier was found to be the most accurate model tested. Features identified as significant risk factors for symptomatic RP in prior univariate and multivariate analyses were found to be the most important predictors in the machine learning models tested. These features included prior radiation treatment to the thorax or lung resection, location of tumor in the right lower lobe, a higher T Stage and age. When this model was used to classify cases of symptomatic RP, it had an AUC of 0.86 and an accuracy of 87%, correctly predicting 36 out of 42 pneumonitis cases. The model had a false negative rate of 14% and false positive rate of 13%. <h3>Conclusion</h3> A machine learning model was developed to identify pretreatment factors predictive of symptomatic RP. The advantage of this model when compared to others with a similar goal is that it depends solely on pretreatment factors, and therefore could be applied in a clinical setting prior to radiation therapy. Next steps include testing with an independent dataset to confirm the model's accuracy and prospective studies to verify the model's clinical utility.

Effect of Tumor Location on the Risk of Bilateral Central Lymph Node Metastasis in Unilateral 1-4 cm Papillary Thyroid Carcinoma.

PurposePapillary thyroid carcinoma (PTC) has a high incidence of lymph node metastasis (LNM). Our aim was to determine whether tumor location is a useful feature to predict bilateral central lymph node metastasis (CLNM) in unilateral 1–4 cm PTC.Patients and MethodsData on unilateral 1–4 cm PTC patients from 2016 to 2019 were collected retrospectively. The clinical and pathological characteristics of the tumors and lymph nodes were analyzed statistically.ResultsThe mean patient age was 49.1±12.3 (23–73) years, and the majority were women (n=1334, 75.4%). A total of 1767 patients were analyzed, and 256 (14.5%) had bilateral CLNM. Tumor location was an independent risk factor in predicting bilateral CLNM (p<0.001). The odds of bilateral CLNM were the highest in the near isthmus (OR 6.452, 95% CI: 3.658–11.379, p<0.001). In a multivariate regression model adjusting for other risk factors, near-isthmus tumors had the highest risk of bilateral CLNM (OR 7.319, 95% CI: 3.844–13.933, p<0.001), followed by lower lobe tumors (OR 2.338, 95% CI: 1.315–4.155, p=0.004) and middle lobe tumors (OR 1.845, 95% CI: 1.035–3.291, p=0.038), compared to upper lobe tumors.ConclusionTumor location is an independent risk factor in predicting the risk of bilateral CLNM. Near-isthmus tumors carry the highest risk of bilateral CLNM.

Influence of bilateral mediastinal lymph node dissection on survival in non-small cell lung cancer patients – Randomized study

ObjectivesThis study aimed to analyze the effect of bilateral mediastinal lymphadenectomy (BML) on survival of non-small cell lung cancer (NSCLC) patients. The hypothesis was: BML offers survival benefit as compared with SLND. MethodsA randomized clinical trial including stage I–IIIA NSCLC patients was performed. All patients underwent anatomical lung resection. BML was performed during the same operation via additional cervical incision (BML group). In the control group, standard lymphadenectomy (systematic lymph node dissection, SLND) was performed. ResultsIn total, 102 patients were randomized. No significant difference was found in the type of lung resection, blood loss, chest tube output, air leak, pain, and complications (p = 0.188–0.959). In the BML group, the operative time was longer (318 vs 223 min, p < 0.001) with higher number of removed N2 nodes (24 vs 14, p < 0.001). The 5-year survival rate was 72 % in the BML group vs 53 % in the SLND group (OR 2.33, 95 % CI 0.95–5.69, p = 0.062). Separate comparisons for different lobar locations of the tumor have shown no significant difference in survival for the right lung tumors and left upper lobe tumors. For the left lower lobe tumors, survival time was longer in the BML group (p = 0.021), and the 5-year survival rate was 90.9 % vs 37.5 %, (OR 16.66, 95 % CI 1.36–204.04, p = 0.0277). ConclusionsIn patients with NSCLC located in the left lower lobe, bilateral lymph node dissection may be associated with better survival. The invasiveness of BML is comparable to that of SLND.

Bronchoscopic Management of Endobronchial Atypical Carcinoid With Argon Plasma Coagulation and Laser: A Rare Case With Literature Review

Atypical carcinoid belongs to a spectrum of neuroendocrine tumors that can present as central airway obstruction. We treated a 58-year-old female who presented with recurrent pneumonia. Flexible bronchoscopy showed complete obstruction of the tumor in the right lower lobe. The tumor was excised by electrocautery snare followed by laser and argon plasma coagulation (APC). Endobronchial biopsy showed atypical carcinoid with lymph node metastasis. Succeeding bronchoscopic management, the patient’s symptoms improved. In our patient, bronchoscopy with laser and APC was performed to prevent tumor recurrence after resection and reduce the risk of recurrent postobstructive pneumonia. Surveillance computed tomography at six months showed no evidence of recurrence. Bronchoscopic management should be considered in poor surgical candidates or patients with metastatic disease.

MA12.05 Is there a Role for Surgery in Stage I Small Cell Lung Cancer? A National VA Database Analysis

Historically, limited stage Small Cell Lung Cancer (SCLC) has been treated with concurrent chemoradiation (CRT). While current NCCN guidelines recommend consideration of lobectomy in node-negative cT1-T2 SCLC, data regarding the role of surgery in very limited SCLC is lacking. To our knowledge, only one retrospective study has evaluated the role of surgery in stage I SCLC. Data from the National VA Cancer Cube were compiled. A total of 1,028 patients with pathologically confirmed Stage I SCLC were studied. Only 661 patients that either received surgery or CRT were included. Interval-censored Weibull and Cox proportional hazard regression models were used to estimate median overall survival (OS) and hazard ratio (HR), respectively. Two survival curves were compared by a Wald test. Subset analysis was performed based on the location of the tumor in the upper vs lower lobe as delineated by ICD-10 codes C34.1 and C34.3. Four-hundred and forty-two patients received concurrent CRT; while 219 underwent treatment that contained surgery (92 surgery only, 84 surgery/chemo, 39 surgery/chemo/radiation and 4 surgery/radiation). The median OS for the surgery-inclusive treatment was 3.87 years (95% CI 3.25-4.60) while median OS for the CRT cohort was 2.43 years (95% CI 2.15-2.72). HR of death for surgery-inclusive treatment when compared to CRT is 0.65 (95% CI 0.54-0.79; p<0.001). Subset analysis based on the location of the tumor in upper lobe and lower lobe showed improved survival with surgery as compared to CRT regardless of the location. HR for upper lobe was 0.61 (95% CI 0.48-0.78; p<0.001) and lower lobe 0.60 (95% CI 0.41-0.87; p=0.007). Multivariable regression analysis accounting for age and ECOG-PS shows a HR 0.60 (95% CI 0.42-0.85; p=0.004) favoring surgery. Surgery was used in less than a third of patients with stage I SCLC who received treatment. Surgery-inclusive multimodality treatment was associated with a longer overall survival as compared to chemoradiation, independent of age, performance status or tumor location. Our study suggests a more expansive role for surgery in stage I SCLC.

Correlation between spread through air spaces (STAS) and other clinicopathological parameters in lung cancer

Background“Spread through airspace” (STAS) is defined as micropapillary clusters, solid nests or single cells of tumor extending beyond the edge of the tumor into the air spaces of the surrounding lung parenchyma. It is associated with reduced overall survival and disease-free survival. Assessment of STAS in lung cancer appears to be necessary to guide clinical interventions. However, data on the correlation between the status of STAS and other lung cancer clinicopathological parameters are scarce. MethodsWe reviewed 240 resected lung cancers and investigated the clinical significance of STAS in relation to other relevant lung cancer clinicopathological variables. We performed univariate and multivariate logistic regression analyses with STAS as a dependent variable. ResultsOf the total 240 patients, STAS was observed in 67 (27.9 %) of them. STAS is highly prevalent in adenocarcinoma with a micropapillary growth pattern (70.0 %) than in other lung cancer growth patterns. STAS was frequently reported in wedge resections (31.0%) than in lobectomy specimens (26.7 %). STAS was significantly associated with advanced pN stage (p < 0.001) and lymphovascular invasion (p = 0.005). In multivariate models, we found that lung cancers in the right lower lobe (RLL) (OR, 2.674; 95 % CI = 1.313−5.448, p = 0.007), micropapillary lung cancer growth pattern (OR = 5.199, 95 % CI = 1.220−22.162, p = 0.026), and pN2 stage (OR = 3.683, 95 % CI = 1.324−10.245, p = 0.013) serve as independent predictors for STAS. ConclusionOur findings suggest that the presence of STAS is associated with right lower lobe tumors, micropapillary adenocarcinoma, and pN2 tumor stage. Hence, it could serve as one of the prognostically significant histologic findings in lung cancer. It is thus valid to mandate reporting STAS status in CAP surgical pathology lung cancer case summaries.