scholarly journals Anatomical resections are superior to wedge resections for overall survival in patients with Stage 1 typical carcinoids†

2018 ◽  
Vol 55 (2) ◽  
pp. 273-279 ◽  
Author(s):  
Pier Luigi Filosso ◽  
Francesco Guerrera ◽  
Nicola Rosario Falco ◽  
Pascal Thomas ◽  
Mariano Garcia Yuste ◽  
...  
Keyword(s):  
Overall Survival ◽  
Propensity Score ◽  
Surgical Procedure ◽  
Propensity Scores ◽  
Cox Model ◽  
Wedge Resection ◽  
Hazard Ratio ◽  
Shared Frailty ◽  
Stage 1 ◽  
The Impact

Abstract OBJECTIVES Typical carcinoids (TCs) are rare, slow-growing neoplasms, usually characterized by satisfactory surgical outcomes. Due to the rarity of TCs, international guidelines for the management of particular clinical presentations currently do not exist. In particular, non-anatomical resections (wedges) are sometimes advocated for Stage 1 TCs because of their indolent behaviour. The aim of this paper was to evaluate the most effective type of surgery for Stage 1 TCs, using the European Society of Thoracic Surgeons retrospective database of the Neuroendocrine Tumors of the Lung Working Group. METHODS We analysed the effect of surgical procedure on the survival of patients with Stage 1 TCs. Overall survival (OS) was calculated from the date of intervention. The cumulative incidence of cause-specific death (tumour- and non-tumour-related) was also estimated. The impact of the surgical procedure (i.e. lobectomy vs segmentectomy vs wedge resection) on survival was investigated using the Cox model with shared frailty (for OS, accounting for the within-centre correlation) and the Fine and Gray model (for cause-specific mortality) using the approach based on the multinomial propensity score. Effects were estimated including in the model the logit-transformed propensity scores of segmentectomy and wedge resection as covariates. RESULTS A total of 876 patients with Stage 1 TCs (569 women, 65%) were included in this study. The median age was 60 years (interquartile range 47–69). At the last follow-up, 66 patients had died: The 5-year OS rate was 94.3% [95% confidence interval (CI) 92.2–95.9]. The 5-year cumulative incidences of tumour- and non-tumour-related deaths were 2.4% (95% CI 1.4–3.9) and 3.9% (95% CI 2.5–5.6%), respectively. The analysis performed using the multinomial propensity score approach confirmed the significantly worse survival of patients treated with a wedge resection compared to those treated with a lobectomy (hazard ratio 2.01, 95% CI 1.09–3.69; P = 0.024). Similar effects of wedge resection are detectable for cause-specific deaths: tumour-related (hazard ratio 2.28, 95% CI 0.86–6.02; P = 0.096) and non-tumour-related (hazard ratio 1.74, 95% CI 0.89–3.40; P = 0.105). CONCLUSIONS In a large cohort of patients, we were able to demonstrate the superiority of anatomical surgical resection in Stage 1 TCs in terms of OS. This result should therefore be considered for future clinical guidelines for the management of TCs.

Maintenance Thalidomide May Improve Progression Free but Not Overall Survival; Results from the Myeloma IX Maintenance Randomisation

Blood ◽  
2008 ◽  
Vol 112 (11) ◽  
pp. 656-656 ◽  
Author(s):  
Gareth J Morgan ◽  
Graham H Jackson ◽  
Faith E Davies ◽  
Mark T Drayson ◽  
Roger G Owen ◽  
...  
Keyword(s):  
Overall Survival ◽  
Recovery Time ◽  
Cell Clone ◽  
Cox Model ◽  
Continuous Variable ◽  
Hazard Ratio ◽  
High Dose ◽  
Prognostic Features ◽  
Significant Difference ◽  
The Impact

Abstract The role of maintenance therapy for the long term control of the plasma cell clone in patients induced into response with either intensive or conventional treatment is an important outstanding question. We addressed this in the MRC Myeloma IX study which incorporates intensive and non-intensive pathways selected according to PS and age. In the intensive pathway patients were randomised to either CTD or CVAD induction, followed by High Dose Melphalan (HDM) before being randomised to either thalidomide or no maintenance. In the non-intensive pathway patients were randomised to either MP or attenuated CTD prior to the maintenance randomisation. For patients randomised to thalidomide it was initiated at d100 following HDM or at the end of induction in the non-intensive arm with the aim of delivering 100mg daily until relapse. A dose reduction algorithm for side effects was used. Between the years of 2003–8, 820 patients were entered into the maintenance randomisation, median age 64 (intensive 59, non-intensive 73), median follow-up 32 months. Prognostic features were evenly distributed between the arms. FISH and cytogenetics were done using standard methods. Response was assessed by IWG criteria. For overall survival (OS) there was a non-significant trend in favour of the no maintenance arm, which enables us, by calculating confidence limits on the hazard ratio, to make the assertion that no maintenance could be up to 7% worse than thalidomide at 5 years (p=.005). Further analysis showed that there was no significant difference in OS in either the intensive or the non-intensive arm. The duration of time on thalidomide maintenance appeared to make no difference to OS. There was a non-significant improvement in progression free survival (PFS) across the maintenance randomisation as a whole and in the intensive pathway a significant benefit of maintenance was seen in the patients achieving less than a VGPR post initial induction therapy prior to HDM, (hazard ratio 1.9, p=.007). This PFS difference did not translate into a survival benefit because the survival after progression in the PR patients receiving maintenance thalidomide was poor (p=.002). In addition we looked at the time spent off thalidomide, the recovery time, (the time between stopping thalidomide and progression) as a possible predictor of survival after progression. Treated as a continuous variable in the Cox model this showed a trend for longer survival after relapse in those with longer recovery time (p=.056). In the non-intensive pathway a similar but less pronounced effect of thalidomide maintenance on PFS was seen. These results are consistent with a consolidation rather than a maintenance effect for thalidomide in this setting. The impact of maintenance in different cytogenetic subgroups was also determined [17p-, 13q-, 14q abnormalities including t(4;14), t(14;16), t(6;14), t(14;20) and t(11;14)]. For the 17p- group, the difference in OS between no thalidomide and thalidomide is large (HR = 4.55, p=.02) with the thalidomide patients faring worse, although this is based on only 30 patients. For the non 17p- group there is no difference in PFS (HR = 1.24, p=.37), in the 17p- group, however, the PFS is worse. In addition, of the 22, 17p- patients receiving CTD or CTDa as initial therapy, the 10 who received no thalidomide maintenance are all still alive, whereas 9/12 of those who went on to receive thalidomide maintenance have died. It seems that thalidomide given at induction and again in maintenance, may be particularly detrimental in 17p- patients. Although thalidomide maintenance may improve PFS, there is no demonstrable benefit on OS. It is important to identify 17p- in order to exclude these patients from receiving thalidomide maintenance.

Comparative effectiveness of adjuvant chemotherapy (AC) versus observation in patients with ≥ pT3 and/or pN+ bladder cancer (BCa).

2015 ◽  
Vol 33 (7_suppl) ◽  
pp. 292-292 ◽  
Author(s):  
Matt D. Galsky ◽  
Kristian Stensland ◽  
Erin L. Moshier ◽  
John Sfakianos ◽  
Russell Bailey McBride ◽  
...  
Keyword(s):  
Sensitivity Analysis ◽  
Overall Survival ◽  
Propensity Score ◽  
Survival Data ◽  
Comparative Effectiveness ◽  
Propensity Scores ◽  
Proportional Hazards ◽  
Private Insurance ◽  
Cox Proportional Hazards ◽  
The Impact

292 Background: Though Level I evidence supports the use of neoadjuvant chemotherapy (NAC) in BCa, the data supporting AC has been mixed. Experience suggests an adequately powered trial to definitively assess the role of AC is unlikely to be completed. Alternative approaches to evidence development are necessary. Methods: Patients who underwent cystectomy for ≥pT3 and/or pN+ M0 BCa were identified from the National Cancer Database. Patients who received NAC and/or diagnosed after 2006 (most recent year with survival data) were excluded. Logistic regression was used to calculate propensity scores representing the predicted probabilities of assignment to AC versus observation based on: age, demographics, year of diagnosis, pT stage, margin status, lymph node density, distance to hospital, hospital cystectomy volume, and hospital type and location. A propensity score-matched cohort of AC versus observation (1:2) patients was created. Stratified Cox proportional hazards regression was used to estimate the hazard ratio (HR) for overall survival for the matched sample while propensity score adjusted and inverse probability of treatment weighted proportional hazards models were used to estimate adjusted HR for the full sample. A sensitivity analysis examined the impact of comorbidities. Results: 3,294 patients undergoing cystectomy alone and 937 patients undergoing cystectomy plus AC met inclusion criteria.Patients receiving AC were significantly more likely to: be younger, have more lymph nodes examined and involved, have higher pT stage, have positive margins, reside in the Northeast and closer to the hospital, and have private insurance. AC was associated with improved overall survival (Table). The results were robust to sensitivity analysis for comorbidities. Conclusions: AC was associated with improved survival in patients with ≥pT3 and/or pN+ BCa in this large comparative effectiveness analysis. [Table: see text]

scholarly journals Procedural times in early non-intubated VATS program - a propensity score analysis

2021 ◽  
Vol 21 (1) ◽  
Author(s):  
Isabella Metelmann ◽  
Johannes Broschewitz ◽  
Uta-Carolin Pietsch ◽  
Gerald Huschak ◽  
Uwe Eichfeld ◽  
...  
Keyword(s):  
Propensity Score ◽  
Surgical Procedure ◽  
Recovery Time ◽  
Propensity Score Analysis ◽  
Wedge Resection ◽  
University Hospital ◽  
Implementation Phase ◽  
Score Analysis ◽  
Significant Difference ◽  
Procedural Time

Abstract Background Non-intubated video-assisted thoracic surgery (NiVATS) has been introduced to surgical medicine in order to reduce the invasiveness of anesthetic procedures and avoid adverse effects of intubation and one-lung ventilation (OLV). The aim of this study is to determine the time effectiveness of a NiVATS program compared to conventional OLV. Methods This retrospective analysis included all patients in Leipzig University Hospital that needed minor VATS surgery between November 2016 and October 2019 constituting a NiVATS (n = 67) and an OLV (n = 36) group. Perioperative data was matched via propensity score analysis, identifying two comparable groups with 23 patients. Matched pairs were compared via t-Test. Results Patients in NiVATS and OLV group show no significant differences other than the type of surgical procedure performed. Wedge resection was performed significantly more often under NiVATS conditions than with OLV (p = 0,043). Recovery time was significantly reduced by 7 min (p = 0,000) in the NiVATS group. There was no significant difference in the time for induction of anesthesia, duration of surgical procedure or overall procedural time. Conclusions Recovery time was significantly shorter in NiVATS, but this effect disappeared when extrapolated to total procedural time. Even during the implementation phase of NiVATS programs, no extension of procedural times occurs.

Propensity score specification for optimal estimation of average treatment effect with binary response

2020 ◽  
Vol 29 (12) ◽  
pp. 3623-3640
Author(s):  
John A Craycroft ◽  
Jiapeng Huang ◽  
Maiying Kong
Keyword(s):  
Propensity Score ◽  
Treatment Effect ◽  
Propensity Scores ◽  
Optimal Estimation ◽  
Theoretical Explanation ◽  
Average Treatment Effect ◽  
Adaptive Lasso ◽  
Confounding Bias ◽  
Average Treatment ◽  
The Impact

Propensity score methods are commonly used in statistical analyses of observational data to reduce the impact of confounding bias in estimations of average treatment effect. While the propensity score is defined as the conditional probability of a subject being in the treatment group given that subject’s covariates, the most precise estimation of average treatment effect results from specifying the propensity score as a function of true confounders and predictors only. This property has been demonstrated via simulation in multiple prior research articles. However, we have seen no theoretical explanation as to why this should be so. This paper provides that theoretical proof. Furthermore, this paper presents a method for performing the necessary variable selection by means of elastic net regression, and then estimating the propensity scores so as to obtain optimal estimates of average treatment effect. The proposed method is compared against two other recently introduced methods, outcome-adaptive lasso and covariate balancing propensity score. Extensive simulation analyses are employed to determine the circumstances under which each method appears most effective. We applied the proposed methods to examine the effect of pre-cardiac surgery coagulation indicator on mortality based on a linked dataset from a retrospective review of 1390 patient medical records at Jewish Hospital (Louisville, KY) with the Society of Thoracic Surgeons database.

Neoadjuvant Therapy Followed by Resection Versus Upfront Resection for Resectable Pancreatic Cancer: A Propensity Score Matched Analysis

2017 ◽  
Vol 35 (5) ◽  
pp. 515-522 ◽  
Author(s):  
Ali A. Mokdad ◽  
Rebecca M. Minter ◽  
Hong Zhu ◽  
Mathew M. Augustine ◽  
Matthew R. Porembka ◽  
...  
Keyword(s):  
Overall Survival ◽  
Propensity Score ◽  
Adjuvant Therapy ◽  
Neoadjuvant Therapy ◽  
Pancreatic Adenocarcinoma ◽  
Early Stage ◽  
Clinical Stage ◽  
Pancreatic Head ◽  
Hazard Ratio ◽  
Stage I

Purpose To compare overall survival between patients who received neoadjuvant therapy (NAT) followed by resection and those who received upfront resection (UR)—as well as a subgroup of UR patients who also received adjuvant therapy—for early-stage resectable pancreatic adenocarcinoma. Patients and Methods Adult patients with resected, clinical stage I or II adenocarcinoma of the head of the pancreas were identified in the National Cancer Database from 2006 to 2012. Patients who underwent NAT followed by curative-intent resection were matched by propensity score with patients whose tumors were resected upfront. Overall survival was compared by using a Cox proportional hazards regression model. Early postoperative and oncologic outcomes were evaluated. Results We identified 15,237 patients with clinical stage I or II resected pancreatic head adenocarcinoma. From the NAT group, 2,005 patients (95%) were matched with 6,015 patients who underwent UR. The NAT group was associated with improved survival compared with UR (median survival, 26 months v 21 months, respectively; stratified log-rank P < .01; hazard ratio, 0.72; 95% CI, 0.68 to 0.78). Patients in the UR group had higher pathologic T stage (pT3 and T4: 86% v 73%; P < .01), higher positive lymph nodes (73% v 48%; P < .01), and higher positive resection margin (24% v 17%; P < .01). Compared with a subset of UR patients who received adjuvant therapy, NAT patients had a better survival (adjusted hazard ratio, 0.83; 95% CI, 0.73 to 0.89). Conclusion NAT followed by resection has a significant survival benefit compared with UR in early-stage, resected pancreatic head adenocarcinoma. These findings support the use of NAT, particularly as a patient selection tool, in the management of resectable pancreatic adenocarcinoma.

Using Propensity Scores to Reduce Selection Bias in Mathematics Education Research

2010 ◽  
Vol 41 (2) ◽  
pp. 147-168 ◽  
Author(s):  
Suzanne E. Graham
Keyword(s):  
Education Research ◽  
Mathematics Education ◽  
Propensity Score ◽  
Selection Bias ◽  
Propensity Scores ◽  
Mathematics Education Research ◽  
Causal Inferences ◽  
Propensity Score Methods ◽  
Mathematics Classrooms ◽  
The Impact

Selection bias is a problem for mathematics education researchers interested in using observational rather than experimental data to make causal inferences about the effects of different instructional methods in mathematics on student outcomes. Propensity score methods represent 1 approach to dealing with such selection bias. This article describes general principles underlying propensity score methods and illustrates their application to mathematics education research using 2 examples investigating the impact of problem-solving emphasis in mathematics classrooms on students' subsequent mathematics achievement and course taking. Limitations of the method are discussed.

Identification and Characterization of Recurrent Venous Thrombosis In Cancer Patients

Blood ◽  
2010 ◽  
Vol 116 (21) ◽  
pp. 3328-3328
Author(s):  
Catherine Weber ◽  
Nelly G. Adel ◽  
Elyn Riedel ◽  
Gerald A. Soff
Keyword(s):  
Risk Factors ◽  
Lung Cancer ◽  
Overall Survival ◽  
Cancer Patients ◽  
Cancer Diagnosis ◽  
Hazard Ratio ◽  
Older Age ◽  
Recurrent Thrombosis ◽  
Recurrent Vte ◽  
The Impact

Abstract Abstract 3328 Background: Venous thromboembolism (VTE) is a common cause of morbidity and mortality in cancer patients. Standard of care for treatment is Low Molecular Weight Heparin, but recurrence of VTE remains a concern. We performed a retrospective analysis of our institutional experience, to characterize the patients who had a recurrence of VTE while on therapeutic doses of Dalteparin. Objectives: 1. To determine the VTE recurrence rate for cancer patients on therapeutic Dalteparin. 2. To elucidate potential risk factors for recurrence. 3. To determine the impact of recurrent VTE on overall survival. Methods: Patients beginning treatment for VTE with dalteparin between 1/1/2008 and 12/10/ 2009 were retrospectively identified through the hospital's electronic medical records system and cases of recurrent VTE were characterized. Overall survival was estimated using the Kaplan-Meier method and the influence of VTE recurrence on overall survival was analyzed as a time-dependent covariate using a Cox proportional hazards model. Results: 1,392 patients, treated for VTE with dalteparin were included in this study. 34 recurrent VTE episodes were identified. The overall incidence of recurrent thrombosis by six months was 2.3% (95% CI: 1.7%-3.3%). Older age was significantly associated with recurrence (p=0.04). Lung cancer patients had a significantly elevated risk of recurrence (5.6%, p=0.03). No other cancer types were associated with a significant trend to increased recurrent VTE rates. The incidence of recurrent VTE was higher among females compared to males (3.0% vs. 1.6%), although this trend was not statistically significant (P = 0.08). After adjusting for gender, sex and cancer diagnosis, developing a recurrent VTE was associated with a 3.0-fold hazard ratio of death (<0.0001). Conclusions: The rate of recurrent VTE in cancer patients at MSKCC is low in comparison with previously published reports. However, we identified both older age and lung cancer diagnosis as statistically significant risk factors for recurrent VTE. Females also experienced a higher rate of recurrent thrombosis when compared to males, although this result was not statistically significant. The hazard ratio for death was three times that for a patient with recurrent thrombosis when compared to one without subsequent VTE, suggesting recurrence of VTE remains an important influence on cancer-associated mortality. Disclosures: No relevant conflicts of interest to declare.

Propensity score–based comparison of outcomes with 3D conformal radiotherapy (3D-CRT) versus intensity-modulated radiation therapy (IMRT) in treatment of esophageal cancer.

2012 ◽  
Vol 30 (4_suppl) ◽  
pp. 66-66
Author(s):  
Steven H. Lin ◽  
Bevan H Myles ◽  
Lu Wang ◽  
Peter F. Thall ◽  
Ara A. Vaporciyan ◽  
...  
Keyword(s):  
Esophageal Cancer ◽  
Propensity Score ◽  
Propensity Scores ◽  
Cox Model ◽  
Performance Status ◽  
Potential Bias ◽  
Current Standard ◽  
Radiation Technology ◽  
Esophageal Cancers ◽  
3D Crt

66 Background: Although 3D-CRT is the current standard for treatment of esophageal cancers, IMRT improves dose conformality and reduces radiation exposure to normal tissue. There is no assessment of long term clinical outcomes comparing these two modalities. Methods: Between 1998-2008, 676 patients (3D-CRT=413, IMRT=263) with stage Ib-IVa (AJCC 2002 edition) esophageal cancers were treated with chemoradiation with or without surgery. To correct for potential bias inherent in observational studies, we employed inverse probability of treatment weighted (IPW) methods based on propensity scores. IPW survival plots and IPW log rank tests were used to adjust for potential bias in treatment selection. Treatment probabilities (propensity scores) were estimated using logistic regression. Results: IMRT patients were less likely to receive induction chemotherapy (35.7% vs 46.7%, p<0.01) and had poorer performance status (KPS≤80: 66.5% vs 50.0%, p<0.01). A fitted multivariate IPW-adjusted Cox model showed that overall survival was significantly associated with age (HR 1.10 for 10 years older, p=0.02), KPS (≤70 vs 90-100, HR 1.5, p=0.0002), having surgery (HR 0.56, p<0.0001), lower vs upper esophagus (HR 1.4, p=0.009), stage (3-4a vs 1-2, HR 2.6, p<0.01), and radiation modality (IMRT vs 3D-CRT, HR 0.68, p<0.0001). 3D-CRT patients had a greater risk of dying at 5 years compared to IMRT (72.6% vs 52.9%, p<0.0001) without a difference in cancer-specific mortality (Gray’s test p=0.86), time to local recurrence (p=0.27) or distant metastasis (p=0.13). Cumulative incidence of documented cardiac deaths trended higher in the 3D-CRT group (p=0.16), but most deaths were due to unknown causes (5 year estimate: 13.4% in 3D-CRT vs 4.2% in IMRT, Gray’s test p<0.0001). Analyses using propensity score as a covariate gave very similar results. Conclusions: There was a substantially higher risk of non-cancer related deaths in 3D-CRT versus IMRT. While the true cause of death cannot be determined for many 3D-CRT patients, our results suggest that improvements in radiation technology may improve treatment-related mortality in management of esophageal cancer.

An updated overall survival analysis with correction for protocol-planned crossover of the international, phase III, randomized, placebo-controlled trial of regorafenib in advanced gastrointestinal stromal tumors after failure of imatinib and sunitinib (GRID).

2015 ◽  
Vol 33 (3_suppl) ◽  
pp. 110-110 ◽  
Author(s):  
George D. Demetri ◽  
Peter Reichardt ◽  
Yoon-Koo Kang ◽  
Jean-Yves Blay ◽  
Heikki Joensuu ◽  
...  
Keyword(s):  
Overall Survival ◽  
Failure Time ◽  
Cox Model ◽  
Controlled Trial ◽  
Progression Free Survival ◽  
High Rate ◽  
Phase Iii ◽  
Primary Analysis ◽  
Significant Difference ◽  
The Impact

110 Background: The GRID study showed that regorafenib improves progression-free survival compared with placebo in patients with advanced GIST after failure of at least imatinib and sunitinib (HR 0.27; 1-sided p<0.0001; Demetri 2013). At the time of the primary analysis, no significant difference in the secondary endpoint of overall survival (OS) was observed (HR 0.77; p=0.199), but this result may have been confounded by the high rate of crossover to regorafenib (85%) of placebo patients at progression. We conducted exploratory analyses of updated OS data to assess the effect of correcting for this protocol-planned crossover. Methods: The data cut-off for this updated OS analysis was 31 January 2014 (2 years after the primary analysis). OS was corrected using two randomization-based methods: rank preserving structural failure time (RPSFT) and iterative parameter estimation (IPE); both methods are considered as best choice among all correction analytics. Hazard ratios and 95% CI were derived using the Cox model. Results: A total of 139 deaths had occurred at the time of data cut-off: 91 events (68.4% of patients) in the regorafenib group and 48 (72.7%) in the placebo group. A total of 22 patients remained on regorafenib treatment (median duration 2.1 years, range 0.9–2.4). The updated hazard ratio for OS favored regorafenib (0.85, 95% CI: 0.60 - 1.21; p=0.18). Median OS was estimated as 17.4 months in both groups, with crossover from placebo. The corrected HRs for OS are less than the uncorrected HR (Table). Conclusions: The updated analysis of OS in the GRID trial is consistent with the primary analysis. An exploratory analysis correcting for the impact of cross-over on OS suggests a survival benefit for regorafenib in GIST. Clinical trial information: NCT01271712. [Table: see text]

Neoadjuvant therapy for localized gastrointestinal stromal tumors (GISTs): A propensity score weighted analysis.

2020 ◽  
Vol 38 (15_suppl) ◽  
pp. e23516-e23516
Author(s):  
Kathryn E. Marqueen ◽  
Erin Moshier ◽  
Michael Buckstein ◽  
Celina Ang
Keyword(s):  
Overall Survival ◽  
Logistic Regression ◽  
Propensity Score ◽  
Survival Benefit ◽  
Postoperative Mortality ◽  
Phase Iii ◽  
R0 Resection ◽  
Treatment Groups ◽  
Significant Difference ◽  
The Impact

e23516 Background: Retrospective and single-arm prospective studies have reported clinical benefit associated with receipt of neoadjuvant imatinib for GISTs. In the absence of randomized phase III data, the impact of neoadjuvant systemic therapy (NAT) on survival, in comparison to upfront resection, remains unknown. Methods: We identified N = 14,402 patients with complete clinical, demographic, treatment and pathologic data within the National Cancer Database (2004-2016) who underwent resection of localized GIST of the stomach, esophagus, small bowel, and colorectum, with or without ≥3 months of NAT. Inverse probability of treatment weighting (IPTW) was used to adjust for covariable imbalance among treatment groups, with the propensity score estimated by logistic regression. The effect of NAT on overall survival was estimated with a weighted time-dependent Cox proportional hazards model. A weighted logistic regression was used to estimate the effect of NAT on 90-day postoperative mortality and R0 resection. Results: 759 (5.3%) patients received NAT followed by resection, compared to 13,643 (94.7%) who underwent upfront resection. Median length of NAT was 6.3 months. 53% of NAT patients were male vs. 49% of UR patients, 68% vs. 66% had primary gastric GIST, and 73% vs 49% were high risk. Patients receiving NAT had larger tumors (p < 0.001) and higher mitotic index (p = 0.003). There was a significant survival benefit associated with receipt of NAT (table). 90-day postoperative mortality rate was 3/759 (0.4%) among NAT patients vs. 307/13,643 (2.3%) UR patients. Receipt of NAT was significantly associated with lower odds of 90-day postoperative mortality (table). Of the 13,562 patients with information on margin status, the R0 resection rate was 635/716 (88.7%) for the neoadjuvant group vs. 11,823/12,846 (92%), with no significant difference between treatment groups (table). Conclusions: After adjustment for imbalance in prognostic and demographic factors, this analysis demonstrates that receipt of NAT for localized GIST is associated with a modest overall survival benefit. Although NAT patients had higher risk features, NAT was associated with a lower risk of 90-day postoperative mortality, with no difference in likelihood of achieving an R0 resection. [Table: see text]

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