Interobserver Variability in the International Study Group for Pancreas Surgery (ISGPS)-Defined Complications After Pancreatoduodenectomy: An International Cross-Sectional Multicenter Study.

OBJECTIVE: To determine the interobserver variability for complications of pancreatoduodenectomy as defined by the International Study Group for Pancreatic Surgery (ISGPS) and others. SUMMARY BACKGROUND DATA: Good interobserver variability for the definitions of surgical complications is of major importance in comparing surgical outcomes between and within centers. However, data on interobserver variability for pancreatoduodenectomy-specific complications are lacking. METHODS: International cross-sectional multicenter study including 52 raters from 13 high-volume pancreatic centers in 8 countries on 3 continents. Per center, 4 experienced raters scored 30 randomly selected patients after pancreatoduodenectomy. In addition, all raters scored six standardized case vignettes. This variability and the 'within centers' variability were calculated for twofold scoring (no complication/grade A vs grade B/C) and threefold scoring (no complication/grade A vs grade B vs grade C) of postoperative pancreatic fistula (POPF), post-pancreatoduodenectomy hemorrhage (PPH), chyle leak (CL), bile leak (BL), and delayed gastric emptying (DGE). Interobserver variability is presented with Gwet's AC-1 measure for agreement. RESULTS: Overall, 390 patients after pancreatoduodenectomy were included. The overall agreement rate for the standardized cases vignettes for twofold scoring was 68% (95%-CI: 55%-81%, AC1 score: moderate agreement) and for threefold scoring 55% (49%-62%, AC1 score: fair agreement). The mean 'within centers' agreement for twofold scoring was 84% (80%-87%, AC1 score; substantial agreement). CONCLUSION: The interobserver variability for the ISGPS defined complications of pancreatoduodenectomy was too high even though the 'within centers' agreement was acceptable. Since these findings will decrease the quality and validity of clinical studies, ISGPS has started efforts aimed at reducing the interobserver variability.

Evolution of Initial Treatment for Desmoid Tumors.

INTRODUCTION: Desmoid tumors (DTs) are rare, fibroblastic cell proliferations that can exhibit locally aggressive behavior but lack metastatic potential. Initial management has traditionally involved upfront resection; however, contemporary guidelines and expert panels have increasingly advocated for prioritizing active surveillance strategies. METHODS: A single-institution, retrospective chart review identified all patients diagnosed with a primary DT at any site from 2007 to 2020. The primary outcome was the initial management strategy over time. Secondary outcomes included treatment-free survival (TFS) and time to treatment (TTT) for those undergoing active surveillance, as well as recurrence-free survival (RFS) and time to recurrence for those undergoing resection. RESULTS: Overall, 103 patients were included, with 68% female and a median follow-up of 44 months [24-74]. The most common tumor locations included the abdominal wall (27%), intra-abdominal/mesenteric (25%), chest wall (19%), and extremity (10%). Initial management included resection (60%), systemic therapy (20%), active surveillance (18%), and cryoablation (2%). Rates of surgical resection significantly decreased (p < 0.001) over time, from 69.6% prior to 2018 to 29.2% after 2018. For those treated with upfront resection, 5-year RFS was 41.2%, and for patients undergoing initial active surveillance, TFS was 66.7% at 2 years, with a median TTT of 4 months [4-10]. CONCLUSIONS: This single-institution cohort at a tertiary medical center spanning over a decade demonstrates the transition to active surveillance for initial management of DTs, and highlights salient metrics in the era of surveillance. This trend mirrors recommended treatment strategies by expert panels and consensus guidelines.

Mediator kinase inhibition impedes transcriptional plasticity and prevents resistance to ERK/MAPK-targeted therapy in KRAS-mutant cancers.

Acquired resistance remains a major challenge for therapies targeting oncogene activated pathways. KRAS is the most frequently mutated oncogene in human cancers, yet strategies targeting its downstream signaling kinases have failed to produce durable treatment responses. Here, we developed multiple models of acquired resistance to dual-mechanism ERK/MAPK inhibitors across KRAS-mutant pancreatic, colorectal, and lung cancers, and then probed the long-term events enabling survival against this class of drugs. These studies revealed that resistance emerges secondary to large-scale transcriptional adaptations that are diverse and cell line-specific. Transcriptional reprogramming extends beyond the well-established early response, and instead represents a dynamic, evolved process that is refined to attain a stably resistant phenotype. Mechanistic and translational studies reveal that resistance to dual-mechanism ERK/MAPK inhibition is broadly susceptible to manipulation of the epigenetic machinery, and that Mediator kinase, in particular, can be co-targeted at a bottleneck point to prevent diverse, cell line-specific resistance programs.

Contemporary trends and outcomes after liver transplantation and resection for intrahepatic cholangiocarcinoma.

BACKGROUND: Liver transplantation (LT) has been shown to be superior to resection in highly selected patients with perihilar cholangiocarcinoma (CCA), yet has traditionally been contraindicated for intrahepatic CCA (iCCA). Herein, we aimed to examine contemporary trends and outcomes for surgical resection and LT for iCCA. METHODS: The National Cancer Database was queried for patients presenting with stage I-III iCCA between 2010 and 2018 who underwent resection or LT. Overall survival (OS) was compared with Kaplan-Meier and multivariable Cox proportional hazards methods stratified by management. Secondary analysis of patients undergoing transplant for CCA was performed with the United Network for Organ Sharing database. RESULTS: Of 2565 patients, 2412 (94.0%) underwent resection and 153 (5.96%) LT of whom 84 (54.9%) received neoadjuvant therapy. Utilization of LT remained between 3.9% and 7.8% annually. Unadjusted 5-year OS was higher for LT than resection (59.8% vs 39.9%, P = .0067), yet adjusted analysis revealed no significant difference in mortality (hazard ratio, 0.91; 95% CI, 0.66-1.27; P = .58). On secondary analysis including 437 patients with all subtypes of CCA, unadjusted 5-year OS was higher for non-CCA indications (79% vs 52%-54%, P < .001). CONCLUSION: Utilization of LT for iCCA remains low and many cases are likely incidental. Although partial hepatectomy remains the standard of care for patients with resectable disease, our findings suggest that highly selected patients with unresectable iCCA may achieve favorable outcomes after LT. Granular, prospective data are needed to identify patients most likely to benefit from transplant and allocate scarce liver grafts.

Comprehensive Assessment of the Intrinsic Pancreatic Microbiome.

OBJECTIVE: We sought to comprehensively profile tissue and cyst fluid in patients with benign, precancerous, and cancerous conditions of the pancreas to characterize the intrinsic pancreatic microbiome. SUMMARY BACKGROUND DATA: Small studies in pancreatic ductal adenocarcinoma (PDAC) and intraductal papillary mucinous neoplasm (IPMN) have suggested that intra-pancreatic microbial dysbiosis may drive malignant transformation. METHODS: Pancreatic samples were collected at the time of resection from 109 patients. Samples included tumor tissue (control, n=20; IPMN, n=20; PDAC, n=19) and pancreatic cyst fluid (IPMN, n=30; SCA, n=10; MCN, n=10). Assessment of bacterial DNA by quantitative PCR and 16S ribosomal RNA gene sequencing was performed. Downstream analyses determined the relative abundances of individual taxa between groups and compared intergroup diversity. Whole-genome sequencing data from 140 patients with PDAC in the National Cancer Institute's Clinical Proteomic Tumor Analysis Consortium (CPTAC) were analyzed to validate findings. RESULTS: Sequencing of pancreatic tissue yielded few microbial reads regardless of diagnosis, and analysis of pancreatic tissue showed no difference in the abundance and composition of bacterial taxa between normal pancreas, IPMN, or PDAC groups. Low-grade dysplasia (LGD) and high-grade dysplasia (HGD) IPMN were characterized by low bacterial abundances with no difference in tissue composition and a slight increase in Pseudomonas and Sediminibacterium in HGD cyst fluid. Decontamination analysis using the CPTAC database confirmed a low-biomass, low-diversity intrinsic pancreatic microbiome that did not differ by pathology. CONCLUSIONS: Our analysis of the pancreatic microbiome demonstrated very low intrinsic biomass that is relatively conserved across diverse neoplastic conditions and thus unlikely to drive malignant transformation.

Simple versus radical cholecystectomy and survival for pathologic stage T1B gallbladder cancer.

BACKGROUND: Radical cholecystectomy is recommended for T1B and greater gallbladder cancer, however, there are conflicting reports on the utility of extended resection for T1B disease. Herein, we characterize outcomes following simple and radical cholecystectomy for pathologic stage T1B gallbladder cancer. METHODS: The National Cancer Database (NCDB) was queried for patients with pathologic T1B gallbladder cancer diagnosed from 2004 to 2018. Patients were stratified by surgical management. Overall survival (OS) was compared with Kaplan-Meier and multivariable Cox proportional hazards methods. RESULTS: Altogether, 950 patients were identified with pathologic T1B gallbladder cancer: 187 (19.7 %) receiving simple and 763 (80.3 %) radical cholecystectomy. Median OS was 89.5 (95 % CI 62.5-137) and 91.4 (95 % CI 75.9-112) months for simple and radical cholecystectomy, respectively (log-rank p = 0.55). Receipt of simple cholecystectomy was not associated with greater hazard of mortality compared to radical cholecystectomy (HR 1.23, 95 % CI 0.95-1.59, p = 0.12). DISCUSSION: In this analysis, we report comparable outcomes with simple cholecystectomy among patients with pathologic T1B gallbladder cancer. These findings suggest that highly selected patients, such as those with R0 resection and imaging at low risk for residual disease and/or nodal metastasis, may not benefit from extended resection; however, radical cholecystectomy remains standard of care until prospective validation can be achieved.

Initial Report: Personalized Circulating Tumor DNA and Survival in Patients with Resectable Pancreatic Cancer.

ABSTRACT: BACKGROUND: Pancreatic adenocarcinoma (PDAC) is highly lethal with up to 80% of resected patients experiencing disease recurrence within 2 years (Watanabe, Nakamura, Kimura et al in Int J Mol Sci 23(19):11521, 2022). Cross-sectional imaging and serum tumor markers are used for monitoring post-operative recurrence; however, both have significant limitations (Edland, Tjensvoll, Oltedal et al in Mol Oncol 17:1857-1870, 2023). Circulating tumor DNA (ctDNA) has emerged as a valuable prognostic tool to measure molecular residual disease (MRD) and predict recurrence in solid tumors (Watanabe, Nakamura, Kimura et al in Int J Mol Sci 23(19):11521, 2022). In this study, we evaluated the feasibility of a personalized, tumor-informed ctDNA assay to detect recurrence prior to standard surveillance tools in patients with PDAC. PATIENTS AND METHODS: After Institutional Review Board (IRB) approval (Pro00106870), we assessed serial ctDNA measurements (n = 177) from 35 patients with resectable PDAC treated by either upfront resection or neoadjuvant chemotherapy. Plasma samples (median 4 ml, interquartile range 0.6-5.9 ml) were isolated from blood collected in EDTA tubes and banked at diagnosis, during neoadjuvant therapy if applicable, on the day of surgery, and every 2-3 months postoperatively. A tumor-informed assay (Signatera™, Natera, Inc.) that tracks up to 16 individual-specific, somatic single nucleotide variants in the corresponding patient's plasma samples were used for ctDNA detection. Survival was calculated using Kaplan-Meier curves, and significance was determined with the log-rank test. RESULTS: Personalized ctDNA assays were successfully designed for all patients (with 32/35 patients having 16-plex assays). Median follow-up from initial treatment was 13 months (range 1-26 months; Table 1). ctDNA-positivity at any time point was observed in 40% (14/35) of patients. During the follow-up period, 18 patients (51%) developed radiographic evidence of recurrence after a median of 9 months of follow-up (range 1-26 months). At the time of radiographic recurrence, 50% (9/18) of patients were ctDNA-positive. During the immediate postoperative period (up to 9 weeks post-surgery), RFS and OS were significantly inferior in patients who were ctDNA-positive versus ctDNA-negative (RFS 97 versus 297 days, p < 0.001; OS 110 versus 381 days, p < 0.001; Fig. 1). Table 1 Cohort demographics (N = 35); patient demographics, tumor characteristics, and survival Gender (%) Female 17 (49%) Male 18 (51%) Median age (IQR) 70 years (65-75 years) Neoadjuvant treatment (%) 11 (31%) Median sample plasma volume (IQR) 4.0 mL (0.6-5.9 mL) Median follow-up (range) 13 months (1-26 months) Median initial CA 19-9 in U/mL (IQR) 56 (18-160) Median tumor size in cm (IQR) 2.5 (1.8-3.3) Median number of positive lymph nodes (IQR) 1 (0-3) Median recurrence-free survival 9.4 months Median overall survival N/A (not reached) Fig. 1 a Overview plot showing longitudinal ctDNA status, treatment regimen, and clinical outcomes for each patient (N = 35); median follow-up from the start of the neoadjuvant therapy/surgery was 13 months (range 1-26 months); ctDNA at any time point was 40% (14/35); out of the 35 patients, 18 (51%) developed radiographic evidence of recurrence (median RFS: 9 months), and of these 18 patients with clinical recurrence, 9 (50%) were ctDNA-positive and the remaining ctDNA-negative; notably, all ctDNA-negative patients with recurrence had suboptimal plasma volume available for ctDNA analysis; b, c Kaplan-Meier estimates representing the association of ctDNA status with (b) RFS and (c) OS, at MRD time point (9 weeks post-surgery) DISCUSSION: Our study demonstrates the feasibility of tumor-informed ctDNA-based MRD testing in resectable PDAC and shows that MRD detected by ctDNA within the immediate postoperative period portends a dismal prognosis. This information is valuable for both patients and clinicians in setting prognostic expectations.

Are enhanced recovery protocols after pancreatoduodenectomy still efficient when applied in elderly patients? A systematic review and individual patient data meta-analysis.

BACKGROUND: This meta-analysis investigated the effects of enhanced recovery after surgery (ERAS) protocols compared to conventional care on postoperative outcomes in patients aged 70 years or older undergoing pancreatoduodenectomy (PD). METHODS: Five databases were systematically searched. Comparative studies with available individual patient data (IPD) were included. The main outcomes were postoperative morbidity, length of stay, readmission and postoperative functional recovery elements. To assess an age-dependent effect, the group was divided in septuagenarians (70-79 years) and older patients (≥80 years). RESULTS: IPD were obtained from 15 of 31 eligible studies comprising 1109 patients. The overall complication and major complication rates were comparable in both groups (OR 0.92 [95% CI: 0.65-1.29], p = .596 and OR 1.22 [95% CI: 0.61-2.46], p = .508). Length of hospital stay tended to be shorter in the ERAS group compared to the conventional care group (-0.14 days [95% CI: -0.29 to 0.01], p = .071) while readmission rates were comparable and the total length of stay including days in hospital after readmission tended to be shorter in the ERAS group (-0.28 days [95% CI: -0.62 to 0.05], p = .069). In the subgroups, the length of stay was shorter in octogenarians treated with ERAS (-0.36 days [95% CI: -0.71 to -0.004], p = .048). The readmission rate increased slightly but not significantly while the total length of stay was not longer in the ERAS group. CONCLUSION: ERAS in the elderly is safe and its benefits are preserved in the care of even in patients older than 80 years. Standardized care protocol should be encouraged in all pancreatic centers.

Mediator Kinase Inhibition Impedes Transcriptional Plasticity and Prevents Resistance to ERK/MAPK-Targeted Therapy in KRAS-Mutant Cancers.

Acquired resistance remains a major challenge for therapies targeting oncogene activated pathways. KRAS is the most frequently mutated oncogene in human cancers, yet strategies targeting its downstream signaling kinases have failed to produce durable treatment responses. Here, we developed multiple models of acquired resistance to dual-mechanism ERK/MAPK inhibitors across KRAS-mutant pancreatic, colorectal, and lung cancers, and then probed the long-term events enabling survival against this class of drugs. These studies revealed that resistance emerges secondary to large-scale transcriptional adaptations that are diverse and cell line-specific. Transcriptional reprogramming extends beyond the well-established early response, and instead represents a dynamic, evolved process that is refined to attain a stably resistant phenotype. Mechanistic and translational studies reveal that resistance to dual-mechanism ERK/MAPK inhibition is broadly susceptible to manipulation of the epigenetic machinery, and that Mediator kinase, in particular, can be co-targeted at a bottleneck point to prevent diverse, cell line-specific resistance programs.

Tumor size and survival in intrahepatic cholangiocarcinoma treated with surgical resection or ablation.

OBJECTIVES: We performed a retrospective analysis within a national cancer registry on outcomes following resection or ablation for intrahepatic cholangiocarcinoma (iCCA). METHODS: The National Cancer Database was queried for patients with clinical stage I-III iCCA diagnosed during 2010-2018, who underwent resection or ablation. Overall survival (OS) was compared with Kaplan-Meier and multivariable Cox proportional hazards methods. RESULTS: Of 2140 patients, 1877 (87.7%) underwent resection and 263 (12.3%) underwent ablation, with median tumor sizes of 5.5 and 3 cm, respectively. Overall, resection was associated with greater median OS (41.2 months (95% confidence interval [95% CI]: 37.6-46.2) vs. 28 months (95% CI: 15.9-28.6) on univariable analysis (p < 0.0001). There was no significant difference on multivariable analysis (p = 0.42); however, there was a significant interaction between tumor size and management. On subgroup analysis of patients with tumors <3 cm, there was no difference in OS between resection versus ablation. However, ablation was associated with increased mortality for tumors ≥3 cm. CONCLUSION: Although resection is associated with improved OS for tumors ≥3 cm, we observed no difference in survival between management strategies for tumors < 3 cm. Ablation may be an alternative therapeutic strategy for small iCCA, particularly in patients at risk for high surgical morbidity.

Impact of Tumor Size and Management on Survival in Small Gastric Gastrointestinal Stromal Tumors.

BACKGROUND: Society guidelines remain inconsistent on the role of endoscopic and radiographic surveillance as an alternative to surgical resection of small gastric gastrointestinal stromal tumors (GISTs). Herein, we aimed to assess survival among patients with gastric GISTs undergoing observation versus surgical resection, stratified by tumor size. METHODS: The National Cancer Database (NCDB) was queried for gastric GISTs < 2 cm diagnosed from 2010-2017. Patients were stratified by management strategy-observation vs surgical resection. The primary outcome, overall survival (OS), was examined with Kaplan-Meier and multivariable Cox proportional hazard methods. Subgroup analyses were conducted on tumors < 1 cm and 1-2 cm in size. RESULTS: Altogether, 1208 patients were identified: 439 (36.3%) undergoing observation and 769 (63.7%) receiving surgical resection. In the overall cohort, patients undergoing surgical resection demonstrated improved survival (93.6 vs. 88.8% 5-year OS, p=0.02). In multivariable analysis, upfront surgical resection was not associated with a reduction in mortality; however, there was a significant interaction with tumor size. For patients with tumors < 1 cm, there was no difference in survival based on management strategy. However, resection of tumors 1-2 cm was associated with improved survival relative to surveillance. CONCLUSIONS: While surgical resection and surveillance were associated with similar survival for patients with gastric GISTs < 1 cm, this NCDB analysis suggests that patients with tumor size ≥ 1 cm may benefit from upfront surgical resection. Prospective studies comparing these two approaches and their impact on recurrence-free and disease-specific survival are needed to better align consensus guidelines and recommendations.

Comparing Survival After Resection, Ablation, and Radiation in Small Intrahepatic Cholangiocarcinoma.

BACKGROUND: Hepatectomy is the cornerstone of curative-intent treatment for intrahepatic cholangiocarcinoma (ICC). However, in patients unable to be resected, data comparing efficacy of alternatives including thermal ablation and radiation therapy (RT) remain limited. Herein, we compared survival between resection and other liver-directed therapies for small ICC within a national cancer registry. PATIENTS AND METHODS: Patients with clinical stage I-III ICC < 3 cm diagnosed 2010-2018 who underwent resection, ablation, or RT were identified in the National Cancer Database. Overall survival (OS) was compared using Kaplan-Meier and multivariable Cox proportional hazards methods. RESULTS: Of 545 patients, 297 (54.5%) underwent resection, 114 (20.9%) ablation, and 134 (24.6%) RT. Median OS was similar between resection and ablation [50.5 months, 95% confidence interval (CI) 37.5-73.9; 39.5 months, 95% CI 28.7-58.4, p = 0.14], both exceeding that of RT (20.9 months, 95% CI 14.1-28.3). RT patients had high rates of stage III disease (10.4% RT vs. 1.8% ablation vs. 11.8% resection, p < 0.001), but the lowest rates of chemotherapy utilization (9.0% RT vs. 15.8% ablation vs. 38.7% resection, p < 0.001). In multivariable analysis, resection and ablation were associated with reduced mortality compared with RT [hazard ratio (HR) 0.44, 95% CI 0.33-0.58 and HR 0.53, 95% CI 0.38-0.75, p < 0.001, respectively]. CONCLUSION: Resection and ablation were associated with improved survival in patients with ICC < 3 cm compared with RT. Acknowledging confounders, anatomic constraints of ablation, limitations of available data, and need for prospective study, these results favor ablation in small ICC where resection is not feasible.

Trends in Receipt of Adjuvant Chemotherapy and its Impact on Survival in Resected Biliary Tract Cancers.

BACKGROUND: Resection remains the cornerstone of curative-intent treatment for biliary tract cancers (BTCs). However, recent randomized data also support a role for adjuvant chemotherapy (AC). This study aimed to characterize trends in the use of AC and subsequent outcomes in gallbladder cancer and cholangiocarcinoma (CCA). METHODS: The National Cancer Database (NCDB) was queried for patients with resected, localized BTC from 2010 to 2018. Trends in AC were compared among BTC subtypes and stages of disease. Multivariable logistic regression was used to identify factors associated with receipt of AC. Survival analysis was performed with Kaplan-Meier and multivariable Cox proportional hazards methods. RESULTS: The study identified 7039 patients: 4657 (66%) with gallbladder cancer, 1159 (17%) with intrahepatic CCA (iCCA), and 1223 (17%) with extrahepatic CCA (eCCA). Adjuvant chemotherapy was administered to 2172 (31%) patients, increasing from 23% in 2010 to 41% in 2018. Factors associated with AC included female sex, year of diagnosis, private insurance, care at an academic center, higher education, eCCA (vs iCCA), positive margins, and stage II or III disease (vs stage I). Alternatively, increasing age, higher comorbidity score, gallbladder cancer (vs iCCA), and farther travel distance for treatment were associated with reduced odds of AC. Overall, AC was not associated with a survival advantage. However, subgroup analysis showed that AC was associated with a significant reduction in mortality among patients with eCCA. CONCLUSIONS: Among the patients with resected BTC, those who received AC were in the minority. In the context of recent randomized data and evolving recommendations, emphasis on guideline concordance with a focus on at-risk populations may improve outcomes.

Hepatic artery infusion for unresectable colorectal cancer liver metastases: Palliation and conversion.

Patients with unresectable colorectal liver metastases are commonly treated with systemic chemotherapy to convert their disease to an operable state. Unfortunately, many patients remain unresectable after first-line chemotherapy and resort to second- and third-line regimens with poor results. Liver-directed strategies have historically been used in this setting. There has been a renewed interest in offering hepatic artery infusion chemotherapy combined with systemic chemotherapy to improve resectability or palliate disease. Prospective studies over the past 2 decades have produced encouraging data, even in chemorefractory patients. This therapy has expanded to multiple centers across North America and worldwide with similar results. This review addresses these data, specifically focusing on conversion to resection and palliation of colorectal liver metastases after patients have received multiple lines of systemic chemotherapy.

Racial disparities in time to laparoscopic cholecystectomy for acute cholecystitis.

BACKGROUND: Disparities in healthcare exist, yet few data are available on racial differences in time from admission to surgery. This study aimed to compare time from admission to laparoscopic cholecystectomy for acute cholecystitis between non-Hispanic Black and non-Hispanic White patients. METHODS: Patients who underwent laparoscopic cholecystectomy for acute cholecystitis from 2010 to 2020 were identified using NSQIP. Time to surgery and additional preoperative, operative, and postoperative variables were analyzed. RESULTS: In the univariate analysis, 19.4% of Black patients experienced a time to surgery >1 day compared with 13.4% of White patients (p < 0.0001). In the multivariable analysis, controlling for potential confounding factors, Black patients were found to be more likely than White patients to experience a time to surgery >1 day (OR 1.23, 95% CI 1.17-1.30, p < 0.0001). CONCLUSIONS: Further investigation is indicated to better define the nature and significance of gender, race, and other biases in surgical care. Surgeons should be aware that biases may adversely impact patient care and should strive to identify and proactively address them to promote health equity in surgery.

The Impact of Age in the Treatment of Non-comorbid Patients with Rectal Cancer: Survival Outcomes from the National Cancer Database.

BACKGROUND: Multimodal therapy has improved survival outcomes for rectal cancer (RC) significantly with an exemption for older patients. We sought to assess whether older non-comorbid patients receive substandard oncological treatment for localized RC referring to the National Comprehensive Cancer Network (NCCN) guidelines and whether it affects survival outcomes. METHODS: This is a retrospective study using patient data from the National Cancer Data Base (NCDB) for histologically confirmed RC from 2002 to 2014. Non-comorbid patients between ≥50 and ≤85 years and defined treatment for localized RC were included and assigned to a younger (<75 years) and an older group (≥75 years). Treatment approaches and their impact on relative survival (RS) were analyzed using loess regression models and compared between both groups. Furthermore, mediation analysis was performed to measure the independent relative effect on age and other variables on RS. Data were assessed using the Strengthening the Reporting of Observational studies in Epidemiology (STROBE) checklist. RESULTS: Of 59,769 included patients, 48,389 (81.0%) were assigned to the younger group (<75 years). Oncologic resection was performed in 79.6% of the younger patients compared to 67.2% of the older patients (p < 0.001). Chemotherapy (74.3% vs. 56.1%) and radiotherapy (72.0% vs. 58.1%) were provided less often in older patients, respectively (p < 0.001). Increasing age was associated with enhanced 30- and 90-day mortality with 0.6% and 1.1% in the younger and 2.0% and 4.1% in the elderly group (p < 0.001) and worse RS rates [multivariable adjusted HR: 1.93 (95% CI 1.87-2.00), p < 0.001]. Adherence to standard oncological therapy resulted in a significant increase in 5-year RS (multivariable adjusted HR: 0.80 (95% CI 0.74-0.86), p < 0.001). Mediation analysis revealed that RS was mainly affected by age itself (84%) rather than the choice of therapy. CONCLUSIONS: The likelihood to receive substandard oncological therapy increases in the older population and negatively affects RS. Since age itself has a major impact on RS, better patient selection should be performed to identify those that are potentially eligible for standard oncological care regardless of their age.