Phenotyping Hepatic Immune-Related Adverse Events in the Setting of Immune Checkpoint Inhibitor Therapy.

PURPOSE: We present and validate a rule-based algorithm for the detection of moderate to severe liver-related immune-related adverse events (irAEs) in a real-world patient cohort. The algorithm can be applied to studies of irAEs in large data sets. METHODS: We developed a set of criteria to define hepatic irAEs. The criteria include: the temporality of elevated laboratory measurements in the first 2-14 weeks of immune checkpoint inhibitor (ICI) treatment, steroid intervention within 2 weeks of the onset of elevated laboratory measurements, and intervention with a duration of at least 2 weeks. These criteria are based on the kinetics of patients who experienced moderate to severe hepatotoxicity (Common Terminology Criteria for Adverse Events grades 2-4). We applied these criteria to a retrospective cohort of 682 patients diagnosed with hepatocellular carcinoma and treated with ICI. All patients were required to have baseline laboratory measurements before and after the initiation of ICI. RESULTS: A set of 63 equally sampled patients were reviewed by two blinded, clinical adjudicators. Disagreements were reviewed and consensus was taken to be the ground truth. Of these, 25 patients with irAEs were identified, 16 were determined to be hepatic irAEs, 36 patients were nonadverse events, and two patients were of indeterminant status. Reviewers agreed in 44 of 63 patients, including 19 patients with irAEs (0.70 concordance, Fleiss' kappa: 0.43). By comparison, the algorithm achieved a sensitivity and specificity of identifying hepatic irAEs of 0.63 and 0.81, respectively, with a test efficiency (percent correctly classified) of 0.78 and outcome-weighted F1 score of 0.74. CONCLUSION: The algorithm achieves greater concordance with the ground truth than either individual clinical adjudicator for the detection of irAEs.

KRAS Sequence Variation as Prognostic Marker in Patients With Young- vs Late-Onset Colorectal Cancer.

Importance: The understanding of the association between KRAS sequence variation status and clinical outcomes in colorectal cancer (CRC) has evolved over time. Objective: To characterize the association of age at onset, tumor sidedness, and KRAS sequence variation with survival among patients diagnosed with CRC. Design, Setting, and Participants: This cross-sectional study used data extracted from the Surveillance, Epidemiology, and End Results database. Patients diagnosed with adenocarcinoma of the colon or rectum from 2010 through 2015 were included and were classified as having young-onset (YO) cancer if diagnosed between ages 20 to 49 years and late-onset (LO) cancer if diagnosed at age 50 years or older. Data were analyzed from April 2021 through August 2023. Main Outcomes and Measures: CRC cause-specific survival (CSS) was summarized using Fine and Gray cumulative incidence and Kaplan-Meier curves. Estimation of subdistribution hazard ratios (sHRs) for the association of KRAS status, age at onset, and tumor location with CRC CSS was conducted using the Fine and Gray competing risk model. Cox proportional hazards regression was used to estimate and compare HRs. Results: Among 21 661 patients with KRAS sequence variation status (mean [SD] age at diagnosis, 62.50 [13.78] years; 9784 females [45.2%]), 3842 patients had YO CRC, including 1546 patients with KRAS variants, and 17 819 patients had LO CRC, including 7311 patients with KRAS variants. There was a significant difference in median CSS time between patients with variant vs wild-type KRAS (YO: 3.0 years [95% CI, 2.8-3.3 years] vs 3.5 years [95% CI, 3.3-3.9 years]; P = .02; LO: 2.5 years [95% CI, 2.4-2.7 years] vs 3.4 years [95% CI, 3.3-3.6 years]; P < .001). Tumors with variant compared with wild-type KRAS were associated with higher risk of CRC-related death (YO: sHR, 1.09 [95% CI, 1.01-1.18]; P = .03; LO: sHR, 1.06 [95% CI, 1.02-1.09]; P = .002). Among patients with YO cancer, mortality hazards increased by location, from right (sHR, 1.02 [95% CI, 0.88-1.17) to left (sHR, 1.15 [95% CI, 1.02-1.29) and rectum (sHR, 1.16 [95% CI, 0.99-1.36), but no trend by tumor location was seen for LO cancer. Conclusions and Relevance: In this study of patients diagnosed with CRC, KRAS sequence variation was associated with increased mortality among patients with YO and LO tumors. In YO cancer, variant KRAS-associated mortality risk was higher in distal tumors than proximal tumors.

Immune biomarkers associated with COVID-19 disease severity in an urban, hospitalized population.

Objectives: We sought to identify immune biomarkers associated with severe Coronavirus disease 2019 (COVID-19) in patients admitted to a large urban hospital during the early phase of the SARS-CoV-2 pandemic. Design: The study population consisted of SARS-CoV-2 positive subjects admitted for COVID-19 (n = 58) or controls (n = 14) at the Los Angeles County University of Southern California Medical Center between April 2020 through December 2020. Immunologic markers including chemokine/cytokines (IL-6, IL-8, IL-10, IP-10, MCP-1, TNF-α) and serologic markers against SARS-CoV-2 antigens (including spike subunits S1 and S2, receptor binding domain, and nucleocapsid) were assessed in serum collected on the day of admission using bead-based multiplex immunoassay panels. Results: We observed that body mass index (BMI) and SARS-CoV-2 antibodies were significantly elevated in patients with the highest COVID-19 disease severity. IP-10 was significantly elevated in COVID-19 patients and was associated with increased SARS-CoV-2 antibodies. Interactions among all available variables on COVID-19 disease severity were explored using a linear support vector machine model which supported the importance of BMI and SARS-CoV-2 antibodies. Conclusions: Our results confirm the known adverse association of BMI on COVID-19 severity and suggest that IP-10 and SARS-CoV-2 antibodies could be useful to identify patients most likely to experience the most severe forms of the disease.

Trends in Epidemiology of Esophageal Cancer in the US, 1975-2018.

Importance: Esophageal cancer (EC) is the 7th most common cancer worldwide and 14th in the US. More data are needed to study the changing incidence patterns of its 2 primary histologic subtypes, squamous cell carcinoma of the esophagus (SCE) and adenocarcinoma of the esophagus (ACE). Objective: To examine temporal trends in incidence rates of EC, ACE, and SCE from 1975 through 2018. Design, Setting, and Participants: In this population-based cross-sectional study, data were derived from 9 Surveillance, Epidemiology, and End Results (SEER) registries from January 1975 through December 2018 and from all 21 registries for January 2000 through December 2018 for patients with a diagnosis of EC from 1975 through 2018 (International Classification of Disease-Oncology, Third Edition codes). Age-adjusted incidence rates (AAIRs) of EC, ACE, and SCE were calculated. The timing and magnitude of the annual percentage change (APC) in incidence were examined using Joinpoint regression analyses. Data analysis was started in 2021 and updated and completed in 2023. Main Outcome and Measures: The APC for age-adjusted EC incidence rates as stratified by histology, anatomical location, stage, sex, age, race and ethnicity, and geographic region. Results: A total of 47 648 patients with a diagnosis of EC were retained for analysis. These included 22 419 (47.1%) with a diagnosis of SCE, 22 217 (46.6%) with ACE, and 3012 (6.3%) with other subtypes. The AAIR for EC changed from 4.14 per 100 000 population in 1975 to 4.18 in 2018, AAIRs of SCE declined from 3.06 in 1975 to 1.15 in 2018 as well as for ACE, and AAIRs increased from 0.42 in 1975 to 2.78 in 2018. From 1975 through 2004, EC incidence significantly increased (APC, 0.53; 95% CI, 0.4 to 0.7) but significantly decreased (APC, -1.03; 95% CI, -1.3 to -0.7) from then until 2018. The APC of SCE significantly continued to decline (-2.80, 95% CI, -3.0 to -2.6), and ACE increased from 2000 to 2006 (APC, 2.51; 95% CI, 1.0 to 4.0) but has since stabilized from 2006 to 2018. Conclusions and Relevance: The results of this cross-sectional study suggest that the incidence of EC modestly declined since 2004 and that the incidence of SCE continued to decline while the incidence rate of ACE plateaued for more than a decade. Understanding factors associated with plateaued rates of ACE may help inform public health interventions.

Chemotherapy Treatment Costs and Clinical Outcomes of Colon Cancer in the U.S. Military Health System's Direct and Private Sector Care Settings.

INTRODUCTION: Identifying low-value cancer care may be an important step in containing costs associated with treatment. Low-value care occurs when the medical services, tests, or treatments rendered do not result in clinical benefit. These may be impacted by care setting and patients' access to care and health insurance. We aimed to study chemotherapy treatment and the cost paid by the Department of Defense (DoD) for treatment in relation to clinical outcomes among patients with colon cancer treated within the U.S. Military Health System's direct and private sector care settings to better understand the value of cancer care. MATERIALS AND METHODS: A cohort of patients aged 18 to 64 years with primary colon cancer diagnosed between January 1, 1999, and December 31, 2014, were identified in the Military Cancer Epidemiology database. Multivariable time-dependent Cox proportional hazards regression models were used to assess the relationship between chemotherapy treatment and the cost paid by the DoD (in quartiles, Q) and the outcomes of cancer progression, cancer recurrence, and all-cause death modeled as adjusted hazard ratios (aHRs) and 95% confidence intervals (95% CIs). The Military Cancer Epidemiology data were approved for research by the Uniformed Services University of the Health Sciences' Institutional Review Board. RESULTS: The study included 673 patients using direct care and 431 patients using private sector care. The median per patient chemotherapy costs in direct care ($111,202) were lower than in private sector care ($350,283). In direct care, higher chemotherapy costs were associated with an increased risk of any outcome but not with all-cause death. In private sector care, higher chemotherapy costs were associated with a higher risk of any outcome and with all-cause death (aHR, 2.67; 95% CI, 1.20-5.92 for Q4 vs. Q1). CONCLUSIONS: The findings in the private sector may indicate low-value care in terms of the cost paid by the DoD for chemotherapy treatment and achieving desirable survival outcomes for patients with colon cancer in civilian health care. Comprehensive evaluations of value-based care among patients treated for other tumor types may be warranted.

Potential association between public medical insurance, waitlist mortality, and utilization of living donor liver transplantation: An analysis of the Scientific Registry of Transplant Recipients.

BACKGROUND: The Affordable Care Act (ACA) and subsequent Medicaid expansion has increased utilization of public health insurance. Living donor liver transplantation (LDLT) increases access to transplant and is associated with improved survival but consistently represents < 5% of LT in the United States. STUDY DESIGN: National registry data were analyzed to evaluate the impact of insurance payor on waitlist mortality and LDLT rates at LDLT centers since implementation of the ACA. RESULTS: Public insurance [Medicare RR 1.18 (1.13-1.22) P < .001, Medicaid RR 1.22 (1.18-1.27) P < .001], Latino ethnicity (P < .001), and lower education level (P = .02) were associated with increased waitlist mortality at LDLT centers. LDLT recipients were more likely to have private insurance (70.4% vs. 59.4% DDLT, P < .001), be Caucasian (92.1% vs. 83% DDLT, P < .001), and have post-secondary education (66.8% vs. 54.1% DDLT, P < .001). Despite 78% of LDLT centers being located in states with Medicaid expansion, there was no change in LDLT utilization among recipients with Medicaid (P = .196) or Medicare (P = .273). CONCLUSION: Despite Medicaid expansion, registry data suggests that patients with public medical insurance may experience higher waitlist mortality and underutilize LDLT at centers offering LDLT. It is possible that Medicaid expansion has not increased access to LDLT.

Paradoxical androgen receptor regulation by small molecule enantiomers.

Small molecules that target the androgen receptor (AR) are the mainstay of therapy for lethal castration-resistant prostate cancer (CRPC), yet existing drugs lose their efficacy during continued treatment. This evolution of resistance is due to heterogenous mechanisms which include AR mutations causing the identical drug to activate instead of inhibit the receptor. Understanding in molecular detail the paradoxical phenomenon wherein an AR antagonist is transformed into an agonist by structural mutations in the target receptor is thus of paramount importance. Herein, we describe a reciprocal paradox: opposing antagonist and agonist AR regulation determined uniquely by enantiomeric forms of the same drug structure. The antiandrogen BMS-641988, which has (R)-chirality at C-5 encompasses a previously uncharacterized (S)-stereoisomer that is, surprisingly, a potent agonist of AR, as demonstrated by transcriptional assays supported by cell imaging studies. This duality was reproduced in a series of novel compounds derived from the BMS-641988 scaffold. Coupled with in silico modeling studies, the results inform an AR model that explains the switch from potent antagonist to high-affinity agonist in terms of C-5 substituent steric interactions with helix 12 of the ligand binding site. They imply strategies to overcome AR drug resistance and demonstrate that insufficient enantiopurity in this class of AR antagonist can confound efforts to correlate structure with function.

Meta-analysis and meta-regression of outcomes for adult living donor liver transplantation versus deceased donor liver transplantation.

Prior single center or registry studies have shown that living donor liver transplantation (LDLT) decreases waitlist mortality and offers superior patient survival over deceased donor liver transplantation (DDLT). The aim of this study was to compare outcomes for adult LDLT and DDLT via systematic review. A meta-analysis was conducted to examine patient survival and graft survival, MELD, waiting time, technical complications, and postoperative infections. Out of 8600 abstracts, 19 international studies comparing adult LDLT and DDLT published between 1/2005 and 12/2017 were included. U.S. outcomes were analyzed using registry data. Overall, 4571 LDLT and 66,826 DDLT patients were examined. LDLT was associated with lower mortality at 1, 3, and 5 years posttransplant (5-year HR 0.87 [95% CI 0.81-0.93], p < .0001), similar graft survival, lower MELD at transplant (p < .04), shorter waiting time (p < .0001), and lower risk of rejection (p = .02), with a higher risk of biliary complications (OR 2.14, p < .0001). No differences were observed in rates of hepatic artery thrombosis. In meta-regression analysis, MELD difference was significantly associated with posttransplant survival (R2 0.56, p = .02). In conclusion, LDLT is associated with improved patient survival, less waiting time, and lower MELD at LT, despite posing a higher risk of biliary complications that did not affect survival posttransplant.

Contribution Of Care Source To Cancer Treatment Cost Variation In The US Military Health System.

The US Military Health System (MHS) provides universal access to health care for more than nine million eligible beneficiaries through direct care in military treatment facilities or purchased care in civilian facilities. Using information from linked cancer registry and administrative databases, we examined how care source contributed to cancer treatment cost variation in the MHS for patients ages 18-64 who were diagnosed with colon, female breast, or prostate cancer in the period 2003-14. After accounting for patient, tumor, and treatment characteristics, we found the independent contribution of care source to total variation in cost to be 8 percent, 12 percent, and 2 percent for colon, breast, and prostate cancer treatment, respectively. About 20-50 percent of the total cost variance remained unexplained and may be related to organizational and administrative factors.

Role of lymph node ratio in selection of adjuvant treatment (chemotherapy vs. chemoradiation) in patients with resected gastric cancer.

BACKGROUND: Recent randomized controlled trials have failed to show a survival difference between adjuvant chemotherapy (CT) and adjuvant chemoradiotherapy (CRT) in patients with resected gastric cancer (GC). However, a subset of patients with lymph node (LN) positive disease may still benefit from CRT. Additional evidence is needed to help guide physicians in identifying patients in whom CRT should be considered. Our objective was then to compare survival outcomes based on lymph node ratio (LNR) (ratio of metastatic to harvested LNs) for patients with gastric and gastroesophageal junction (GEJ) adenocarcinoma treated with surgery and either CT or CRT. METHODS: This retrospective population-based study used California Cancer Registry (CCR) data from 2004 to 2013. It included 1,493 patients diagnosed with stage IB-III gastric/GEJ adenocarcinoma and treated with CT or CRT following total or partial gastrectomy. Overall survival (OS) was the primary outcome and GC-specific survival was secondary. Mortality hazards ratios (HR) for these outcomes were computed using propensity score weighted Cox regression models, stratified by LNR strata categories as 0%, 1-9%, 10-25% and >25%. RESULTS: Out of 1,493 patients that met inclusion criteria, 462 were treated with CT while 1,031 received CRT. Median follow-up for all subjects was 76 months and median survival was 54 months for CRT and 35 for the CT cohort, P<0.001. Compared to CT, CRT was associated with improved survival among patients with LNR of 10-25% [HR =0.62 (95% CI, 0.46-0.83)] and >25% [HR =0.67 (95% CI, 0.56-0.80)]. Similar findings were observed for GC-specific survival and for analyses limited to patients that had at least 15 LNs evaluated. CONCLUSIONS: LNR appears to be a simple and readily available measure that could be used in treatment planning for resected GC. CRT offers significant survival advantage over CT among patients with high LN disease burden (LNR of ≥10%).

Impact of Breast Reconstruction on Time to Definitive Surgical Treatment, Adjuvant Therapy, and Breast Cancer Outcomes.

BACKGROUND: Delays in surgery and adjuvant treatment for breast cancer are associated with decreased survival. However, the time between diagnosis and surgery is rising, partly attributed to the added complexity of immediate breast reconstruction (IBR). We sought to investigate time to treatment and survival outcomes in breast cancer patients undergoing IBR. METHODS: We performed a retrospective review of 2004-2014 California Cancer Registry data for stage 0-III breast cancer patients undergoing mastectomy. Time to surgery, adjuvant systemic therapy and radiation therapy, propensity score, and covariate-adjusted overall mortality hazard ratios (HRs) were assessed by IBR status. RESULTS: Of 56,782 patients, 13,738 (24.2%) underwent IBR, with a median follow-up of 68.8 months. Median time between diagnosis and surgery was increased for patients undergoing IBR compared with those without {49 days (interquartile range [IQR] 34-73) vs. 35 days (IQR 21-56), p < 0.001}. IBR did not affect the interval from surgery to adjuvant chemotherapy or radiation, but prolonged time to endocrine therapy by 5 days (p = 0.014). Significantly lower survival was observed when time to surgery exceeded 120 days (vs. 0-30 days; HR 1.14 [1.02-1.28], p = 0.023), and improved survival with IBR (vs. without; HR 0.67 [0.61-0.74], p < 0.001). The benefit associated with reconstruction persisted for all age groups except age 80 + years, while surgical delay > 120 days demonstrated significantly lower survival in women < 60 years of age. CONCLUSIONS: While IBR delays time to definitive surgery, its use did not substantially affect time to adjuvant treatment or survival outcomes. Further research is ongoing to mitigate the effects of potential selection bias in favor of IBR.

High-Risk Stage II Colon Cancer: Not All Risks Are Created Equal.

INTRODUCTION: Adjuvant chemotherapy is recommended in patients with stage II colon cancer with high-risk features (HRF). However, there is no quantification of the amount of risk conferred by each HRF or the overall survival (OS) benefit gained by chemotherapy based on the risk factor. OBJECTIVE: To assess survival benefits associated with adjuvant chemotherapy among stage II colon cancer patients having one or more HRF [T4 tumors, less than 12 lymph nodes examined (< 12LN), positive margins, high-grade tumor, perineural invasion (PNI), and lymphovascular invasion (LVI)]. METHODS: Patients diagnosed with stage II colon cancer between 2010 and 2013 were identified from California Cancer Registry. Propensity score weighted all-cause mortality hazard ratios (HR) were calculated for combinations of HRF. RESULTS: A total of 5160 stage II colon cancer patients were identified, of which 2398 had at least one HRF and 510 of 2398 (21%) received adjuvant chemotherapy. Compared with patients with a single HRF, presence of any 2 or ≥ 3 HRF showed increasingly poorer survival [HR 1.42, 95% confidence interval (CI) 1.16-1.73 and HR 2.50, 95% CI 1.96-3.20, respectively]. Chemotherapy was associated with improved overall survival only among patients with T4 as the single HRF (HR 0.51, 95% CI 0.34-0.78) or combinations involving T4 as T4/< 12 LN (HR 0.31, 95% CI 0.11-0.90), T4/high grade (HR 0.26, 95% CI 0.11-0.61), and T4/LVI (HR 0.16, 95% CI 0.04-0.61). CONCLUSIONS: Not all high-risk features have similar adverse effects on OS. T4 tumors and their combination with other HRF achieve the most survival benefit with adjuvant therapy. Type and number of high-risk features should be taken into consideration when recommending adjuvant chemotherapy in stage II colon cancer.

Comparison of perioperative chemotherapy with adjuvant chemoradiotherapy for resectable gastric cancer: findings from a population-based study.

BACKGROUND: Both perioperative chemotherapy (PC) and adjuvant chemoradiotherapy (CRT) improve survival in resectable gastric cancer; however, these treatments have never been formally compared. Our objective was to evaluate treatment trends and compare survival outcomes for gastric cancer patients treated with surgery and either PC or CRT. METHODS: We performed a retrospective population-based cohort study between 2007 through 2013 using California Cancer Registry data. Patients diagnosed with stage IB-III gastric adenocarcinoma and treated with total or partial gastrectomy were eligible for this study. Based on the type of treatment received, patients were grouped into surgery-only, PC, or CRT. Primary and secondary outcomes were overall survival (OS) and gastric cancer-specific survival (GCCS) respectively. Mortality hazards ratios (HRs) for each of these outcomes were computed using propensity score weighted and covariate-adjusted Cox regression models, stratified by clinical node status. RESULTS: Of 2,146 patients who underwent surgical resection, 1,067 had surgery-only, while 771 and 308 received PC or CRT, respectively. Median OS was 25, 33, and 52 months for surgery-only, PC, and CRT, respectively; P<0.001. Overall, patients treated with PC had significantly poorer survival compared to CRT (HR =1.45; 95% CI: 1.22-1.73). PC was also associated with higher mortality in patients with signet ring histology (HR =1.66; 95% CI: 1.21-2.28) and clinical node negative cancer (HR =1.85; 95% CI: 1.32-2.60). Survival was not different between PC vs. CRT in clinical node positive patients (HR =1.29; 95% CI: 0.84-2.08). Of note, the percentage of patients receiving PC increased from 17.5% in 2007-2008, to 41.5% in 2013-2014; P<0.001. CONCLUSIONS: Despite the rapid adoption of PC, overall, CRT is associated with better survival than PC. Specifically, clinical node negative and signet ring histology patients had better survival when treated with CRT compared to PC. Based on these findings, we recommend against indiscriminate adoption of PC and consideration for CRT over PC in clinical node negative patients.

Association of Primary Tumor Site With Mortality in Patients Receiving Bevacizumab and Cetuximab for Metastatic Colorectal Cancer.

Importance: Biologic therapy (BT) (eg, bevacizumab or cetuximab) is increasingly used to treat metastatic colorectal cancer (mCRC). Recent investigations have suggested that right- or left-sided primary tumor origin affects survival and response to BT. Objective: To evaluate the association of tumor origin with mortality in a diverse population-based data set of patients receiving systemic chemotherapy (SC) and bevacizumab or cetuximab for mCRC. Design, Setting, and Participants: This population-based nonconcurrent cohort study of statewide California Cancer Registry data included all patients aged 40 to 85 years diagnosed with mCRC and treated with SC only or SC plus bevacizumab or cetuximab from January 1, 2004, through December 31, 2014. Patients were stratified by tumor origin in the left vs right sides. Interventions: Treatment with SC or SC plus bevacizumab or cetuximab. Main Outcomes and Measures: Mortality hazards by tumor origin (right vs left sides) were assessed for patients receiving SC alone or SC plus bevacizumab or cetuximab. Subgroup analysis for patients with wild-type KRAS tumors was also performed. Results: A total of 11 905 patients with mCRC (6713 men [56.4%] and 5192 women [43.6%]; mean [SD] age, 60.0 [10.9] years) were eligible for the study. Among these, 4632 patients received SC and BT. Compared with SC alone, SC plus bevacizumab reduced mortality among patients with right- and left-sided mCRC, whereas SC plus cetuximab reduced mortality only among patients with left-sided tumors and was associated with significantly higher mortality for right-sided tumors (hazard ratio [HR], 1.31; 95% CI, 1.14-1.51; P < .001). Among patients treated with SC plus BT, right-sided tumor origin was associated with higher mortality among patients receiving bevacizumab (HR, 1.31; 95% CI, 1.25-1.36; P < .001) and cetuximab (HR, 1.88; 95% CI, 1.68-2.12; P < .001) BT, compared with left-sided tumor origin. In patients with wild-type KRAS tumors (n = 668), cetuximab was associated with reduced mortality among only patients with left-sided mCRC compared with bevacizumab (HR, 0.75; 95% CI, 0.63-0.90; P = .002), whereas patients with right-sided mCRC had more than double the mortality compared with those with left-sided mCRC (HR, 2.44; 95% CI, 1.83-3.25, P < .001). Conclusions and Relevance: Primary tumor site is associated with response to BT in mCRC. Right-sided primary tumor location is associated with higher mortality regardless of BT type. In patients with wild-type KRAS tumors, treatment with cetuximab benefited only those with left-sided mCRC and was associated with significantly poorer survival among those with right-sided mCRC. Our results underscore the importance of stratification by tumor site for current treatment guidelines and future clinical trials.