Universal germline genetic testing in patients with hematologic malignancies using DNA isolated from nail clippings

Not available.

Pathogenic germline variants in patients with endometrial cancer of diverse ancestry

BACKGROUND

Racial disparities in outcomes exist in endometrial cancer (EC). The contribution of ancestry-based variations in germline pathogenic variants (gPVs) is unknown.

METHODS

Germline assessment of ≥76 cancer predisposition genes was performed in patients with EC undergoing tumor-normal Memorial Sloan Kettering Cancer Center Integrated Mutation Profiling of Actionable Cancer Targets sequencing from January 1, 2015 through June 30, 2021. Self-reported race/ethnicity and Ashkenazi Jewish ancestry data classified patients into groups. Genetic ancestry was inferred from Memorial Sloan Kettering Cancer Center Integrated Mutation Profiling of Actionable Cancer Targets. Rates of gPV and genetic counseling were compared by ancestry.

RESULTS

Among 1625 patients with EC, 216 (13%) had gPVs; 15 had >1 gPV. Rates of gPV varied by self-reported ancestry (Ashkenazi Jewish, 40/202 [20%]; Asian, 15/124 [12%]; Black/African American (AA), 12/171 [7.0%]; Hispanic, 15/124 [12%]; non-Hispanic (NH) White, 129/927 [14%]; missing, 5/77 [6.5%]; p = .009], with similar findings by genetic ancestry (p < .001). We observed a lower likelihood of gPVs in patients of Black/AA (odds ratio [OR], 0.44; 95% CI, 0.22-0.81) and African (AFR) ancestry (OR, 0.42; 95% CI, 0.18-0.85) and a higher likelihood in patients of Ashkenazi Jewish genetic ancestry (OR, 1.62; 95% CI; 1.11-2.34) compared with patients of non-Hispanic White/European ancestry, even after adjustment for age and molecular subtype. Somatic landscape influenced gPVs with lower rates of microsatellite instability-high tumors in patients of Black/AA and AFR ancestry. Among those with newly identified gPVs (n = 114), 102 (89%) were seen for genetic counseling, with lowest rates among Black/AA (75%) and AFR patients (67%).

CONCLUSIONS

In those with EC, gPV and genetic counseling varied by ancestry, with lowest rates among Black/AA and AFR patients, potentially contributing to disparities in outcomes given implications for treatment and cancer prevention.

PLAIN LANGUAGE SUMMARY

Black women with endometrial cancer do worse than White women, and there are many reasons for this disparity. Certain genetic changes from birth (mutations) can increase the risk of cancer, and it is unknown if rates of these changes are different between different ancestry groups. Genetic mutations in 1625 diverse women with endometrial cancer were studied and the lowest rates of mutations and genetic counseling were found in Black and African ancestry women. This could affect their treatment options as well as their families and may make disparities worse.

Pathogenic germline variants in non-BRCA1/2 homologous recombination genes in ovarian cancer: Analysis of tumor phenotype and survival

OBJECTIVE

To define molecular features of ovarian cancer (OC) with germline pathogenic variants (PVs) in non-BRCA homologous recombination (HR) genes and analyze survival compared to BRCA1/2 and wildtype (WT) OC.

METHODS

We included patients with OC undergoing tumor-normal sequencing (MSK-IMPACT) from 07/01/2015-12/31/2020, including germline assessment of BRCA1/2 and other HR genes ATM, BARD1, BRIP1, FANCA, FANCC, NBN, PALB2, RAD50, RAD51B, RAD51C, and RAD51D. Biallelic inactivation was assessed within tumors. Progression-free (PFS) and overall survival (OS) were calculated from pathologic diagnosis using the Kaplan-Meier method with left truncation. Whole-exome sequencing (WES) was performed in a subset.

RESULTS

Of 882 patients with OC, 56 (6.3%) had germline PVs in non-BRCA HR genes; 95 (11%) had BRCA1-associated OC (58 germline, 37 somatic); and 59 (6.7%) had BRCA2-associated OC (40 germline, 19 somatic). High rates of biallelic alterations were observed among germline PVs in BRIP1 (11/13), PALB2 (3/4), RAD51B (3/4), RAD51C (3/4), and RAD51D (8/10). In cases with WES (27/35), there was higher tumor mutational burden (TMB; median 2.5 [1.1-6.0] vs. 1.2 mut/Mb [0.6-2.6]) and enrichment of HR-deficient (HRD) mutational signatures in tumors associated with germline PALB2 and RAD51B/C/D compared with BRIP1 PVs (p < 0.01). Other features of HRD, including telomeric-allelic imbalance (TAI) and large-scale state transitions (LSTs), were similar. Although there was heterogeneity in PFS/OS by gene group, only BRCA1/2-associated OC had improved survival compared to WT OC (p < 0.01).

CONCLUSIONS

OCs associated with germline PVs in non-BRCA HR genes represent a heterogenous group, with PALB2 and RAD51B/C/D associated with an HRD phenotype.

Patients' Preferences for Adjunctive Parkinson's Disease Treatments: A Discrete-Choice Experiment

Background

Several adjunctive medications are available to reduce OFF time between levodopa/carbidopa (LD/CD) doses for people with Parkinson's disease (PD).

Objective

To explore how individuals with PD balance benefits and burdens when considering adjunctive medications.

Methods

US adults (30-83 years) with self-reported PD, currently treated with LD/CD, who experienced OFF episodes were recruited through the Fox Insight study to complete a discrete-choice experiment survey. Respondents selected among experimentally designed profiles for hypothetical adjunctive PD treatments that varied in efficacy (additional ON time), potential adverse effects (troublesome dyskinesia, risk of diarrhea, risk of change in bodily fluid color), and dosing frequency or the option "No additional medicine". Data were analyzed with random-parameters logit models.

Results

Respondents (N=480) would require ≥60 additional minutes of daily ON time to accept either a 40% risk of change in bodily fluid color or 10 additional minutes with troublesome dyskinesia daily. Respondents would require 40 additional minutes of daily ON time to accept a 10% risk of diarrhea and 22 additional minutes of daily ON time to switch from 1 additional pill each day to 1 pill with each LD/CD dose. On average, respondents preferred adjunctive PD medication over no additional medication. Results predicted that 59.1% of respondents would select a hypothetical treatment profile similar to opicapone, followed by no additional medication (27.5%) and a hypothetical treatment profile similar to entacapone (13.4%).

Limitations

The data collected were based on responses to hypothetical choice profiles in the survey questions. The attributes and levels selected for this study were intended to reflect the characteristics of opicapone and entacapone; attributes associated with other adjunctive therapies were not evaluated.

Conclusion

Patients with PD expressed interest in adjunctive treatment to increase ON time and would accept reduced ON time to avoid adverse effects.

The Impact of Germline Alterations in Appendiceal Adenocarcinoma

PURPOSE

More than 10% of assessed patients with appendiceal adenocarcinoma have a pathogenic (P) or likely pathogenic (LP) germline variant, including genes implicated in heritable gastrointestinal cancer syndromes, such as Lynch syndrome. We defined the clinical and molecular impact of heritable alterations in appendiceal adenocarcinoma to evaluate the need for dedicated appendiceal screening and prevention strategies in patients with LP/P germline variants.

EXPERIMENTAL DESIGN

We performed an integrated germline and somatic molecular analysis for patients with confirmed appendiceal adenocarcinoma. Patients underwent paired tumor-normal sequencing for up to 90 hereditary cancer risk genes and 505 genes for somatic mutation profiling. We defined the cooccurrence of LP/P germline variants and second-hit pathogenic somatic alterations. The associations between germline variants and patient clinicopathologic features were also evaluated.

RESULTS

Twenty-five of 237 patients (10.5%) carried pathogenic or likely pathogenic germline variants in cancer susceptibility genes. Clinicopathologic characteristics and appendiceal adenocarcinoma-specific survival were similar in patients with or without germline variants. Most (92%, N = 23/25) patients with germline variants demonstrated no second-hit somatic alterations, including loss of heterozygosity. Two patients with a germline APC I1307K low-penetrance founder variant exhibited secondary somatic pathogenic alterations in APC. However, only one patient tumor exhibited APC-mediated WNT signaling dysregulation: a plausible consequence of multiple somatic APC mutations with no germline variant contribution. Four patients had germline variants in PMS2 or MSH2 associated with Lynch syndrome, yet their cancers were microsatellite-stable.

CONCLUSIONS

Germline variants are likely incidental without a contributory driver role in appendiceal adenocarcinoma. Appendiceal adenocarcinoma screening in patients with germline variants is not clearly merited.

Germline drivers of gynecologic carcinosarcomas

OBJECTIVES

To describe the prevalence of germline pathogenic variants (gPVs) in endometrial and ovarian carcinosarcomas and determine if gPVs are drivers of carcinosarcoma.

METHODS

Patients with endometrial or ovarian carcinosarcomas who underwent clinical tumor-normal sequencing from 1/1/2015 to 6/1/2021 and consented to germline assessment of ≥76 cancer predisposition genes were included. In patients with gPVs, biallelic inactivation was identified through analysis of loss of heterozygosity and somatic pathogenic alterations.

RESULTS

Of 216 patients identified, 167 (77%) were diagnosed with endometrial carcinosarcoma and 49 (23%) with ovarian carcinosarcoma. Overall, 33 gPVs were observed in 29 patients (13%); 20 gPVs (61%) had biallelic loss in tumors. The rate of high-penetrance gPVs overall was 7% (16 of 216); 88% of high-penetrance gPVs had biallelic loss. In the endometrial carcinosarcoma cohort, 22 gPVs were found in 19 (11%) of 167 patients; 12 gPVs (55%) had biallelic loss in tumors, including 8 (89%) of 9 in high-penetrance gPVs. Among the ovarian carcinosarcoma cohort, 11 gPVs were found in 10 (20%) of 49 patients; 8 gPVs (73%) had biallelic loss in tumors, and all evaluable high-penetrance gPVs (n = 6) had biallelic loss. All gPVs in homologous recombination (BRCA1, BRCA2, RAD51C) and Lynch syndrome (MSH2, MSH6) genes had biallelic loss in tumors (n = 15).

CONCLUSIONS

gPVs in genes affecting homologous recombination- or Lynch-associated mismatch repair exhibited biallelic inactivation within tumors, suggesting likely drivers of gynecologic carcinosarcoma. Our data support germline testing for patients with gynecologic carcinosarcomas, given implications for treatment and risk-reduction in patients and at-risk family members.

Biochemically recurrent prostate cancer: rationalisation of the approach to imaging

AIM

To assess the utility of magnetic resonance imaging (MRI) in addition to the additive benefit of the conventional imaging techniques, computed tomography (CT) and nuclear medicine (NM) bone scintigraphy, for investigation of biochemical recurrence (BCR) post-prostatectomy where access to prostate specific membrane antigen (PSMA) positron-emission tomography (PET)-CT is challenging.

MATERIALS AND METHODS

Relevant imaging over a 5-year period was reviewed. Ethical approval was granted by the internal review board. All patients with suspected BCR, defined as a PSA ≥0.2 ng/ml on two separate occasions, underwent a retrospective imaging review. This was performed on PACS archive search database in a single centre using search terms "PSA" and "prostatectomy" in the three imaging methods; MRI, CT, and NM bone scintigraphy. All PSMA PET CT performed were recorded.

RESULTS

One hundred and eighty-five patients were identified. Patients with an MRI pelvis that demonstrated distant metastases (i.e., pelvic bone metastases or lymph node involvement more cranial to the bifurcation of the common iliac arteries) were more likely to have a positive CT and/or NM bone scintigraphy. The Pearson correlation coefficient between the findings of M1 disease at MRI pelvis and the presence of distant metastases at CT thorax, abdomen, pelvis and NM bone scintigraphy was calculated at 0.81 (p<0.01) and 0.91 (p<0.01) respectively.

CONCLUSION

An imaging strategy based on risk stratification and technique-specific selection criteria leads to more appropriate use of resources, and in turn, increases the yield of conventional imaging methods. MRI prostate findings can be used to predict the additive value of CT/NM bone scintigraphy allowing a more streamlined approach to their use.

Targeting stromal cell sialylation reverses T cell-mediated immunosuppression in the tumor microenvironment

Immunosuppressive tumor microenvironments (TMEs) reduce the effectiveness of immune responses in cancer. Mesenchymal stromal cells (MSCs), precursors to cancer-associated fibroblasts (CAFs), promote tumor progression by enhancing immune cell suppression in colorectal cancer (CRC). Hyper-sialylation of glycans promotes immune evasion in cancer through binding of sialic acids to their receptors, Siglecs, expressed on immune cells, which results in inhibition of effector functions. The role of sialylation in shaping MSC/CAF immunosuppression in the TME is not well characterized. In this study, we show that tumor-conditioned stromal cells have increased sialyltransferase expression, α2,3/6-linked sialic acid, and Siglec ligands. Tumor-conditioned stromal cells and CAFs induce exhausted immunomodulatory CD8+ PD1+ and CD8+ Siglec-7+/Siglec-9+ T cell phenotypes. In vivo, targeting stromal cell sialylation reverses stromal cell-mediated immunosuppression, as shown by infiltration of CD25 and granzyme B-expressing CD8+ T cells in the tumor and draining lymph node. Targeting stromal cell sialylation may overcome immunosuppression in the CRC TME.

Comprehensive analysis of germline drivers in endometrial cancer

BACKGROUND

We sought to determine the prevalence of germline pathogenic variants (gPVs) in unselected patients with endometrial cancer (EC), define biallelic gPVs within tumors, and describe their associations with clinicopathologic features.

METHODS

Germline assessment of at least 76 cancer predisposition genes was performed in patients with EC undergoing clinical tumor-normal Memorial Sloan Kettering-Integrated Mutation Profiling of Actionable Cancer Targets (MSK-IMPACT) sequencing from January 1, 2015, to June 30, 2021. In patients with gPVs, biallelic alterations in ECs were identified through analysis of loss of heterozygosity and somatic PVs. Clinicopathologic variables were compared using nonparametric tests.

RESULTS

Of 1625 patients with EC, 216 (13%) had gPVs, and 15 patients had 2 gPVs. There were 231 gPVs in 35 genes (75 [32%] high penetrance; 39 [17%] moderate penetrance; and 117 [51%] low, recessive, or uncertain penetrance). Compared with those without gPVs, patients with gPVs were younger (P = .002), more often White (P = .009), and less obese (P = .025) and had differences in distribution of tumor histology (P = .017) and molecular subtype (P < .001). Among 231 gPVs, 74 (32%) exhibited biallelic inactivation within tumors. For high-penetrance gPVs, 63% (47 of 75) of ECs had biallelic alterations, primarily affecting mismatch repair (MMR) and homologous recombination related genes, including BRCA1,BRCA2, RAD51D, and PALB2. Biallelic inactivation varied across molecular subtypes with highest rates in microsatellite instability-high (MSI-H) or copy-number (CN)-high subtypes (3 of 12 [25%] POLE, 30 of 77 [39%] MSI-H, 27 of 60 [45%] CN-high, 9 of 57 [16%] CN-low; P < .001).

CONCLUSIONS

Of unselected patients with EC, 13% had gPVs, with 63% of gPVs in high-penetrance genes (MMR and homologous recombination) exhibiting biallelic inactivation, potentially driving cancer development. This supports germline assessment in EC given implications for treatment and cancer prevention.

Molecular Classification of Appendiceal Adenocarcinoma

PURPOSE

Appendiceal adenocarcinomas (ACs) are rare, histologically diverse malignancies treated as colorectal cancers despite having distinct biology and clinical behavior. To guide clinical decision making, we defined molecular subtypes of AC associated with patient survival, metastatic burden, and chemotherapy response.

PATIENTS AND METHODS

A comprehensive molecular analysis was performed in patients with AC to define molecular subtypes. Associations between molecular subtype and overall survival, intraoperative peritoneal cancer index, and first-line chemotherapy response were assessed adjusting for histopathologic and clinical variables using multivariable Cox proportional hazards, linear regression, and logistic regression models.

RESULTS

We defined distinct molecular lineages of mucinous appendiceal adenocarcinoma (MAAP) from co-occurring mutations in GNAS, RAS, and TP53. Of 164 MAAP tumors, 24 were RAS-mutant (mut) predominant (RAS-mut/GNAS-wild-type [wt]/TP53-wt) with significantly decreased mutations and chromosomal alterations compared with tumors with GNAS mutations (GNAS-mut predominant) or TP53 mutations (TP53-mut predominant). No patient with RAS-mut predominant subtype metastatic MAAP died of cancer, and overall survival in this subgroup was significantly improved compared with patients with GNAS-mut (P = .05) and TP53-mut (P = .004) predominant subtypes. TP53-mut predominant subtypes were highly aneuploid; increased tumor aneuploidy was independently (P = .001) associated with poor prognosis. The findings retained significance in patients with any metastatic AC. RAS-mut predominant metastases exhibited reduced peritoneal tumor bulk (P = .04) and stromal invasion (P < .001) compared with GNAS-mut or TP53-mut predominant tumors, respectively. Patients with RAS-mut predominant MAAP responded more to first-line chemotherapy (50%) compared with patients with GNAS-mut predominant tumors (6%, P = .03).

CONCLUSION

AC molecular patterns identify distinct molecular subtypes: a clinically indolent RAS-mut/GNAS-wt/TP53-wt subtype; a chemotherapy-resistant GNAS-mut predominant subtype; and an aggressive, highly aneuploid TP53-mut predominant subtype. Each subtype exhibits conserved clinical behavior irrespective of histopathology.

Use of Bayesian decision analysis to maximize value in patient-centered randomized clinical trials in Parkinson's disease

A fixed one-sided significance level of 5% is commonly used to interpret the statistical significance of randomized clinical trial (RCT) outcomes. While it is necessary to reduce the false positive rate, the threshold used could be chosen quantitatively and transparently to specifically reflect patient preferences regarding benefit-risk tradeoffs as well as other considerations. How can patient preferences be explicitly incorporated into RCTs in Parkinson's disease (PD), and what is the impact on statistical thresholds for device approval? In this analysis, we apply Bayesian decision analysis (BDA) to PD patient preference scores elicited from survey data. BDA allows us to choose a sample size (n ) and significance level (α ) that maximizes the overall expected value to patients of a balanced two-arm fixed-sample RCT, where the expected value is computed under both null and alternative hypotheses. For PD patients who had previously received deep brain stimulation (DBS) treatment, the BDA-optimal significance levels fell between 4.0% and 10.0%, similar to or greater than the traditional value of 5%. Conversely, for patients who had never received DBS, the optimal significance level ranged from 0.2% to 4.4%. In both of these populations, the optimal significance level increased with the severity of the patients' cognitive and motor function symptoms. By explicitly incorporating patient preferences into clinical trial designs and the regulatory decision-making process, BDA provides a quantitative and transparent approach to combine clinical and statistical significance. For PD patients who have never received DBS treatment, a 5% significance threshold may not be conservative enough to reflect their risk-aversion level. However, this study shows that patients who previously received DBS treatment present a higher tolerance to accept therapeutic risks in exchange for improved efficacy which is reflected in a higher statistical threshold.

Disparities in cancer genetics care by race/ethnicity among pan-cancer patients with pathogenic germline variants

BACKGROUND

Germline risk assessment is increasing as part of cancer care; however, disparities in subsequent genetic counseling are unknown.

METHODS

Pan-cancer patients were prospectively consented to tumor-normal sequencing via custom next generation sequencing panel (Memorial Sloan Kettering-Integrated Mutation Profiling of Actionable Cancer Targets) inclusive of germline analysis of ≥76 genes from January 2015 through December 2019 (97.5% research nonbillable) with protocol for genetics referral. Rates of pathogenic/likely pathogenic germline variants (PVs) and downstream counseling were compared across ancestry groups (mutually exclusive groups based on self-reported race/ethnicity and Ashkenazi Jewish [AJ] heritage) using nonparametric tests and multivariable logistic regression models.

RESULTS

Among 15,775 patients (59.6%, non-Hispanic [NH]-White; 15.7%, AJ; 20.5%, non-White [6.9%, Asian; 6.8%, Black/African American (AA); 6.7%, Hispanic; 0.1%, Other], and 4.2%, unknown), 2663 (17%) had a PV. Non-White patients had a lower PV rate (n = 433, 13.4%) compared to NH-Whites (n = 1451, 15.4%) and AJ patients (n = 683, 27.6%), p < .01, with differences in mostly moderate and low/recessive/uncertain penetrance variants. Among 2239 patients with new PV, 1652 (73.8%) completed recommended genetic counseling. Non-White patients had lower rates of genetic counseling (67.7%) than NH-White (73.7%) and AJ patients (78.8%), p < .01, with lower rates occurring in Black/AA (63%) compared to NH-White patients, even after adjustment for confounders (odds ratio, 0.60; 95% confidence interval, 0.37-0.97; p = .036). Non-White, particularly Black/AA and Asian, probands had a trend toward lower rates and numbers of at-risk family members being seen for counseling/genetic testing.

CONCLUSIONS

Despite minimizing barriers to genetic testing, non-White patients were less likely to receive recommended cancer genetics follow-up, with potential implications for oncologic care, cancer risk reduction, and at-risk family members.

LAY SUMMARY

Genetic testing is becoming an important part of cancer care, and we wanted to see if genetics care was different between individuals of different backgrounds. We studied 15,775 diverse patients with cancer who had genetic testing using a test called MSK-IMPACT that was covered by research funding. Clinically important genetic findings were high in all groups. However, Black patients were less likely to get recommended counseling compared to White patients. Even after removing many roadblocks, non-White and especially Black patients were less likely to get recommended genetics care, which may affect their cancer treatments and families.

An Ambulatory Pathway for the Investigation of Patients with Suspected Pulmonary Embolism

Aims The aim of this project was to provide an ambulatory pathway for diagnosis and management of patients with suspected Pulmonary Embolism (PE) with "low-risk" features. Methods A structured algorithm for the management of suspected PE was designed and implemented in April 2021. This involved the development of local guidelines to identify those "low-risk" patients with suspected PE, through the use of modified sPESI and Hestia criteria. This pathway was audited monthly to establish effect on admission and hospital length of stay. Results 51 CT PAs were performed by the Emergency Department in April 2021. Total number of CT confirmed PEs in April was 7(11%). 12 "low-risk" patients with suspected PE were identified and placed on the "Ambulatory Suspected Pulmonary Embolism Pathway". One (8.3%) patient on this pathway had a confirmed PE. Patients placed on this pathway spent significantly less time in the Emergency Department and in hospital with greater satisfaction by physicians using this pathway. Conclusion This pathway has succeeded in significantly decreasing length of stay both in the ED and in hospital for patients with suspected and confirmed PE.

Diagnostic yield and clinical relevance of expanded genetic testing for cancer patients

BACKGROUND

Genetic testing (GT) for hereditary cancer predisposition is traditionally performed on selected genes based on established guidelines for each cancer type. Recently, expanded GT (eGT) using large hereditary cancer gene panels uncovered hereditary predisposition in a greater proportion of patients than previously anticipated. We sought to define the diagnostic yield of eGT and its clinical relevance in a broad cancer patient population over a 5-year period.

METHODS

A total of 17,523 cancer patients with a broad range of solid tumors, who received eGT at Memorial Sloan Kettering Cancer Center between July 2015 to April 2020, were included in the study. The patients were unselected for current GT criteria such as cancer type, age of onset, and/or family history of disease. The diagnostic yield of eGT was determined for each cancer type. For 9187 patients with five common cancer types frequently interrogated for hereditary predisposition (breast, colorectal, ovarian, pancreatic, and prostate cancer), the rate of pathogenic/likely pathogenic (P/LP) variants in genes that have been associated with each cancer type was analyzed. The clinical implications of additional findings in genes not known to be associated with a patients' cancer type were investigated.

RESULTS

16.7% of patients in a broad cancer cohort had P/LP variants in hereditary cancer predisposition genes identified by eGT. The diagnostic yield of eGT in patients with breast, colorectal, ovarian, pancreatic, and prostate cancer was 17.5%, 15.3%, 24.2%, 19.4%, and 15.9%, respectively. Additionally, 8% of the patients with five common cancers had P/LP variants in genes not known to be associated with the patient's current cancer type, with 0.8% of them having such a variant that confers a high risk for another cancer type. Analysis of clinical and family histories revealed that 74% of patients with variants in genes not associated with their current cancer type but which conferred a high risk for another cancer did not meet the current GT criteria for the genes harboring these variants. One or more variants of uncertain significance were identified in 57% of the patients.

CONCLUSIONS

Compared to targeted testing approaches, eGT can increase the yield of detection of hereditary cancer predisposition in patients with a range of tumors, allowing opportunities for enhanced surveillance and intervention. The benefits of performing eGT should be weighed against the added number of VUSs identified with this approach.

Evaluation of prognostic risk models for postoperative pulmonary complications in adult patients undergoing major abdominal surgery: a systematic review and international external validation cohort study

BACKGROUND

Stratifying risk of postoperative pulmonary complications after major abdominal surgery allows clinicians to modify risk through targeted interventions and enhanced monitoring. In this study, we aimed to identify and validate prognostic models against a new consensus definition of postoperative pulmonary complications.

METHODS

We did a systematic review and international external validation cohort study. The systematic review was done in accordance with the Preferred Reporting Items for Systematic Reviews and Meta-Analyses guidelines. We searched MEDLINE and Embase on March 1, 2020, for articles published in English that reported on risk prediction models for postoperative pulmonary complications following abdominal surgery. External validation of existing models was done within a prospective international cohort study of adult patients (≥18 years) undergoing major abdominal surgery. Data were collected between Jan 1, 2019, and April 30, 2019, in the UK, Ireland, and Australia. Discriminative ability and prognostic accuracy summary statistics were compared between models for the 30-day postoperative pulmonary complication rate as defined by the Standardised Endpoints in Perioperative Medicine Core Outcome Measures in Perioperative and Anaesthetic Care (StEP-COMPAC). Model performance was compared using the area under the receiver operating characteristic curve (AUROCC).

FINDINGS

In total, we identified 2903 records from our literature search; of which, 2514 (86·6%) unique records were screened, 121 (4·8%) of 2514 full texts were assessed for eligibility, and 29 unique prognostic models were identified. Nine (31·0%) of 29 models had score development reported only, 19 (65·5%) had undergone internal validation, and only four (13·8%) had been externally validated. Data to validate six eligible models were collected in the international external validation cohort study. Data from 11 591 patients were available, with an overall postoperative pulmonary complication rate of 7·8% (n=903). None of the six models showed good discrimination (defined as AUROCC ≥0·70) for identifying postoperative pulmonary complications, with the Assess Respiratory Risk in Surgical Patients in Catalonia score showing the best discrimination (AUROCC 0·700 [95% CI 0·683-0·717]).

INTERPRETATION

In the pre-COVID-19 pandemic data, variability in the risk of pulmonary complications (StEP-COMPAC definition) following major abdominal surgery was poorly described by existing prognostication tools. To improve surgical safety during the COVID-19 pandemic recovery and beyond, novel risk stratification tools are required.

FUNDING

British Journal of Surgery Society.

Abstract 3474: Molecular subtypes characterize appendiceal adenocarcinoma genomic evolution and disease behavior

Appendiceal adenocarcinoma (AC) are rare gastrointestinal tumors that exhibit a heterogeneous spectrum of tumor histology and differentiation patterns. Personalized AC treatments are limited by the lack of robust histopathological or genomic predictors of disease behavior. We utilized the MSK IMPACT sequencing panel to profile genomic signature patterns in somatic mutations, copy number alterations, and germline mutations in a large curated dataset of patients with AC.

We evaluated co-occurrence and clonality patterns between frequently altered genes in AC (RAS, GNAS, TP53) to establish five molecular subtypes of mucinous appendiceal adenocarcinoma (MAAP): RAS mutated-only, GNAS mutated, TP53 & KRAS mutated, TP53 mutated-only, and none (all wild-type). In multivariable Cox regression models, patients with RAS mutated-only tumors exhibit a nearly non-lethal disease course compared to other molecular subtypes, including TP53 mutated-only tumors (hazard ratio for death: 75.6, p&lt;0.001). Inclusion of tumor molecular subtype in conventional multivariable models improves model prognostic strength. In addition, MAAP-derived molecular subtypes prognosticate patient survival in a separate cohort of 248 patients with right-sided, mismatch-repair-proficient metastatic colorectal cancer.

Molecular characterization of AC also reveals differences in tumor biology and behavior. In addition to an improved prognosis, RAS mutated-only MAAP tumors exhibit significantly lower tumor mutational quantity and aneuploidy compared to other subtypes in multivariable models (p&lt;0.001). Together with clonality patterns, this suggests that RAS mutated-only tumors exhibit a relatively younger molecular age. In a subset of patients with MAAP who underwent cytoreductive surgery, patients with RAS-only tumors demonstrate significantly lower intra-operative assessed peritoneal cancer indices (PCI) compared to patients with other molecular subtypes (p=0.049). Microscopic assessment of surgical samples reveals that RAS mutated-only tumors are significantly less likely (p&lt;0.001) to exhibit destructive metastatic stromal invasion compared to GNAS and TP53 mutated subtypes. Molecular subtype is also a significant independent predictor of both radiographic and biochemical response to first line chemotherapy for patients with AC.

Overall, through a comprehensive profiling of the AC mutational landscape we introduce a unique disease entity of RAS-only mutated MAAP that exhibits dramatically low lethality, low peritoneal spread, and decreased tissue invasiveness despite high-risk histological characteristics. The behavior of this clinically-metastatic, but molecularly-young subtype introduces a new characterization of metastatic pathogenesis and risk that may apply to other premalignant and malignant diseases.

Citation Format: Michael B. Foote, Henry Walch, Walid Chatila, Efsevia Vakiani, Chris Chandler, Felix Steinrucke, Garrett Nash, Zsofia Stadler, Sebastian Chung, Yelena Kemel, Anna Maio, Margaret Sheehan, Nikolaus Shultz, Luis A. Diaz, Andrea Cercek. Molecular subtypes characterize appendiceal adenocarcinoma genomic evolution and disease behavior [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2022; 2022 Apr 8-13. Philadelphia (PA): AACR; Cancer Res 2022;82(12_Suppl):Abstract nr 3474.

Including People with Parkinson’s Disease in Clinical Study Design and Execution: A Call to Action

The proactive inclusion of patients in the design and execution of clinical studies has been an emerging focus for decades. Such participatory research helps to design studies better, by addressing relevant research questions and defining outcomes that matter to patients. Yet, much remains to be learned about the best methods and exact impacts of patient engagement in research in general, and more specifically, about the specific challenges that come with Parkinson’s disease. Here we present the lived experiences of patient researchers living with Parkinson’s disease, as a motivation for the value of their perspectives in research and as a call to action for empirical research on how to successfully include patient researchers.

A Surgical Presentation of Churg-Strauss Syndrome

Eosinophilic granulomatosis with polyangiitis (EGPA) or Churg-Strauss syndrome (CSS) is a rare, autoimmune vasculitis usually affecting small and medium-sized blood vessels in its later phases. It is a diffuse, systemic, multisystem disease that is reported to present with gastrointestinal manifestations but very rarely as an acute abdomen secondary to eosinophilic peritonitis. A 28-year-old relatively healthy male with a pre-existing diagnosis of inactive pulmonary sarcoidosis presented to the emergency department with an acute abdomen. After an exploratory laparotomy, multi-specialty involvement, and extensive investigations to exclude other differentials, a diagnosis of EGPA was made. The patient was treated with systemic glucocorticoids initially, followed by a tapering course of steroids and anti-interleukin 5 monoclonal antibodies as maintenance upon remission. EGPA can manifest in a myriad of ways including an acute abdomen, and medical treatment is useful in managing this presentation. Surgeons should be aware of the atypical causes of acute abdomen and should routinely broaden their differential diagnosis to include medical pathologies.

Screen-detected ductal carcinoma in situ, 2008-2020: An observational study

OBJECTIVES

The purpose of this study was to evaluate the grade distribution of screen-detected ductal carcinoma in situ (DCIS) diagnosed in Ireland, in the context of the clinical trials currently underway to determine if active surveillance is a feasible management option for low-risk DCIS.

SETTING

BreastCheck is the national breast screening programme in Ireland, offering screening to women aged 50 to 69 every two years.

METHODS

This study was a secondary analysis of data collected by BreastCheck on all screen-detected DCIS diagnosed in the 12 years of nationwide screening. Incidence and detection rates were calculated. Descriptive analysis of the cases was performed and, for comparative analysis, grade of DCIS was analysed as a binary variable (high vs. low/intermediate) in keeping with the inclusion criteria for active surveillance trials. Analysis was performed in IBM Statistical Package for Social Sciences, version 26.

RESULTS

Between 2008 and 2020, 2240 women were diagnosed with DCIS through BreastCheck; 876 (39.1%) were low/intermediate-grade. The overall incidence rate has remained relatively stable during this period. Women with low/intermediate-grade DCIS were younger than women with high-grade DCIS (56 (interquartile range: 56-61) years v 57 (interquartile range: 53-61) years; p < 0.001). They were also more likely to have been diagnosed at an initial screening episode compared with those who had high-grade lesions (42.5% v 29.0%; p < 0.001).

CONCLUSION

If current clinical trials recommend active surveillance as a feasible option for DCIS, up to 40% of women with screen-detected DCIS may be eligible. These women are younger and often diagnosed on initial screening episode, so may require longer active follow-up.

Multiple Primary Cancers in Patients Undergoing Tumor-Normal Sequencing Define Novel Associations

BACKGROUND

Cancer survivors are developing more subsequent tumors. We sought to characterize patients with multiple (≥2) primary cancers (MPC) to assess associations and genetic mechanisms.

METHODS

Patients were prospectively consented (01/2013-02/2019) to tumor-normal sequencing via a custom targeted panel (MSK-IMPACT). A subset consented to return of results of ≥76 cancer predisposition genes. International Agency for Research on Cancer (IARC) 2004 rules for defining MPC were applied. Tumor pairs were created to assess relationships between cancers. Age-adjusted, sex-specific, standardized incidence ratios (SIR) for first to second cancer event combinations were calculated using SEER rates, adjusting for confounders and time of ascertainment. Associations were made with germline and somatic variants.

RESULTS

Of 24,241 patients, 4,340 had MPC (18%); 20% were synchronous. Most (80%) had two primaries; however, 4% had ≥4 cancers. SIR analysis found lymphoma-lung, lymphoma-uterine, breast-brain, and melanoma-lung pairs in women and prostate-mesothelioma, prostate-sarcoma, melanoma-stomach, and prostate-brain pairs in men in excess of expected after accounting for synchronous tumors, known inherited cancer syndromes, and environmental exposures. Of 1,580 (36%) patients who received germline results, 324 (21%) had 361 pathogenic/likely pathogenic variants (PV), 159 (44%) in high penetrance genes. Of tumor samples analyzed, 55% exhibited loss of heterozygosity at the germline variant. In those with negative germline findings, melanoma, prostate, and breast cancers were common.

CONCLUSIONS

We identified tumor pairs without known predisposing mutations that merit confirmation and will require novel strategies to elucidate genetic mechanisms of shared susceptibilities.

IMPACT

If verified, patients with MPC with novel phenotypes may benefit from targeted cancer surveillance.

188 IMPROVING THE ASSESSMENT AND MANAGEMENT OF FALLS IN OLDER PEOPLE BY THE EMERGENCY DEPARTMENT IN THE HOME

Background

Falls among older adults are the injury pattern that causes the most morbidity and mortality. Assessing and managing these in the patients’ homes is challenging; it requires a comprehensive, systematic approach. This quality Improvement Project used a Comprehensive Geriatric Assessment for older adults who have suffered fall, carried out by an Emergency Department in the Home (EDITH) practitioner in the patient’s home.

Aim: To improve the evaluation and management of older people who have fallen and are attended to by the Emergency Department in the Home.

Methods

This OD project was carried out using the HSE People’s Needs Defining Change model. A new, streamlined version of the Comprehensive Geriatric Assessment tool was developed and introduced, and this was implemented and altered over two PDSA cycles.

Results

Documentation of falls improved dramatically, from a median of three out of 12 domains included to a median of 11 domains included. Users’ feedback helped the CGA evolve and was incredibly positive about the change.

Conclusion

This project shows that a CGA can be used successfully in patients’ own homes to assess risk factors for falling. The HSE’s People’s Needs Defining Change can be used to implement community-based projects. The community CGA tool could be explored by other areas and organisations in the future.

Factors Influencing Patient Preferences for Telehealth Cancer Genetic Counseling During the COVID-19 Pandemic

PURPOSE

With onset of the COVID-19 pandemic, telehealth became the primary modality for health care appointments. This study examined patient experiences with and preferences for telehealth at a cancer genetic counseling clinic throughout the first 6 months of the pandemic (March-August 2020).

METHODS

An anonymous survey assessed patient demographics; usage and prior experience with technology; emotional responses, technical experiences, and satisfaction with the telehealth appointment (via the Genetic Counseling Satisfaction Scale and Visit-Specific Satisfaction Questionnaire); preference for future telehealth; and recommendation of telehealth to others.

RESULTS

Among 380 respondents, most were highly satisfied with the telehealth appointment (with 65.6% and 66.4% of participants completing the Genetic Counseling Satisfaction Scale and Visit-Specific Satisfaction Questionnaire, respectively). Multivariable analyses indicated several notable findings. Adjusting for relevant covariates, participants with less education felt significantly more concerned about telehealth than those with highest educational attainment. Participants age 40-69 years were generally more comfortable, relieved, and grateful that their appointment was scheduled as telehealth than were those older than 70 years. Women were marginally more relieved and grateful for telehealth appointments than men. As the pandemic progressed, significantly more participants were highly satisfied with their telehealth appointment and participants trended toward having greater preferences for future telehealth use. Most participants (78.6%) would recommend telehealth to others, although 50.8% preferred future in-person appointments.

CONCLUSION

As the pandemic progressed, patients expressed increasing preferences for and satisfaction with telehealth. Service delivery models that incorporate individual patient preferences should be developed with special consideration to factors such as age, sex, and education level.

Germline RAD51B variants confer susceptibility to breast and ovarian cancers deficient in homologous recombination

Pathogenic germline mutations in the RAD51 paralog genes RAD51C and RAD51D, are known to confer susceptibility to ovarian and triple-negative breast cancer. Here, we investigated whether germline loss-of-function variants affecting another RAD51 paralog gene, RAD51B, are also associated with breast and ovarian cancer. Among 3422 consecutively accrued breast and ovarian cancer patients consented to tumor/germline sequencing, the observed carrier frequency of loss-of-function germline RAD51B variants was significantly higher than control cases from the gnomAD population database (0.26% vs 0.09%), with an odds ratio of 2.69 (95% CI: 1.4-5.3). Furthermore, we demonstrate that tumors harboring biallelic RAD51B alteration are deficient in homologous recombination DNA repair deficiency (HRD), as evidenced by analysis of sequencing data and in vitro functional assays. Our findings suggest that RAD51B should be considered as an addition to clinical germline testing panels for breast and ovarian cancer susceptibility.

Shelling the myth: allergies to Iodine containing substances and risk of reaction to Iodinated contrast media

PURPOSE

In excess of 100 million procedures using iodinated radio-contrast media are conducted each year. There is a common misunderstanding regarding the links between allergy to iodinated substances and the risk of allergic reaction to intravenous iodinated contrast agents. These perceived risks are managed via administration of corticosteroids or avoidance of iodinated contrast altogether.

METHODS

An extensive review of published literature on scientific databases and international guidelines was conducted in order to inform the research question. A questionnaire was formulated and distributed to hospital doctors in four tertiary centres. Within this questionnaire, hospital doctors were presented with six different scenarios of bona fide allergy to iodinated substances (e.g. shellfish) and asked to select the treatment response option which they deemed to be the most suitable from a choice of three (standard contrast scan/delay scan with pre-medication/change to non-contrast scan).

RESULTS

Eighty-seven questionnaire responses were received. Contrast (standard protocol) was the most appropriate regimen in the setting of all the listed allergies. This was identified correctly by 76%, 69%, 44%, 32%, 18% and 14% for kiwi, fish, poly-food, shellfish, betadine and tincture of iodine allergies, respectively.

CONCLUSIONS

There is a lack of understanding amongst local junior medical staff regarding administration of iodinated contrast media to patients with a history of allergy to iodinated substances. These misconceptions may potentiate the unnecessary usage of pre-medication and ordering of non-contrast scans in the setting of a gold-standard enhanced scan. Findings from this study suggest that there is a need for future education efforts targeted during the basic specialty training stage.

Therapeutic Implications of Germline Testing in Patients With Advanced Cancers

PURPOSE

Tumor mutational profiling is increasingly performed in patients with advanced cancer. We determined the extent to which germline mutation profiling guides therapy selection in patients with advanced cancer.

METHODS

Patients with cancer undergoing tumor genomic profiling were prospectively consented for germline cancer predisposition gene analysis (2015-2019). In patients harboring germline likely pathogenic or pathogenic (LP/P) alterations, therapeutic actionability was classified using a precision oncology knowledge base. Patients with metastatic or recurrent cancer receiving germline genotype-directed therapy were determined.

RESULTS

Among 11,947 patients across > 50 malignancies, 17% (n = 2,037) harbored a germline LP/P variant. By oncology knowledge base classification, 9% (n = 1042) had an LP/P variant in a gene with therapeutic implications (4% level 1; 4% level 3B; < 1% level 4). BRCA1/2 variants accounted for 42% of therapeutically actionable findings, followed by CHEK2 (13%), ATM (12%), mismatch repair genes (11%), and PALB2 (5%). When limited to the 9,079 patients with metastatic or recurrent cancer, 8% (n = 710) harbored level 1 or 3B genetic findings and 3.2% (n = 289) received germline genotype-directed therapy. Germline genotype-directed therapy was received by 61% and 18% of metastatic cancer patients with level 1 and level 3B findings, respectively, and by 54% of BRCA1/2, 75% of mismatch repair, 43% of PALB2, 35% of RAD51C/D, 24% of BRIP1, and 19% of ATM carriers. Of BRCA1/2 patients receiving a poly(ADP-ribose) polymerase inhibitor, 45% (84 of 188) had tumors other than breast or ovarian cancer, wherein the drug, at time of delivery, was delivered in an investigational setting.

CONCLUSION

In a pan-cancer analysis, 8% of patients with advanced cancer harbored a germline variant with therapeutic actionability with 40% of these patients receiving germline genotype-directed treatment. Germline sequence analysis is additive to tumor sequence analysis for therapy selection and should be considered for all patients with advanced cancer.

Paired Tumor-Normal Sequencing Provides Insights Into the TP53-Related Cancer Spectrum in Patients With Li-Fraumeni Syndrome

BACKGROUND

Genetic testing for Li-Fraumeni syndrome (LFS) is performed by using blood specimens from patients selected based on phenotype-dependent guidelines. This approach is problematic for understanding the LFS clinical spectrum because patients with nonclassical presentations are missed, clonal hematopoiesis-related somatic blood alterations cannot be distinguished from germline variants, and unrelated tumors cannot be differentiated from those driven by germline TP53 defects.

METHODS

To provide insights into the LFS-related cancer spectrum, we analyzed paired tumor-blood DNA sequencing results in 17 922 patients with cancer and distinguished clonal hematopoiesis-related, mosaic, and germline TP53 variants. Loss of heterozygosity and TP53 mutational status were assessed in tumors, followed by immunohistochemistry for p53 expression on a subset to identify those lacking biallelic TP53 inactivation.

RESULTS

Pathogenic/likely pathogenic TP53 variants were identified in 50 patients, 12 (24.0%) of which were clonal hematopoiesis related and 4 (8.0%) of which were mosaic. Twelve (35.3%) of 34 patients with germline TP53 variants did not meet LFS testing criteria. Loss of heterozygosity of germline TP53 variant was observed in 96.0% (95% confidence interval [CI] = 79.7% to 99.9%) of core LFS spectrum-type tumors vs 45.5% (95% CI = 16.8% to 76.6%) of other tumors and 91.3% (95% CI = 72.0% to 98.9%) of tumors from patients who met LFS testing criteria vs 61.5% (95% CI = 31.6% to 86.1%) of tumors from patients who did not. Tumors retaining the wild-type TP53 allele exhibited wild-type p53 expression.

CONCLUSIONS

Our results indicate that some TP53 variants identified in blood-only sequencing are not germline and a substantial proportion of patients with LFS are missed based on current testing guidelines. Additionally, a subset of tumors from patients with LFS do not have biallelic TP53 inactivation and may represent cancers unrelated to their germline TP53 defect.

Patient-Centered Identification of Meaningful Regulatory Endpoints for Medical Devices to Treat Parkinson's Disease

Introduction. A growing literature has developed on identifying outcomes that matter to patients. This study demonstrates an approach involving patient and regulatory perspectives to identify outcomes that are meaningful in the context of medical devices for Parkinson’s disease (PD). Methods. A systematic process was used for specifying relevant regulatory endpoints by synthesizing inputs of various sources and stakeholders. First, a literature review was conducted to identify important benefits, risks, and other considerations for medical devices to treat PD; patient discussion groups (n = 6) were conducted to refine the list of considerations, followed by a survey (n = 29) to prioritize them; and patient and Food and Drug Administration (FDA) reviewers informed specification of the final endpoints. Two FDA clinicians gave clinical and regulatory perspectives at each step. Results. Movement symptoms were ranked as most important (ranked 1 or 2 by 72% of participants) and psychological and cognitive symptoms as the next most important (ranked 1 or 2 by 52% of participants). Within movement symptoms, falls, impaired movement, bradykinesia, resting tremor, stiffness, and rigidity were ranked highly. Overall, nine attributes were identified and prioritized as patient-centric for use in clinical trial design and quantitative patient preference studies. These attributes were benefits and risks related to therapeutics for PD as well as other considerations, including time until a medical device is available for patient use. Discussion. This prospective approach identified meaningful and relevant benefits, risks, and other considerations that may be used for clinical trial design and quantitative patient preference studies. Although PD was the focus of this study, the approach can be used to study patient perspectives about other disease or treatment areas.

Characterization of a germline splice site variant MLH1 c.678-3T>A in a Lynch syndrome family

Germline mutations in the DNA mismatch repair (MMR) genes cause Lynch syndrome. Classification and interpretation of intronic variants, especially those outside the consensus ± 1 ~ 2 splice sites are challenging as it is uncertain whether such variants would affect splicing accuracy and efficiency. The assessment of the pathogenicity of splice site variants in MLH1 is further complicated by the various isoforms due to alternative splicing. In this report, we describe a 42-year-old female with Lynch syndrome who carries a germline variant, MLH1 c.678-3T>A, in the splice acceptor site of intron 8. Functional studies and semiquantitative analysis demonstrated that this variant causes a significant increase in the transcripts with exon 9 or exon 9 and 10 deletions, which presumably leads to premature protein truncation or abnormal protein. In addition, we also observed MSI-H and loss of MLH1 by IHC in patient's tumor tissue. This variant also segregated with Lynch Syndrome related cancers in three affected family members. Based on these evidence, the MLH1 c.678-3T>A variant is considered pathogenic.

Disparities in pan-cancer patients undergoing germline cancer risk assessment by self-reported race/ethnicity and ancestry

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Background: Disparities in access to germline testing for cancer patients (pts) have been demonstrated; however, disparities in post-testing care are unknown. We sought to evaluate germline findings and subsequent genetic counseling/care in cancer pts undergoing tumor-germline sequencing to explore differences by self-reported ancestry. Methods: Pan-cancer pts were prospectively consented to tumor-normal sequencing via a custom NGS panel (MSK-IMPACT) from 1/2015-12/2019 inclusive of germline analysis up to 88 genes. Germline analysis was performed as a research non-billable test in 97.5% of cases. Referral to clinical genetics service (CGS) was recommended for all pts with a new positive (likely pathogenic/pathogenic) germline variant (PV). Ancestry was defined using self-reported Federal definitions of race/ethnicity and designations of Ashkenazi Jewish (AJ) ancestry. Pts were categorized into mutually exclusive groups: AJ, White, Non-White (Asian, Black/African American, Hispanic, Other), and unknown. All pts self-identifying as Hispanic were classified as such, regardless of race. Abstracted data on germline findings and downstream CGS follow-up were compared across groups using non-parametric statistical tests. Results: Among the 15,775 pts in this cohort (59.6% White, 15.7% AJ, 20.5% Non-White [6.9% Asian, 6.8% Black, 6.7% Hispanic, 0.1% Other], and 4.2% unknown), 2663 (17%) had a PV. AJ pts had the highest rates of PV (n = 683, 27.6%), and Non-White pts had a lower proportion of PV (n = 433, 13.6%) compared to Whites (n = 1451, 15.5%), p < 0.01, with differences mostly due to increased prevalence of moderate/low penetrance variants in White and AJ pts . These findings were consistent across multiple tumor types. Prior knowledge of the PV (424/2663, 16%) was more common in Non-White (19.9%) and AJ (19.2%) than White pts (13.4%), p < 0.01. Among 2239 pts with new PV, all were referred to CGS, and 1652 (73.8%) pts were seen. Non-White pts had lower rates of completing visits (67.7%) than White (73.7%) and AJ pts (78.8%), p < 0.01, with the lowest rates occurring in Black (63%) and Hispanic (68.1%) pts. All pts without a visit (n = 587) received a close out letter including 139 pts (6.2% of pts with new PV) who had no documentation of receipt of results in the medical record. Higher rates of non-disclosure were observed in Non-White (6.7%) compared to White (5.4%) and AJ (3.4%) pts with new PV, p = 0.032; non-disclosure did not vary by gene penetrance. There was a non-significant trend towards lower rates of cascade testing at CGS in Asian and Black pts with ongoing analysis. Conclusions: Even when traditional barriers to genetic testing were minimized, Non-White pts were less likely to receive recommended cancer genetics follow-up for subsequent cancer risk counseling, with potential implications for oncological care, cancer risk reduction, and at-risk family members.

Prevalence and Characterization of Biallelic and Monoallelic NTHL1 and MSH3 Variant Carriers From a Pan-Cancer Patient Population

NTHL1 and MSH3 have been implicated as autosomal recessive cancer predisposition genes. Although individuals with biallelic NTHL1 and MSH3 pathogenic variants (PVs) have increased cancer and polyposis risk, risks for monoallelic carriers are uncertain. We sought to assess the prevalence and characterize NTHL1 and MSH3 from a large pan-cancer patient population.

MATERIALS AND METHODS

Patients with pan-cancer (n = 11,081) underwent matched tumor-normal sequencing with consent for germline analysis. Medical records and tumors were reviewed and analyzed. Prevalence of PVs was compared with reference controls (Genome Aggregation Database).

RESULTS

NTHL1-PVs were identified in 40 patients including 39 monoallelic carriers (39/11,081 = 0.35%) and one with biallelic variants (1/11,081 = 0.009%) and a diagnosis of isolated early-onset breast cancer. NTHL1-associated mutational signature 30 was identified in the tumors of the biallelic patient and two carriers. Colonic polyposis was not identified in any NTHL1 patient. MSH3-PVs were identified in 13 patients, including 12 monoallelic carriers (12/11,081 = 0.11%) and one with biallelic MSH3 variants (1/11,081 = 0.009%) and diagnoses of later-onset cancers, attenuated polyposis, and abnormal MSH3-protein expression. Of the 12 MSH3 carriers, two had early-onset cancer diagnoses with tumor loss of heterozygosity of the wild-type MSH3 allele. Ancestry-specific burden tests demonstrated that NTHL1 and MSH3 prevalence was not significantly different in this pan-cancer population versus controls.

CONCLUSION

NTHL1 and MSH3 germline alterations were not enriched in this pan-cancer patient population. However, tumor-specific findings, such as mutational signature 30 and loss of heterozygosity of the wild-type allele, suggest the potential contribution of monoallelic variants to tumorigenesis in a subset of patients.

Parkinson's Patients' Tolerance for Risk and Willingness to Wait for Potential Benefits of Novel Neurostimulation Devices: A Patient-Centered Threshold Technique Study

Background. Parkinson’s disease (PD) is neurodegenerative, causing motor, cognitive, psychological, somatic, and autonomic symptoms. Understanding PD patients’ preferences for novel neurostimulation devices may help ensure that devices are delivered in a timely manner with the appropriate level of evidence. Our objective was to elicit preferences and willingness-to-wait for novel neurostimulation devices among PD patients to inform a model of optimal trial design. Methods. We developed and administered a survey to PD patients to quantify the maximum levels of risks that patients would accept to achieve potential benefits of a neurostimulation device. Threshold technique was used to quantify patients’ risk thresholds for new or worsening depression or anxiety, brain bleed, or death in exchange for improvements in “on-time,” motor symptoms, pain, cognition, and pill burden. The survey elicited patients’ willingness to wait to receive treatment benefit. Patients were recruited through Fox Insight, an online PD observational study. Results. A total of 2740 patients were included and a majority were White (94.6%) and had a 4-year college degree (69.8%). Risk thresholds increased as benefits increased. Threshold for depression or anxiety was substantially higher than threshold for brain bleed or death. Patient age, ambulation, and prior neurostimulation experience influenced risk tolerance. Patients were willing to wait an average of 4 to 13 years for devices that provide different levels of benefit. Conclusions. PD patients are willing to accept substantial risks to improve symptoms. Preferences are heterogeneous and depend on treatment benefit and patient characteristics. The results of this study may be useful in informing review of device applications and other regulatory decisions and will be input into a model of optimal trial design for neurostimulation devices.

"Something Is Wrong Here": An Interview With Sarah Cox About Damming Canadian Rivers for Hydroelectricity

Only one-third of the world's rivers remain free flowing, and one million species face extinction. In the climate crisis, the race for "clean energy" is on. Over the last century, the Canadian government has built hundreds of hydropower dams and is pushing ahead with more big dams despite decades of science showing their irreversible and significant social, environmental, and economic harms. Canada markets its hydropower as "clean" and "renewable." In her book, Breaching the Peace: The Site C Dam and a Valley's Stand Against Big Hydro, journalist Sarah Cox documents the externalities caused by Canada's megadams and the ongoing struggle by indigenous people, farmers, and activists to stop one of the largest and most controversial dams located on the Peace River in British Columbia, Canada. Meg Sheehan, environmental attorney, interviewed Cox during the COVID-19 pandemic to get the story behind Canada's hydropower policy and how things can change.

Abstract PO-034: A collaborative approach to increase germline testing and counseling uptake within New York City’s underserved patient population

Background: Understanding the role of genetic drivers in cancer is a fundamental component of precision medicine. Further, identification of germline mutations provides important clinical data for patients. Understanding the risk conferred by inheriting certain mutations can guide treatment and screening behaviors for both patients and their family members. Despite the importance of testing, minority patients are less likely to undergo germline testing. Patient and physician reported barriers include limited or no knowledge of genetic tests, limited knowledge of hereditary cancer syndromes, lack of educational materials, time constraints, lack of genetic counselors, and out-of-pocket costs. Objective: To describe how an academic-community collaboration between local healthcare institutions addresses some known barriers to germline testing and counseling in a typically underrepresented patient population. Methods: The Cancer Health Equity Research Program (CHERP) at Memorial Sloan Kettering (MSK) partners with local community hospitals, which serve diverse populations, to provide somatic and germline testing to their cancer patients under the research protocol, MSK-IMPACT™ (Integrated Mutation Profiling of Actionable Cancer Targets). Testing and counseling are provided by the Center for Molecular Oncology and Clinical Genetics Service at MSK. Site clinicians are trained on study procedures to ensure they are prepared to educate their patients on the purpose of genetic testing. Non-clinical MSK research staff (NCMRS) are trained as consenting professionals and delegated to a site to address clinic time constraints. NCMRS facilitate the collection, shipment, and tracking of biospecimens and collaborate with MSK’s Clinical Genetics Service on behalf of the sites. To address both educational and language barriers, a subtitled video on germline testing, translated informed consents, and translated educational brochures are provided to each site. Results: Since March 2018, 270 patients from our CHERP sites agreed to germline testing. Self-reported race is as follows: 35 Asian (13.0%), 123 Black (45.6%), 25 Caucasian (9.3%), 1 Pacific Islander (0.4%), 11 Other (4.1%), and 75 Unknown (27.8%). Additionally, 99 (36.7%) patients identified as Hispanic and Hispanics represent 90.7% of self-reported Unknown race and 100% of the self-reported Other race. Of the 270 patients, 201 have had successful germline testing (62 patients ineligible and 7 pending results) with 26 (12.9%) having a positive finding. Genetic counseling was provided for 17 (65.4%) of these patients, with 6 sessions in-person and 11 telegenetic sessions. Conclusion: Disparities in genetic testing are well documented and efforts to expand access to testing and counseling for minority patients are urgently needed. In partnership with local hospitals, CHERP addresses many of the barriers that contribute to these disparities and demonstrated success in providing germline testing and counseling for minority patients.

Citation Format: Kenya P. Vado, Thomas Reynolds, Kellie Jack, Linda Bulone, Margaret Kemeny, Jason Gonsky, Lewis Kampel, Shadai Mcmillan, Anna Maio, Margaret Sheehan, Erin Salo-Mullen, Sandy Naupari, Jesse Galle, Alisha Williams, Zsofia Stadler, Mark Robson, David Solit, Paul Sabbatini, Carol Brown. A collaborative approach to increase germline testing and counseling uptake within New York City’s underserved patient population [abstract]. In: Proceedings of the AACR Virtual Conference: Thirteenth AACR Conference on the Science of Cancer Health Disparities in Racial/Ethnic Minorities and the Medically Underserved; 2020 Oct 2-4. Philadelphia (PA): AACR; Cancer Epidemiol Biomarkers Prev 2020;29(12 Suppl):Abstract nr PO-034.

Abstract 1122: Germline mutation prevalence in young adults with cancer

The identification of germline pathogenic variants in young adult cancer patients is especially critical given risk of second primary cancers, need for appropriate long-term surveillance, potential reproductive implications, and cascade testing of at-risk family members. We sought to determine the prevalence of germline susceptibility in cancer patients, age 18-39, across diverse solid tumor phenotypes. A total of 1201 cases, diagnosed between ages 18-39 were prospectively ascertained from 2015-2019 under a human subjects-approved protocol that provided result transmission of germline analysis. A next-generation sequencing panel consisting of up to 88 genes previously implicated in cancer predisposition (MSK-IMPACT) was utilized. Based on SEER data, we refined our population of young cancer patients into those with 1) early-onset cancer (EO-CA), defined as cancer wherein age 39 is &gt;1 standard deviation (STD) below the mean age of diagnosis for that cancer type and 2) young-adult cancer (YA-CA), defined as cancer wherein age 39 is &lt;1 STD below the mean age at cancer diagnosis. Among EO-CA (n=877) cases, the most common cancers included colorectal, breast, kidney, pancreas, and ovarian cancer, while among YA-CAs (n=324), the most frequent diagnoses were sarcoma, brain, testicular and thyroid cancer. Germline prevalence of likely pathogenic or pathogenic variants (PV) was 21% in the EO-CA versus 13% in YA-CA patients (p=0.002), with an enrichment of high- and moderate-penetrance PVs in the EO-CA cohort (15% vs 10%; p=0.01). Among EO-CAs, the most commonly mutated genes were BRCA2, BRCA1, CHEK2 and ATM, with pancreas, breast, and kidney cancer harboring the highest rates of germline PVs. In contrast, in the YA-CA cohort, TP53 and SDHA mutations predominated. Among YA-CA patients with sarcoma, the 18.1% mutation prevalence was similar to the prevalence in EO-CAs. Matched tumor analyses assessing biallelic inactivation is on-going and will be presented. Among young adults with early-onset phenotypes of malignancies typically presenting at later ages, the increased prevalence of germline PVs supports a role for genetic testing irrespective of tumor type.

Citation Format: Zsofia K. Stadler, Anna Maio, Angelika Padunan, Yelena Kemel, Erin Salo-Mullen, Margaret Sheehan, Kimeisha Belanfanti, Prince R. Tejada, Ozge Birsoy, Diana Mandelker, Liying Zhang, Jesse Galle, Darren Feldman, Laura Boucai, Julia Glade Bender, Anna Piotrowski, Carol Aghajanian, Karen A. Cadoo, Maria I. Carlo, Michael Walsh, Yelena Janjigian, Eileen O'Reilly, Lisa M. DeAngelis, David B. Solit, Barry Taylor, Andrea Cercek, William Tap, Mark E. Robson, Michael F. Berger, Kenneth Offit, Luis A. Diaz. Germline mutation prevalence in young adults with cancer [abstract]. In: Proceedings of the Annual Meeting of the American Association for Cancer Research 2020; 2020 Apr 27-28 and Jun 22-24. Philadelphia (PA): AACR; Cancer Res 2020;80(16 Suppl):Abstract nr 1122.

Targeted therapy based on germline analysis of tumor-normal sequencing (MSK-IMPACT) in a pan-cancer population

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Background: Tumor mutational profiling for identification of somatic alterations for targeted treatment is increasingly being performed in advanced cancer patients (pts). We sought to assess the clinical utility of germline mutation profiling for targeted therapeutic interventions in a pan-cancer patient population. Methods: All pts who had germline genetic testing through a prospective protocol via a next-generation sequencing panel (MSK-IMPACT) were identified (N=11,975) from 2015-5/2019. The medical record of pts with likely pathogenic/pathogenic germline (LP/P) alterations in genes with known therapeutic targets were reviewed to identify germline-targeted treatment either in a clinical or research setting. Results: We identified 2,043 (17.1%) pts who harbored LP/P variants in a cancer predisposition genes including 777 (6.5%) in genes with potentially targetable therapeutic implications: 416 BRCA1/2, 149 DNA mismatch repair genes (Lynch syndrome, LS), 122 ATM, 45 PALB2, 26 RAD51C/D, 7 RET, 4 TSC, 3 PTCH1, 2 ALK, 1 EGFR, 1 MET and 1 KIT. Of those with advanced disease (n=554), 45.3% received targeted therapeutic treatment (Table) including 50.9% BRCA1/2, 58.3% LS (67.4% of microsatellite-high LS cases), 41.7% PALB2, 36.8% RAD51C/D and 19.3% ATM carriers. Of patients receiving a poly (ADP-ribose) polymerase inhibitor (PARP-I) in the setting of a BRCA1/2 mutation, 55.1% had breast or ovarian cancer; however, 44.8% had other tumors, including pancreas, prostate, bile duct, gastric, wherein the drug was given in a research setting. Among PALB2 pts receiving PARP-Is, 53.3% (8/15) had breast or pancreas cancer; 46.7% had cancer of the prostate, ovary or unknown primary. Conclusions: In our pan-cancer analysis, 6.5% of pts harbored a targetable germline variant highlighting the importance of germline analysis in advanced cancer pts for selection of both FDA-approved treatments and clinical trial participation with germline-targeted therapeutics. [Table: see text]

The Impact of the Storm Emma on Irish Emergency Department Attendances

Aim The impact of severe weather events on Irish EDs has not yet been characterised. The aim of this study was to examine the impact of Storm Emma on the attendance patterns to an Irish ED. Methods Data was collected for 64hrs prior to the red alert (Pre-Red), 38hrs of the red alert (Red) and for the 256 hrs (10 days) post the red alert (Post-Red) during Storm Emma. A Comparison was made with the same time periods in 2017. Results There was a statistically significant decrease in attendance during the Red period in 2018, compared with 2017 (119 vs. 234, p<0.001), with a rebound surge in attendances in the Post-Red period (1,861 vs 1,578, p<0.001). Mean patient experience times were significantly longer in the Post-Red period in 2018 (9.5+/-9.5hrs vs 7.9+/-8.2hrs, p<0.001). Conclusion This study has detailed the impact of a severe weather event on an Irish ED and will help inform preparedness for the future.

Abstract P6-09-01: RAD51B loss-of-function variants confer susceptibility to hereditary breast and ovarian cancers and result in tumors with genomic features of homologous recombination repair defects

Introduction: Germline pathogenic variants in genes in the homologous recombination (HR) pathway such as BRCA1, BRCA2, ATM, PALB2, RAD51C and RAD51D confer an increased risk of breast and ovarian cancers. Screening for germline variants in these cancer susceptibility genes is critical as prophylactic measures and monitoring can be performed in these individuals to minimize their risk of developing breast and/or ovarian cancers. More recently, it has been recognized that cancers arising in carriers of germline pathogenic (P)/ likely pathogenic (LP) variants in HR genes often show a homologous recombination (HR) deficient (HRD) phenotype and can be targeted with platinum agents or PARP inhibitors. RAD51B is a RAD51 paralog that binds to RAD51C and functions as a heterodimer in the HR pathway. Whilst RAD51B germline variants have been reported in isolated cases of breast and ovarian cancers, it is unclear as to whether RAD51B P/LP germline variants would confer predisposition to these cancer types. Materials and Methods: We screened 9,287 consecutive unselected cancer patients who consented for both tumor and germline testing using the MSK-IMPACT platform for the presence of RAD51B germline truncating variants. Selected RAD51B germline mutant breast cancers identified by MSK-IMPACT were subjected to whole-exome sequencing (WES) analysis to determine the dominant mutational signatures using DeconstructSigs. Functional assays were performed to ascertain the impact of RAD51B loss on HR DNA repair and PARP inhibitor sensitivity using genome editing methods in non-malignant breast epithelial cell lines. Results: Out of the 9,287 cancer patients, we detected likely pathogenic loss of function RAD51B germline variants in 11 patients (0.12%), which was similar to the frequency detected in the gnomAD database (0.09%). All female carriers of RAD51B loss of function variants (n=8) had breast or ovarian cancers (8/1,619 breast or ovarian cancers, 0.5%). The observed carrier frequencies of germline truncating variants in RAD51B was statistically enriched in breast and ovarian cancer patients compared to individuals in the gnomAD database (0.5% vs 0.09% P=0.0003; odds ratio = 5.06 (95% CI: 2.1-10.3)). Although segregation studies were not available, 9/11 of the RAD51B germline loss of function variant carriers had a personal or family history of breast or ovarian cancers. All five breast and ovarian cancers from RAD51B mutation carriers investigated by WES were found to harbor RAD51B bi-allelic inactivation through loss of heterozygosity of the RAD51B wild-type allele. In addition, these five cases were found to display genomic features of HRD including high large-scale state transition scores and a dominant mutational signature 3. CRISPR/Cas9 genome editing of RAD51B in a non-malignant breast epithelial cell model revealed that RAD51B deficient cells display PARP inhibitor sensitivity similar to that reported in BRCA1 and BRCA2 deficient cell lines. Conclusion: RAD51B loss-of-function germline variants confer susceptibility to breast and ovarian cancer development. Breast and ovarian cancers occurring in the context of RAD51B germline mutations harbor bi-allelic inactivation of RAD51B through loss-of-heterozygosity of the wild-type allele, genomic features of HRD and are likely sensitive to PARP inhibition. Albeit rarely germline mutated, RAD51B should be considered as an addition to clinical germline testing panels for hereditary breast and ovarian cancer syndrome patients. &lt;!–EndFragment→

Citation Format: Diana SReis-FilhoReis-Filho Mandelker, Semanti Mukherjee, Jeremy Setton, Pier Selenica, Yelena Kemel, Ozge Ceyhan-Birsoy, Margaret Sheehan, Kaitlyn Tkachuk, David N Brown, Simon Powell, Britta Weigelt, Mark E Robson, Nadeem Riaz, Kenneth Offit, Jorge S Reis-Filho. RAD51B loss-of-function variants confer susceptibility to hereditary breast and ovarian cancers and result in tumors with genomic features of homologous recombination repair defects [abstract]. In: Proceedings of the 2019 San Antonio Breast Cancer Symposium; 2019 Dec 10-14; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2020;80(4 Suppl):Abstract nr P6-09-01.

Neoadjuvant radiotherapy for rectal cancer management

Thirty per cent of all colorectal tumours develop in the rectum. The location of the rectum within the bony pelvis and its proximity to vital structures presents significant therapeutic challenges when considering neoadjuvant options and surgical interventions. Most patients with early rectal cancer can be adequately managed by surgery alone. However, a significant proportion of patients with rectal cancer present with locally advanced disease and will potentially benefit from down staging prior to surgery. Neoadjuvant therapy involves a variety of options including radiotherapy, chemotherapy used alone or in combination. Neoadjuvant radiotherapy in rectal cancer has been shown to be effective in reducing tumour burden in advance of curative surgery. The gold standard surgical rectal cancer management aims to achieve surgical removal of the tumour and all draining lymph nodes, within an intact mesorectal package, in order to minimise local recurrence. It is critically important that all rectal cancer cases are discussed at a multidisciplinary meeting represented by all relevant specialties. Pre-operative staging including CT thorax, abdomen, pelvis to assess for distal disease and magnetic resonance imaging to assess local involvement is essential. Staging radiology and MDT discussion are integral in identifying patients who require neoadjuvant radiotherapy. While Neoadjuvant radiotherapy is potentially beneficial it may also result in morbidity and thus should be reserved for those patients who are at a high risk of local failure, which includes patients with nodal involvement, extramural venous invasion and threatened circumferential margin. The aim of this review is to discuss the role of neoadjuvant radiotherapy in the management of rectal cancer.

A Standardized Aspiration-First Approach for Thrombectomy to Increase Speed and Improve Recanalization Rates

BACKGROUND AND PURPOSE

Direct aspiration is a recognized technique for revascularization in large-vessel ischemic strokes. There is ongoing debate regarding its efficacy compared with stent retrievers. Every delay in achieving revascularization and a decrease in reperfusion rates reduces the likelihood of patients achieving functional independence. We propose a standardized setup technique for aspiration-first for all anterior circulation thrombectomy procedures for increasing speed and recanalization rates.

MATERIALS AND METHODS

We analyzed 127 consecutive patients treated by a standardized approach to thrombectomy with an intention to perform aspiration-first compared with 127 consecutive patients treated with a stent retriever-first approach. Key time metrics evaluated included groin to first angiogram, first angiogram to reperfusion, groin to first reperfusion, and length of the procedure. The degree of successful recanalization (TICI 2b-3) and the number of passes were compared between the 2 groups.

RESULTS

In 127 patients who underwent the standardized technique, the median time from groin puncture to first reperfusion was 18 minutes compared with 26 minutes (P < .001). The duration of the procedure was shorter compared with the stent retriever group (26 minutes in the aspiration first group versus 47 minutes, P < .001) and required fewer passes (mean, 2.4 versus 3.1; P < .05). A higher proportion of patients had a TICI score of 2b-3 in the aspiration-first group compared with stent retriever group (96.1% versus 85.8%, P < .005).

CONCLUSIONS

Our study highlights the increasing speed and recanalization rates achieved with fewer passes in a standardized approach to thrombectomy with an intention to attempt aspiration-first. Any attempt to reduce revascularization time and increase successful recanalization should be used.

Understanding inherited risk in unselected newly diagnosed patients with endometrial cancer

PURPOSE

Mutations in DNA mismatch repair (MMR) genes and PTEN, diagnostic of Lynch and Cowden syndromes, respectively, represent the only established inherited predisposition genes in endometrial cancer to date. The prevalence of other cancer predisposition genes remains unclear. We sought the prevalence of pathogenic germline variants in unselected patients with endometrial cancer attending for surgical consultation.

PATIENTS AND METHODS

Patients were prospectively consented (4/2016-5/2017) to an IRB-approved protocol of tumor-normal sequencing via a custom next-generation sequencing panel (MSK-IMPACT) with return of germline results for >75 cancer predisposition genes. Tumors were assessed for microsatellite instability (MSI). Per institutional standards, all tumors underwent Lynch syndrome screening via IHC for MMR proteins.

RESULTS

Of 156 patients who consented to germline genetic testing, 118 (76%) had stage I disease. Tumors were endometrioid in 104 (67%), of which 60 (58%) were grade 1. Twenty-four pathogenic germline variants were identified in 22 patients (14%)-7 (4.5%) with highly penetrant cancer syndromes and 15 (9.6%) with variants in moderate-, low-penetrance, or recessive genes. Of these, 5 (21%) were in Lynch syndrome genes (2 MSH6, 2 PMS2, and 1 MLH1). All 5 tumors had concordant IHC staining; 2 (40%) were definitively MSI-high by next-generation sequencing. One patient had a known BRCA1 mutation; 1 had SMARCA4 deletion. The remaining 17 variants (71%) were incremental findings in moderate- and low-penetrance variants or genes associated with recessive disease.

CONCLUSION

In unselected patients with predominantly low-risk, early-stage endometrial cancer, germline multi-gene panel testing identifies cancer predisposition gene variants in 14%. This finding may have implications for future cancer screening and risk-reduction recommendations. Universal IHC screening for Lynch syndrome successfully identifies the majority (71%) of high-penetrance germline mutations.

Clinical implications of microsatellite instability in mucinous colorectal cancer

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Background: Colorectal Cancer(CRC) is becoming increasingly recognised as a heterogeneous tumor type. Mucinous histological subtype is identified in 10-15% of CRCs, most commonly those with microsatellite instability (MSI), and has traditionally been associated with unfavorable outcomes and poor response to chemotherapy. In contrast, MSI is associated with relatively favourable pathological features and better outcomes, compared with CRCs with microsatellite stability (MSS), such that under the 2010 WHO classification, MSI mucinous CRC is considered low grade, while MSS mucinous CRC is classified as high grade. The aim of this study is to establish the significance of microsatellite stability status in non-metastatic mucinous colorectal cancer. Methods: Between 2010 and 2017, 69 patients with stage II or stage III mucinous colorectal cancer were identified. Microsatellite status was tested in all patients (MSS or MSI), and histological and clinical data, as well as recurrence rates, were assessed in both groups. MSI status was established using polymerase chain reaction(PCR) technique. Results: Sixty-nine patients with mucinous CRC were identified. The median age for the entire group was 73 years (range 32-87), no difference in gender was identified. 63%(n=43) and 37%(n=26) were stage II and stage III respectively at diagnosis. The majority of mucinous CRCs were right-sided (72%). 33% (n=23) were identified as microsatellite unstable (MSI). MSI status was associated with right sided tumours (78% right-sided vs 22% left-sided, p<0.05), older age at diagnosis (mean 76 years vs 68 years, p=0.01), and lower TNM staging at diagnosis (83% vs 52% diagnosed stage 2, p=0.007) compared with the MSS group. A lower disease recurrence rate was identified in the MSI group (4.3% vs 13% in MSS group) at median follow-up time of 33 months (range 8-93 months). Conclusions: In patients with mucinous colorectal cancer, MSI status is a useful marker of favourable histological and clinical features, and is associated with better outcomes. Our study supports the current 2010 WHO classification, and highlights the clinical and prognostic significance of MSI status in this patient cohort.