Unraveling the potential clinical utility of circulating tumor DNA detection in colorectal cancer-evaluation in a nationwide Danish cohort

BACKGROUND

Increasingly, circulating tumor DNA (ctDNA) is proposed as a tool for minimal residual disease (MRD) assessment. Digital PCR (dPCR) offers low analysis costs and turnaround times of less than a day, making it ripe for clinical implementation. Here, we used tumor-informed dPCR for ctDNA detection in a large colorectal cancer (CRC) cohort to evaluate the potential for post-operative risk assessment and serial monitoring, and how the metastatic site may impact ctDNA detection. Additionally, we assessed how altering the ctDNA-calling algorithm could customize performance for different clinical settings.

PATIENTS AND METHODS

Stage II-III CRC patients (N = 851) treated with a curative intent were recruited. Based on whole-exome sequencing on matched tumor and germline DNA, a mutational target was selected for dPCR analysis. Plasma samples (8 ml) were collected within 60 days after operation and-for a patient subset (n = 246)-every 3-4 months for up to 36 months. Single-target dPCR was used for ctDNA detection.

RESULTS

Both post-operative and serial ctDNA detection were prognostic of recurrence [hazard ratio (HR) = 11.3, 95% confidence interval (CI) 7.8-16.4, P < 0.001; HR = 30.7, 95% CI 20.2-46.7, P < 0.001], with a cumulative ctDNA detection rate of 87% at the end of sample collection in recurrence patients. The ctDNA growth rate was prognostic of survival (HR = 2.6, 95% CI 1.5-4.4, P = 0.001). In recurrence patients, post-operative ctDNA detection was challenging for lung metastases (4/21 detected) and peritoneal metastases (2/10 detected). By modifying the cut-off for calling a sample ctDNA positive, we were able to adjust the sensitivity and specificity of our test for different clinical contexts.

CONCLUSIONS

The presented results from 851 stage II-III CRC patients demonstrate that our personalized dPCR approach effectively detects MRD after operation and shows promise for serial ctDNA detection for recurrence surveillance. The ability to adjust sensitivity and specificity shows exciting potential to customize the ctDNA caller for specific clinical settings.

Exploring D-Lactate as a Biomarker for Acute Intestinal Necrosis in 2958 Patients: A Prospective Cross-Sectional Study

BACKGROUND

Timely diagnosis of acute intestinal necrosis (AIN) is lifesaving, but challenging due to unclear clinical presentation. D-lactate has been proposed as an AIN biomarker.

OBJECTIVES

We aimed to test the diagnostic performance in a clinical setting.

METHODS

We performed a cross-sectional prospective study, including all adult patients with acute referral to a single tertiary gastrointestinal surgical department during 2015-2016 and supplemented by enrollment of high-risk in-hospital patients suspected of having AIN during 2016-2019. AIN was verified intraoperatively, and D-lactate was analyzed using an automatic spectrophotometric set-up. A D-lactate cut-off for AIN was estimated using the receiver operating characteristic curve. The performance according to patient subgroups was estimated using the area under the receiver operating characteristic curve (AUC). Given the exploratory nature of this study, a formal power calculation was not feasible.

RESULTS

Forty-four AIN patients and 2914 controls were enrolled. The D-lactate cut-off was found to be 0.0925 mM. Due to lipemic interference, D-lactate could not be quantified in half of the patients, leaving 23 AIN patients and 1456 controls for analysis. The AUC for the diagnosis of AIN by D-lactate was 0.588 (95% confidence interval 0.475-0.712), with a sensitivity of 0.261 and specificity of 0.892. Analysis of high-risk patients showed similar results (AUC 0.579; 95% confidence interval 0.422-0.736).

CONCLUSION

D-lactate showed low sensitivity for AIN in both average-risk and high-risk patients. Moreover, lipemic interference precluded valid spectrophotometric assessment of D-lactate in half of the patients, further disqualifying the clinical utility of D-lactate as a diagnostic marker for AIN.

Monocyte recruitment in venous pulmonary embolism at time of cancer diagnosis in upper gastrointestinal cancer patients

Upper gastrointestinal cancer is frequently complicated by venous thromboembolisms (VTE), especially pulmonary embolisms (PE) increase the mortality rate. Monocytes are a part of the innate immune system and up-regulation may indicate an ongoing inflammatory response or infectious disease and has lately been associated with a moderate risk of suffering from VTE. This prospectively study aims to compare the incidence of pulmonary embolism with markers of coagulation and compare it to the absolute monocyte count. A consecutive cohort of 250 patients with biopsy proven upper gastrointestinal cancer (i.e. pancreas, biliary tract, esophagus and gastric cancer) where included at the time of cancer diagnosis and before treatment. All patients underwent bilateral compression ultrasonography for detection of deep vein thrombosis (DVT). Of these 143 had an additionally pulmonary angiografi (CTPA) with the staging computer tomography. 13 of 250 patients (5.2%) had a DVT and 11 of 143 (7.7%) had CTPA proven PE. PE was significantly more common among patients with elevated D-dimer (OR 11.62, 95%CI: 1.13-119, P = 0.039) and elevated absolute monocyte count (OR 7.59, 95%CI: 1.37-41.98, P = 0.020). Only patients with pancreatic cancer had a significantly higher risk of DVT (OR 11.03, 95%CI: 1.25-97.43, P = 0.031). The sensitivity of absolute monocyte count was 63.6 (95%CI: 30.8-89.1) and specificity 80.3 (95%CI: 72.5-86.7), with a negative predictive value of 96.4 (95%CI: 91-99) in PE. An increased absolute monocyte count was detected in patients suffering from PE but not DVT, suggesting a possible interaction with the innate immune system.

Prospective evaluation of bowel function and quality of life after colon cancer surgery - is it time for routine screening for late sequelae?

AIM

Bowel dysfunction after colon cancer (CC) surgery is widely neglected in current follow up programmes. This study explored changes in bowel function and quality of life (QoL) from three (3 m) to twelve months (12 m) after surgery in CC patients undergoing right- or left-sided colon resection (RightSCR/LeftSCR) and investigated differences between the two groups 12 m after surgery.

METHOD

CC patients undergoing surgical resection in 2018-2020 at five surgical departments were included in this population-based prospective cohort study. Included patients completed electronic surveys consisting of a collection of validated scores 3 m and 12 m after surgery.

RESULTS

A total of 708 CC patients (423 RightSCR, 285 LeftSCR) were included. In RightSCR, no improvement was observed from 3 m to 12 m in most scores/items, on the contrary, symptom worsening in flatus- and faecal incontinence and urgency was observed (p < 0.05). Also, the proportion of patients rating their bowel function as very good/good decreased (p < 0.05) in this group. In LeftSCR improvement was found in flatus and faecal incontinence, urgency and night-time defaecation (p < 0.02), while no improvement was observed in the remaining scores/items. At 12 m, higher proportions of RightSCR than LeftSCR reported loose stools, incontinence and urgency (all p < 0.001), whereas LeftSCR more often reported hard stools and flatus incontinence (p < 0.05). Among all CC patients 18.3% reported bowel-related impairment of QoL at 12 m with no differences between the two groups.

CONCLUSION

From 3 m to 12 m no significant change was observed in the majority of bowel function and QoL scores/items, however, some symptoms worsened in RightSCR, while a few improved in LeftSCR. Bowel dysfunction and impaired QoL were still common in both groups at 12 m, although the symptom pattern differed between the groups. These findings call for a systematic screening for bowel dysfunction to ensure early treatment of symptoms.

Promoter hypermethylation of SFRP1 as a prognostic and potentially predictive blood-based biomarker in patients with stage III or IV pancreatic ductal adenocarcinoma

BACKGROUND

Pancreatic ductal adenocarcinoma remains one of the major causes of cancer-related mortality globally. Unfortunately, current prognostic biomarkers are limited, and no predictive biomarkers exist. This study examined promoter hypermethylation of secreted frizzled-related protein 1 (phSFRP1) in cfDNA as a prognostic biomarker and predictor of treatment effect in patients with metastatic FOLFIRINOX-treated PDAC and locally advanced PDAC.

METHODS

We performed methylation-specific PCR of the SFRP1 genes' promoter region, based on bisulfite treatment. Survival was assessed as time-to-event data using the pseudo-observation method and analyzed with Kaplan-Meier curves and generalized linear regressions.

RESULTS

The study included 52 patients with FOLFIRINOX-treated metastatic PDAC. Patients with unmethylated (um) SFRP1 (n = 29) had a longer median overall survival (15.7 months) than those with phSFRP1 (6.8 months). In crude regression, phSFRP1 was associated with an increased risk of death of 36.9% (95% CI 12.0%-61.7%) and 19.8% (95% CI 1.9-37.6) at 12 and 24-months, respectively. In supplementary regression analysis, interaction terms between SFRP1 methylation status and treatment were significant, indicating reduced benefit of chemotherapy. Forty-four patients with locally advanced PDAC were included. phSFRP1 was associated with an increased risk of death at 24-months CONCLUSIONS: This indicates that phSFRP1 is a clinically useful prognostic biomarker in metastatic PDAC and possibly in locally advanced PDAC. Together with existing literature, results could indicate the value of cfDNA-measured phSFRP1 as a predictive biomarker of standard palliative chemotherapy in patients with metastatic PDAC. This could facilitate personalized treatment of patients with metastatic PDAC.

Quality of life and symptom burden after rectal cancer surgery: a randomised controlled trial comparing patient-led versus standard follow-up

PURPOSE

After curatively intended rectal cancer (RC) surgery, new follow-up strategies are warranted, seeking more individualised care and targeting health-related quality of life (HRQoL) and functional outcomes. The FURCA trial aimed to investigate the effect of patient-led follow-up on HRQoL and symptom burden 3 years after surgery.

METHODS

RC patients from four Danish centres were randomised 1:1 to intervention (patient-led follow-up with patient education and self-referral to a specialist nurse) or control (standard follow-up with five routine doctor visits). Patients in both groups had a computed tomography (CT) at 1 and 3 years. The primary outcome (HRQoL) was assessed by the Functional Assessment of Cancer Therapy - colorectal (FACT-C) score (Ward et al. in Qual Life Res. 8(3):181-95, 18). Secondary outcomes were functional measures, patient involvement and satisfaction and cancer recurrence at 3 years.

RESULTS

From Feb 2016 to Aug 2018, 336 patients were included of whom 248 completed 3 years of follow-up. Between-group differences were found neither for the primary endpoint, nor for functional outcomes. The recurrence rate did not differ between the groups. Patient involvement and satisfaction were higher in the intervention group with statistical significance in almost half of the items.

CONCLUSIONS

We found no effect on HRQoL and symptom burden from patient-led follow-up, although it may improve patient-perceived involvement and satisfaction.

IMPLICATIONS FOR CANCER SURVIVORS

The findings in this study suggest that patient-led follow-up is a more tailored approach to meet cancer survivors' needs and might improve their ability to cope with survivorship.

CLINICALTRIALS

GOV IDENTIFIER

R97-A6511-14-S23.

Exploring I-FABP, endothelin-1 and L-lactate as biomarkers of acute intestinal necrosis: a case-control study

OBJECTIVE

Acute intestinal necrosis (AIN) is a disease with devastating high mortality. AIN due to obstructed arterial blood flow has a blurred clinical presentation. Timely diagnosis is paramount, and a blood-based biomarker is warranted to increase patient survival. We aimed to assess intestinal fatty acid binding protein (I-FABP) and endothelin-1 as diagnostic biomarkers for AIN. To our knowledge, this is the first study exploring endothelin-1 in AIN patients from a general surgical population.

DESIGN

We conducted a single-centre nested case-control study comparing acutely admitted AIN patients to age- and sex-matched non-AIN patients during 2015-2016. I-FABP and endothelin-1 were analysed using an enzyme-linked immunosorbent assay. L-lactate levels were also measured in all patients. Cut-offs were estimated using receiver operator characteristic curves, and the diagnostic performance was estimated using the area under the receiver operator characteristic curve (AUC).

RESULTS

We identified 43 AIN patients and included 225 matched control patients. Median levels of I-FABP, endothelin-1 and L-lactate were 3550 (IQR: 1746-9235) pg/ml, 3.91 (IQR: 3.33-5.19) pg/ml and 0.92 (IQR: 0.74-1.45) mM in AIN patients and 1731 (IQR: 1124-2848) pg/ml, 2.94 (IQR: 2.32-3.82) pg/ml and 0.85 (IQR: 0.64-1.21) mM in control patients, respectively. The diagnostic performances of endothelin-1 and of I-FABP + endothelin-1 combined were moderate. Endothelin-1 alone revealed an AUC of 0.74 (0.67; 0.82). The sensitivity and specificity of endothelin-1 were 0.81 and 0.64, respectively.

CONCLUSION

I-FABP and endothelin-1 are promising biomarkers for AIN, with moderate diagnostic performance compared with the commonly used biomarker L-lactate.

PREREGISTRATION

ClinicalTrials.gov: NCT05665946.

Promoter hypermethylation of SFRP1 as a prognostic and potentially predictive blood-based biomarker in patients with localized pancreatic ductal adenocarcinoma

Introduction

Current prognostic blood-based biomarkers for pancreatic adenocarcinoma (PDAC) are limited. Recently, promoter hypermethylation of SFRP1 (phSFRP1) has been linked to poor prognosis in patients with gemcitabine-treated stage IV PDAC. This study explores the effects of phSFRP1 in patients with lower stage PDAC.

Methods

Based on a bisulfite treatment process, the promoter region of the SFRP1 gene was analyzed with methylation-specific PCR. Kaplan-Meier curves, log-rank tests, and generalized linear regression analysis were used to assess restricted mean survival time survival at 12 and 24 months.

Results

The study included 211 patients with stage I-II PDAC. The median overall survival of patients with phSFRP1 was 13.1 months, compared to 19.6 months in patients with unmethylated SFRP1 (umSFRP1). In adjusted analysis, phSFRP1 was associated with a loss of 1.15 months (95%CI -2.11, -0.20) and 2.71 months (95%CI -2.71, -0.45) of life at 12 and 24 months, respectively. There was no significant effect of phSFRP1 on disease-free or progression-free survival. In stage I-II PDAC, patients with phSFRP1 have worse prognoses than patients with umSFRP1.

Discussion

Results could indicate that the poor prognosis may be caused by reduced benefit from adjuvant chemotherapy. SFRP1 may help guide the clinician and be a possible target for epigenetically modifying drugs.

The effect of antithrombotic treatment on the fecal immunochemical test for colorectal cancer screening: a nationwide cross-sectional study

BACKGROUND : Screening for colorectal cancer (CRC) using the fecal immunochemical test (FIT) has been widely adopted. The use of antithrombotic treatment is increasing in the Western world. This study aimed to assess the effects of antithrombotic treatment on the FIT-based Danish national screening program for CRC. METHODS : This was a cross-sectional study of all individuals returning a FIT from 2014 until 2016. The effect of antithrombotic treatment on FIT positivity and the positive predictive value (PPV) were assessed using proportions and multivariable Poisson regression. RESULTS : Of 884 036 invited individuals, we identified 551 570 participants. A positive FIT was observed in 9052 of 77 007 individuals (11.8 %) receiving antithrombotic treatment compared with 28 387 of 474 587 individuals (6.0 %) receiving no treatment. The adjusted relative risk (RR) for a positive FIT was 1.59 (95 %CI 1.56-1.63) for any treatment. Nonvitamin K oral anticoagulants (NOACs) were associated with the largest increase in FIT positivity (adjusted RR 2.40, 95 %CI 2.48-2.54). The proportion of CRC detected at colonoscopy was slightly lower among patients on antithrombotic treatment (6.0 %, 95 %CI 5.5 %-6.6 %) than among treatment-naïve patients (6.4 %, 95 %CI 6.1 %-6.7 %). The PPV for CRC or high risk adenomas was decreased nearly twofold in patients treated with NOAC (adjusted RR 0.58, 95 %CI 0.51-0.66]). CONCLUSION : Antithrombotic treatment was associated with a decreased PPV in FIT-based CRC screening.

Bowel dysfunction following pelvic organ cancer: a prospective study on the treatment effect in nurse-led late sequelae clinics

BACKGROUND

Bowel dysfunction following treatment of pelvic organ cancer is prevalent and impacts the quality of life (QoL). The present study aimed to evaluate the feasibility and effects of treating bowel dysfunction in two nurse-led late sequelae clinics.

MATERIAL AND METHODS

Treatment effects were monitored prospectively by patient-reported outcome measures collected at baseline and discharge. Change in bowel function was evaluated by 15 bowel symptoms, the St. Mark's Incontinence Score, the Patients Assessment of Constipation-Symptoms (PAC-SYM) score and self-rated bowel function. QoL was evaluated by the EuroQol 5-dimension 5-level (EQ-5D-5L) utility score and by measuring the impact of bowel function on QoL.

RESULTS

From June 2018 to December 2021, 380 cancer survivors (46% rectal, 15% gynaecological, 13% anal, 12% colon, 12% prostate, and 2% other cancers) completed a baseline questionnaire and started treatment for bowel dysfunction. At referral, 96% of patients were multisymptomatic. The most frequent symptoms were faecal urgency (95%), fragmented defaecation (93%), emptying difficulties (92%), flatus/faecal incontinence (flatus 89%, liquid 59%, solid 33%), and obstructed defaecation (79%). In total, 169 patients were discharged from the clinics in the follow-up period. At discharge, 69% received conservative treatment only and 24% also received transanal irrigation; 4% were surgically treated; 3% discontinued treatment. Improvements were seen in all 15 bowel symptoms (p < 0.001), the mean St. Mark's Incontinence Score (12.0 to 9.9, p < 0.001), the mean PAC-SYM score (1.04 to 0.84, p < 0.001) and the mean EQ-5D-5L utility score (0.78 to 0.84, p < 0.001). Self-rated bowel function improved in 56% (p < 0.001) of cases and the impact of bowel function on QoL improved in 46% (p < 0.001).

CONCLUSION

Treatment of bowel dysfunction in nurse-led late sequelae clinics is feasible and significantly improved bowel function and QoL.

Abstract B047: Promoter hypermethylation of SFRP1 as a prognostic and predictive blood-based biomarker in patients with stage IV pancreatic ductal adenocarcinoma

Background: Pancreatic ductal adenocarcinoma (PDAC) is a disease with an abysmal prognosis. Unfortunately, no reliable prognostic or predictive blood-based biomarkers are currently available. An increasingly promising prognostic and predictive tool in cancer is the analysis of genetic and epigenetic alterations in cell-free DNA. One such alteration, promoter hypermethylation (ph) of SFRP1, has recently been linked to poor prognosis in gemcitabine-treated patients with stage IV PDAC. This study aimed to further examine phSFRP1 as a clinically relevant prognostic and predictive biomarker in FOLFIRINOX-treated patients with stage IV PDAC. Methods: Serum samples from patients with stage IV PDAC, treated with first-line FOLFIRINOX, were obtained from two danish biobanks. All blood samples were drawn before the initiation of palliative treatment. Based on a bisulfite treatment, we conducted a methylation-specific polymerase chain reaction analysis of the promoter region of the gene SFRP1. Methylation status was dichotomized based on the measured Cycle threshold. Survival according to SFRP1 promoter methylation status was assessed with Kaplan-Meier curves, log-rank tests, and Cox proportional hazard regression models. The adjusted Cox regression model included SFRP1 promoter methylation status, WHO performance status, age &gt; 65 years, and sex. Results: Fifty-two FOLFIRINOX-treated patients with stage IV PDAC were included in the study. Patients with phSFRP1 (n = 23) had a median overall survival (mOS) of 6.8 months, significantly shorter than patients with unmethylated (um) SFRP1 (n = 29) who had a mOS of 15.7 months (log-rank test, p &lt; 0.01). Likewise, in both crude and adjusted Cox-regression analysis, patients with phSFRP1 had an hazard ratio for death of 2.78 (95% CI 1.55-4.99) and 2.82 (95% CI 1.55-5.14) respectively, compared to patients with umSFRP1. Conclusions: Results indicate that FOLFIRINOX-treated stage IV PDAC patients with phSFRP1 have significantly shorter survival than patients with umSFRP1. Combined with previous literature, this indicates the value of phSFRP1 as a blood-based prognostic biomarker in patients with stage IV PDAC, regardless of the given first-line palliative chemotherapy. In addition, it indicates that phSFRP1 may also have predictive value for chemotherapy sensitivity in patients with stage IV PDAC. This knowledge may facilitate individualized treatment of patients with stage IV PDAC. Additionally, SFRP1 could be a valuable target for treatment with hypomethylating drugs to improve treatment response.

Citation Format: Benjamin E. Stubbe, Stine D. Henriksen, Poul H. Madsen, Anders C. Larsen, Henrik B. Krarup, Inge S. Pedersen, Julia S. Johansen, Carsten P. Hansen, Ole Thorlacius-Ussing. Promoter hypermethylation of SFRP1 as a prognostic and predictive blood-based biomarker in patients with stage IV pancreatic ductal adenocarcinoma [abstract]. In: Proceedings of the AACR Special Conference on Pancreatic Cancer; 2022 Sep 13-16; Boston, MA. Philadelphia (PA): AACR; Cancer Res 2022;82(22 Suppl):Abstract nr B047.

Colorectal cancer incidences in Lynch syndrome: a comparison of results from the prospective lynch syndrome database and the international mismatch repair consortium

OBJECTIVE

To compare colorectal cancer (CRC) incidences in carriers of pathogenic variants of the MMR genes in the PLSD and IMRC cohorts, of which only the former included mandatory colonoscopy surveillance for all participants.

METHODS

CRC incidences were calculated in an intervention group comprising a cohort of confirmed carriers of pathogenic or likely pathogenic variants in mismatch repair genes (path_MMR) followed prospectively by the Prospective Lynch Syndrome Database (PLSD). All had colonoscopy surveillance, with polypectomy when polyps were identified. Comparison was made with a retrospective cohort reported by the International Mismatch Repair Consortium (IMRC). This comprised confirmed and inferred path_MMR carriers who were first- or second-degree relatives of Lynch syndrome probands.

RESULTS

In the PLSD, 8,153 subjects had follow-up colonoscopy surveillance for a total of 67,604 years and 578 carriers had CRC diagnosed. Average cumulative incidences of CRC in path_MLH1 carriers at 70 years of age were 52% in males and 41% in females; for path_MSH2 50% and 39%; for path_MSH6 13% and 17% and for path_PMS2 11% and 8%. In contrast, in the IMRC cohort, corresponding cumulative incidences were 40% and 27%; 34% and 23%; 16% and 8% and 7% and 6%. Comparing just the European carriers in the two series gave similar findings. Numbers in the PLSD series did not allow comparisons of carriers from other continents separately. Cumulative incidences at 25 years were < 1% in all retrospective groups.

CONCLUSIONS

Prospectively observed CRC incidences (PLSD) in path_MLH1 and path_MSH2 carriers undergoing colonoscopy surveillance and polypectomy were higher than in the retrospective (IMRC) series, and were not reduced in path_MSH6 carriers. These findings were the opposite to those expected. CRC point incidence before 50 years of age was reduced in path_PMS2 carriers subjected to colonoscopy, but not significantly so.

Preoperative findings on non-specific CT in patients with primary acute intestinal ischemia: a case-control study

PURPOSE

Primary acute intestinal ischaemia (AII) is an abdominal catastrophe caused by intravascular obstruction of blood supply. It is difficult to diagnose. Computerized tomography (CT) scan is the modality of choice for diagnostic evaluation. Majority of previous studies have evaluated CT findings in patients where AII was suspected. However, unveiling the unique radiological findings also in not initially suspected AII patients, might lead to the timely management of AII patients, and is the aim of this study.

METHODS

In a single-center, retrospective case-control study, preoperative radiological findings from abdominal CT scans in 48 patients with primary AII were compared with 80 non-ischemic controls. Radiological findings were analyzed using multivariable logistical regression with adjustment for age and gender and reported as odds ratios (OR) with 95% confidence intervals (CI) and p values.

RESULTS

Thirty-nine (81%) cases with AII were referred to an abdominal CT scan without a specific clinical suspicion of AII. Three main radiological categories (intestinal wall pathology [OR 7.4, CI 2.3-24.0, p value < 0.001], gastrointestinal vessel pathology [OR 19.3, CI 4.6-80.5, p value < 0.001) and intestinal diameter [OR 4.7, CI 1.6-13.4, p value 0.004]) were significantly different in AII patients. Subgroup analysis implied that pneumatosis intestinalis, increased contrast enhancement in the bowel wall, inferior mesenteric artery arteriosclerosis and colonic contraction were predictors of AII.

CONCLUSION

Radiological changes within the intestinal wall, luminal diameter and gastrointestinal vessels are independent predictors of AII. Awareness of these radiological findings, therefore, plays a central role in patients with an indistinct clinical picture in early recognition and treatment of a life-threatening AII.

TRIAL REGISTRATION NUMBER

NCT04361110 (April 24, 2020), retrospectively registered.

Abstract 1959: Sensitive detection of circulating tumor DNA by whole genome sequencing: Validation of MRDetect using serial blood samples from stage III colorectal cancer patients

Background: While detection of circulating tumor DNA (ctDNA) is associated with poor cancer prognosis, the clinical utility for guiding treatment decisions is unresolved. Patients with minimal residual disease (MRD) often have less than one genome equivalent of ctDNA per 10 mL blood. Consequently, it is stochastic whether a 10 mL sample contains ctDNA from a particular genomic locus. Consequently, the sensitivity of ctDNA detection methods targeting a limited number of tumor loci is heavily affected by sampling bias. To overcome this challenge, we developed MRDetect; a whole genome sequencing (WGS) approach, which detects ctDNA using the patient-specific cumulative signal from tens of thousands of mutations throughout the genome. Recently, we showed how MRDetect found ctDNA fractions down to 10-4. Here, we performed a validation study to confirm the prognostic impact of MRDetect.

Aim: Validation of MRDetect for sensitive ctDNA detection to monitor residual disease in stage III colorectal cancer (CRC) patients treated with curative intent.

Methods: From a large, uniform cohort of stage III CRC patients n = 146), we had plasma samples collected every third month (n = 938, median = 9 per patient) and a median follow-up of 34 months. For each patient, a genome-wide mutational signature was established by WGS of tumor and matched normal DNA. Enhanced by an AI-based error suppression model, this signature was used to detect ctDNA in 1-2 mL plasma samples using WGS (20x coverage). We used de-novo point mutation and copy number variation analysis to investigate cancer evolution after treatment. To evaluate the reproducibility of MRDetect, aliquot samples (n = 2x190 samples) from 5 recurrence and 10 non-recurrence patients were processed and sequenced at two independent laboratories. Outcome measures: ctDNA status, tumor fraction, false positive rate, Time To ctDNA Recurrence (TTcR), and Time To radiological Recurrence (TTrR).

Results: Analysis of paired samples showed great reproducibility with high agreement between both ctDNA status calls (Cohens Kappa = 0.81) and the estimated tumor fractions (r2 = 0.99). MRDetect revealed post-operative ctDNA in all recurrence patients (5/5) with detected tumor fractions down to 2 x 10-4. Median TTcR was 0.9 month (range 0.5 - 7.3 months) while median TTrR was 12.8 months (range 11.3 - 31.1 months). The false positive rate was 1% (1/100), assessed in longitudinal samples from the 10 non-relapsing patients. Tumor evolution dynamics in plasma samples revealed novel amplification and deletions, which were absent in the primary tissue but confirmed in metachronous metastases. We will present results from the full cohort at AACR 2022.

Conclusion: MRDetect detects ctDNA with high sensitivity and specificity and enables effective postoperative assessment of MRD, cancer evolution dynamics and early relapse detection.

Citation Format: Amanda Frydendahl, Thomas Reinert, Jesper Nors, Sunil Deochand, Dillon Maloney, Noah Friedman, Tomer Lauterman, Danielle Afterman, Imane Bourzgui, Nidhi Ramaraj, Zohar Donenhirsh, Ronel Veksler, Ravi Kandasamy, Iman Tavassoly, Jonathan Rosenfeld, Anders Husted Andersen, Uffe S. Løve, Per V. Andersen, Ole Thorlacius-Ussing, Lene Hjerrild Iversen, Kåre Andersson Gotschalck, Boris Oklander, Asaf Zviran, Claus Lindbjerg Andersen. Sensitive detection of circulating tumor DNA by whole genome sequencing: Validation of MRDetect using serial blood samples from stage III colorectal cancer patients [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 1959.

Microscopic Colitis Patients Possess a Perturbed and Inflammatory Gut Microbiota

BACKGROUND

Microscopic colitis (MC), an inflammatory disease of the colon, is characterized by chronic non-bloody diarrhea with characteristic inflammation and for some, collagen deposits in mucosal biopsies. The etiology of MC is unclear, although previous findings implicate luminal factors and thus the gut microbiome. However, the relationships between fecal microbiota and MC are relatively unexplored.

METHODS

Stool microbiota of MC (n = 15) and healthy controls (HC; n = 21) were assessed by 16S rRNA V4 amplicon sequencing and analysis performed in QIIME. Gut microbiota functions were predicted using Piphillin and inflammatory potential assessed using an in vitro HT29 colonocyte cell assay.

RESULTS

MC patient fecal microbiota were less diverse (Faiths index; p < 0.01) and compositionally distinct (PERMANOVA, weighted UniFrac, R² = 0.08, p = 0.02) compared with HC subjects. MC microbiota were significantly depleted of members of the Clostridiales, enriched for Prevotella and more likely to be dominated by this genus (Chi² = 0.03). Predicted pathways enriched in MC microbiota included those related to biosynthesis of antimicrobials, and sphingolipids, to glycan degradation, host defense evasion, and Th17 cell differentiation and activation. In vitro, exposure of cultured colonocytes to cell-free products of MC patient feces indicates reduced gene expression of IL-1B and occludin and increased GPR119 and the lymphocyte chemoattractant CCL20.

CONCLUSION

MC gut microbiota are distinct from HC and characterized by lower bacterial diversity and Prevotella enrichment and distinct predicted functional pathways. Limited in vitro experiments indicate that compared with cell-free products from healthy fecal microbiota, MC microbiota induce distinct responses when co-cultured with epithelial cells, implicating microbiota perturbation in MC-associated mucosal dysfunction.

Circulating Tumor DNA in Stage III Colorectal Cancer, beyond Minimal Residual Disease Detection, toward Assessment of Adjuvant Therapy Efficacy and Clinical Behavior of Recurrences

PURPOSE

Sensitive methods for risk stratification, monitoring therapeutic efficacy, and early relapse detection may have a major impact on treatment decisions and patient management for stage III colorectal cancer patients. Beyond assessing the predictive power of postoperative ctDNA detection, we explored the added benefits of serial analysis: assessing adjuvant chemotherapy (ACT) efficacy, early relapse detection, and ctDNA growth rates.

EXPERIMENTAL DESIGN

We recruited 168 patients with stage III colorectal cancer treated with curative intent at Danish and Spanish hospitals between 2014 and 2019. To quantify ctDNA in plasma samples (n = 1,204), 16 patient-specific somatic single-nucleotide variants were profiled using multiplex-PCR, next-generation sequencing.

RESULTS

Detection of ctDNA was a strong recurrence predictor postoperatively [HR = 7.0; 95% confidence interval (CI), 3.7-13.5; P < 0.001] and directly after ACT (HR = 50.76; 95% CI, 15.4-167; P < 0.001). The recurrence rate of postoperative ctDNA-positive patients treated with ACT was 80% (16/20). Only patients who cleared ctDNA permanently during ACT did not relapse. Serial ctDNA assessment after the end of treatment was similarly predictive of recurrence (HR = 50.80; 95% CI, 14.9-172; P < 0.001), and revealed two distinct rates of exponential ctDNA growth, slow (25% ctDNA-increase/month) and fast (143% ctDNA-increase/month; P < 0.001). The ctDNA growth rate was prognostic of survival (HR = 2.7; 95% CI, 1.1-6.7; P = 0.039). Serial ctDNA analysis every 3 months detected recurrence with a median lead-time of 9.8 months compared with standard-of-care computed tomography.

CONCLUSIONS

Serial postoperative ctDNA analysis has a strong prognostic value and enables tumor growth rate assessment. The novel combination of ctDNA detection and growth rate assessment provides unique opportunities for guiding decision-making.See related commentary by Morris and George, p. 438.

Danish guidelines for management of non-APC-associated hereditary polyposis syndromes

Hereditary Polyposis Syndromes are a group of rare, inherited syndromes characterized by the presence of histopathologically specific or numerous intestinal polyps and an increased risk of cancer. Some polyposis syndromes have been known for decades, but the development in genetic technologies has allowed the identification of new syndromes.. The diagnosis entails surveillance from an early age, but universal guideline on how to manage and surveille these new syndromes are lacking. This paper represents a condensed version of the recent guideline (2020) from a working group appointed by the Danish Society of Medical Genetics and the Danish Society of Surgery on recommendations for the surveillance of patients with hereditary polyposis syndromes, including rare polyposis syndromes.

[New hereditary polyposis syndromes in the patient with intestinal polyps]

Hereditary polyposis syndromes (HPS) are a group of rare, inherited syndromes characterised by the presence of histopathological specific or numerous intestinal polyps and a high risk of intestinal and extraintestinal cancer. During the last decade, several new HPS have been discovered, as it is possible to detect pathogenic germline variants in genes not previously known to be associated with polyposis. This review summarises the current knowledge on the syndromes and discusses genetic testing as part of the diagnostic pipeline when suspecting a polyposis syndrome.

Usefulness of Imaging Response Assessment after Irreversible Electroporation of Localized Pancreatic Cancer-Results from a Prospective Cohort

Simple Summary

Irreversible electroporation (IRE) is a novel therapy that is being studied for the treatment of nonmetastatic pancreatic cancer. The current methods for evaluating the treatment response after IRE have been adapted from the Response Evaluation Criteria in Solid Tumors (RECIST). However, it is uncertain whether these methods are appropriate, because the methods have not been validated. The aim of the current study was to evaluate the correlation between survival time and the most commonly used imaging assessment methods on FDG-PET/CT scans. We confirmed that the Response Evaluation Criteria in Solid Tumors (RECIST) are correlated with survival, when applied as intended. However, no correlation was found when the often-used lesion-level method was used. FDG-PET-derived data did not provide any benefit over conventional CT data. Several novel methods for lesion-level analysis were explored.

Abstract

(1) Background: Irreversible electroporation (IRE) is a nonthermal ablation technique that is being studied in nonmetastatic pancreatic cancer (PC). Most published studies use imaging outcomes as an efficacy endpoint, but imaging interpretation can be difficult and has yet to be correlated with survival. The aim of this study was to examine the correlation of imaging endpoints with survival in a cohort of IRE-treated PC patients. (2) Methods: Several imaging endpoints were examined before and after IRE on ¹⁸F-fluorodeoxyglucose positron emission tomography (PET) with computed tomography. Separate analyses were performed at the patient and lesion levels. Mortality rate (MR) ratios for imaging endpoints after IRE were estimated. (3) Results: Forty-one patients were included. Patient-level analysis revealed that progressive disease (PD), as defined by RECIST 1.1, is correlated with a higher MR at all time intervals, but PD, as defined by EORTC PET response criteria, is only correlated with the MR in the longest interval. No correlation was found between PD, as defined by RECIST, and the MR in the lesion-level analysis. (4) Conclusions: Patient-level PD, as defined by RECIST, was correlated with poorer survival after IRE ablation, whereas no correlations were observed in the lesion-level analyses. Several promising lesion-level outcomes were identified.

Serial circulating tumor DNA analysis to assess recurrence risk, benefit of adjuvant therapy, growth rate and early relapse detection in stage III colorectal cancer patients

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Background: Challenges in the postoperative management of stage III colorectal cancer include: 1) selection of high-risk patients for adjuvant chemotherapy (ACT), 2) lack of markers to assess ACT efficacy, 3) assessment of recurrence risk after ACT, and 4) lack of markers to guide treatment decisions for high-risk patients e.g. additional therapy or intensified surveillance. Circulating tumor DNA (ctDNA) is a promising marker with potential to mitigate the challenges. Here we used serial ctDNA measurements to assess the correlation between recurrence and ctDNA detection: postoperative, during and after ACT, and during surveillance; and to assess growth rates of metachronous metastases. Uniquely, we also used concurrent CT scans and ctDNA measurements to compare the sensitivity for detecting recurrence. Methods: Stage III CRC patients treated with curative intent at Danish and Spanish hospitals in 2014-2019 were recruited (n = 166). Blood samples (n = 1227) were collected prior to and immediately after surgery, and every third month for up to 36 months. Per patient 16 personal mutations were used to quantify plasma ctDNA (Signatera, bespoke mPCR NGS assay). Results: Detection of ctDNA was a strong recurrence predictor, both postoperatively (HR 7.2, 95% CI 3.8-13.8, P< 0.001), directly after ACT (HR = 18.2, 95% CI 7.1-46, P < 0.001), and when measured serially after end of treatment (HR = 41, 95% CI 16-100, P < 0.001). The recurrence rate of postoperative ctDNA positive patients treated with ACT was 80% (16/20). Patients who stayed ctDNA positive during ACT all recurred. Serial post-treatment ctDNA measurements revealed exponential growth for all recurrence patients following either a SLOW (26%-increase/month) or a FAST (126%-increase/month) pattern (P < 0.001). From ctDNA detection to radiologic recurrence, ctDNA levels of FAST patients increased by a median 117-fold, and up to 554-fold. The 3-year overall survival was 43% for FAST patients and 100% for SLOW and non-recurrence patients (HR = 41.3, 95% CI 7.5-228, P < 0.001). Coinciding CT scans and ctDNA measurements (n = 113 patients, 235 coinciding events, median 2 per patient) showed a high agreement (92%) and ctDNA either detected residual disease before the CT scan (n = 7 patients) or at the same time (n = 14 patients). The median lead-time was 7.5 months. Conclusions: The study confirmed the prognostic power of serial postoperative ctDNA analysis. Moreover, it provided novel analyses demonstrating that ctDNA is more sensitive for recurrence detection than CT scans and can be used for tumor growth rate assessments. The difference between FAST and SLOW growing tumors suggest that growth rates could guide whom to start on systemic therapy rapidly and whom to send for diagnostic imaging. Altogether, the study highlights many potential utilities of ctDNA in guiding clinical decision-making.

Cell-free DNA promoter hypermethylation as a diagnostic marker for pancreatic ductal adenocarcinoma - An external validation study

BACKGROUND

We recently identified a diagnostic prediction model based on promoter hypermethylation of eight selected genes in plasma cell-free (cf) DNA, which showed promising results as a diagnostic biomarker for pancreatic ductal adenocarcinoma (PDAC). The aim of the present study was to validate this biomarker profile in an external patient cohort and examine any additional effect of serum CA 19-9.

METHODS

Patients with PDAC (n = 346, stage I-IV) and chronic pancreatitis (n = 25) were included. Methylation-specific PCR of a 28-gene panel was performed on serum cfDNA samples. The previously developed diagnostic prediction model (age>65 years, BMP3, RASSF1A, BNC1, MESTv2, TFPI2, APC, SFRP1 and SFRP2) was validated alone and in combination with serum CA 19-9 in this external patient cohort.

RESULTS

Patients with PDAC had a higher number of hypermethylated genes (mean 8.11, 95% CI 7.70-8.52) than patients with chronic pancreatitis (mean 5.60, 95% CI 4.42-6.78, p = 0.011). Validation of the diagnostic prediction model yielded an AUC of 0.77 (95% CI 0.69-0.84). The combination of serum CA 19-9 and our test had an AUC of 0.93 (95% CI 0.89-0.96) in the primary study and 0.85 (95% CI 0.79-0.91) in the validation study.

CONCLUSION

In this validation study, PDAC was associated with a higher number of hypermethylated genes in serum cfDNA than chronic pancreatitis. Our diagnostic test was superior to the predictive value of serum CA 19-9 alone in both the primary and the validation study. The combination of our test with CA 19-9 may serve as a clinically useful diagnostic biomarker for PDAC.

Irreversible electroporation of pancreatic cancer - Effect on quality of life and pain perception

BACKGROUND

Most pancreatic cancer (PC) patients are incurable and may need palliative treatment at some point in time. Irreversible electroporation (IRE) is a novel ablative treatment, which aims to provide local tumor control. The aim of this study was to examine how consolidative treatment with IRE affects quality of life (QOL) and pain perception (PP) in patients with non-metastatic pancreatic cancer.

METHODS

Secondary outcomes were extracted from a prospective cohort of non-metastatic PC patients treated with IRE from 2013 to 2019. Patients filled in two questionnaires examining QOL and PP at different timepoints during treatment and follow-up. Data from a selected panel of subscales were extracted and analyzed using a mixed random intercept regression model.

RESULTS

Subscales from 41 patients at four different timepoints were included in the model. Global health status, physical functioning, fatigue, nausea and vomiting, appetite loss and mean pain interference were negatively impacted (p < 0.05) in the short- and mid-term, corresponding to a low or moderate clinical effect size. However, all negative effects showed a tendency to dissipate over time.

CONCLUSIONS

IRE treatment negatively impacted QOL and PP in the short- and mid-term. No positive long-term effects of IRE were found.

Fully automatic d-lactate assay using a modified commercially available method

Intestinal infarction is the fast-evolving endpoint of impaired blood perfusion to an intestinal segment which may have fatal outcome. Early diagnosis and treatment within 6 h reduce mortality. Currently, d-lactate is a promising biomarker, however, not available in the acute clinical setting. The aim of this study is implementation of d-lactate analysis in a routine clinical setting. We used a spectrophotometric method, based on enzymatic oxidation of d-lactate by d-lactate dehydrogenase (D-LDH) coupled to the reduction of nicotinamide-adenine dinucleotide (NAD⁺). The amount of NADH formed in this reaction is equivalent to d-lactate. The primary concern in this method is interfering NADH formed by oxidation of l-lactate by l-lactate dehydrogenase (L-LDH). A commercially available kit for d-lactate measurement was implemented on our existing automated routine laboratory equipment including pH-inactivation of L-LDH. Our setup fulfilled clinical quality goals. We were able to measure d-lactate with an acceptable performance of the analysis and a short turn-around time. The method can be used to distinguish between the expected cut-off for intestinal ischemia around 0.3 mM and the upper reference limit of 0.05 mM. With a turnaround time of just 9 min, the analysis has potential as a readily available detection of circulating d-lactate for early diagnosis of intestinal ischemia.

Cell-Free DNA Methylation as Blood-Based Biomarkers for Pancreatic Adenocarcinoma—A Literature Update

Pancreatic adenocarcinoma has a horrible prognosis, which is partly due to difficulties in diagnosing the disease in an early stage. Additional blood-born biomarkers for pancreatic adenocarcinoma are needed. Epigenetic modifications, as changes in DNA methylation, is a fundamental part of carcinogenesis. The aim of this paper is to do an update on cell-free DNA methylation as blood-based biomarkers for pancreatic adenocarcinoma. The current literature including our studies clearly indicates that cell-free DNA methylation has the potential as blood-based diagnostic and prognostic biomarkers for pancreatic adenocarcinoma. However, still no clinical applicable biomarker for pancreatic adenocarcinoma based on DNA methylation do exist. Further well-designed validation studies are needed.

The timing of venous thromboembolism in ovarian cancer patients: A nationwide Danish cohort study

BACKGROUND AND AIM

Venous thromboembolism (VTE) is associated with excess mortality and morbidity in cancer, and is influenced by patient-, tumor-, and treatment-related factors. We aimed to investigate the impact of such factors in a national cohort of patients with epithelial ovarian cancer (EOC).

METHODS

Patients in the Danish Gynecologic Cancer Database (DGCD) with EOC from 2005 to 2014 were followed from time of diagnosis to VTE, or censoring. Surgery, chemotherapy, and vascular epithelial growth factor (VEGF)-inhibitors were included as time-varying exposures in Cox proportional hazard regression models.

RESULTS

A total of 551 VTE events were registered in 4991 EOC patients. Median follow-up time was 2.9 years. The 2-year cumulative incidence of VTE was 7.2%. Patients were at highest risk during the first year after EOC diagnosis. Previous VTE was associated with a hazard ratio (HR) of 3.26 (95% confidence interval [CI] 2.42-4.39). Exposure to major pelvic surgery was associated with a HR of 3.21 (95% CI 2.29-4.50). Exposure to chemotherapy or (VEGF)-inhibitors were associated with HRs of 1.91 (95% CI 1.56-2.33) and 1.05 (95% CI 0.57-1.93), respectively. Hazard ratios for patients with clear cell histopathology was 1.46 (95% CI 0.97-2.20) and 2.42 for International Federation of Gynaecology and Obstetrics stage III--IV (95% CI 1.93-3.03).

CONCLUSIONS

EOC is associated with a high risk of VTE, particularly within the first year after diagnosis. Major pelvic surgery and chemotherapy were strongly associated with VTE. Person-related risk factors were increasing age and previous VTE. Advanced stage was an independent tumor-related risk factor. These findings support the indication for thrombosis prophylaxis during chemotherapy.

Long-term gastrointestinal sequelae in colon cancer survivors: prospective pilot study on identification, the need for clinical evaluation and effects of treatment

AIM

The aim of the present pilot study was to describe the type and frequency of long-term gastrointestinal symptoms within a well-defined cohort of colon cancer survivors, their wish for clinical evaluation and treatment outcomes.

METHOD

A screening survey was sent to colon cancer survivors 12, 24 and 36 months after surgery. Based on their main symptoms, patients who wished to have a consultation were referred to the gastroenterological or surgical unit of our late cancer sequelae clinic. Treatment effect was monitored by questionnaires on bowel symptoms and the EuroQol five-dimensional (EQ-5D) quality-of-life score.

RESULTS

Overall, 953 patients who had survived colon cancer received the screening survey and 767 replied (response rate 80.5%). Of these, 76 (9.9%; 95% CI 7.9%-12.2%) were referred for algorithm-based clinical evaluation and treatment of bowel dysfunction. The majority were women (69.7%) who had undergone a right-sided colonic resection (65.8%). Patients reported various symptoms, mainly including urgency, fragmented defaecation, loose stools and incontinence for liquid stools. Patients with emptying difficulties and low anterior resection syndrome-like symptoms were referred to the surgical unit and patients with diarrhoea were referred to the gastroenterological unit for clinical work-up. Our main endpoint, mean EQ-5D index after treatment, was improved compared with baseline (baseline 0.809, after treatment 0.846; p = 0.049). After treatment, self-rated bowel function and several bowel symptoms were improved as well.

CONCLUSION

This study highlights the importance of identifying colon cancer survivors in need of treatment of late gastrointestinal sequelae and clinical management in a multidisciplinary team setting.

Systematic screening for late sequelae after colorectal cancer-a feasibility study

AIM

The aim of this study was to test the feasibility of a new method for systematic screening for late sequelae (LS) following colorectal cancer treatment.

METHOD

Patients with colorectal cancer from five Danish hospitals were invited to complete a survey about LS at 3, 12, 24 and 36 months after surgery as part of their follow-up. The survey consisted primarily of validated tools, supplemented by a few ad hoc items, measuring bowel, urinary and sexual dysfunction, pain and quality of life and an additional question regarding request for contact. Patients completed surveys electronically or on paper.

RESULTS

Of the 1721 invited patients, 1386 (80.5%) were included (1085 with colon cancer and 301 with rectal cancer) of whom 72.5% responded electronically. Patients responding electronically were 7.6 years younger than those responding on paper (P < 0.001). Since some patients answered more than once, the dataset consisted of 2361 surveys. Patients with colon cancer requested phone contact in 19.0% of the surveys, and 8.4% were referred to treatment for LS, primarily bowel dysfunction. Among patients with rectal cancer, 30.8% requested phone contact and 16.2% were referred for treatment of LS, mainly due to bowel and sexual dysfunction.

CONCLUSION

This is the first paper investigating a new method of systematic screening for LS following colorectal cancer using electronic patient-reported outcome measures. The study shows that in the Danish population a high response rate can be obtained with this method and that close to three-quarters of patients respond electronically. Patients with rectal cancer had a higher need for phone contact and treatment of LS than patients with colon cancer.

Circulating tumor DNA analysis for assessment of recurrence risk, benefit of adjuvant therapy, and early relapse detection after treatment in colorectal cancer patients

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Background: Timely detection of recurrence, as well as identification of patients at high risk of recurrence after surgery and after completion of adjuvant therapy, are major challenges in the treatment of colorectal cancer (CRC). Postsurgical circulating tumor DNA (ctDNA) analysis is a promising tool for the identification of patients with minimal residual disease (MRD) and a high risk of recurrence. The objective of this prospective, multicenter study was to determine whether serial postsurgical ctDNA analysis could identify the patients at high risk of recurrence, provide an assessment of adjuvant therapy efficacy and detect relapse earlier than standard-of-care radiological imaging. Methods: The cohort comprises 265 stage I-III CRC patients, the to-date largest cohort assessed for ctDNA. All patients had the tumor resected and a subset of 62.6% (166 /265) was additionally treated with ACT. Plasma samples (n = 1503) were collected at various time points for a median follow-up of 28.4 months (range: 1.2-51.0 months). Individual tumors and matched germline DNA were whole-exome sequenced and somatic single nucleotide variants (SNVs) were identified. Personalized multiplex PCR assays were designed to track tumor-specific SNVs (Signatera, bespoke mPCR NGS assay) in each patient’s plasma sample. Results: Postoperative ctDNA status prior to ACT was assessed in 218 patients, of which 9.17% (20/218) were identified to be MRD-positive and 75% (15/20) eventually relapsed. The remaining 25% (5/20) of MRD-positive patients that did not relapse, received ACT. In contrast, only 13.6% (27/198) of MRD-negative cases relapsed (HR: 11: 95% CI: 5.7-20; p < 0.001). Longitudinal ctDNA-positive status, post-definitive therapy (n = 202) was associated with a HR of 36 (95% CI: 16-81; p < 0.001). For a subset of 155 patients postoperative CEA and ctDNA measurements were compared, wherein, ctDNA-positive status was found to be significantly associated with RFS (HR, 7.1; 95% CI, 3.4-15; P < 0.001) compared to CEA (HR, 1.2; 95% CI, 0.46-3.1; P = 0.73). Serial ctDNA analysis detected MRD up to a median of 8 months (0.56 - 21.6 months) ahead of radiologic relapse. Conclusion: Postoperative ctDNA positive status was associated with markedly reduced RFS compared to CEA. The study also shows that effective therapy can be curative in a portion of MRD-positive patients. In a longitudinal setting, ctDNA analysis predicted the risk of recurrence and is a more reliable biomarker for treatment response monitoring.

Incidental detection of colorectal lesions on 18 F-FDG-PET/CT is associated with high proportion of malignancy: A study in 549 patients

Background and study aims  Further diagnostics of incidental colorectal lesions on ¹⁸ F-fluorodeoxyglucose (FDG) positron emission tomography/computed tomography (PET/CT) is questionable. Therefore, we aimed to evaluate the clinical importance of incidentally detected colorectal lesions on FDG-PET/CT. Patients and methods  In the North Denmark Region, a retrospective study was performed among 19,987 patients who had an FDG-PET/CT from January 2006 to December 2015. Among these patients, we identified patients with a colonoscopy within 12 months from the PET/CT scan and a description of incidental colorectal PET-avid lesions on the PET/CT. PET findings were compared with colonoscopy-detected lesions and eventually histopathology. Results  Incidental PET-avid lesions were observed in 549 patients. Colonoscopy revealed lesions in 457 (83 %), among whom 338 patients had a final histopathological diagnosis. Malignant and premalignant lesions were found in 297 patients (54 % among patients with a PET-avid lesion). The lesions were cancer in 76 patients and adenoma in 221 patients of whom 30 had high-grade and 191 low-grade adenomas. The findings changed patient management in 166 cases (30 % of all patients with a PET-avid lesion). A colonoscopy-based surveillance program was initiated for 80 % of patients with high-grade adenoma. No patients with PET-avid lesions but normal colonoscopy developed colorectal cancer during 3 years of observation (median observation time 7 years). Conclusions  Incidental colorectal FDG uptake was infrequently observed, but when present, it was associated with a high rate of malignant or premalignant lesions. Our results indicate that patients with incidental colorectal FDG uptake should be referred to diagnostic work-up including colonoscopy.

The Microbiota Profile in Inflamed and Non-Inflamed Ileal Pouch-Anal Anastomosis

The objective was to determine the bacterial composition in inflamed and non-inflamed pouches for comparison to the microbiota of healthy individuals. Pouch patients and healthy individuals were included between November 2017 and June 2019 at the Department of Gastrointestinal Surgery, Aalborg University Hospital, Denmark. A faecal sample was collected from all participants for microbiota analysis using 16S rRNA amplicon sequencing. Overall, 38 participants were included in the study. Eleven patients with a normally functioning pouch, 9 patients with chronic pouchitis, 6 patients with familial adenomatous polyposis, and 12 healthy individuals. Patients with chronic pouchitis had overall lower microbial diversity and richness compared to patients with a normal pouch function (p < 0.001 and p = 0.009) and healthy individuals (p < 0.001 and p < 0.001). No significant difference was found between patients with familial adenomatous polyposis and chronic pouchitis (microbial diversity p = 0.39 and richness p = 0.78). Several taxa from the family Enterobacteriaceae, especially genus Escherichia, were associated primarily with patients with chronic pouchitis, while taxa from the genus Bacteroides primarily were associated with healthy individuals and patients with a normally functioning pouch. Finally, a microbial composition gradient could be established from healthy individuals through patients with normal pouch function and familial adenomatous polyposis to patients with chronic pouchitis.

Consumption of yoghurt favours remission after faecal microbiota transplantation for chronic pouchitis

PURPOSE

The gut microbiota is conceivably a key factor in the aetiology of pouchitis. Faecal microbiota transplantation (FMT) has been suggested as a promising new treatment for chronic pouchitis, where treatment options often are few. However, little is known about the influence of the diet on the clinical effects of FMT. We assessed the diet of patients with chronic pouchitis undergoing FMT to investigate the influence of diet on the clinical outcome after FMT.

METHODS

Nine patients with chronic pouchitis were allocated to treatment with FMT delivered by enema from five faecal donors for 14 consecutive days in a 6-month prospective, open-label, single-centre cohort pilot study. A dietary questionnaire was completed at baseline for all patients and donors. Patients underwent a pouchoscopy at baseline and at 30-day follow-up, and the Pouchitis Disease Activity Index (PDAI) was assessed.

RESULTS

Patients' diets were generally similar, when comparing patients in remission post-FMT (PDAI < 7) with those who relapsed (PDAI ≥ 7). Consumption of grains trended to be different between the two groups (p = 0.06), where patients in relapse consumed more bread products than did patients in remission. However, consumption of yoghurt was significantly different between the two groups (p = 0.04), with patients in remission consuming more yoghurt (mean 1.1 s/d vs 0.2 s/d).

CONCLUSION

Gastroenterologist performing clinical studies on FMT for chronic pouchitis should be aware of dietary habits as contributing factors for the clinical effect of FMT.

Fecal Microbiota Transplantation in the Treatment of Chronic Pouchitis: A Systematic Review

The objective was to evaluate available literature on treatment of chronic pouchitis with fecal microbiota transplantation (FMT) focusing on clinical outcomes, safety, and different approaches to FMT preparation and delivery. A systematic review of electronic databases was conducted using Medline, EMBASE, and the Cochrane Central Register of Controlled Trials Library from inception through April 2020. Human studies of all study types reporting results of FMT to treat chronic pouchitis were included. Nine studies, reporting FMT treatment of 69 patients with chronic pouchitis were found eligible for the review. Most studies were case series and cohort studies rated as having fair to poor quality due to high risk of bias and small sample size. Only one randomized controlled trial was included, finding no beneficial effect of FMT. In total clinical response after FMT was reported in 14 (31.8%) out of 44 evaluated patients at various timepoints after FMT, and clinical remission in ten (22.7%) patients. Only minor self-limiting adverse events were reported. FMT varied greatly regarding preparation, length of treatment, and route of delivery. The effects of FMT on symptoms of chronic pouchitis are not established, though some studies show promising results. Future controlled well-designed studies are warranted.

Imaging response evaluation after local ablative treatments in locally advanced pancreatic cancer: an expedited systematic review

BACKGROUND

Several local ablative modalities have been introduced for the treatment of locally advanced pancreatic cancer (LAPC). However, there is no consensus on how to evaluate the imaging response after treatment. A systematic review was performed regarding the use of imaging for response assessment in LAPC.

METHODS

A systematic literature search was conducted in PubMed. Studies reporting imaging outcomes were included in the review. Studies were excluded if the imaging outcomes could not be differentiated between different disease stages, tumor histology or surgical approaches.

RESULTS

Thirty-four studies were included in the analysis. Fourteen studies used standardized response criteria, while six studies did not report the response evaluation method. The rest used self-determined criteria, absolute size comparisons or similar methods. One study found a correlation between early systemic progression (<6 months) and overall survival.

CONCLUSION

There was notable variation in the use of imaging for response assessment in LAPC. This significantly hinders cross-comparison of results among studies. There is currently only sparse evidence of an association between imaging responses and overall survival. The field calls for standardized recommendations regarding the choice of response assessment method, timing of scans, target definition and reporting of outcomes.

Long-term outcomes after perioperative treatment with omega-3 fatty acid supplements in colorectal cancer

Background

This study aimed to evaluate the effect of perioperative supplementation with omega‐3 fatty acids (n‐3 FA) on perioperative outcomes and survival in patients undergoing colorectal cancer surgery.

Methods

Patients scheduled for elective resection of colorectal cancer between 2007 and 2010 were randomized to either an n‐3 FA‐enriched oral nutrition supplement (ONS) twice daily or a standard ONS (control) for 7 days before and after surgery. Outcome measures, including postoperative complications, 3‐year cumulative incidence of local or metastatic colorectal cancer recurrence and 5‐year overall survival, were compared between the groups.

Results

Of 148 patients enrolled in the study, 125 (65 patients receiving n‐3 FA‐enriched ONS and 60 receiving standard ONS) were analysed. There were no differences in postoperative complications after surgery (P = 0·544). The risk of disease recurrence at 3 years was similar (relative risk 1·66, 95 per cent c.i. 0·65 to 4·26).The 5‐year survival rate of patients treated with n‐3 FA was 69·2 (95 per cent c.i. 56·5 to 78·9) per cent, compared with 81·7 (69·3 to 89·4) per cent in the control group (P = 0·193). After adjustment for age, stage of disease and adjuvant chemotherapy, n‐3 FA was associated with higher mortality compared with controls (hazard ratio 1·73, 95 per cent c.i. 1·06 to 2·83; P = 0·029). The interaction between n‐3 FA and adjuvant chemotherapy was not statistically significant.

Conclusion

Perioperative supplementation with n‐3 FA did not confer a survival benefit in patients undergoing colorectal cancer surgery. n‐3 FA did not benefit the subgroup of patients treated with adjuvant chemotherapy or decrease the risk of disease recurrence.

The association of serum lipid levels with colorectal cancer recurrence

BACKGROUND

Biologic and epidemiologic evidence suggests that tumor cells depend on reprogrammed lipid metabolic function for survival and growth. Lipids may promote tumor recurrence by providing energy needed for proliferation. Studies have found associations of serum lipids with cancer incidence, mortality, and disease-free mortality, though they have yet to evaluate the prognostic potential of serum lipids for colorectal cancer (CRC) recurrence.

METHODS

341 Danish CRC patients who underwent surgical resection were actively followed between 2003-2011 from date of surgery until December 31, 2012, or death. Serum lipids including low-density lipoprotein cholesterol (LDL-C), high-density lipoprotein cholesterol (HDL-C), and triglycerides (TG), were collected at regular intervals. Lipids were assigned as time-varying exposures evaluated with a one-year lag. Cox proportional hazards models were used to assess recurrence rate, adjusting for clinically relevant covariates. A restricted analysis was performed in a group of non-statin users (n = 236).

RESULTS

Among 341 CRC patients, increased HDL-C appeared to have a beneficial impact on recurrence-free survival (RFS) for CRC patients, especially among statin users (hazard ratio [HR] for 0.1 mmol/L increase = 0.58; 95 % confidence interval [CI]: 0.43, 0.78). Increased LDL-C and TG were not associated with RFS. Increased lipids showed a near-null effect on CRC recurrence [e.g. HR (95 % CI) for 0.1 mmol/L increase LDL = 1.01 (0.97, 1.19)] among non-statin users.

CONCLUSION

Serum lipid levels of LDL-C and TG do not appear to be associated with CRC recurrence. Further investigation of the role of HDL-C in CRC recurrence may be of interest based on the suggestive inverse association observed here.

Clinical results and microbiota changes after faecal microbiota transplantation for chronic pouchitis: a pilot study

Objectives: Research evidence suggests that chronic pouchitis is associated with intestinal dysbiosis. Faecal microbiota transplantation (FMT) has been proposed as a possible treatment. We performed a 6-month prospective, open-label, single-centre cohort pilot-study (NCT03538366) to investigate if FMT could improve clinical outcome and alter gut microbiota in patients with chronic pouchitis.Materials and methods: Nine adult patients with chronic pouchitis were included and allocated to 14 days FMT by enemas from five faecal donors, with a 6-month follow-up. Pouchitis severity was assessed using pouchitis disease activity index (PDAI) before and after FMT. Changes in gut microbiota, and engraftment of donor's microbiota were assessed in faecal samples.Results: All patients were treated with FMT for 14 continuous days. Overall, four of nine patients receiving FMT were in clinical remission at 30-day follow-up, and three patients remained in remission until 6-month follow-up. Clinical symptoms of pouchitis improved significantly between inclusion and 14-day follow-up (p = .02), but there was no improvement in PDAI between inclusion (mean 8.6) and 30-day follow-up (mean 5.2). Treatment with FMT caused a substantial shift in microbiota and increased microbial diversity in six patients, resembling that of the donors, with a high engraftment of specific donor microbiota.Conclusions: Symptomatic benefit in FMT treatment was found for four of nine patients with chronic pouchitis with increased microbial diversity and high engraftment of donor's microbiota. A larger, randomised controlled study is required to fully evaluate the potential role of FMT in treating chronic pouchitis.

Application of the Adaptive Validation Substudy Design to Colorectal Cancer Recurrence

Background

Among men and women diagnosed with colorectal cancer (CRC), 20-50% will develop a cancer recurrence. Cancer recurrences are not routinely captured by most population-based registries; however, linkage across Danish registries allows for the development of predictive models to detect recurrence. Successful application of such models in population-based settings requires validation against a gold standard to ensure the accuracy of recurrence identification.

Objective

We apply a recently developed validation study design for prospectively collected validation data to validate predicted CRC recurrences against gold standard diagnoses from medical records in an actively followed cohort of CRC patients in Denmark.

Methods

We use a Bayesian monitoring framework, traditionally used in clinical trials, to iteratively update classification parameters (positive and negative predictive values, and sensitivity and specificity) in an adaptive validation substudy design. This design allows determination of the sample size necessary to estimate the corresponding parameters and to identify when validation efforts can cease based on predefined criteria for parameter values and levels of precision.

Results

Among 355 men and women diagnosed with CRC in Denmark and actively followed semi-annually, there were 63 recurrences diagnosed by active follow-up and 70 recurrences identified by a predictive algorithm. The adaptive validation design met stopping criteria for the classification parameters after 120 patients had their recurrence information validated. This stopping point yielded parameter estimates for the classification parameters similar to those obtained when the entire cohort was validated, with 66% less patients needed for the validation study.

Conclusion

In this proof of concept application of the adaptive validation study design for outcome misclassification, we demonstrated the ability of the method to accurately determine when sufficient validation data have been collected. This method serves as a novel validation substudy design for prospectively collected data with simultaneous implementation of a validation study.

Treatment of locally advanced pancreatic cancer with irreversible electroporation - a Danish single center study of safety and feasibility

OBJECTIVES

Irreversible electroporation (IRE) is a novel non-thermal ablative technique applied in the treatment of unresectable locally advanced pancreatic cancer (LAPC). This paper reports on the initial experience with IRE of unresectable LAPC in our institution.

METHODS

From October 2013 to March 2018, patients with unresectable LAPC referred for IRE at the Department of Gastrointestinal Surgery, Aalborg University Hospital, were considered for inclusion in the study. Ninety-day morbidity, 30-day mortality, pain score, length of hospital stay (LOS) and overall survival (OS) were recorded.

RESULTS

We included 33 patients receiving 40 IRE ablations in total. The median visual analogue scale (VAS)-score was four (range 0-10) two hours after IRE, and one (range 0-8) eight hours after IRE. The median LOS was one day (range 1-13 days). Post-procedural complications occurred in 21 of 40 ablations (53%), of which eight (20%) were major (Clavien-Dindo grade III or more). A proportion of the observed complications might be attributed to disease progression and not IRE per se. Although not statistically significant, we observed increased severity of complications in tumors above 3.5 cm. The 30-day mortality was 5% (2/40). The median OS was 10.7 months (range 0.6-53.8 months) from the initial IRE procedure, and 18.5 months (range 4.9-65.8 months) from time of diagnosis.

CONCLUSIONS

In our institution, IRE seems as a feasible consolidative treatment of unresectable LAPC with an acceptable safety profile. The oncological outcome of IRE in patients with unresectable LAPC is to be further evaluated in a planned phase 2 clinical trial (CHEMOFIRE-2).

Pre- and Postoperative State of Coagulation and Fibrinolysis in Plasma of Patients with Benign and Malignant Colorectal Disease - A Preliminary Study

This study was carried out in order to compare the coagulation balance in patients with colorectal cancer before and after surgical removal of tumor with an age matched non-malignancy control group. Furthermore, it was studied whether preoperative coagulation state in cancer patients was correlated to the postoperative development of deep venous thrombosis (DVT) diagnosed by venography. Plasma was collected preoperatively in 93 cancer patients and 30 controls, and postoperatively on day one, two, seven, and ninety in 88 cancer patients and 18 controls. Prothrombin fragment 1 + 2 (F1 + 2), thrombin-antithrombin complex (TAT), and total fibrin(ogen) degradation products (TDP) were quantitated in plasma by enzyme linked immunosorbent assays (ELISA). As compared to controls, patients admitted for cancer treatment displayed significantly higher levels of F1 + 2 and TAT. Patients suffering from advanced colorectal cancer had significantly higher levels of TAT and TDP as compared to patients with localized colorectal cancer. Twenty-three percent of cancer patients developed DVT postoperatively. Preoperatively these patients displayed significantly higher TDP levels, and postoperatively higher levels of F1 + 2, TAT, and TDP compared to cancer patients without DVT. The marked activation of blood coagulation and fibrinolysis observed in all patients following major abdominal surgery was even more pronounced in patients not cured for cancer.

Abstract LB-166: Antibiotic prescriptions and colorectal cancer recurrence risk: A Danish nationwide prospective cohort study

The large number of colorectal cancer survivors, coupled with the financial burden of colorectal cancer, makes it critical to identify factors associated with cancer recurrence. The human gut microbiome is one of the most densely populated bacterial communities known to exist. It plays a vital role in the host's gut physiology and potentially contributes to colorectal cancer progression. Given the prevalence and often overuse of antibiotics in the population, and their effects on the gut microbiome, the potential influence of antibiotics on the clinical course of colorectal cancer is of great public health importance. Using data from Danish medical registries, we followed 21,152 patients (5,036 with recurrences) diagnosed with stage I-III colorectal cancer from 2001 to 2011. We examined the association between pre- and post-diagnostic antibiotic use and cancer recurrence. After adjustment for potential confounders (age at diagnosis, sex, year of diagnosis, stage, tumor location, cancer treatment, comorbidities, inflammatory bowel disease, and use of statins, non-steroidal anti-inflammatory drugs and aspirin), any antibiotic prescription 90 days prior to colorectal cancer diagnosis was not associated with recurrence [adjusted hazard ratio (aHR) = 1.06, 95% confidence interval (CI): 0.98, 1.14]. However, antibiotic use after cancer diagnosis was associated with a higher risk of recurrence (aHR = 1.23, 95% CI: 1.16, 1.31). Additional ongoing analyses address cancer-specific and all-cause mortality and different time-lag periods. Their results also will be presented at the meeting. Our preliminary findings support further investigation into the possible roles of the gut microbiome and agents that alter its composition and diversity in colorectal cancer progression.

Citation Format: Veronika Fedirko, Deirdre Cronin-Fenton, Anders Hammerich Riis, Henrik Toft Sørensen, Claus Lindbjerg Andersen, Ole Thorlacius-Ussing, Timothy Lash. Antibiotic prescriptions and colorectal cancer recurrence risk: A Danish nationwide prospective cohort study [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2018; 2018 Apr 14-18; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2018;78(13 Suppl):Abstract nr LB-166.

Final results of a European, multicentre, prospective, observational study of Permacol™ collagen paste injection for the treatment of anal fistula

AIM

Permacol™ collagen paste (Permacol™ paste) is an acellular cross-linked porcine dermal collagen matrix suspension for use in soft-tissue repair. The use of Permacol™ paste in the filling of anorectal fistula tract is a new sphincter-preserving method for fistula repair. The MASERATI100 study was a prospective, observational clinical study with the objective to assess the efficacy of Permacol™ collagen paste for anal fistula repair in 100 patients.

METHOD

Patients (n = 100) with anal fistula were treated, at 10 European surgical sites, with a sphincter-preserving technique using Permacol™ paste. Fistula healing was assessed at 1, 3, 6 and 12 months post-treatment, with the primary end-point being healing at 6 months. Faecal continence and patient satisfaction were surveyed at each follow-up; adverse events (AEs) were monitored throughout the follow-up.

RESULTS

At 6 months postsurgery, 56.7% of patients were healed and the percentage healed was largely maintained, with 53.5% healed at 12 months. Regarding AEs, 29.0% of patients had at least one AE, and 16.0% of patients had one or more procedure-related AE. Most AEs reported were minor and similar to those commonly observed after fistula treatment, and the incidence of serious adverse events was low (4.0% of patients). Regardless of treatment outcome, 73.0% of patients were satisfied or very satisfied with the procedure.

CONCLUSION

Permacol™ paste is a promising sphincter-preserving treatment for anal fistulae and has minimal adverse side-effects.

The prognostic efficacy of cell-free DNA hypermethylation in colorectal cancer

Epigenetic alterations in colorectal cancer (CRC) cause important differences in the underlying tumor biology and aggressiveness. DNA hypermethylation is central for the development of CRC but the prognostic impact remains elusive. We aimed to assess the association between cell-free hypermethylated DNA and stage and survival in colorectal cancer (CRC). We analyzed pre-treatment plasma samples from 193 patients with CRC. Thirty gene-promoter regions were analyzed using methylation specific PCR. We compared the median number (range) of hypermethylated promoter regions with CRC stage, and constructed a multivariable Cox-regression model adjusted for stage, to evaluate the added prognostic information. The median number of hypermethylated promoter regions was nine (0-28) in patients with distant metastasis compared to five (0-19) in patients without metastatic disease (p < 0.0001). The majority of the hypermethylated promoter regions inferred a poor prognosis. Cox-regression analysis adjusted for patient age, sex, pre-treatment CEA-levels, and disease stage, showed that RARB (HR = 1.99, 95% CI [1.07, 3.72]) and RASSF1A (HR = 3.35, 95% CI [1.76, 6.38]) hypermethylation inferred a significant effect on survival. The risk of metastasis increase with the number of cell-free hypermethylated promoter regions. The presence of RARB and RASSF1A hypermethylation indicated aggressive disease, regardless of stage at the time of diagnosis.

Long-term Risk of Cancer Following Ileal Pouch-anal Anastomosis for Ulcerative Colitis

BACKGROUND

The overall risk of cancer following ileal pouch-anal anastomosis [IPAA] is unknown, and pouch cancer surveillance is controversial. We evaluated long-term risk of cancer in a national cohort of patients with ulcerative colitis and IPAA, with emphasis on pouch cancer.

METHODS

Data on incident cancers were extracted from the national Danish Cancer Registry. Incidence rates for all site-specific cancers were compared between patients with IPAA and a gender- and age-matched comparison cohort from the background population to obtain incidence rate ratios [IRRs].

RESULTS

A total of 1723 patients with IPAA, operated for ulcerative colitis in the period 1980-2010, were matched to 8615 individuals from the background population. During a median follow-up of 12.9 years (interquartile range [IQR] 7.7-19.6 years), two pouch cancers [0.12%] were found after 16 and 27 years, respectively. In the population comparison cohort, 38 intestinal cancers [0.45%] were found, of which 35 were colorectal. The risk of hepatobiliary cancer was higher for patients with IPAA {IRR = 13.0 (95% confidence interval [CI]: 3.1-76.1)}, and half of the affected patients had coexisting primary sclerosing cholangitis. The risk of cancer overall following IPAA was identical to that of the comparison cohort: IRR = 1.05 [0.84-1.31].

CONCLUSIONS

Pouch cancer following IPAA is very rare, questioning the need for general, rather than selective, surveillance. The overall cancer risk is comparable to that of the background population, and the increased risk of hepatobiliary cancer is likely an effect of coexisting liver disease and not causally related to IPAA.