Oncomicrobial Community Profiling Identifies Clinicomolecular and Prognostic Subtypes of Colorectal Cancer.

BACKGROUND & AIMS: Dysbiosis of gut microbiota is linked to the development of colorectal cancer (CRC). However, microbiota-based stratification of CRC tissue and how this relates to clinicomolecular characteristics and prognosis remains to be clarified. METHODS: Tumor and normal mucosa from 423 patients with stage I to IV CRC were profiled by bacterial 16S rRNA gene sequencing. Tumors were characterized for microsatellite instability (MSI), CpG island methylator phenotype (CIMP), APC, BRAF, KRAS, PIK3CA, FBXW7, SMAD4, and TP53 mutations, subsets for chromosome instability (CIN), mutation signatures, and consensus molecular subtypes (CMS). Microbial clusters were validated in an independent cohort of 293 stage II/III tumors. RESULTS: Tumors reproducibly stratified into 3 oncomicrobial community subtypes (OCSs) with distinguishing features: OCS1 (Fusobacterium/oral pathogens, proteolytic, 21%), right-sided, high-grade, MSI-high, CIMP-positive, CMS1, BRAF V600E, and FBXW7 mutated; OCS2 (Firmicutes/Bacteroidetes, saccharolytic, 44%), and OCS3 (Escherichia/Pseudescherichia/Shigella, fatty acid ß-oxidation, 35%) both left-sided and exhibiting CIN. OCS1 was associated with MSI-related mutation signatures (SBS15, SBS20, ID2, and ID7) and OCS2 and OCS3 with SBS18 related to damage by reactive oxygen species. Among stage II/III patients, OCS1 and OCS3 both had poorer overall survival compared with OCS2 for microsatellite stable tumors (multivariate hazard ratio [HR], 1.85; 95% confidence interval [CI], 1.15-2.99; P = .012; and HR, 1.52; 95% CI 1.01-2.29; P = .044, respectively) and left-sided tumors (multivariate HR, 2.66; 95% CI, 1.45-4.86; P = .002; and HR, 1.76; 95% CI, 1.03-3.02; P = .039, respectively). CONCLUSIONS: OCS classification stratified CRCs into 3 distinct subgroups with different clinicomolecular features and outcomes. Our findings provide a framework for a microbiota-based stratification of CRC to refine prognostication and to inform the development of microbiota-targeted interventions.

Characteristics and outcomes of participants in colorectal cancer biomarker trials versus a real-world cohort.

BACKGROUND: The restrictive eligibility criteria of therapy-focused cancer clinical trials can limit the external validity of the results. The characteristics and survival outcomes of patients enrolled in stand-alone biomarker studies have yet to be explored. We examined the characteristics of patients enrolled in a series of biomarker studies in stage II and III colorectal cancer (CRC) and of the broader patient population from which the study cohorts were recruited. MATERIAL AND METHODS: We examined three distinct trial scenarios: a retrospective cohort study (RCS) where archival tissue samples were analyzed, a prospective observational study (POS) where blood samples were collected but patients received standard treatment and a randomized clinical trial (RCT) where biomarker analysis could inform clinical care. Clinical data for each study time period were extracted from a prospective registry. RESULTS: For all CRC patients (n = 4033) in this study, the median age was 70 years and 54% were ECOG 0. For patients in the RCS (n = 450), POS (n = 284) and RCT (n = 230), the median age was 72, 65 and 64 years, with 45%, 74% and 79% being ECOG 0. For the POS and RCT, 33% and 36% of all patients with the relevant disease stage were enrolled over the study recruitment period. Survival outcomes were similar for patients in the RCS and POS. RCT outcome data are not available. CONCLUSION: As for therapy-based trials, enrollment in prospective biomarker studies may be selective, despite relatively broad eligibility criteria. Characteristics and recruitment were similar for POS and RCT patients, indicating study complexity may not necessarily limit patient recruitment. For the prospective biomarker study cohorts examined, the selective recruitment did not significantly impact survival outcomes, suggesting potential for high external validity.

Prognostic significance of postsurgery circulating tumor DNA in nonmetastatic colorectal cancer: Individual patient pooled analysis of three cohort studies.

Studies in multiple solid tumor types have demonstrated the prognostic significance of ctDNA analysis after curative intent surgery. A combined analysis of data across completed studies could further our understanding of circulating tumor DNA (ctDNA) as a prognostic marker and inform future trial design. We combined individual patient data from three independent cohort studies of nonmetastatic colorectal cancer (CRC). Plasma samples were collected 4 to 10 weeks after surgery. Mutations in ctDNA were assayed using a massively parallel sequencing technique called SafeSeqS. We analyzed 485 CRC patients (230 Stage II colon, 96 Stage III colon, and 159 locally advanced rectum). ctDNA was detected after surgery in 59 (12%) patients overall (11.0%, 12.5% and 13.8% for samples taken at 4-6, 6-8 and 8-10 weeks; P = .740). ctDNA detection was associated with poorer 5-year recurrence-free (38.6% vs 85.5%; P < .001) and overall survival (64.6% vs 89.4%; P < .001). The predictive accuracy of postsurgery ctDNA for recurrence was higher than that of individual clinicopathologic risk features. Recurrence risk increased exponentially with increasing ctDNA mutant allele frequency (MAF) (hazard ratio, 1.2, 2.5 and 5.8 for MAF of 0.1%, 0.5% and 1%). Postsurgery ctDNA was detected in 3 of 20 (15%) patients with locoregional and 27 of 60 (45%) with distant recurrence (P = .018). This analysis demonstrates a consistent long-term impact of ctDNA as a prognostic marker across nonmetastatic CRC, where ctDNA outperforms other clinicopathologic risk factors and MAF further stratifies recurrence risk. ctDNA is a better predictor of distant vs locoregional recurrence.

Tumour infiltrating lymphocyte status is superior to histological grade, DNA mismatch repair and BRAF mutation for prognosis of colorectal adenocarcinomas with mucinous differentiation.

Mucinous colorectal adenocarcinoma (CRC) is conventionally defined by extracellular mucin comprising >50% of the tumour area, while tumours with ≤50% mucin are designated as having a mucinous component. However, these definitions are largely arbitrary and comparisons of clinico-molecular features and outcomes by proportion of mucinous component are limited. A cohort of 1643 patients with stage II/III cancer was examined for tumour mucinous component, DNA mismatch repair (MMR) status, BRAF mutation and tumour infiltrating lymphocytes (TILs). Tumours with ≤50% mucinous component exhibited similar characteristics as mucinous tumours, including association with female gender, proximal location, high grade, TIL-high, defective MMR (dMMR) and BRAF mutation. Proportion of mucinous component did not stratify disease-free survival (DFS). In univariate analysis dMMR status, but not histological grade, stratified survival for mucinous and mucinous component tumours; however, in multivariate analysis dMMR status was not an independent predictor. BRAF mutation prognostic value depended on mucinous differentiation and MMR status, with poor prognosis limited to non-mucinous pMMR tumours (HR 2.61, 95% CI 1.69-4.03; p < 0.001). TIL status was a strong independent predictor of DFS in mucinous/mucinous component tumours (HR 0.40, 95% CI 0.23-0.67; p < 0.001), and a superior predictor of prognosis compared with histological grade, MMR and BRAF mutation. Mucinous component and mucinous stage II/III CRCs exhibit clinico-molecular resemblances, with histological grade and BRAF mutation lacking prognostic value. Prognosis for these tumours was instead strongly associated with TIL status, with the most favourable outcomes in TIL-high dMMR tumours, whilst TIL-low tumours had poor outcomes irrespective of MMR status.

Serial circulating tumour DNA analysis during multimodality treatment of locally advanced rectal cancer: a prospective biomarker study.

OBJECTIVE: For patients with locally advanced rectal cancer (LARC), adjuvant chemotherapy selection following surgery remains a major clinical dilemma. Here, we investigated the ability of circulating tumour DNA (ctDNA) to improve risk stratification in patients with LARC. DESIGN: We enrolled patients with LARC (T3/T4 and/or N+) planned for neoadjuvant chemoradiotherapy. Plasma samples were collected pretreatment, postchemoradiotherapy and 4-10 weeks after surgery. Somatic mutations in individual patient's tumour were identified via massively parallel sequencing of 15 genes commonly mutated in colorectal cancer. We then designed personalised assays to quantify ctDNA in plasma samples. Patients received adjuvant therapy at clinician discretion, blinded to the ctDNA results. RESULTS: We analysed 462 serial plasma samples from 159 patients. ctDNA was detectable in 77%, 8.3% and 12% of pretreatment, postchemoradiotherapy and postsurgery plasma samples. Significantly worse recurrence-free survival was seen if ctDNA was detectable after chemoradiotherapy (HR 6.6; P<0.001) or after surgery (HR 13.0; P<0.001). The estimated 3-year recurrence-free survival was 33% for the postoperative ctDNA-positive patients and 87% for the postoperative ctDNA-negative patients. Postoperative ctDNA detection was predictive of recurrence irrespective of adjuvant chemotherapy use (chemotherapy: HR 10.0; P<0.001; without chemotherapy: HR 22.0; P<0.001). Postoperative ctDNA status remained an independent predictor of recurrence-free survival after adjusting for known clinicopathological risk factors (HR 6.0; P<0.001). CONCLUSION: Postoperative ctDNA analysis stratifies patients with LARC into subsets that are either at very high or at low risk of recurrence, independent of conventional clinicopathological risk factors. ctDNA analysis could potentially be used to guide patient selection for adjuvant chemotherapy.

Stage-based Variation in the Effect of Primary Tumor Side on All Stages of Colorectal Cancer Recurrence and Survival.

BACKGROUND: Multiple studies have defined the prognostic and potential predictive significance of the primary tumor side in metastatic colorectal cancer (CRC). However, the currently available data for early-stage disease are limited and inconsistent. MATERIALS AND METHODS: We explored the clinicopathologic, treatment, and outcome data from a multisite Australian CRC registry from 2003 to 2016. Tumors at and distal to the splenic flexure were considered a left primary (LP). RESULTS: For the 6547 patients identified, the median age at diagnosis was 69 years, 55% were men, and most (63%) had a LP. Comparing the outcomes for right primary (RP) versus LP, time-to-recurrence was similar for stage I and III disease, but longer for those with a stage II RP (hazard ratio [HR], 0.68; 95% confidence interval [CI], 0.52-0.90; P < .01). Adjuvant chemotherapy provided a consistent benefit in stage III disease, regardless of the tumor side. Overall survival (OS) was similar for those with stage I and II disease between LP and RP patients; however, those with stage III RP disease had poorer OS (HR, 1.30; 95% CI, 1.04-1.62; P < .05) and cancer-specific survival (HR, 1.55; 95% CI, 1.19-2.03; P < .01). Patients with stage IV RP, whether de novo metastatic (HR, 1.15; 95% CI, 0.95-1.39) or relapsed post-early-stage disease (HR, 1.35; 95% CI, 1.11-1.65; P < .01), had poorer OS. CONCLUSION: In early-stage CRC, the association of tumor side and effect on the time-to-recurrence and OS varies by stage. In stage III patients with an RP, poorer OS and cancer-specific survival outcomes are, in part, driven by inferior survival after recurrence, and tumor side did not influence adjuvant chemotherapy benefit.

Super-Selective Mesenteric Embolization Provides Effective Control of Lower GI Bleeding.

Introduction. We aimed to assess the efficacy and safety of digital subtraction angiography (DSA) and super-selective mesenteric artery embolization (SMAE) in managing lower GI bleeding (LGIB). Method. A retrospective case series of patients with LGIB treated with SMAE in our health service. Patients with confirmed active LGIB, on either radionuclide scintigraphy (RS) or contrast-enhanced multidetector CT angiography (CE-MDCT), were referred for DSA +/- SMAE. Data collected included patient characteristics, screening modality, bleeding territory, embolization technique, technical and clinical success, short-term to medium-term complications, 30-day mortality, and progression to surgery related to procedural failure or complications. Results. There were fifty-five hospital admissions with acute unstable lower gastrointestinal bleeding which were demonstrable on CE-MDCT or RS over a 31-month period. Eighteen patients proceed to embolization, with immediate success in all. Eight patients (44%) had clinical rebleeding after intervention, warranting repeated imaging. Only one case (5.6%) demonstrated radiological rebleeding and was reembolized. Complication rate was excellent: no bowel ischaemia, ischaemic stricture, progression to surgery, or 30-day mortality. Conclusion. SMAE is a viable, safe, and effective first-line management for localised LGIB. Our results overall compare favourably with the published experiences of other institutions. It is now accepted practice at our institution to manage localised LGIB with embolization.

Examining the impact of regular aspirin use and PIK3CA mutations on survival in stage 2 colon cancer.

BACKGROUND/AIM: Data suggest aspirin improves survival in colorectal cancer (CRC) harbouring PIK3CA mutations. The impact of aspirin is thought predominantly to be through an anti-inflammatory effect. The aim of this study is to explore the effect of aspirin use on survival in a real-world cohort of stage 2 colon cancer (CC) patients. METHODS: A prospective CRC database identified patients diagnosed with stage 2 CC between 2000 and 2011. PIK3CA mutation status was determined by next generation sequencing. Neutrophil-lymphocyte ratio greater than 5 at diagnosis represented systemic inflammation. Chart review was used to record regular aspirin use at diagnosis. Clinico-pathological features and survival data were available. Survival analyses used the Cox proportional hazards method. RESULTS: Of 488 patients with stage 2 CC, 95 patients were aspirin users and 70 patients had PIK3CA mutations. Aspirin users were more likely to be older (median: 76.4 years vs 68.3 years, P < 0.001), to be less fit (American Society of Anaesthetists Score 3-4: 58% vs 31%, P < 0.001) and to have systemic inflammation (neutrophil-lymphocyte ratio > 5: 39% vs 27%, P = 0.027). Regular aspirin use did not significantly improve recurrence-free survival. In the PIK3CA mutated group, there was a trend towards improved recurrence-free survival (hazard ratio: 0.45, P = 0.42). CONCLUSIONS: Our study did not demonstrate a significant survival advantage from aspirin use in stage 2 PIK3CA mutated CC. The 'real-world' nature of our cohort and the subsequent uncontrolled differences in age and fitness in aspirin users are likely to have contributed to this result. Defining the true impact of aspirin in CRC requires prospective randomised clinical trials.

Circulating tumor DNA analysis detects minimal residual disease and predicts recurrence in patients with stage II colon cancer.

Detection of circulating tumor DNA (ctDNA) after resection of stage II colon cancer may identify patients at the highest risk of recurrence and help inform adjuvant treatment decisions. We used massively parallel sequencing-based assays to evaluate the ability of ctDNA to detect minimal residual disease in 1046 plasma samples from a prospective cohort of 230 patients with resected stage II colon cancer. In patients not treated with adjuvant chemotherapy, ctDNA was detected postoperatively in 14 of 178 (7.9%) patients, 11 (79%) of whom had recurred at a median follow-up of 27 months; recurrence occurred in only 16 (9.8 %) of 164 patients with negative ctDNA [hazard ratio (HR), 18; 95% confidence interval (CI), 7.9 to 40; P < 0.001]. In patients treated with chemotherapy, the presence of ctDNA after completion of chemotherapy was also associated with an inferior recurrence-free survival (HR, 11; 95% CI, 1.8 to 68; P = 0.001). ctDNA detection after stage II colon cancer resection provides direct evidence of residual disease and identifies patients at very high risk of recurrence.

The rapidly escalating cost of treating colorectal cancer in Australia.

AIMS: Considerable progress in cancer treatment is leading to better outcomes, but the cost of therapy is placing increasing pressure on the health system. Understanding the real-world cost of therapies for each stage will become increasingly important in informing treatment selection and health policy. METHODS: To explore the cost of treating colorectal cancer in the modern era, data were entered onto a prospective database at four hospitals. We estimated the impact of bevacizumab by using data from July 2009, and projected the likely impact of the recent listing of cetuximab. The utility of these data for estimating the cost-effectiveness of treatment was explored. RESULTS: Cancer stage and age at diagnosis were major determinants of treatment received and the associated cost. The cost of early stage disease has not substantially changed whereas therapies such as oxaliplatin and irinotecan were significant contributors to substantial increases in stage IV disease, now $71,156 per patient. Bevacizumab has added at least $10,247 per patient and we estimate that cetuximab will add a further $12,022. An exploratory analysis of the cost-effectiveness of oxaliplatin for adjuvant therapy of stage III colon cancer suggests that this is well within the accepted range. CONCLUSION: These data suggest that recent progress in the treatment of later stages of colorectal cancer is being achieved at significant financial cost. The increased costs of managing later stages of disease make an investment in prevention and early detection ever more attractive.

Impact of Diabetes Status and Medication on Presentation, Treatment, and Outcome of Stage II Colon Cancer Patients.

Diabetes is a risk factor for colorectal cancer and several reports suggest worse cancer-specific outcomes in diabetes patients. Recent studies in multiple tumour types indicate metformin may positively impact on cancer-specific and overall survival. A population-based series of stage II colorectal cancer patients treated and followed from 2000 to 2013 were analysed for baseline characteristics, treatment, and outcomes. 1116 patients with stage II colon cancer were identified, 55.5% were male and median age was 70.9 years (range 20.5-101.2). The diabetes patients (21.6%, n = 241) were older than nondiabetes patients (median 74.0 versus 69.6, p = 0.0001). There was no impact of diabetes on cancer presentation or pathology. Diabetes patients were less likely to receive adjuvant treatment (13.7 versus 24.8%, p = 0.002) but were equally likely to complete treatment (69.7 versus 67.7%, p = 1.00). Diabetes did not significantly impact cancer recurrence (HR = 1.07, 95% CI 0.71-1.63) or overall survival (HR = 1.23, 95% CI 0.88-1.72), adjusted for age. Diabetes medication did not impact cancer recurrence or survival. Cancer presentation and outcomes in diabetes patients are comparable to those of nondiabetes patients in those with stage II colon cancer. The effect of metformin merits further evaluation in patients with colon cancer.

Translation of clinical trial outcomes to metastatic colorectal cancer patients in community practice.

AIM: As multiple new agents have been added to the treatment options for patients with metastatic colorectal cancer, survival outcomes in clinical trials have continued to improve. Similarly, improved outcomes in routine clinical care would be anticipated, but have yet to be demonstrated. Here, we aim to explore whether survival gains demonstrated in clinical trials are reproducible in routine practice, and whether factors beyond new therapies may be contributing to improved outcomes. METHODS: Comparison of comprehensive treatment and outcome data for consecutive patients diagnosed in 2003-2006 versus 2007-2010 at four specialist hospitals in Australia. RESULTS: Data were available on 965 patients; median age 66.1 years (range 19-93), 572 (59%) were male. For the latter time period, there was an increase in patients receiving any treatment (74% vs 66%, P = 0.014), initial combination chemotherapy (57% vs 44%, P < 0.001) and bevacizumab (15% vs 2%, P < 0.001). There was no change in the percentage undergoing resection of distant metastatic disease. For the latter time period, overall survival was improved (median 24.8 vs 17.4 months, P < 0.001), including patients not receiving any active treatment (11.9 vs 6.4 months, P = 0.014). CONCLUSION: Survival outcomes in routine clinical care for patients with metastatic colorectal cancer have markedly improved in recent years following the introduction of multiple new active therapies. The improved outcome of untreated patients suggests earlier diagnosis and improved supportive care may also be contributing to survival gains.

Lymph node yield following colorectal cancer surgery.

BACKGROUND: Lymph node yield (LNY) is a measure of quality of care and a strong prognostic factor for outcome from colorectal cancer (CRC). The main aims of this study were to determine LNY across multiple Australian centres and the clinico-pathologic factors that influence yield. METHODS: Analysis of data from prospective CRC databases at 11 Australian centres between January 1988 and May 2008 was undertaken utilizing the linkage and analysis resources of BioGrid Australia. The LNY depending on different clinico-pathologic patient characteristics was evaluated. RESULTS: In total, 10,082 cases (54.1% men, 45.9% women) were identified. Median LNY was 12 (range 0-174). LNY increased significantly (P < 0.001) over time, from a mean of 8.5 in 1988 to 13 in 2008. LNY also varied significantly between surgical centres. Female gender, younger age, right-sided disease, higher T and N stage, specific operation types and absence of preoperative radiotherapy were all significantly associated with higher LNY. CONCLUSIONS: While varying across centres, the median LNYs in Australia are acceptable and have improved significantly over recent years. Multiple clinico-pathologic factors significantly influence the number of nodes retrieved.

Initial impact of Australia's National Bowel Cancer Screening Program.

OBJECTIVE: To examine the initial impact of the National Bowel Cancer Screening Program (NBCSP), which was launched in May 2006 and offers faecal occult blood testing to Australians aged 55 or 65 years. DESIGN AND SETTING: Review of data on colorectal cancer (CRC) cases diagnosed between May 2006 and June 2008 from a prospective database used at 19 Australian hospitals, linked and analysed by BioGrid Australia. MAIN OUTCOME MEASURES: Number of CRC cases detected through the NBCSP or symptomatic presentation, and differences by sex, stage at diagnosis, tumour location and level of socioeconomic disadvantage. RESULTS: 1628 cases of CRC were identified; 1268 had information on the patients' test status as part of the NBCSP, and 40 of these (3.2%) were recorded as being detected by the NBCSP. Of 75 CRC cases in patients aged 55 or 65 at diagnosis, 22 were NBCSP-detected. Overall, there was no difference in NBCSP-detected cases by sex. The distribution of tumour locations was similar between NBCSP-detected cases and symptomatic cases, but NBCSP-detected cancers were diagnosed at an earlier stage than symptomatic cancers (stage I, 40% v 14%; stage IV, 3% v 15%, respectively). Of patients diagnosed through the NBCSP, 63% were from areas of least socioeconomic disadvantage (deciles 8-10) and 18% were from the most disadvantaged areas (deciles 1-4) (P=0.0375). CONCLUSION: Initiation of the Australian NBCSP has had a measurable impact on CRC stage at diagnosis, and an improvement in survival would be anticipated. The lower uptake among people from disadvantaged areas is of concern.

Preoperative chemotherapy and radiotherapy for locally advanced rectal cancer.

BACKGROUND: The adjuvant treatment of rectal cancer is a rapidly evolving field. The standard approach is a combination of chemotherapy and radiotherapy, with the optimal treatment combination and sequencing yet to be determined. Here, we report our early experience of preoperative chemotherapy and radiotherapy (CRT) in locally advanced rectal cancer at Radiation Oncology Victoria to determine its efficacy and the rate of sphincter preservation. METHODS: Sixty-nine patients (46 men and 23 women) with locally advanced rectal cancer (T3-4 or N1) were treated with preoperative CRT followed by surgical resection of disease. Chemotherapy consisted of either bolus or continuous venous infusion of 5-fluorouracil (5-FU). Radiotherapy to a dose of 45 Gy was delivered to the pelvis followed by a boost of 5.4-14.4 Gy in the majority of patients. Surgical resection was carried out 4-8 weeks following completion of preoperative CRT. Univariate and multivariate analyses were performed to examine variables that may influence local recurrence and overall survival rates. RESULTS: All patients underwent a complete macroscopic resection, including the three patients that had unrecognized distant metastases discovered at the time of operation. Only two patients had microscopic residual disease. Sphincter preservation was achieved in 16 of 25 patients who were thought to require an abdominoperineal resection. Tumour and/or nodal downstaging were achieved in 47 patients (68%), with a pathological complete response in 12 (17%). At a median follow up of 29 months post-surgery, five patients (7.2%) have developed a local recurrence. Overall 21 patients (30%) have progressed and 12 (18%) have died. Treatment-related toxicity was acceptable and there was no treatment-related mortality. There was no significant relationship found between the pathological response to treatment and any clinical endpoint. CONCLUSIONS: Our results confirm the high response rates and acceptable toxicity of preoperative treatment. Further studies are required to better define the impact of preoperative chemotherapy and radiotherapy on long-term outcomes.