Metachronous colorectal cancer metastasis: Who, what, when and what to do about it.

Metachronous colorectal cancer (CRC) metastasis occurs due to micrometastatic disease, in up to 23% of patients who have undergone curative-intent treatment. Metachronous metastasis tends to occur within 2 years of initial treatment. Diagnosis relies on posttreatment surveillance strategies. Care for patients with metachronous CRC metastasis is complex and requires careful multidisciplinary consideration. Those with isolated and technically resectable diseases are recommended to undergo metastasectomy with adjunct chemotherapy, however, survival, even after curative-intent resection, is poor.

Fusobacterium nucleatum and Bacteroides fragilis detection in colorectal tumours: Optimal target site and correlation with total bacterial load.

BACKGROUND: Mucosal infiltration by certain bacterial species may contribute to the development and progression of colorectal cancer (CRC). There is considerable variation in reported detection rates in human CRC samples and the extent to which bacterial infiltration varies across regions of the primary tumour is unknown. This study aimed to determine if there is an optimal site for bacterial detection within CRC tumours. METHODS: Presence of target bacterial species was assessed by quantitative real-time PCR (qPCR) in 42 human CRC tumours. Abundance in primary tumour regions, normal epithelium and at metastatic sites was investigated in an expanded cohort of 51 patients. Species presence/absence was confirmed by diversity profiling in five patients. Correlation with total bacterial load and clinicopathological features was assessed. RESULTS: Fusobacterium nucleatum and Bacteroides fragilis were detected in tumours from 43% and 24% of patients, respectively (17% positive for both species). The optimal detection site was the tumour luminal surface (TLS). Patients testing positive at the TLS frequently tested negative at other sites, including central tumour and invasive margin. F. nucleatum was detected at a higher frequency in tumour versus normal epithelium (p < 0.01) and was associated with more advanced disease (p = 0.01). Detection of both species correlated with total bacterial load. However, corroboration of qPCR results via diversity profiling suggests detection of these species may indicate a specific microbial signature. CONCLUSIONS: This study supports a role for F. nucleatum in CRC development. Presence of F. nucleatum and B. fragilis varies across primary tumour regions, with the TLS representing the optimal site for bacterial detection.

PD-L1+ dendritic cells in the tumor microenvironment correlate with good prognosis and CD8+ T cell infiltration in colon cancer.

BACKGROUND: The prognostic value of tumor-associated dendritic cells (DC) in colon cancer remains poorly understood. This may be in part due to the interchangeable expression of immunostimulatory and immunoinhibitory molecules on DC. Here we investigated the prognostic impact of CD11c+ DC co-expressing the immunoinhibitory molecule PD-L1 and their spatial relationship with CD8+ T-cells in patients treated for stage III colon cancer. METHODS: Tissue microarrays containing representative cores of central tumor, leading edge, and adjacent normal tissue from 221 patients with stage III colon cancer were immunostained for CD8, CD11c, PD-L1, and cytokeratin using immunofluorescent probes. Cells were quantified using StrataQuest digital image analysis software, with intratumoral and stromal regions analyzed separately. Kaplan-Meier estimates and Cox regression were used to assess survival. RESULTS: Intratumoral CD8+ cell density (HR = .52, 95% confidence interval [CI] .33-.83, P = .007), stromal CD11c+ cell density (HR = .52, 95% CI .33-.83, P = .006), intratumoral CD11c+ PD-L1+ cell density (HR = .57, 95% CI .35-.92, P = .021), and stromal CD11c+ PD-L1+ cell density (HR = .48, 95% CI .30-.77, P = .003) on leading-edge cores were all significantly associated with good survival. CD8+ cell density was positively correlated with both CD11c+ cell density and CD11c+ PD-L1+ cell density in tumor epithelium and stromal compartments. CONCLUSION: Here we showed that PD-L1-expressing DC in the tumor microenvironment are associated with improved survival in stage III colon cancer and likely reflect an immunologically "hot" tumor microenvironment. Further investigation into the expression of immunomodulatory molecules by tumor-associated DC may help to further elucidate their prognostic value.

The Prognostic and Predictive Value of SOX2+ Cell Densities in Patients Treated for Colorectal Cancer.

SOX2 (sex-determining region-Y homeobox-2) is a transcription factor essential for the maintenance of pluripotency and is also associated with stem-cell-like properties in preclinical cancer models. Our previous study on a cohort of stage III colon cancer patients demonstrated high SOX2+ cell densities were associated with poor prognosis. However, most patients were treated with adjuvant chemotherapy so the prognostic value of SOX2 could not be assessed independently from its value as a predictive marker for non-response to chemotherapy. This study aimed to assess whether SOX2 was a true prognostic marker or a marker for chemotherapy response in a historical cohort of patients, a high proportion of whom were chemotherapy-naïve. SOX2 immunostaining was performed on tissue micro-arrays containing tumor cores from 797 patients with stage II and III colorectal cancer. SOX2+ cell densities were then quantified with StrataQuest digital image analysis software. Overall survival was assessed using Kaplan-Meier estimates and Cox regression. It was found that high SOX2+ cell densities were not associated with poor overall survival. Furthermore, all patients had a significant improvement in survival after 5-fluorouracil (5-FU) treatment, irrespective of their SOX2+ cell density. Therefore, SOX2+ cell densities were not associated with prognosis or chemotherapy benefit in this study. This is in contrast to our previous study, in which most patients received oxaliplatin as part of their treatment, in addition to 5-FU. This suggests SOX2 may predict response to oxaliplatin treatment, but not 5-FU.

Optimisation of multiplex immunofluorescence for a non-spectral fluorescence scanning system.

The use of multi-colour immunofluorescence (IF) for immunophenotyping in formalin-fixed paraffin-embedded tissue sections is gaining popularity worldwide. This technique allows for the simultaneous detection of multiple markers on the same tissue section, thereby yielding more complex information than is possible by chromogenic immunohistochemistry (IHC). However, many commercially-available multiplex IF kits are designed for use in conjunction with a multispectral imaging system, to which many research groups have limited access. Here we present two 5-colour IF panels designed for T cell characterisation in human colorectal tissue, which can be imaged using a non-spectral fluorescence slide scanner with standard band-pass filters. We describe the optimisation process and the key considerations in developing a multiplex fluorescence assay, and discuss some of the advantages and disadvantages of using multiplex IF with a non-spectral imaging system.

Expression of PD-L1 and SOX2 during rectal tumourigenesis: Potential mechanisms for immune escape and tumour cell invasion.

Immunoediting is defined as a process whereby tumour cells develop the capacity to escape immune cell recognition. Accumulating evidence suggests that cancer stem-like cells (CSCs) have an enhanced capacity to interact with the immune system. The expression of CSCs and immune cell-associated markers has been demonstrated to change with disease progression from premalignant lesions to invasive cancer. The present study investigated the expression of putative CSC and immune cell-associated markers in different stages of progression from dysplasia to invasive malignancy in rectal lesions. Immunohistochemistry was performed for the CSC markers Lgr5 and SOX2 and the immune-associated markers CD8, Foxp3 and PD-L1 in 79 cases of endoscopically-excised rectal lesions, ranging from low grade adenoma (LG) to invasive adenocarcinoma (AdCa). CD8 and Foxp3 expression significantly increased with advances in disease progression [AdCa vs. LG: Odds ratio (OR) 4.33; 95% confidence interval (CI), 1.16-16.3; P=0.03 and OR, 40.5; 95% CI, 6.57-249.6; P<0.0001, respectively]. An increase in programmed death-ligand 1 (PD-L1) expression was also observed with disease progression (OR, 24.0; 95% CI, 4.23-136.2; P=0.0003). The expression of sex determining region Y-box 2 (SOX2) did not correlate with disease progression, although an elevated expression was observed in areas with high grade dysplasia. Increased PD-L1 expression may be a mechanism by which tumour cells evade immune recognition, facilitating tumour cell invasion in rectal cancer. The expression of SOX2 in areas with high grade dysplasia may indicate the de-differentiation of tumour cells, or the activation of migration pathways for invasion.

Tumour-infiltrating regulatory T cell density before neoadjuvant chemoradiotherapy for rectal cancer does not predict treatment response.

Neoadjuvant (preoperative) chemoradiotherapy (CRT) decreases the risk of rectal cancer recurrence and reduces tumour volume prior to surgery. However, response to CRT varies considerably between individuals and factors associated with response are poorly understood. Foxp3+ regulatory T cells (Tregs) inhibit anti-tumour immunity and may limit any response to chemotherapy and radiotherapy. We have previously reported that a low density of Tregs in the tumour stroma following neoadjuvant CRT for rectal cancer is associated with improved tumour regression. Here we have examined the association between Treg density in pre-treatment diagnostic biopsy specimens and treatment response, in this same patient cohort. We aimed to determine whether pre-treatment tumour-infiltrating Treg density predicts subsequent response to neoadjuvant CRT. Foxp3+, CD8+ and CD3+ cell densities in biopsy samples from 106 patients were assessed by standard immunohistochemistry (IHC) and evaluated for their association with tumour regression grade and survival. We found no association between the density of any T cell subset pre-treatment and clinical outcome, indicating that tumour-infiltrating Treg density does not predict response to neoadjuvant CRT in rectal cancer. Taken together with the findings of the previous study, these data suggest that in the context of neoadjuvant CRT for rectal cancer, the impact of chemotherapy and/or radiotherapy on anti-tumour immunity may be more important than the state of the pre-existing local immune response.

Neoadjuvant chemoradiotherapy for rectal cancer: how important is tumour regression?

BACKGROUND: Pathological complete response following neoadjuvant chemoradiotherapy (CRT) for locally advanced rectal cancer is associated with reduced local recurrence and improved long-term outcome. However, the prognostic value of a partial response, or of tumour regression in patients with metastatic disease, is less clear. METHODS: We present a single-centre cohort study of 205 patients with stage II-IV rectal cancer treated with surgery and neoadjuvant CRT between 2006 and 2013. Tumour regression was assessed using the Dworak system. RESULTS: The probability of 3-year recurrence-free survival (RFS) was 95% for Dworak grade 4, 82% for grade 3, 64% for grade 2 and 53% for grade 1 (P = 0.0005). In univariate regression analysis, Dworak grade was associated with RFS (hazard ratio (HR) 0.51, P < 0.0001; trend analysis) and cancer-specific survival (HR 0.52, P = 0.002). In multivariate analysis, Dworak grade remained an independent predictor of RFS (HR 0.62, P = 0.012), along with clinical metastases stage, resection margin status, the presence or absence of extramural venous invasion and type of surgical procedure. CONCLUSIONS: Tumour regression grade after neoadjuvant CRT was an independent prognostic factor for RFS, highlighting the importance of the degree of local response to CRT.

Surgical volume influences survival in patients undergoing resections for stage II colon cancers.

BACKGROUND: There is current interest in the correlation between surgical volume and outcomes. Survival in patients with rectal cancer appears to improve when carried out by surgeons who do high volumes of procedures. A similar correlation for patients with colon cancer has never been clearly established. The aim of this study was to determine whether surgical volume was an independent predictor for survival in patients undergoing surgery for stage II colon cancer. METHODS: Population-based findings were collected from all patients diagnosed with stage II colon cancer in Western Australia between 1993 and 2003. The Kaplan-Meier product limit estimate of survival was used to calculate overall and cancer-specific survival. The Cox proportional hazards model was used to define the correlation between a number of covariates and survival. The results are recorded as hazard ratio (HR) with 95% confidence intervals (CI). RESULTS: From 1993 to 2003, 1467 patients underwent resections for stage II colon cancers. Significant independent predictors for overall survival were surgeon carrying out more than 25 procedures (P = 0.0001, HR 0.657, 95%CI 0.532-0.811), surgery in a private hospital (P = 0.0001, HR 0.487, 95%CI 0.400-0.594), use of chemotherapy (P = 0.001, HR 0.664, 95%CI 0.496-0.837), age at diagnosis (P = 0.0001, HR 1.014, 95%CI 1.027-1.044) and T staging and vascular invasion (T4 and vascular positive P = 0.001, HR 1.850, 95%CI 1.294-2.645). CONCLUSIONS: Surgical volume was a significant independent predictor for survival in patients undergoing resections for stage II colon cancers. Surgeons carrying out only 25 procedures over a 10-year period outperformed surgeons doing fewer cases.

Changing patterns of recurrence after treatment for colorectal cancer.

BACKGROUND: The management of patients with colorectal cancer has changed appreciably over the last 16 years. The aims of this study were to compare the rates and patterns of disease recurrence over the last 10 years with a historical control group. MATERIALS AND METHODS: Data was obtained from a prospective database that had recorded all patients presenting with colorectal cancer from 1996 to 2006. This data was compared with a retrospective data set that included all patients treated with colorectal cancer at the same institution from 1989 to 1995. The Kaplan-Meier technique was used to calculate the 5 year recurrence and local recurrence rates for the two groups. RESULTS: There were 710 patients in the study group and 475 patients in the control group. There were more patients with rectal cancer and stage I cancer in the study group. When comparing the study group vs the control group, there was an increase in the time to recurrence (2.1 vs 1.6 years, n.s.) and a decrease in the 5 year recurrence rate for patients undergoing curative resections (17% [95% CI 12%-20%] vs 42% [95% CI 36%-49%], p < 0.001). These changes were noted for both colon (16% vs 34%, p < 0.001) and rectal cancers (18% vs 50%, p < 0.001). There was also a decrease in local recurrence in patients with rectal cancer (8.8% [95% CI 4.5%-13.1%] vs 33.6% [95% CI 23.6%-43.6%], p < 0.001). CONCLUSIONS: Within this institution, there has been a significant trend during the last 16 years towards reduced disease recurrence, both local and metastatic, and a prolongation in the time to develop recurrence.

Resolving microcarcinoids in ulcerative colitis: report of a case.

Ulcerative colitis is known to predispose to the development of neoplasia, especially adenocarcinoma. Microcarcinoids represent small nests of gut endocrine cells located in the mucosa and submucosa of the bowel. Such lesions have been identified in association with chronic inflammation and the concern is that they may represent a precursor lesion for invasive carcinoid tumors. Yet carcinoid tumors are rarely reported in patients with ulcerative colitis. This case report documents a 56-year-old male with ulcerative colitis who was found on random biopsies to have microcarcinoids in his rectal submucosa. Following treatment of his colitis, there was complete resolution of both the inflammation and the microcarcinoids. However, on subsequent follow-up at six months, the patient's colitis has returned and so have the microcarcinoids. We explore the issue of whether these lesions represent true neoplasias that should be resected, or whether they represent cellular hyperplasia in response to the inflammatory stimulus.

Cost-effectiveness of colorectal cancer screening: comparison of community-based flexible sigmoidoscopy with fecal occult blood testing and colonoscopy.

BACKGROUND AND AIMS: To determine the cost-effectiveness of screening for colorectal cancer using flexible sigmoidoscopy once every 10 years, compared with annual and biennial rehydrated Hemoccult fecal occult blood testing and colonoscopy once every 10 years, or no screening. METHODS: A Markov model was developed in order to simulate the progression of a cohort of asymptomatic, average-risk individuals aged 55-64 years who were moving through a defined series of states towards death. The main outcome measures were: cases of colorectal cancer averted, colorectal cancer deaths averted, and cost per life-year saved. RESULTS: Colonoscopy averted the greatest number of cases of colorectal cancer (35%), followed by flexible sigmoidoscopy (25%), and annual (24%) and biennial (14%) fecal occult blood testing. Colonoscopy averted the greatest number of deaths from colorectal cancer (31%), followed by annual fecal occult blood testing (29%), flexible sigmoidoscopy (21%) and biennial fecal occult blood testing (19%). Flexible sigmoidoscopy was the most efficient in terms of cost per life-year saved (16,801 Australian dollars), followed by colonoscopy (19,285 Australian dollars), biennial (41,183 Australian dollars), and annual (46,900 Australian dollars) fecal occult blood testing. CONCLUSIONS: Flexible sigmoidoscopy and colonoscopy are cost-effective strategies for reducing the disease burden of colorectal cancer.

Review of survival curves for colorectal cancer.

PURPOSE: Actuarial and Product Limited (i.e., Kaplan-Meier) estimates of survival are commonly used in the literature to describe outcomes in patients treated for cancer. Terms such as cancer-specific and cancer-free survival are frequently quoted, although often without clear definitions. This study was designed to compare survival estimates using the Kaplan-Meier method on the same population of patients but using different definitions of what constitutes an event. This was to highlight some of the variation that can occur when different techniques are used to perform these calculations. METHODS: Data were obtained from a prospective database that had recorded all patients presenting with colorectal cancer from 1996 to 2002. Using this information, we calculated the 1) overall (all-cause mortality), 2) cancer-specific, 3) cancer-free, 4) recurrence-free, and 5) relative survival (and 95 percent confidence intervals) at five years postpresentation. RESULTS: The study included 497 patients with a mean age of 68 years, and a male-to-female ratio of 1.3:1. They were followed for a mean of 2.2 years (standard deviation, +/-1.1), with 50 patients (10.1 percent) followed for more than five years. The various survivals at five years were: 1) overall survival, 55.6 percent (95 percent confidence interval, 49.1-62.1 percent), 2) cancer-specific survival, 67 percent (95 percent confidence interval, 60.9-73.1 percent), 3) cancer-free survival, 49.9 percent (95 percent confidence interval, 43.6-56.2 percent), 4) recurrence-free survival, 43.5 percent (95 percent confidence interval, 37.2-49.8 percent), and 5) relative survival, 73.4 percent (95 percent confidence interval, 65.4-81.4 percent). CONCLUSIONS: The five-year survival calculations for this group of patients with colorectal cancer varied by as much as 30 percent depending on how the data was censored. This highlights that there needs to be a clear and accountable definition on how survival curves are calculated and presented in the literature to allow for meaningful interpretation and comparisons.

Flexible sigmoidoscopy screening for colorectal neoplasia in average-risk people: evaluation of a five-year rescreening interval.

OBJECTIVE: To determine the prevalence of colorectal neoplasia detected by rescreening people with average risk five years after initial screening by flexible sigmoidoscopy. DESIGN: Prospective survey of results of a colorectal cancer screening program. PARTICIPANTS: People aged 55-64 years with no symptoms or family history of colorectal cancer who were recruited from the community for flexible sigmoidoscopy screening five years previously (July 1995 to December 1996) and had no colorectal neoplasms detected. SETTING: Fremantle Hospital, Western Australia, a community-based teaching hospital, December 2000 to June 2001. MAIN OUTCOME MEASURES: Number and size of colorectal neoplasms (adenomas or cancer) compared between rescreened patients and initial screening population (all 982 people screened between July 1995 and December 1996). RESULTS: 803 people were eligible for rescreening; 138 were no longer at the recorded address, and 361 of the remaining 665 (54%) were rescreened. Rescreening found a significantly lower prevalence of colorectal adenomas than initial screening (8% [95% CI, 5%-11%] versus 14% [95% CI, 13%-15%]; P < 0.05) and also a lower percentage of adenomatous polyps over 5 mm in diameter (32% [95% CI, 15%-49%] versus 51% [95% CI, 46%-56%]; no significant difference). CONCLUSION: Average-risk people who have been screened for colorectal neoplasms, with none found, have a low prevalence of neoplastic lesions five years later. Longer rescreening intervals need to be considered.

The management of patients with the short bowel syndrome.

The surgeon is invariably the primary specialist involved in managing patients with short bowel syndrome. Because of this they will play an important role in co-ordinating the management of these patients. The principal aims at the initial surgery are to preserve life, then to preserve gut length, and maintain its continuity. In the immediate postoperative period, there needs to be a balance between keeping the patient alive through the use of TPN and antisecretory agents and promoting gut adaptation with the use of oral nutrition. If the gut fails to adapt during this period, then the patient may require therapy with more specific agents to promote gut adaptation such as growth factors and glutamine. If following this, the patient still has a short gut syndrome, then the principal options remain either long term TPN, or intestinal transplantation which remains a difficult and challenging procedure with a high mortality and morbidity due to rejection.