Colorectal cancer staging and adjuvant chemotherapy

Colorectal cancer and its attributable risk factors in East Asia, 1990-2030

BACKGROUND

The disease burden of colorectal cancer in East Asia has been at a high level. However, the epidemiological characteristics of the disease burden in this region have not been systematically studied.

METHOD

Data were obtained from the Global Burden of Disease 2019 program. Joinpoint analysis was used to identify long-term trends in mortality of colorectal cancer. Independent effects of age, period, and cohort were detected by the age-period-cohort model. The Bayesian age-period-cohort model was performed to predict the burden of colorectal cancer across East Asia by 2030.

RESULTS

From 1990 to 2019, the average annual percentage change (AAPC) showed upward trends in mainland China (1.05 [95% confidence interval (CI)], 0.82, 1.28) as well as Taiwan Province of China (1.81 [95% CI], 1.51, 2.10) but downward in Japan (-0.60 [95% CI], -0.70, -0.49) (P < 0.05). Attributable risk factors for colorectal cancer in East Asia remained stable over 30 years, while the risk of metabolic factors is noteworthy in the future. In the next decade, the age-standardized death rate (ASDR) of colorectal cancer in China was predicted to surpass that of Japan and South Korea in expectation.

CONCLUSION

The mortality of colorectal cancer is escalating in developing countries, while it is gradually declining in high-income countries across East Asia. Nonetheless, the disease burden of colorectal cancer in high-income countries remains substantial level.

Optimizing the radiosynthesis of [68Ga]DOTA-MLN6907 peptide containing three disulfide cyclization bonds - a GCC specific chelate for clinical radiopharmaceuticals

In the present study, the effect of radiolabeling conditions on radiolabeling efficiency and achievable specific activity of a DOTA-conjugated highly-lipophilic peptide containing three disulfide cyclization bonds was examined. The peptide is designed to bind specifically (with high affinity) to cell-surface receptor guanylyl cyclase C (GCC), which is universally expressed by colorectal cancer cells. The effect of systematic variation of chemical parameters pH, mass of peptide, acetate buffer concentration (ionic strength), and inclusion of ethanol in the radiolabeling reaction vessel on achievable specific activity and labeling efficiency was examined. In addition, a unique approach to acetone-based elution of ⁶⁸Ga from an initial cation-exchange pre-concentration column is introduced, which improved radiochemical yield and radiochemical purity. For the evaluation of the acetone-based method, two different post-radiolabeling reverse-phase (C18) approaches to purify the final radiolabeled peptide were tested. These results revealed the potential for peptide degradation via the cleavage of disulfide cyclization bonds to form free thiols when using one of these C18 cartridges. The final optimized procedure enabled radiolabeling efficiency of greater than 99% and specific activity greater than 35 MBq/nmole in less than 30 min. The optimized parameters were amenable to the use of an automated ⁶⁸Ge/⁶⁸Ga generator and fluid-handling system for clinical production of the GCC receptor-specific [⁶⁸Ga]DOTA-MLN6907 peptide. The chemical characteristics of individual peptides govern the most appropriate radiolabeling conditions for the preparation of radiopharmaceuticals.

Evidence-based Guidelines for Precision Risk Stratification-Based Screening (PRSBS) for Colorectal Cancer: Lessons learned from the US Armed Forces: Consensus and Future Directions

Colorectal cancer (CRC) is the third most common cause of cancer-related death in the United States (U.S.), with estimates of 143,460 new cases and 51,690 deaths for the year 2012. Numerous organizations have published guidelines for CRC screening; however, these numerical estimates of incidence and disease-specific mortality have remained stable from years prior. Technological, genetic profiling, molecular and surgical advances in our modern era should allow us to improve risk stratification of patients with CRC and identify those who may benefit from preventive measures, early aggressive treatment, alternative treatment strategies, and/or frequent surveillance for the early detection of disease recurrence. To better negotiate future economic constraints and enhance patient outcomes, ultimately, we propose to apply the principals of personalized and precise cancer care to risk-stratify patients for CRC screening (Precision Risk Stratification-Based Screening, PRSBS). We believe that genetic, molecular, ethnic and socioeconomic disparities impact oncological outcomes in general, those related to CRC, in particular. This document highlights evidence-based screening recommendations and risk stratification methods in response to our CRC working group private-public consensus meeting held in March 2012. Our aim was to address how we could improve CRC risk stratification-based screening, and to provide a vision for the future to achieving superior survival rates for patients diagnosed with CRC.

GUCY2C molecular staging personalizes colorectal cancer patient management

While the most significant prognostic and predictive marker in the management of colorectal cancer patients is cancer cells in regional lymph nodes, approximately 30% of patients whose lymph nodes are ostensibly free of tumor cells by histopathology ultimately develop recurrent disease reflecting occult metastases. Molecular techniques utilizing highly specific markers and ultra-sensitive detection technologies have emerged as powerful staging platforms to establish prognosis and predict responsiveness to chemotherapy in colorectal cancer patients. This review describes the evolution of the tumor suppressor GUCY2C as a prognostic and predictive molecular biomarker that quantifies occult tumor burden in regional lymph nodes for staging patients with colorectal cancer.

Molecular staging individualizing cancer management

Although the most important prognostic and predictive marker in colorectal cancer is tumor cells in lymph nodes, approximately 30% of patients who are node-negative die from occult metastases. Molecular staging employing specific markers and sensitive detection technologies has emerged as a powerful platform to assess prognosis in node-negative colon cancer. Integrating molecular staging into algorithms that individualize patient management will require validation and the definition of relationships between occult tumor cells, prognosis, and responses to chemotherapy.

Molecular staging estimates occult tumor burden in colorectal cancer

Tumor cells in regional lymph nodes are a key prognostic marker of survival and predictive marker of response to adjuvant chemotherapy in colorectal cancer. However, clinicopathologic techniques to detect lymph node metastases remain imperfect, and approximately 30% of patients with lymph nodes negative by histology (pN0) develop recurrent disease, reflecting occult metastases that escape detection. These observations underscore an unmet clinical need for accurate approaches to identify occult nodal metastases in colorectal cancer patients. GUCY2C is a receptor whose expression normally is restricted to intestinal epithelial cells, but is universally overexpressed by colorectal cancer cells. A prospective, multicenter, blinded clinical trial established the prognostic utility of GUCY2C qRT-PCR to detect occult nodal metastases in pN0 colorectal cancer patients. Molecular staging revealed that approximately 13% of pN0 patients were free of cancer cells, while approximately 87% had GUCY2C results that suggested occult metastases. The presence of occult nodal metastases was the most powerful independent predictor of time to recurrence and disease-free survival. These observations establish the utility of molecular detection of occult nodal metastases for assessing prognostic risk in pN0 colorectal cancer patients. Advancing GUCY2C into staging paradigms in clinical laboratories will require validation in independent patient populations, definition of the relationship between the quantity of occult tumor metastases and risk, and determination of the utility of GUCY2C qRT-PCR to identify pN0 patients who might benefit from adjuvant chemotherapy.

GUCY2C reverse transcriptase PCR to stage pN0 colorectal cancer patients

The most important prognostic marker of survival and predictive marker of response to adjuvant chemotherapy in colon cancer patients is tumor cells in regional lymph nodes. Despite their importance, standard techniques to assess nodal metastases remain imperfect, as approximately 30% of patients with histology-negative lymph nodes (pN0) die of recurrent disease, reflecting occult metastases that escape detection. These observations highlight the clinical need for novel, accurate approaches to detect occult lymph node metastases in patients with colon cancer. GUCY2C is a biomarker whose expression normally is restricted to intestinal cells, but is near universally overexpressed by colorectal cancer cells. Recently, a prospective, multicenter, blinded clinical trial demonstrated for the first time that the prognostic utility of GUCY2C quantitative reverse transcriptase (qRT)-PCR to detect occult lymph node metastases in pN0 colorectal cancer patients. Molecular staging revealed that approximately 13% of pN0 patients were free of tumor cells, while approximately 87% had GUCY2C results that suggested occult metastases. The presence of occult lymph node metastases was the strongest independent predictor of time to recurrence and disease-free survival. These observations establish the utility of molecular detection of occult lymph node metastases for estimating prognostic risk in pN0 colorectal cancer patients. Advancing this molecular diagnostic into staging paradigms in clinical laboratories will require validation in independent patient populations, definition of the relationship between the quantity of occult tumor metastases and risk, and determination of the utility of GUCY2C qRT-PCR to identify pN0 patients who might benefit from adjuvant chemotherapy.

Previstage GCC colorectal cancer staging test: a new molecular test to identify lymph node metastases and provide more accurate information about the stage of patients with colorectal cancer

Colorectal cancer (CRC) is the third most common cancer and a leading cause of death for both men and women in North America. The staging of the CRC at the time of diagnosis is the single most important prognostic factor in determining recurrence and survival. Until 2008, accurate evaluation of CRC stages I and II was based on examination of regional lymph nodes (LNs) under a microscope to identify cancer cells. This method can detect one cancer cell in 200 normal cells, but analyzes only a fraction of the available tissue from the LN (less than 0.1%). Up to 30% of patients assessed by traditional histopathology methods as having stage II disease (negative LNs) experience a recurrence of their cancer. Previstage GCC Colorectal Cancer Staging Test, a new molecular diagnostic test, is able to identify patients at high risk of recurrence by examining their LNs for guanylyl cyclase C (GCC). GCC is a marker found in cells lining the lumen of the gastrointestinal tract. The expression of GCC is conserved in CRC and metastatic disease. Using an ultrasensitive quantitative reverse transcription (RT)-PCR, the test interrogates a patient's LN tissues to identify GCC levels consistent with metastatic (stage III) disease. The technology employed in Previstage GCC is nearly 100,000 times more sensitive than microscopic staging methods. This molecular diagnostic test allows a more thorough examination of LNs and has an analytic sensitivity of 92% and a specificity of 98%. Such a test can be used to overcome the limitations of staging by traditional histopathology alone.

Guanylyl cyclase C: a molecular marker for staging and postoperative surveillance of patients with colorectal cancer

Staging patients with colorectal cancer defines their prognosis and therapeutic management. Unfortunately, histopathology, the current standard for staging, is relatively insensitive for detecting occult micrometastases and a significant fraction of patients are understaged and, consequently, undertreated. Similarly, current approaches to postoperative surveillance of patients with colorectal cancer detect disease recurrence at a point when interventions have little impact on survival. The detection of rare cells in tissue, for accurately staging patients, and in blood, for detecting disease recurrence, could be facilitated by employing sensitive and specific markers of disease. Guanylyl cyclase C (GCC), the receptor for the diarrheagenic bacterial heat-stable enterotoxin, is expressed selectively by cells derived from intestinal mucosa, including normal intestinal cells and colorectal tumor cells, but not by extragastrointestinal tissues and tumors. The nearly uniform expression of relatively high levels by metastatic colorectal tumors suggests that GCC may be a sensitive and specific molecular marker for metastatic colorectal cancer cells. Employing GCC reverse transcriptase PCR, occult colorectal cancer micrometastases were detected in lymph nodes that escaped detection by histopathology. Moreover, marker expression correlated with the risk of disease recurrence. Similarly, GCC reverse transcriptase PCR revealed the presence of tumor cells in blood of all patients examined with metastatic colorectal cancer and, in some studies, was associated with an increased risk of disease recurrence and mortality. These observations suggest that GCC reverse transcriptase PCR is a sensitive and specific technique for identifying tumor cells in extraintestinal sites and may be useful for staging and postoperative surveillance of patients with colorectal cancer.

Does immunostaining effectively upstage colorectal cancer by identifying micrometastatic nodal disease?

PURPOSE

Measure the association between the incidence of primary tumor staining and the identification of mediastinal lymph node (MLN) using cytokeratins, NM23, DCC-positive tumors, and vascular endothelial growth factor (VEGF) expression in T(2) and T(3)/N(0) colorectal cancers. The impact of MLN on both recurrence and survival was assessed.

MATERIALS AND METHODS

There were 153 CORC patients (T(2), T(3)/N(0)) selected from a prospectively accrued database. All patients had been staged by routine histopathology after a curative resection and no patients received adjuvant chemotherapy. The primary tumors (PT) were assessed with a panel of immunohistochemical stains (cytokeratin, DCC, Nm23, and VEGF). If the PT was positive, the regional nodes were assessed with that marker(s). For any positive tumor marker, all lymph nodes (LNs, mean of 12.6+/-4.2) were stained for this marker.

RESULTS

Patient age ranged from 38 to 86 years with a mean age of 61.56+/-25.56 years. Mean follow-up was 72.1+/-32.4 months. Recurrence rate of the whole group was 19/153 (12.4%) and the mean time to recurrence was 37.6+/-23.6 months (15 to 77 months). Crude mortality was 39.9%, while the cancer specific mortality was 11.2% after the whole follow-up period. The relationship between PT staining and MLNs was: cytokeratin-PT 143 (93.5%)/MLN 9 (6.3%); NM23-PT 51 (33.3%)/MLN 3 (5.9%); DCC-PT 79 (53%)/MLN 3 (3.8%); and VEGF-PT 72 (47%)/MLN 4 (5.6%). Nineteen (12.4%) patients experienced tumor recurrence. No correlation exist between PT and/or MLN staining and either recurrence or survival. No patient with MLN with any stain experienced a recurrence. There was no advantage to using an individual stain or all four stains.

CONCLUSION

Immunohistochemical stains for PT and focused analysis of regional nodes did not improve prediction of survival or recurrence. Sentinel LN evaluation and the provision of adjuvant chemotherapy in node-negative patients should be questioned and not be utilized outside of a research protocol.

Guanylyl cyclase C is a marker of intestinal metaplasia, dysplasia, and adenocarcinoma of the gastrointestinal tract

Gastrointestinal (GI) tumors continue to be major causes of cancer-related mortality, in part, reflecting metastases that escape detection by histopathology. Moreover, although approximately 10% of carcinomas arise from unknown locations, these tumors frequently originate in the GI tract. Guanylyl cyclase C (GC-C) is a receptor selectively expressed by intestinal epithelial cells whose persistent expression by colorectal carcinomas and ectopic expression by adenocarcinomas of the upper GI tract suggest its use as a marker for GI malignancies. Here, expression of GC-C protein, identified by immunohistochemistry, was examined in tissues and tumors arising from the human GI tract. Guanylyl cyclase C protein was expressed by epithelial cells from the duodenum to the rectum, but not by those in normal esophagus and stomach. Expression was retained in tubular adenomas, inflammatory bowel disease, premalignant lesions, and in primary and metastatic adenocarcinomas from the colon, including metastases to lymph nodes and liver. Moreover, GC-C was ectopically expressed in all cases of dysplasia and adenocarcinomas arising from intestinal metaplasia in esophagus and stomach. Thus, GC-C appears to be an immunohistochemical marker for identifying adenocarcinomas of unknown origin, metastases in patients undergoing staging for GI adenocarcinomas, and intestinal metaplasia, dysplasia, and tumors arising therein in the upper GI tract.

Adverse histopathological findings as a guide to patient management after curative resection of node-positive colonic cancer

Background

The aim of this study was to identify patient and tumour characteristics that might assist in developing an improved approach to patient selection for chemotherapy after resection of clinicopathological stage C colonic cancer.

Methods

Clinical, pathological and follow-up data have been collected prospectively for all patients undergoing resection for colorectal cancer at Concord Hospital since 1971. From an initial 2980 patients, after exclusions 378 remained who had a potentially curative operation for colonic cancer with nodal metastases and did not receive adjuvant chemotherapy. Associations between several pathological features and survival were examined by proportional hazards regression.

Results

In a multivariate model, both overall and colonic cancer-specific survival rates were negatively associated with serosal surface involvement, apical node metastasis, high histological grade and venous invasion. The survival of patients with stage C disease who had none of these adverse features was not significantly different from that of patients with stage B lesions. However, survival diminished significantly when one or more of the adverse features were present.

Conclusion

Patients with a stage C tumour but with none of the identified adverse features experience relatively good survival and are unlikely to benefit from adjuvant chemotherapy. In this series such patients accounted for 40·5 per cent of patients with stage C disease.

Pathological staging and therapy of oesophageal and gastric cancer

Oesophageal and gastric cancers are a significant cause of morbidity and mortality worldwide. Despite improvements in surgical techniques, radiation and chemotherapy, the prognosis of both cancers remains poor. Immunohistochemical and experimental studies indicate that the concept of micrometastasis is applicable to oesophageal and gastric cancer. New staging approaches, including immunohistochemistry and real-time reverse transcriptase-polymerase chain reaction (RT-PCR) of various markers, have been proposed for a more accurate staging of oesophageal and gastric cancer. Preliminary results suggest that real-time RT-PCR of markers for intestinal differentiation, such as guanylyl cyclase C (GC-C), might be useful for both the detection of premalignant conditions, such as intestinal metaplasia and the detection of micrometastasis from adenocarcinoma of the upper intestinal tract. Standard curative treatment options for oesophageal cancer include surgery or chemoradiotherapy. Chemotherapy is an option for the treatment of advanced and recurrent oesophageal cancer. Standard curative treatment for gastro-oesophageal junction and gastric cancer includes surgery and adjuvant chemoradiotherapy. Chemotherapy is an option for the treatment of advanced and recurrent gastric cancer.

Use of FTA gene guard filter paper for the storage and transportation of tumor cells for molecular testing

CONTEXT

Efficient methods of storing tumor specimens for molecular testing are needed in the modern surgical pathology laboratory. The FTA Gene Guard system is a novel method for the collection and room temperature storage of blood samples for DNA testing. The method uses index card-sized filter papers that provide an ideal medium on which to store tumor specimens for DNA testing.

OBJECTIVE

To determine whether FTA filter paper can be used in the surgical pathology laboratory to store tumor cells for DNA testing.

DESIGN

Cell suspensions were prepared from 60 surgical specimens, and DNA was extracted either immediately or after storage on FTA paper. The DNA extracted by each method was tested by polymerase chain reaction (PCR) for the beta-globin and interferon gamma genes, and the results were compared. Fifteen lymph node specimens stored on FTA paper were then tested for immunoglobulin heavy chain (IgH) gene rearrangement by PCR, and these results were compared with those obtained for immediately extracted DNA.

SETTING

University medical center.

RESULTS

The DNA extracted from cells stored on FTA paper performed as well in the PCR as the freshly extracted DNA in nearly all cases (>95%). The results of tests for IgH gene rearrangements showed 100% concordance between the 2 methods of DNA extraction.Conclusion.-Cells from surgical specimens can be stored on FTA paper for extended lengths of time, and DNA can be extracted from these cells for PCR-based testing. FTA filter paper is a reliable medium for the storage and/or transport of tumor cells for PCR-based DNA analysis.

GP letter writing in colorectal cancer: a qualitative study

BACKGROUND

The usual mode of communication with the specialist in the UK is a referral letter. Letters now primarily document the GPs' concerns for the patient and are no longer required to persuade the specialist to offer an appointment. The content of referral letters from GPs has failed to satisfy specialists responding to a series of surveys. Evidence suggests that GPs who improve their letters to specialists also refer more cases with significant pathology.

AIMS

The aims of this research are to explore the factors that may influence GPs in writing the referral letter when consulting patients presenting with lower bowel symptoms.

METHODS

A convenience sample of twelve GPs was interviewed in Nottinghamshire and inner city Sheffield practices. A framework approach was utilised in the analysis of data. Data from the interviews followed the prescribed steps, including: familiarisation, identifying a thematic framework, indexing, charting and mapping, and interpretation.

RESULTS

The thematic framework reflected four major themes. These were: (1) the nature and content of referral letters, (2) knowledge about colorectal cancer, (3) issues relating to the quality of referral letters in colorectal cases and (4) factors that effect the use of guidelines for referral.

CONCLUSIONS

GPs only have very short consultations in which to address many and complex issues. Pre-referral assessment in colorectal cases includes intimate examination of the patient. Therefore the writing of the letter of referral is often postponed until long after the patient has left the GP's office. Some GPs do not believe the consultant reads the letter of referral. However, GPs are keen to provide best care and welcome feedback about the quality of their letters. They acknowledge the responsibility to communicate with colleagues effectively and have differing ideas about what constitutes an adequate referral letter.