Multivariate Analysis of the Survival Rate for Treatment Modalities in Incurable Stage IV Colorectal Cancer

Biopsy sampling during self-expandable metallic stent placement in acute malignant colorectal obstruction: a narrative review

BACKGROUND

Histopathology is a crucial part of diagnosis and treatment guidance of colorectal cancer. In Denmark, it is not routine to biopsy during self-expandable metallic stent (SEMS) placement as a treatment option for acute colorectal obstruction of unknown etiology. This is due to lack of knowledge about the risks of hemorrhage, and thus the risk to aggravate the deteriorating overview conditions. Therefore, the aim of this study is to investigate whether there is evidence to avoid biopsy sampling during acute SEMS placement.

METHODS

The PubMed, Embase, and Cochrane Library databases were searched for relevant studies. Studies were included if they described biopsy sampling in relation to SEMS placement. Additionally, national and international guidelines were scrutinized on Google and by visiting the websites of national and international gastrointestinal societies.

RESULTS

In total, 43 studies were included in the review. Among these, one recommended biopsy during SEMS placement, three advised against biopsy, 23 just reported biopsy was performed during the procedure, and 16 reported biopsy before or after the procedure, or the timing was not specified. Among the 12 included guidelines, only two described biopsy during SEMS placement.

CONCLUSION

The literature on the subject is limited. In 24 of the 43 included studies, biopsy sampling was done during SEMS placement without reporting a decrease in the technical success rate. The included guidelines were characterized by a general lack of description of whether biopsy during SEMS placement should be performed or not. Prospective studies are needed in order to establish the real risk of hemorrhage, if any, when a biopsy is obtained.

National statistics about resection of the primary tumor in asymptomatic patients with Stage IV colorectal cancer and unresectable metastases. Need for improvement in data collection. A systematic review with meta-analysis

BACKGROUND

Patients with asymptomatic Stage IV colorectal cancer represent a significant heterogeneous group. National statistics represent an effective method to follow in real time the clinical outcomes of patients, and they may represent an important tool to analyze and to compare different therapeutic approaches. The aim of our study was to analyze the reviews of national data and single institutions reports, which compared the clinical outcomes of patients with asymptomatic Stage IV colorectal cancer and un-resectable metastases who had resection of the primary tumor with those who did not have resection. We gave special attention to the number of missing established relevant variables, to determine the appropriateness of the results of the published studies.

MATERIAL

We performed a systematic review of papers comparing patients who had and who had not primary tumor resection. Screened reports included the time of publication from June 2012 to June 2018; 2556 papers were identified and 27 were included into the review. The primary outcome was observed survival. We analyzed the number of major missing variables in National Data Bases and Single Institution Reports, to assess the overall validity of the conclusions of the analyzed reports.

RESULTS

In the majority of the reports and in the meta-analysis of studies with propensity score matching, resection of the primary tumor was correlated to improved survival and to the possibility for a better response to postoperative chemotherapy.

CONCLUSIONS

The high number of missing significant variables, and a clear clinical selection in single center reports make any analysis error-prone. National statistics might represent a valid method to follow in real time the clinical outcomes of these patients, comparing different therapeutic approaches. There is the need for improvement in national data collection, to make descriptive national statistics the ground for future progress in treatment. (PROSPERO) CRD 42018089691.

Long-Chain Noncoding RNA PVT1 Gene Polymorphisms Are Associated with the Risk and Prognosis of Colorectal Cancer in the Han Chinese Population

Background: To investigate the association between long-chain noncoding RNA (lncRNA) plasmacytoma variant translocation 1 (PVT1) gene polymorphisms and the risk and prognosis of colorectal cancer (CRC) in the Han Chinese population. Methods: A cohort of 225 Han Chinese CRC patients and 225 healthy controls was analyzed for the PVT1 gene genotypes at the loci rs1221464062, rs1366023633, rs1252200336, and rs1273526412. The levels of PVT1 mRNA, hsa-miR-455-5p, and hsa-miR-455-3p in both cancerous tissues and paracancerous normal tissues of the CRC patients were determined by reverse transcription polymerase chain reaction. The survival rate of CRC patients was recorded after 3 years of follow-up. Results: The risk of developing CRC in subjects with the ID genotype of the PVT1 gene locus rs1252200336 was 2.71 times higher compared with the type II genotype; and the D allele was a risk factor for CRC. The survival of CRC patients with the ID/DD genotypes of the PVT1 gene rs1252200336 locus was significantly lower compared with the II genotype. In both the cancerous tissues and the paracancerous normal tissues of CRC patients, the level of lncRNA PVT1 was negatively correlated with the hsa-miR-455-5p and hsa-miR-455-3p levels. In subjects carrying the ID/DD genotypes of the PVT1 gene rs1252200336 locus, the level of the lncRNA PVT1 in cancerous tissues was significantly higher compared with the II genotype, whereas the hsa-miR-455-3p level was significantly lower compared with the II genotype. Conclusion: The PVT1 gene rs1252200336 locus polymorphisms are associated with the risk of developing CRC in the Han Chinese population. The rs1252200336 locus deletion mutation (D) may impact the binding of hsa-miR-455-5p to the lncRNA PVT1 and its role in the development and progression of CRC.

A systematic analysis highlighting deficiencies in reported outcomes for patients with stage IV colorectal cancer undergoing palliative resection of the primary tumour

BACKGROUND

Management of the primary tumour in the presence of unresectable metastatic colorectal cancer (mCRC) is controversial. The role of primary tumour resection (PTR) has been investigated by a number of retrospective cohort studies, with a number on going randomised controlled trials. The aim of this study was to identify the clinical and patient-reported outcomes currently reported in studies that evaluate the role of PTR in mCRC.

METHODS

Literature searches were performed in MEDLINE (via OvidSP) (1966-June 2017), EMBASE (via OvidSP) and the Cochrane Library using terms related to colorectal cancer and primary tumour resection. All studies documenting outcomes following palliative PTR were included. Eligible articles were assessed using the Risk of Bias In Non-Randomised Studies of Intervention (ROBINS-I) tool.

RESULTS

Of 11,209 studies screened, 59 non-randomised studies reporting outcomes on 331,157 patients were included. Patient characteristics regarding performance status and co-morbidity were recorded in 26 (44.1%) and 17 (28.8%) studies. The chemotherapy regime used was reported in 27 (45.8%) studies. The operative setting and the operative approach was reported in 42 (71%) and 14 (23.7%) studies. Post-operative mortality and morbidity were reported in 33 (55.9%) and 35 (59.3%) studies. Overall survival was reported in 49 (83.1%) studies, with 5 different definitions identified. Quality of life was only reported in 1 (1.7%) study.

CONCLUSION

This study demonstrates significant heterogeneity in the selection and definition of outcomes reported following PTR in mCRC. There is significant heterogeneity with a significant under-reporting of important outcomes such as treatment related adverse events and patient reported outcomes.

Meta-analysis of outcomes following resection of the primary tumour in patients presenting with metastatic colorectal cancer

BACKGROUND

It is not clear whether resection of the primary tumour (when there are metastases) alters survival and/or whether resection is associated with increased morbidity. This systematic review and meta-analysis assessed the prognostic value of primary tumour resection in patients presenting with metastatic colorectal cancer.

METHODS

A systematic review of MEDLINE/PubMed was performed on 12 March 2016, with no language or date restrictions, for studies comparing primary tumour resection versus conservative treatment without primary tumour resection for metastatic colorectal cancer. The quality of the studies was assessed using the MINORS and STROBE criteria. Differences in survival, morbidity and mortality between groups were estimated using random-effects meta-analysis.

RESULTS

Of 37 412 initially screened articles, 56 retrospective studies with 148 151 patients met the inclusion criteria. Primary tumour resection led to an improvement in overall survival of 7·76 (95 per cent c.i. 5·96 to 9·56) months (risk ratio (RR) for overall survival 0·50, 95 per cent c.i. 0·47 to 0·53), but did not significantly reduce the risk of obstruction (RR 0·50, 95 per cent c.i. 0·16 to 1·53) or bleeding (RR 1·19, 0·48 to 2·97). Neither was the morbidity risk altered (RR 1·14, 0·77 to 1·68). Heterogeneity between the studies was high, with a calculated I² of more than 50 per cent for most outcomes.

CONCLUSION

Primary tumour resection may provide a modest survival advantage in patients presenting with metastatic colorectal cancer.

Meta-analysis of oncologic effect of primary tumor resection in patients with unresectable stage IV colorectal cancer in the era of modern systemic chemotherapy

Purpose

The management of primary tumors in patients with stage IV colorectal cancer remains unclear. This meta-analysis evaluated the survival benefits of primary tumor resection (PTR) in patients with unresectable stage IV colorectal cancer in the era of modern chemotherapy.

Methods

Multiple comprehensive databases were searched for studies comparing survival outcomes in patients with metastatic colorectal cancer who did and did not undergo PTR. Outcome data were pooled, and overall effect size was calculated using random effect models.

Results

Seventeen nonrandomized studies involving 18,863 patients met the inclusion criteria. Meta-analysis showed that PTR significantly improved overall survival (hazard ratio [HR], 0.63; 95% confidence interval [CI], 0.56–0.71; P < 0.001) and progression free survival (HR, 0.76; 95% CI, 0.67–0.87; P < 0.001). Subgroup analyses and sensitivity analyses, performed by predefined methods, also indicated that PTR improved overall patient survival.

Conclusion

Palliative resection of the primary tumor may have survival benefits in patients with unresectable stage IV colorectal cancer. Randomized controlled trials are needed to determine the optimal treatment for these patients.

Impact of cyclooxygenase-2 and prostaglandin-E2 expression on clinical outcome after pulmonary metastasectomy

BACKGROUND

Pulmonary metastasectomy (PM) is a standard procedure in the treatment of stage IV colorectal cancer (CRC). In most centers the indication for PM is solely based on clinical factors without taking the tumor biology into account. This results in diverse outcomes ranging from long-term remission to early recurrence. Inflammation is considered a hallmark of cancer development and progression. On the other hand the accessibility of CRC cells to the immune system reflects the grade of tumor aggressiveness. We sought to investigate the impact of cyclooxygenase-2 (COX-2) and prostaglandin-E2 (PGE2) expression in pulmonary metastases on different outcome parameters following PM.

METHODS

From 04/2009 to 11/2013 53 patients with complete PM for CRC were included in this single-center study. Tissue samples of resected pulmonary metastases and available corresponding primaries were collected and assessed by immunohistochemistry for COX-2 and PGE2 expression of the tumor tissue and the peritumoral stroma. Results were correlated with clinical outcome parameters.

RESULTS

COX-2 and PGE2 were detected in nearly every pulmonary CRC metastasis. Staining intensities of pulmonary metastases correlated only weakly with intensities found in primary tumors. When dividing metastases in high expressing and low expressing tumors, a trend towards longer recurrence free survival and improved survival was found in tumors with strong COX-2 and PGE2 staining.

CONCLUSIONS

In conclusion, this pilot study shows that COX-2 and PGE2 are uniformly overexpressed in pulmonary metastases from CRC. High expression of COX-2 and PGE2 seems to reflect a beneficial tumor biology with late tumor recurrence and prolonged overall survival after PM.

Meta-analysis of outcomes of patients with stage IV colorectal cancer managed with chemotherapy/radiochemotherapy with and without primary tumor resection

Background

Colorectal cancer is the third leading cause of death worldwide. Currently, novel chemotherapeutic agents are first-line therapy for unresectable stage IV colorectal cancer, while benefits of noncurative primary tumor resection in advanced disease remain debatable.

Objective

This meta-analysis evaluated outcomes of patients with unresectable stage IV colorectal cancer receiving systemic chemotherapy with or without primary tumor resection.

Materials and methods

A database search of PubMed and Cochrane Library databases identified 167 studies that were screened for relevance. After 119 were excluded, 48 were assessed for eligibility and 26 were included for meta-analysis, including 24 retrospective studies, one prospective study, and one randomized, controlled trial. Extracted data included patient demographics (age, sex), clinical data (tumor stage, metastasis), targeted therapy agents, and surgical data (with/without tumor resection). Patients’ overall and progression-free survival was compared between groups with/without primary tumor resection.

Results

The 26 studies included 43,903 patients with colorectal cancer, with 29,639 receiving chemotherapy/radiotherapy plus primary tumor resection, and 14,264 managed medically with chemotherapy/chemoradiotherapy alone without primary tumor resection. Patients receiving primary tumor resection plus chemotherapy/radiotherapy had longer overall survival (hazard ratio [HR 0.59], 95% confidence interval [CI] 0.51–0.68; P<0.001), with significant differences in overall survival between patients with and without primary tumor resection (HR 0.58, 95% CI 0.49–0.68; P<0.001). Longer overall survival was also found among patients receiving primary tumor resection who were treated with bevacizumab/cetuximab targeted therapy agents (HR 0.63, 95% CI 0.46–0.86; P=0.003). Patients from three studies who received primary tumor resection had longer progression-free survival (HR 0.73, 95% CI 0.58–0.91; P=0.005). Results are limited by retrospective data, inconsistent complications data, and publication bias.

Conclusion

Study results support primary tumor resection in stage IV colorectal cancer, but significant biases in studies suggest that randomized trials are warranted to confirm findings.

Prognostic Implications of Primary Tumor Resection in Stage IVB Colorectal Cancer in Elderly Patients

PURPOSE

The aim of this study was to identify prognostic factors in stage IVB colorectal cancer in elderly patients, focusing on the influence of treatment modalities, including palliative chemotherapy and primary tumor resection.

METHODS

A cohort of 64 patients aged over 65 years who presented with stage IVB colorectal cancer at the Gangneung Asan Hospital between July 1, 2001, and December 31, 2009, was analyzed. Demographics, tumor location, tumor grade, performance status, levels of carcinoembryonic antigen (CEA), level of aspartate aminotransferase (AST), and distant metastatic site at diagnosis were analyzed. Using the treatment histories, we analyzed the prognostic implications of palliative chemotherapy and surgical resection of the primary tumor retrospectively.

RESULTS

The cohort consisted of 30 male (46.9%) and 34 female patients (53.1%); the median age was 76.5 years. Primary tumor resection was done on 28 patients (43.8%); 36 patients (56.2%) were categorized in the nonresection group. The median survival times were 12.43 months in the resection group and 3.58 months in the nonresection group (P < 0.001). Gender, level of CEA, level of AST, Eastern Cooperative Oncology Group performance status, tumor location, and presence of liver metastasis also showed significant differences in overall survival. On multivariate analysis, male gender, higher level of CEA, higher AST level, and no primary tumor resection were independent poor prognostic factors. In particular, nonresection of the primary tumor was the most potent/poor prognostic factor in the elderly-patient study group (P = 0.001; 95% confidence interval, 2.33 to 21.99; hazard ratio, 7.16).

CONCLUSION

In stage IVB colorectal cancer in elderly patients, resection of the primary tumor may enhance survival.

A meta-analysis to determine the effect of primary tumor resection for stage IV colorectal cancer with unresectable metastases on patient survival

BACKGROUND

Approximately 20 % of patients diagnosed with colorectal cancer will have distant metastases at first presentation (stage IV disease). The effect of removing the primary tumor on survival for patients with stage IV disease with unresectable metastases remains unclear. To address this a meta-analysis of all studies comparing primary tumor resection with chemotherapy alone in cases of stage IV colorectal cancer with unresectable metastases was performed.

METHODS

A comprehensive search for published studies examining the effect of primary tumor resection in the setting of colorectal cancer with unresectable metastases was performed. Each study was reviewed and data extracted. Random-effects methods were used to combine data.

RESULTS

There were 21 studies including a total of 44,226 patients that met the inclusion criteria. Resection of the primary tumor in patients with unresectable metastases compared with chemotherapy alone was associated with a lower mortality risk (OR 0.28; 95 % CI 0.165-0.474; P < 0.001), translating into a difference in mean survival of 6.4 months in favor of resection (95 % CI 5.025-7.858, P < 0.001). Patients who underwent resection of the primary tumor were more likely to have liver metastasis only (OR 1.551; 95 % CI 1.247-1.929; P < 0.001), were less likely to have ≥2 metastasis (OR 0.653; 95 % CI 0.508-0.839; P = 0.001), and were less likely to have rectal cancer (OR 0.495; 95 % CI 0.390-0.629; P < 0.001). There was significant cross-study heterogeneity.

CONCLUSIONS

Resection of the primary tumor may confer a survival advantage in stage IV colorectal cancer with unresectable metastases but significant selection bias exists in current studies. Randomized controlled trials are essential to validate these findings.

Kolonstents als «Bridge to Surgery»

<b><i>Hintergrund: </i></b>Die Implantation von selbstexpandierenden Metallstents (SEMS) in das Kolorektum – insbesondere als «bridge to surgery» – hat sich zunehmend etabliert, obwohl die Charakteristika des Kolons eine Prothesenimplantation erschweren und bisher noch keine optimalen Stents für diese Lokalisation verfügbar sind. Mit einem Stent lässt sich beim Kolonileus sehr patientenschonend eine sofortige Dekompression des Darms herbeiführen und die sonst notwendige Notfalloperation mit hoher Letalität und Komplikationsrate vermeiden. <b><i>Methode: </i></b>Literaturübersicht. <b><i>Ergebnisse: </i></b>Trotz zahlreicher positiver Studienergebnisse («... Stenting ist sehr effektiv, sicher und komplikationsarm im Vergleich zur Operation ...») ergibt eine kritische Analyse der Publikationen aufgrund vieler Faktoren (Patientenselektion, Stenttyp, Implantationsmethode usw.) jedoch eine hohe Heterogenität. <b><i>Schlussfolgerungen: </i></b>Um gute Resultate zu erzielen, sollte eine Stentimplantation ins Kolon nur nach strenger Indikationsstellung von einem erfahrenen Endoskopiker durchgeführt werden. Dabei ist auch die mögliche Alternative einer endoskopisch eingelegten Dekompressionssonde zu prüfen; ebenso sind onkologische Gesichtspunkte (chirurgische Resektion als einziger kurativer Ansatz) zu beachten.

Review and evaluation of methods correcting for population stratification with a focus on underlying statistical principles

When two or more populations have been separated by geographic or cultural boundaries for many generations, drift, spontaneous mutations, differential selection pressures and other factors may lead to allele frequency differences among populations. If these 'parental' populations subsequently come together and begin inter-mating, disequilibrium among linked markers may span a greater genetic distance than it typically does among populations under panmixia [see glossary]. This extended disequilibrium can make association studies highly effective and more economical than disequilibrium mapping in panmictic populations since less marker loci are needed to detect regions of the genome that harbor phenotype-influencing loci. However, under some circumstances, this process of intermating (as well as other processes) can produce disequilibrium between pairs of unlinked loci and thus create the possibility of confounding or spurious associations due to this population stratification. Accordingly, researchers are advised to employ valid statistical tests for linkage disequilibrium mapping allowing conduct of genetic association studies that control for such confounding. Many recent papers have addressed this need. We provide a comprehensive review of advances made in recent years in correcting for population stratification and then evaluate and synthesize these methods based on statistical principles such as (1) randomization, (2) conditioning on sufficient statistics, and (3) identifying whether the method is based on testing the genotype-phenotype covariance (conditional upon familial information) and/or testing departures of the marginal distribution from the expected genotypic frequencies.