Zarina S. Lalmahomed

Optimizing the outcome of surgery in patients with rectal cancer and synchronous liver metastases

This study evaluated the outcome of patients treated for rectal cancer and synchronous hepatic metastases in the era of effective induction radiotherapy and chemotherapy.

Circulating Tumor Cells and Sample Size: The More, the Better

TO THEEDITOR: With interest we read the article by Jiao et al, 1 who studied the presence of circulating tumor cells (CTCs) in blood of patients with colorectal liver metastases (CRLM) by automated immunomagnetic enrichment and image cytometry using the CellSearch system (Veridex, Raritan, NJ). They showed CTCs to be present in the hepatic macrocirculation in significantly higher numbersthanintheperipheralcirculation(median,187[range,0to500]v median 1 [range 0 to 6]). Despite the number of evaluated patients in this study being small, the low number of detected CTCs in the peripheral circulation may suggest that CTC enumeration and characterization plays no role in this specific patient population. Enumeration and in particular characterization of CTC holds great promise for patient management and research purposes. 2 Of severalassaysenablingCTCdetection(reviewedbyMostertetal 3 ),the CellSearch system has been approved by the US Food and Drug Administration for use in metastatic breast, prostate, and colorectal cancer.Accordingtothemanufacturer’sinstructions,CTCenumeration should be performed in 7.5 mL blood. In the first study of 196 patientswithmetastaticcolorectalcancerwhoseCTCsweremeasured with the CellSearch system. At least 2 CTCs per 7.5 mL blood were detected in 30% of patients, whereas only 17% had 5 CTCs per 7.5 mL blood. 4 In a subsequent publication by Cohen et al 5 investigating the prognostic role of CTCs in advanced colorectal cancer, patients with a CTC count above a threshold of 3 CTCs per 7.5 mL blood had a worse outcome after systemic therapy compared with patients with lower CTC counts. The 430 patients in this study received first-, second-, or third-line chemotherapy, of whom 26% had a CTC count3 CTC threshold, whereas 48% of the patients had1 CTC per 7.5 mL blood. In a third study of 451 patients with metastatic colorectal cancer, at least 3 CTCs per 7.5 mL blood were detected in 29% of the patients. 6 From these studies we can conclude that the number of detectable CTCs in patients with advanced colorectal cancer using the CellSearch System is low to even below detection limit, which is in contrast to other tumor types. In metastatic breast and prostate cancer, the percentage of patients with a CTC count of 5 CTCs per 7.5 mL was 66% and 49%, respectively. 7,8 Not surprisingly and in line with thefindings of Jiao et al, 1 in nonmetastastic colorectal cancer, the number of patients with detectable CTCs is even lower thaninadvanceddisease.Onestudyrevealed2CTCs/7.5mLintwo

‘Staged’ liver resection in synchronous and metachronous colorectal hepatic metastases: differences in clinicopathological features and outcome

Aim  Approximately 25% of the patients with colorectal cancer already have liver metastases at diagnosis and another 30% will develop them subsequently. The features and prognosis of patients with synchronous and metachronus colorectal liver metastases, treated with primary resection first followed by partial liver resection were analysed.

A Systematic Analysis of Oncogenic Gene Fusions in Primary Colon Cancer

Genomic rearrangements that give rise to oncogenic gene fusions can offer actionable targets for cancer therapy. Here we present a systematic analysis of oncogenic gene fusions among a clinically well-characterized, prospectively collected set of 278 primary colon cancers spanning diverse tumor stages and clinical outcomes. Gene fusions and somatic genetic variations were identified in fresh frozen clinical specimens by Illumina RNA-sequencing, the STAR fusion gene detection pipeline, and GATK RNA-seq variant calling. We considered gene fusions to be pathogenically relevant when recurrent, producing divergent gene expression (outlier analysis), or as functionally important (e.g., kinase fusions). Overall, 2.5% of all specimens were defined as harboring a relevant gene fusion (kinase fusions 1.8%). Novel configurations of BRAF, NTRK3, and RET gene fusions resulting from chromosomal translocations were identified. An R-spondin fusion was found in only one tumor (0.35%), much less than an earlier reported frequency of 10% in colorectal cancers. We also found a novel fusion involving USP9X-ERAS formed by chromothripsis and leading to high expression of ERAS, a constitutively active RAS protein normally expressed only in embryonic stem cells. This USP9X-ERAS fusion appeared highly oncogenic on the basis of its ability to activate AKT signaling. Oncogenic fusions were identified only in lymph node-negative tumors that lacked BRAF or KRAS mutations. In summary, we identified several novel oncogenic gene fusions in colorectal cancer that may drive malignant development and offer new targets for personalized therapy. Cancer Res; 77(14); 3814-22. ©2017 AACR.

Trends in treatment for synchronous colorectal liver metastases: Differences in outcome before and after 2000

The traditional treatment for stage IV colorectal cancer has changed from palliative chemotherapy toward an aggressive multimodality approach. In the current study outcome in patients who underwent surgery for synchronous colorectal liver metastases (CLM) in a single center was evaluated.

Molecular characteristics of circulating tumor cells resemble the liver metastasis more closely than the primary tumor in metastatic colorectal cancer

Background CTCs are a promising alternative for metastatic tissue biopsies for use in precision medicine approaches. We investigated to what extent the molecular characteristics of circulating tumor cells (CTCs) resemble the liver metastasis and/or the primary tumor from patients with metastatic colorectal cancer (mCRC). Results The CTC profiles were concordant with the liver metastasis in 17/23 patients (74%) and with the primary tumor in 13 patients (57%). The CTCs better resembled the liver metastasis in 13 patients (57%), and the primary tumor in five patients (22%). The strength of the correlations was not associated with clinical parameters. Nine genes (CDH1, CDH17, CDX1, CEACAM5, FABP1, FCGBP, IGFBP3, IGFBP4, and MAPT) displayed significant differential expressions, all of which were downregulated, in CTCs compared to the tissues in the 23 patients. Patients and Methods Patients were retrospectively selected from a prospective study. Using the CellSearch System, CTCs were enumerated and isolated just prior to liver metastasectomy. A panel of 25 CTC-specific genes was measured by RT-qPCR in matching CTCs, primary tumors, and liver metastases. Spearman correlation coefficients were calculated and considered as continuous variables with r=1 representing absolute concordance and r= -1 representing absolute discordance. A cut-off of r>0.1 was applied in order to consider profiles to be concordant. Conclusions In the majority of the patients, CTCs reflected the molecular characteristics of metastatic cells better than the primary tumors. Genes involved in cell adhesion and epithelial-to-mesenchymal transition were downregulated in the CTCs. Our results support the use of CTC characterization as a liquid biopsy for precision medicine.

Confirmation of a metastasis-specific microRNA signature in primary colon cancer

The identification of patients with high-risk stage II colon cancer who may benefit from adjuvant therapy may allow the clinical approach to be tailored for these patients based on an understanding of tumour biology. MicroRNAs have been proposed as markers of the prognosis or treatment response in colorectal cancer. Recently, a 2-microRNA signature (let-7i and miR-10b) was proposed to identify colorectal cancer patients at risk of developing distant metastasis. We assessed the prognostic value of this signature and additional candidate microRNAs in an independent, clinically well-defined, prospectively collected cohort of primary colon cancer patients including stage I-II colon cancer without and stage III colon cancer with adjuvant treatment. The 2-microRNA signature specifically predicted hepatic recurrence in the stage I-II group, but not the overall ability to develop distant metastasis. The addition of miR-30b to the 2-microRNA signature allowed the prediction of both distant metastasis and hepatic recurrence in patients with stage I-II colon cancer who did not receive adjuvant chemotherapy. Available gene expression data allowed us to associate miR-30b expression with axon guidance and let-7i expression with cell adhesion, migration, and motility.

Completeness of pathology reports in stage II colorectal cancer

Abstract Introduction: The completeness of the pathological examination of resected colon cancer specimens is important for further clinical management. We reviewed the pathological reports of 356 patients regarding the five factors (pT-stage, tumor differentiation grade, lymphovascular invasion, tumor perforation and lymph node metastasis status) that are used to identify high-risk stage II colon cancers, as well as their impact on overall survival (OS). Methods: All patients with stage II colon cancer who were included in the first five years of the MATCH study (1 July 2007 to 1 July 2012) were selected (n = 356). The hazard ratios of relevant risk factors were calculated using Cox Proportional Hazards analyses. Results: In as many as 69.1% of the pathology reports, the desired information on one or more risk factors was considered incomplete. In multivariable analysis, age (HR: 1.07, 95%CI 1.04–1.10, p < .001), moderately- (HR: 0.35, 95%CI 0.18–0.70, p = .003) and well (HR 0.11, 95%CI 0.01–0.89, p = .038) differentiated tumors were significantly associated with OS. Conclusions: Pathology reports should better describe the five high-risk factors, in order to enable proper patient selection for further treatment. Chemotherapy may be offered to stage II patients only in select instances, yet a definitive indication is still unavailable.

Gene length corrected trimmed mean of M-values (GeTMM) processing of RNA-seq data performs similarly in intersample analyses while improving intrasample comparisons

BackgroundCurrent normalization methods for RNA-sequencing data allow either for intersample comparison to identify differentially expressed (DE) genes or for intrasample comparison for the discovery and validation of gene signatures. Most studies on optimization of normalization methods typically use simulated data to validate methodologies. We describe a new method, GeTMM, which allows for both inter- and intrasample analyses with the same normalized data set. We used actual (i.e. not simulated) RNA-seq data from 263 colon cancers (no biological replicates) and used the same read count data to compare GeTMM with the most commonly used normalization methods (i.e. TMM (used by edgeR), RLE (used by DESeq2) and TPM) with respect to distributions, effect of RNA quality, subtype-classification, recurrence score, recall of DE genes and correlation to RT-qPCR data.ResultsWe observed a clear benefit for GeTMM and TPM with regard to intrasample comparison while GeTMM performed similar to TMM and RLE normalized data in intersample comparisons. Regarding DE genes, recall was found comparable among the normalization methods, while GeTMM showed the lowest number of false-positive DE genes. Remarkably, we observed limited detrimental effects in samples with low RNA quality.ConclusionsWe show that GeTMM outperforms established methods with regard to intrasample comparison while performing equivalent with regard to intersample normalization using the same normalized data. These combined properties enhance the general usefulness of RNA-seq but also the comparability to the many array-based gene expression data in the public domain.

High mRNA expression of splice variant SYK short correlates with hepatic disease progression in chemonaive lymph node negative colon cancer patients

Objective Overall and splice specific expression of Spleen Tyrosine Kinase (SYK) has been posed as a marker predicting both poor and favorable outcome in various epithelial malignancies. However, its role in colorectal cancer is largely unknown. The aim of this study was to explore the prognostic role of SYK in three cohorts of colon cancer patients. Methods Total messenger RNA (mRNA) expression of SYK, SYK(T), and mRNA expression of its two splice variants SYK short (S) and SYK long (L) were measured using quantitative reverse transcriptase (RT-qPCR) in 240 primary colon cancer patients (n = 160 patients with chemonaive lymph node negative [LNN] and n = 80 patients with adjuvant treated lymph node positive [LNP] colon cancer) and related to microsatellite instability (MSI), known colorectal cancer mutations, and disease-free (DFS), hepatic metastasis-free (HFS) and overall survival (OS). Two independent cohorts of patients with respectively 48 and 118 chemonaive LNN colon cancer were used for validation. Results Expression of SYK and its splice variants was significantly lower in tumors with MSI, and in KRAS wild type, BRAF mutant and PTEN mutant tumors. In a multivariate Cox regression analysis, as a continuous variable, increasing SYK(S) mRNA expression was associated with worse HFS (Hazard Ratio[HR] = 1.83; 95% Confidence Interval[CI] = 1.08–3.12; p = 0.026) in the LNN group, indicating a prognostic role for SYK(S) mRNA in patients with chemonaive LNN colon cancer. However, only a non-significant trend between SYK(S) and HFS in one of the two validation cohorts was observed (HR = 4.68; 95%CI = 0.75–29.15; p = 0.098). Conclusion In our cohort, we discovered SYK(S) as a significant prognostic marker for HFS for patients with untreated LNN colon cancer. This association could however not be confirmed in two independent smaller cohorts, suggesting that further extensive validation is needed to confirm the prognostic value of SYK(S) expression in chemonaive LNN colon cancer.