KRAS status in patients with colorectal cancer peritoneal carcinomatosis and its impact on outcome

Oncological Outcomes From Cytoreductive Surgery and Heated Intraperitoneal Chemotherapy for Colorectal Cancer Peritoneal Metastases

BACKGROUND

Cytoreductive surgery (CRS) is effective for colorectal cancer peritoneal metastases (CRPM) at increasing overall survival (OS) compared to systemic anticancer treatment (SACT) alone. The addition of Oxaliplatin heated intraperitoneal chemotherapy (HIPEC) has been shown in a randomized controlled trial to result in increased complications without significant OS benefit. This study evaluates outcomes for CRPM patients undergoing CRS+HIPEC with Oxaliplatin (Ox) 368mg/m2 (30 min), versus Mitomycin C (MMC) 35mg/m2 (90min).  METHODS: A prospective CRPM real-world database was used to collect outcomes for patients undergoing CRS+HIPEC at a single center. OS, recurrence-free (RFS), peritoneal RFS (PeRFS) were compared amongst all patients with histologically proven CRPM, those with completeness of cytoreduction (CC) score =0/1, and those with CC score=0/1 who were SACT naïve.  RESULTS: Between April 2005 and April 2021, 409 patients underwent CRS+HIPEC: 271 (66%) had MMC, 138 (34%) Ox. Of these, 395 (97%) had histologically confirmed CRPM, 336 (85%) achieved CC=0/1, 188 (47%) were SACT naïve; median OS =39.5, 44.4, and 47.2 months respectively. MMC versus Ox median OS in CC0/1=43.7 (95% CI 35.9-48.3) versus 50.1 (39.7-70.2) months, P = .28; Median OS in SACT naïve=45.7 (39.4-65.9) versus 59.9 (38.3-82.0) months, P = .31; multivariable analysis for CC0/1, SACT naïve patients showed Ox was comparable to MMC: HR=0.90, (0.64-1.27) P = .55 versus HR=0.88, (0.53-1.44) P = .60, respectively. Ox resulted in a significantly improved PeRFS in CC0/1 patients (MMC=9.0 versus Ox=12.6months, P = .01). A multivariable model for PeRFS showed a HR=0.63, (0.43-0.95), P = .03 for Ox.  CONCLUSION: This study suggests a role for Ox HIPEC in CRPM which should be explored further in clinical trials.

External validation of COMPASS and BIOSCOPE prognostic scores in colorectal peritoneal metastases treated with cytoreductive surgery and hyperthermic intraperitoneal chemotherapy (HIPEC)

INTRODUCTION

The selection of patients undergoing cytoreductive- surgery (CRS) followed by hyperthermic intraperitoneal chemotherapy (HIPEC) is crucial. BIOSCOPE and COMPASS are prognostic scores designed to stratify survival into four classes according to clinical and pathological features. The purpose of this study is to analyze the prognostic role of these scores using a large cohort of patients as an external reference.

METHODS

Overall survival analysis was performed using Log-Rank and Kaplan-Meier curves for each score. The probability of survival at 12, 36, and 60 months was tested using receiver operating characteristic (ROC) curves to determine sensitivity and specificity.

RESULTS

From the validation cohort of 437 patients, the analysis included 410 patients in the COMPASS group and 364 patients in the BIOSCOPE group (100% data completeness). We observed a different patient distribution between classes (high-risk for BIOSCOPE compared to COMPASS, p = 0.0001). Nevertheless, both COMPASS and BIOSCOPE effectively stratified overall survival (Log-Rank, p = 0.0001 in both cases), with a lack of discrimination between COMPASS classes II and III (p = n.s.). COMPASS at 12 m and BIOSCOPE at 60 m showed the best performance in terms of survival prediction (AUC of 0.82 and 0.81). The specificity of the two tests is good (median 81.3%), whereas sensibility is quite low (median 64.2%).

CONCLUSION

Following external validation in a large population of patients with CRC-PM who are eligible for surgery, the COMPASS and BIOSCOPE scores exhibit high inter-test variability but effectively stratify cancer-related mortality risk. While the quality of the scores is similar, BIOSCOPE shows better inter-tier differentiation, suggesting that tumor molecular classification could improve test discrimination capability. More powerful stratification scores with the inclusion of novel predictors are needed.

Molecular Analyses in Peritoneal Metastasis from Colorectal Cancer: A Review-An English Version

Despite a trend showing continued improvement in survival by combing targeted agents in colorectal cancer, the improvement was limited, and clinically meaningful benefits were not achieved in peritoneal metastasis. The role of cytoreductive surgery (CRS) and proportion of the benefit from hyperthermic intraperitoneal chemotherapy (HIPEC) have been questioned. The PRODIGE 7 study aimed to assess the specific contribution of HIPEC to the survival benefit of peritoneal metastasis from colorectal cancer (CRC-PM) by grouping CRS alone versus CRS with oxaliplatin-based HIPEC, but failed to show any survival improvement. Of these criticisms, oxaliplatin resistance was suggested as the main cause of the negative result. In this regard, the relative resistance to oxaliplatin in consensus molecular subtype 4 colorectal cancer (CRC) is of great interest. Recent treatments for metastatic CRC have gradually moved to precision medicine based on individual biological information through high-throughput technology such as next generation sequencing. This review aimed to provide an overview of the current status of studies reporting the molecular knowledge of CRC-PM.

Molecular analyses of peritoneal metastasis from colorectal cancer

Background: Despite a trend showing continued improvement in survival by combing targeted agents for colorectal cancer (CRC), the improvement observed is limited. Moreover, clinically relevant benefits were not achieved in peritoneal metastasis cases. The role of cytoreductive surgery (CRS) and the benefits of hyperthermic intraperitoneal chemotherapy (HIPEC) have been questioned. This review aimed to provide an overview of the current status of the studies reporting on the molecular knowledge of peritoneal metastasis from CRC (CRC-PM).Current Concepts: The PRODIGE 7 study was performed to assess the specific contributions of HIPEC to the survival benefit in CRC-PM cases by comparing CRS treatment alone and CRS with oxaliplatin-based HIPEC. However, this study did not reveal any survival improvement, and oxaliplatin resistance was suggested as the main cause of this negative outcome. Hence, the relative resistance to oxaliplatin in consensus molecular subtype (CMS) 4 CRC is of great interest.Discussion and Conclusion: Recent treatments for metastatic CRC have gradually moved to precision medicine based on individual biological information through high-throughput technology, such as next-generation sequencing. In the transcriptome study, CRC-PM was identified as an almost homogeneous CMS4 classification, which is known to have strong resistance to oxaliplatin-based chemotherapy. These results suggest the need to clarify complex sub-signal transmission pathways derived from transcriptome or proteome studies of CRC-PM. Finally, to compare two studies, it is necessary to establish a representative patient group and consider standardized sample collection, treatment, and analysis.

Molecular characterization of colorectal cancer related peritoneal metastatic disease

A significant proportion of colorectal cancer (CRC) patients develop peritoneal metastases (PM) in the course of their disease. PMs are associated with a poor quality of life, significant morbidity and dismal disease outcome. To improve care for this patient group, a better understanding of the molecular characteristics of CRC-PM is required. Here we present a comprehensive molecular characterization of a cohort of 52 patients. This reveals that CRC-PM represent a distinct CRC molecular subtype, CMS4, but can be further divided in three separate categories, each presenting with unique features. We uncover that the CMS4-associated structural protein Moesin plays a key role in peritoneal dissemination. Finally, we define specific evolutionary features of CRC-PM which indicate that polyclonal metastatic seeding underlies these lesions. Together our results suggest that CRC-PM should be perceived as a distinct disease entity.

Microsatellite and RAS/RAF Mutational Status as Prognostic Factors in Colorectal Peritoneal Metastases Treated with Cytoreductive Surgery and Hyperthermic Intraperitoneal Chemotherapy (HIPEC)

BACKGROUND

Cytoreductive surgery (CRS) with hyperthermic intraperitoneal chemotherapy (HIPEC) leads to prolonged survival for selected patients with colorectal (CRC) peritoneal metastases (PM). This study aimed to analyze the prognostic role of micro-satellite (MS) status and RAS/RAF mutations for patients treated with CRS.

METHODS

Data were collected from 13 Italian centers with PM expertise within a collaborative group of the Italian Society of Surgical Oncology. Clinical and pathologic variables and KRAS/NRAS/BRAF mutational and MS status were correlated with overall survival (OS) and disease-free survival (DFS).

RESULTS

The study enrolled 437 patients treated with CRS-HIPEC. The median OS was 42.3 months [95% confidence interval (CI), 33.4-51.2 months], and the median DFS was 13.6 months (95% CI, 12.3-14.9 months). The local (peritoneal) DFS was 20.5 months (95% CI, 16.4-24.6 months). In addition to the known clinical factors, KRAS mutations (p = 0.005), BRAF mutations (p = 0.01), and MS status (p = 0.04) were related to survival. The KRAS- and BRAF-mutated patients had a shorter survival than the wild-type (WT) patients (5-year OS, 29.4% and 26.8% vs 51.5%, respectively). The patients with micro-satellite instability (MSI) had a longer survival than the patients with micro-satellite stability (MSS) (5-year OS, 58.3% vs 36.7%). The MSI/WT patients had the best prognosis. The MSS/WT and MSI/mutated patients had similar survivals, whereas the MSS/mutated patients showed the worst prognosis (5-year OS, 70.6%, 48.1%, 23.4%; p = 0.0001). In the multivariable analysis, OS was related to the Peritoneal Cancer Index [hazard ratio (HR), 1.05 per point], completeness of cytoreduction (CC) score (HR, 2.8), N status (HR, 1.6), signet-ring (HR, 2.4), MSI/WT (HR, 0.5), and MSS/WT-MSI/mutation (HR, 0.4). Similar results were obtained for DFS.

CONCLUSION

For patients affected by CRC-PM who are eligible for CRS, clinical and pathologic criteria need to be integrated with molecular features (KRAS/BRAF mutation). Micro-satellite status should be strongly considered because MSI confers a survival advantage over MSS, even for mutated patients.

Prognostic Value of KRAS Gene Mutation on Survival of Patients with Peritoneal Metastases of Colorectal Adenocarcinoma

OBJECTIVE

The main objective of the study was to determine the effect of the presence of mutation in the KRAS gene on the survival in patients with colorectal cancer (CRC) and peritoneal metastases (PM).

MATERIALS AND METHODS

A retrospective cohort study was performed. Patients diagnosed with CRC with synchronous or metachronous PM between January 2006 and December 2019 were included. Data on the histopathological, clinical, and treatment factors were collected. The effect of each variable on survival was evaluated by Cox regression.

RESULTS

A total of 149 patients were included (64 women (43%) and 85 men (57%); mean age, 63 years). The long-term survival rate at 36 months was 24% (median, 21 months). KRAS mutation was detected in 75 patients (50.3%). Kaplan-Meier analysis estimated that likelihood of survival was higher in patients with wild-type KRAS tumours (35%) than in mutated-type KRAS (14%) (median: 28 vs. 15, respectively) (P=0.001). Within the categories into which the peritoneal cancer index (PCI) was classified, survival at 36 months depended on the KRAS status. Survival in wild-type KRAS tumours with PCI 1-10 was 71% and with PCI 11-20 was 26%, while in mutant-type KRAS tumours, survival was 41% and 4%, respectively (P=0.025). In the multiple regression analysis, the KRAS mutation was revealed to have an independent prognostic value (HR: 2.144; 95% CI: 1.342-3.424).

CONCLUSION

The mutational status of the KRAS gene has demonstrated a strong association with survival and prognostic utility in patients with CRC with PM.

Effective Strategies to Predict Survival of Colorectal Peritoneal Metastases Patients Eligible for Cytoreductive Surgery and HIPEC

Cytoreductive surgery (CRS) and hyperthermic intraperitoneal chemotherapy (HIPEC), often combined with systemic therapy, can be offered to selected colorectal peritoneal metastases (PM) patients. However, clinical heterogeneity and the lack of high-level evidence challenges determination of the correct treatment strategy. This review aims to provide an overview of current strategies to predict survival of colorectal PM patients treated with CRS and HIPEC, guiding clinicians to select a suitable treatment-strategy and to inform patients about their prognosis. First, the prognostic relevance of several clinicopathological prognostic factors, such as extent of PM, location of primary tumor, histology type, and the presence of lymph node or liver metastases will be discussed. Subsequently, special attention will be given to recent developments in several aspects of tumor biology such as RAF/RAS mutations, circulating tumor DNA, immunoprofiling, and consensus molecular subtypes. Finally, currently available prognostic models to predict survival will be evaluated, concluding these models perform moderate to good, but most of them partly rely on intra-operative data. New insights in tumor biology, as well as the reliable assessment of extent of peritoneal disease by diffusion weighted MRI pose promising opportunities to establish an adequate and clinically meaningful preoperative prognostic model in the near future.

Omics analyses in peritoneal metastasis-utility in the management of peritoneal metastases from colorectal cancer and pseudomyxoma peritonei: a narrative review

High-throughput "-omics" analysis may provide a broader and deeper understanding of cancer biology to define prognostic and predictive biomarkers and identify novel therapy targets. In this review we provide an overview of studies where the peritoneal tumor component of peritoneal metastases from colorectal cancer (PM-CRC) and pseudomyxoma peritonei (PMP) were analyzed. Most of the available data was derived from DNA mutation analysis, but a brief review of findings from transcriptomic and protein expression analysis was also performed. Studies reporting genomic analysis of peritoneal tumor samples from 1,779 PM-CRC and 623 PMP cases were identified. The most frequently mutated genes in PM-CRC were KRAS, APC, SMAD4, BRAF, and PIK3CA, while in PMP KRAS, GNAS, FAT4, TGFBR1, TP53 and SMAD3/4 mutations were most commonly identified. Analyses were performed by single-gene analyses and to some extent targeted next-generation sequencing, and a very limited amount of broad explorative data exists. The investigated cohorts were typically small and heterogeneous with respect to the methods used and to the reporting of clinical data. This was even more apparent regarding transcriptomic and protein data, as the low number of cases examined and quality of clinical data would not support firm conclusions. Even for the most frequently mutated genes, the results varied greatly; for instance, KRAS mutations were reported at frequencies between 20-57% in PM-CRC and 38-100% in PMP. Such variation could be caused by random effects in small cohorts, heterogeneity in patient selection, or sensitivity of applied technology. Although a large number of samples have been subjected to analysis, cross-study comparisons are difficult to perform, and combined with small cohorts and varying quality and detail of clinical information, the observed variation precludes useful interpretation in a clinical context. Although omics data in theory could answer questions to aid management decisions in PM-CRC and PMP, the existing data does not presently support clinical implementation. With the necessary technologies being generally available, the main challenge will be to obtain sufficiently large, representative cohorts with adequate clinical data and standardized reporting of results. Importantly, studies where the focus is specifically on peritoneal disease are needed, where the study designs are aligned with clearly defined research questions to allow robust conclusions. Such studies are highly warranted if patients with PM-CRC and PMP are to derive benefit from recent advances in precision cancer medicine.

The role of molecular biomarkers in outcomes and patient selection for cytoreductive surgery and hyperthermic intraperitoneal chemotherapy for peritoneal metastases of colorectal origin

BACKGROUND

Cytoreductive surgery and hyperthermic intraperitoneal chemotherapy (CRS/HIPEC) is effective in select patients with peritoneal metastases of colorectal (CRC) origin. The impact of different biomarkers in predicting recurrence after CRS/HIPEC is unclear.

METHODS

Retrospective review of patients who underwent CRS/HIPEC for PC of CRC origin from 03/2007-08/2017. Molecular profile of the primary tumor was obtained from pathology reports, whenever available.

RESULTS

Overall, 100 patients underwent CRS/HIPEC for peritoneal metastases of CRC origin. Most patients presented high grade tumor histology (G2/G3, n = 97, 97%), and a majority showed mucinous features (n = 61, 61%). At a median follow-up of 18 months, median DFS for the overall population was 13 months (95% CI 9.6, 16.4). Data reporting at least one mutational analysis was available in 64 patients. Microsatellite stability was detected in 42/50 (84%) patients, mKRAS in 25/51 (49%), and mBRAF in 5/35 (14.3%). On Kaplan-Meier analysis, BRAF was the only mutation associated with poor DFS (16 months, CI 95% 11.7-43.3 vs. 7 months, CI 95% 2.1-11.9, p = .008). On multivariate analysis, mBRAF independently predicted earlier recurrence (p = .032).

CONCLUSIONS

In this analysis, mBRAF was independently associated with earlier recurrence in patients undergoing CRS/HIPEC for CRC, leading to dismal median DFS (7 months). Strict patient selection is advisable in these patients.

A mouse model for peritoneal metastases of colorectal origin recapitulates patient heterogeneity

The peritoneum is a common site of dissemination in patients with colorectal cancer. In order to identify high-risk patients and improve therapeutic strategies, a better understanding of the peritoneal dissemination process and the reasons behind the high heterogeneity that is observed between patients is required. We aimed to create a murine model to further elucidate the process of peritoneal dissemination and to provide an experimental platform for further studies. We developed an in vivo model to assess patterns of peritoneal dissemination of 15 colorectal cancer cell lines. Immune deficient mice were intraperitoneally injected with 10,000 human colorectal cancer cells. Ten weeks after injection, or earlier in case of severe discomfort, the mice were sacrificed followed by dissection including assessment of the outgrowth and localization of peritoneal metastases. Furthermore, using a color-based clonal tracing method, the clonal dynamics of peritoneal nodules were observed. The different cell lines showed great variation in the extent of peritoneal outgrowth, ranging from no outgrowth to localized or widespread outgrowth of cells. An association between KRAS pathway activation and the formation of peritoneal metastases was identified. Also, cell line specific tumor location preferences were observed, with similar patterns of outgrowth in anatomically related areas. Furthermore, different patterns regarding clonal dynamics were found, varying from monoclonal or polyclonal outgrowth to extensively dispersed polyclonal lesions. The established murine model recapitulates heterogeneity as observed in human peritoneal metastases, which makes it a suitable platform for future (intervention) studies.

Prognostic Impact of Primary Side and RAS/RAF Mutations in a Surgical Series of Colorectal Cancer with Peritoneal Metastases

BACKGROUND

Selecting patients with colorectal cancer peritoneal metastases (CRC-PMs) for surgery is still a concern. Biological features have the potential to improve prognostic stratification, but their significance in this clinical setting is still unclear. We assessed the prognostic impact of primary side and KRAS/NRAS/BRAF/PIK3CA mutations in patients treated with either cytoreductive surgery and hyperthermic intraperitoneal chemotherapy (CRS/HIPEC) or CRS alone.

METHODS

We reviewed a prospective database of 152 CRC-PM patients selected to undergo perioperative systemic chemotherapy and CRS with or without HIPEC. Extensive mutational analysis of KRAS, NRAS, BRAF, and PIK3CA was performed by polymerase chain reaction (PCR). In 68 patients, Ion Torrent next-generation sequencing technology was used to characterize the hotspot regions of 50 genes.

RESULTS

The primary tumor was right-sided in 61 patients (40.1%) and left-sided in 91 patients (59.9%). Right-sided primaries were associated with mutated KRAS (p = 0.01) and normal carcinoembryonic antigen (CEA; p = 0.03). KRAS was mutated in 71/152 patients (46.7%), NRAS in 7/152 patients (4.6%), BRAF in 10/152 patients (6.6%), PIK3CA in 17/78 patients (25.0%), TP53 in 37/68 patients (54.4%), APC in 25/68 patients (36.7%), SMAD4 in 13/68 patients (19.1%), and FBXW7 in 5/68 patients (7.4%). Median follow-up was 54.9 months and median survival from PM diagnosis was 45.1 months. The right-sided primary (hazard ratio [HR] 1.62, 95% confidence interval [CI] 0.43-0.89; p = 0.011), BRAF mutations (HR 2.21, 95% CI 1.05-4.63; p = 0.038), and Peritoneal Cancer Index (HR 1.47, 95% CI 1.03-2.10; p = 0.036) independently correlated with poorer survival, while APC mutations univariately correlated with better survival (p = 0.03).

CONCLUSIONS

BRAF mutations and right-sided primary are adverse prognostic factors that may be used to optimize therapeutic strategies. APC may be involved in CRC-PM development and progression.

Systemic chemotherapy plus cetuximab after complete surgery in the treatment of isolated colorectal peritoneal carcinoma: COCHISE phase II clinical trial

Objective

The primary objective of this non-randomised phase II study was to evaluate the combination of systemic chemotherapy plus cetuximab after complete cytoreductive surgery (CCS) for treatment of isolated colorectal peritoneal carcinoma (CRPC). This multicentre, prospective phase II clinical trial was conducted in seven national cancer referral centres, however research published during study recruitment indicated cetuximab treatment as ineffective in patients with mutated KRAS genes, leading to an additional exclusion criterion to the current protocol, excluding patients with mutated KRAS genes. This significantly impacted recruitment and the study did not achieve the necessary recruitment of 46 patients.

Results

Fourteen patients underwent CCS and were included in the study, however one did not provide informed consent and another received only one cycle of chemotherapy leading to 12 patients in the per protocol population for analysis. Adjuvant Folfox Cetuximab was administered when CCS was achieved for patients > 18 years with histologically proven CRPC and no other metastatic disease (liver, lungs, lymphadenopathy, etc.). CRPC median index was 5.00 (range: 1–17). Median PFS was 12.3 months [95% CI (3.7–28.2)] with 8.3% [95% CI (0.5–31.1)] and 0% PFS at 3 and 5 years respectively. Median OS was 43.4 months [95% CI (16.8–60)].

Trial registration Clinical Trials NCT00766142, October 3, 2008. Retrospectively registered

Colorectal Peritoneal Metastases: A Systematic Review of Current and Emerging Trends in Clinical and Translational Research

Colorectal peritoneal metastases (CPM) are associated with abbreviated survival and significantly impaired quality of life. In patients with CPM, radical multimodality treatment consisting of cytoreductive surgery (CRS) combined with hyperthermic intraperitoneal chemotherapy (HIPEC) has demonstrated oncological superiority over systemic chemotherapy alone. In highly selected patients undergoing CRS + HIPEC, overall survival of over 60% has been reported in some series. These are patients in whom the disease burden is limited and where the diagnosis is made at an early stage in the disease course. Early diagnosis and a deeper understanding of the biological mechanisms that regulate CPM are critical to refining patient selection for radical treatment, personalising therapeutic approaches, enhancing prognostication, and ultimately improving long-term survivorship. In the present study, we outline three broad themes which represent critical future research targets in CPM: (1) enhanced radiological strategies for early detection and staging; (2) identification and validation of translational biomarkers for diagnostic, prognostic, and therapeutic deployment; and (3) development of optimized approaches for surgical cytoreduction as well as more precise strategies for intraperitoneal drug selection and delivery. Herein, we provide a contemporary narrative review of the state of the art in these three areas. A systematic review in accordance with PRISMA guidelines was undertaken on all English language studies published between 2007 and 2017. In vitro and animal model studies were deemed eligible for inclusion in the sections pertaining to biomarkers and therapeutic optimisation, as these areas of research currently remain in the early stages of development. Acquired data were then divided into hierarchical thematic categories (imaging modalities, translational biomarkers (diagnostic/prognostic/therapeutic), and delivery techniques) and subcategories. An interactive sunburst figure is provided for intuitive interrogation of the CPM research landscape.

RAS Mutation Status Confers Prognostic Relevance in Patients Treated With Cytoreductive Surgery and Hyperthermic Intraperitoneal Chemotherapy for Colorectal Cancer

BACKGROUND

Metastatic colorectal cancer (mCRC) with peritoneal carcinomatosis is an increasingly prevalent disease that carries significant mortality if left untreated. Cytoreductive surgery with hyperthermic intraperitoneal chemotherapy (CRS/HIPEC) in this patient population is associated with improved outcomes but high morbidity. We sought to study the prognostic significance of the known genomic driver, RAS, in patients with mCRC undergoing CRS/HIPEC to allow for improved assessment of risk-benefit ratio in this patient population.

METHODS

Patients undergoing CRS/HIPEC for mCRC between 2010 and 2017 at our institution were identified. Patient demographics, RAS mutation status, perioperative morbidity, overall survival (OS), and relapse-free survival (RFS) were evaluated.

RESULTS

Forty-seven patients met inclusion criteria. RAS mutant versus RAS wild-type groups were well matched with no difference in the clinicopathologic factors between groups. RAS mutation was associated with decreased RFS but no difference in OS.

CONCLUSIONS

RAS mutation is an independent marker of early recurrence in patients undergoing CRS/HIPEC for mCRC and may identify patients who do not derive benefit from this high-risk procedure.

Metastatic Profile of Colorectal Cancer: Interplay Between Primary Tumor Location and KRAS Status

BACKGROUND

Mutant KRAS tumors are purported to metastasize differently than wild-type KRAS tumors. The biological heterogeneity of tumors from different parts of the colon are also reported to affect metastasis. This study aims to characterize the metastatic profile by evaluating these factors in unison.

METHODS

Retrospective analysis of 899 patients with metastatic colorectal cancers treated from January 2010 to December 2014 was conducted. KRAS mutation status and primary tumors location were correlated with single-site metastasis (liver, lung, and peritoneum) and dual-site metastases (liver-peritoneum, liver-lung, and lung-peritoneum). Patients without KRAS analyses were excluded.

RESULTS

Right-sided tumors had highest frequency of peritoneal metastasis as compared to left-sided or rectal tumors (34.7% versus 15.8% versus 8.8%, P = 0.00) regardless of KRAS status (32.6% versus 38.5%, P = 0.62). Left-sided tumors with wild-type KRAS had greater proportion of liver metastasis (78.6% versus 53.5%, P = 0.00), whereas those with mutant KRAS had greater proportion of lung metastasis (23.3% versus 8.7%, P = 0.02). Rectal tumors with wild-type KRAS tend to spread to the liver (81.4% versus 48.0%, P = 0.00) and not to the peritoneum (2.3% versus 20.0%, P = 0.01). In dual-site metastases, left-sided tumors with wild-type KRAS had more liver-peritoneal metastases (75.0% versus 29.4%, P = 0.00), whereas mutant KRAS had greater lung-liver metastases (64.7% versus 20.8%, P = 0.01). Rectal tumors had the predilection for lung-liver metastases as compared to right-sided and left-sided tumors (92.3% versus 40.0% versus 39.0%, P = 0.00) regardless of KRAS status (100% versus 75%, P = 0.12).

CONCLUSIONS

Our results may streamline surveillance programs based on primary tumor location and KRAS mutational status.

Impact of RAS Mutations in Metastatic Colorectal Cancer After Potentially Curative Resection: Does Site of Metastases Matter?

BACKGROUND

RAS mutation status is an important prognostic factor after resection of liver metastases (LiM) from colorectal cancer (CRC). The prognostic significance of RAS after resection of lung (LuM) and peritoneal (PM) metastases from CRC is unknown.

METHODS

Between 2005 and 2014, all consecutive patients with known RAS status who underwent potentially curative resection for LiM, LuM, or PM were evaluated.

RESULTS

A total of 720 patients with known RAS status underwent resection of LiM (n = 468), LuM (n = 102), and PM (n = 150). RAS mutations were identified in 63 and 58% of patients with LuM and PM, respectively, compared with 41% of patients with LiM (p < 0.001). Five-year overall survival (OS) after resection of PM was 45%, compared with 52% after resection of LiM (p = 0.018) and 64% after resection of LuM (p = 0.005). RAS mutations were associated with significantly worse OS after resection of LiM (p < 0.001), but did not affect OS among patients undergoing resection of LuM (p = 0.41) and PM (p = 0.65).

CONCLUSIONS

RAS mutations are more prevalent among patients undergoing resection of LuM and PM than LiM but do not affect survival after lung and peritoneal metastasectomy, as they do after hepatectomy. These results suggest that the prognostic significance of RAS mutations after resection of metastatic CRC depends on the specific site of metastases.

CTHRC1 is associated with peritoneal carcinomatosis in colorectal cancer: a new predictor for prognosis

Colorectal cancer (CRC) patients with peritoneal carcinomatosis (PC) have a poor prognosis. Over the last decade, increasing evidence has suggested that the Collagen Triple Helix Repeat Containing 1 (CTHRC1) gene is involved in cancer progression and invasion. In this study, we investigated the expression of CTHRC1 in CRC and its potential as a prognostic factor for CRC patients with PC. Microarray analysis of four fresh paired samples showed that the expression of CTHRC1 in peritoneal metastases was higher than that in the corresponding primary tumor. These results were validated using semi-quantitative reverse transcription and polymerase chain reaction. Finally, immunohistochemical analysis showed that CTHRC1 was increased in the peritoneal metastasis group (n = 30) and the primary cancer with peritoneal metastasis group (n = 57) compared to the primary cancer without peritoneal metastasis group (n = 54), both P < 0.001. Cox proportional hazards model analysis showed that high CTHRC1 expression was associated with poor survival (HR = 2.754, P < 0.001, 95 % CI 1.731-4.383). Overall, the results of our study suggest that increased expression of CTHRC1 is associated with PC in CRC patients and could predict poor outcome in CRC patients.

Gene mutations in epidermal growth factor receptor signaling network and their association with survival in Chinese patients with metastatic colorectal cancers

Mutations of the KRAS, BRAF, and PIK3CA genes have been reported in colorectal cancer (CRC), associated with resistance to epidermal growth factor receptor (EGFR)-targeted monoclonal antibody therapy. These reports have mainly emanated from Western countries, however, and little is known about the mutation frequencies of these genes and their prognostic value in Asian patients with CRC. In this study, we analyzed the mutation frequencies of these three genes together with EGFR, and their association with overall survival in 61 Chinese patients with metastatic CRC (mCRC). Gene mutations were examined using pyrosequencing. Kaplan-Meier survival analysis and multivariate Cox proportional hazard analysis were used to assess the prognostic significance of mutations of these four genes for patients' survival. We found that the mutations of KRAS, BRAF, PIK3CA, and EGFR were present in 12 (19.7%), 3 (4.9%), 3 (4.9%), and 0 patients, respectively. Kaplan-Meier survival analysis showed that none of these gene mutations correlated significantly with patients' overall survival. Multivariate Cox proportional hazard analysis showed only treatment regimens and age to be independent prognostic factors. Our findings indicate that EGFR signaling network genes are frequently mutated in Chinese mCRC patients, and these gene mutations do not seem to be associated with patients' overall survival.