High frequency of microsatellite instability in intestinal-type gastric cancer in Korean patients

Molecular characterization of colorectal cancer patients and concomitant patient-derived tumor cell establishment

Background

We aimed to establish a prospectively enrolled colorectal cancer (CRC) cohort for targeted sequencing of primary tumors from CRC patients. In parallel, we established collateral PDC models from the matched primary tumor tissues, which may be later used as preclinical models for genome-directed targeted therapy experiments.

Results

In all, we identified 27 SNVs in the 6 genes such as PIK3CA (N = 16), BRAF (N = 6), NRAS (N = 2), and CTNNB1 (N = 1), PTEN (N = 1), and ERBB2 (N = 1). RET-NCOA4 translocation was observed in one out of 105 patients (0.9%). PDC models were successfully established from 62 (55.4%) of the 112 samples. To confirm the genomic features of various tumor cells, we compared variant allele frequency results of the primary tumor and progeny PDCs. The Pearson correlation coefficient between the variants from primary tumor cells and PDCs was 0.881.

Methods

Between April 2014 and June 2015, 112 patients with CRC who underwent resection of the primary tumor were enrolled in the SMC Oncology Biomarker study. The PDC culture protocol was performed for all eligible patients. All of the primary tumors from the 112 patients who provided written informed consent were genomically sequenced with targeted sequencing. In parallel, PDC establishment was attempted for all sequenced tumors.

Conclusions

We have prospectively sequenced a CRC cohort of 105 patients and successfully established 62 PDC in parallel. Each genomically characterized PDCs can be used as a preclinical model especially in rare genomic alteration event.

Clinicopathologic Characteristics of Microsatellite Instable Gastric Carcinomas Revisited: Urgent Need for Standardization

Microsatellite instable gastric cancer (MSI-GC) is a specific molecular subtype of GC. We studied the phenotypes, genotypes, and clinicopathologic characteristics of MSI-GC in a white GC cohort and compared our findings with an extended literature review. The study cohort consisted of 482 patients. Specimens were available from 452 cases and were used for immunostaining (MLH1, PMS2, MSH2, MSH6) and molecular biological analyses (BAT-25, BAT-26, NR-21, NR-24, NR-27; Epstein-Barr virus in situ hybridization). Thirty-four (7.5%) GCs were MSI. Loss of MLH1 and/or PMS2 was found in 30 (88%) MSI-GC, 3 (9%) showed loss of MSH2 and/or MSH6. One (3%) MSI-GC was identified only by molecular biological testing. A single case was heterogeneous and contained microsatellite-stable and instable tumor areas. Twenty-one (62%) MSI-GCs showed unusual histologic features. MSI-GC was not found in diffuse-type or Epstein-Barr virus-positive GC. MSI-GC was significantly more prevalent in elderly patients, distal stomach, and was associated with a significantly lower number of lymph node metastases and a significantly better overall and tumor-specific survival. MSI-GC constitutes a small but relevant subgroup of GC with distinct clinicopathologic characteristics. Our literature review illustrates the shortcomings of missing standardized testing algorithms with prevalences of MSI-GC ranging from 0% to 44.5%. Future studies should test the hypothesis that patients with MSI-GCs may not need adjuvant/perioperative chemotherapy. However, this will require a standardized, quality-controlled diagnostic algorithm of MSI for GC.

Microsatellite Instability of Gastric and Colorectal Cancers as a Predictor of Synchronous Gastric or Colorectal Neoplasms

BACKGROUND/AIMS

Microsatellite instability (MSI) plays a crucial role in gastrointestinal carcinogenesis. The aim of this study was to clarify whether MSI is a useful marker for predicting synchronous gastric and colorectal neoplasms.

METHODS

Consecutive patients who underwent both esophagogastroduodenoscopy and colonoscopy before the resection of gastric or colorectal cancers were included. MSI was analyzed using two mononucleotide and three dinucleotide markers.

RESULTS

In total, 434 gastric cancers (372 microsatellite stability [MSS], 21 low incidence of MSI [MSI-L], and 41 high incidence of MSI [MSI-H]) and 162 colorectal cancers (138 MSS, 9 MSI-L, and 15 MSI-H) were included. Patients with MSI gastric cancer had a higher prevalence of synchronous colorectal cancer, colorectal adenoma, and gastric adenoma than those with MSS gastric cancers (4.8% vs 0.5%, p=0.023; 11.3% vs 3.2%, p=0.011; 3.2% vs 1.2%, p=0.00, respectively). The prevalence of synchronous colorectal adenomas was highest in MSI-L gastric cancers (19.0%), compared with MSI-H (7.3%) or MSS (3.2%) gastric cancers (p=0.002). In addition, there were no significant differences in the prevalence rates of synchronous colorectal adenoma among the MSI-H (13.3%), MSI-L (11.1%), and MSS (12.3%) colorectal cancers (p=0.987).

CONCLUSIONS

The presence of MSI in gastric cancer may be a predictor of synchronous gastric and colorectal neoplasms, whereas MSI in colorectal cancer is not a predictor of synchronous colorectal adenoma.

Low prevalence of microsatellite instability in interval gastric cancers

BACKGROUND AND AIM

Esophagogastroduodenoscopy (EGD) is recommended at 2-year intervals in countries with a high prevalence of gastric cancer. The aim of this study was to determine whether interval gastric cancers that develop within 2 years of a previous complete screening are associated with microsatellite instability (MSI).

METHODS

Newly diagnosed gastric cancer patients who had undergone gastrectomy were included. Of these 459 patients, 177 were classified as interval gastric cancer since they were diagnosed within 2 years of a previous EGD. Noninterval gastric cancer patients were subclassified into 65 patients who underwent previous EGD between the past 2 and 10 years and 217 patients without EGD during the last 10 years. Analysis for MSI was conducted using two mononucleotide and three dinucleotide markers.

RESULTS

MSI was found more frequently in noninterval gastric cancers than in interval gastric cancers (p = 0.009). Interval gastric cancers were associated with a higher prevalence of early gastric cancer (p = 0.006), smaller size (p < 0.001), and lower TNM stages (p = 0.006). On logistic regression analysis, noninterval gastric cancers were related to MSI (p = 0.010) and larger size (≥4 cm) (p = 0.009). Subjects with interval gastric cancer showed better survival than those with noninterval gastric cancer (p = 0.006).

CONCLUSIONS

During a 2-year screening interval, noninterval gastric cancers tend to be larger, more advanced, and associated with MSI. Biannual EGD screening is effective for detecting small gastric cancers at an early stage, but is not useful in detecting gastric cancers with MSI.

Gastric cancers with microsatellite instability exhibit high fluorodeoxyglucose uptake on positron emission tomography

BACKGROUND

Gastric cancers exhibit various degrees of (18)F-fluorodeoxyglucose (FDG) uptakes on positron emission tomography/computed tomography (PET/CT) imaging. The aim of this study was to evaluate whether FDG uptake in gastric cancer varies according to the microsatellite instability (MSI) status.

METHODS

Consecutive gastric cancer patients who underwent PET/CT imaging and MSI analysis were included in the study. The maximum standardized uptake value (SUVmax) of gastric cancer was assessed using PET/CT imaging.

RESULTS

Of 131 gastric cancers, 16 exhibited a high incidence of MSI (MSI-H) and 3 exhibited a low incidence of MSI (MSI-L). In 29 subjects who showed no uptake on PET/CT imaging the gastric cancers were all microsatellite stable (MSS). Gastric cancers with MSI were related to age older than 60 years (p = 0.002), cancer volume larger than 10 cm(3) (p = 0.015), and the presence of FDG uptake on PET/CT imaging (p = 0.001). A higher SUVmax of gastric cancer was linked to the presence of MSI (p < 0.001).

CONCLUSION

The presence of MSI is related to FDG uptake in gastric cancer. Care should be taken with MSS gastric cancers, because they show lower SUVmax on PET/CT imaging than MSI gastric cancers.

Early Gastric Cancer-Like Advanced Gastric Cancer versus Advanced Gastric Cancer-Like Early Gastric Cancer

Background/Aims

Improvements in the endoscopic evaluation and management of gastric cancer have made it possible to determine the depth of invasion during endoscopic examination. The aim of this study was to elucidate the differences between early gastric cancer (EGC) that resembles advanced gastric cancer (AGC) and AGC that resembles EGC.

Methods

We retrieved cases of EGC-like AGC and AGC-like EGC from consecutive gastric cancers that had been completely resected. The endoscopic diagnoses and clinicopathological findings were analyzed.

Results

AGC-like EGCs were located mainly in the distal part of the stomach, whereas EGC-like AGCs were located mainly in the proximal part of the stomach (p<0.001). Sixty percent of AGC-like EGCs were moderately differentiated adenocarcinomas, while 64% of EGC-like AGCs were poorly differentiated adenocarcinomas (p=0.015). According to Lauren's classification, 68% of AGC-like EGCs were intestinal type, whereas 71% of EGC-like AGCs were diffuse type (p=0.020).

Conclusions

AGC-like EGCs predominate in the distal part of the stomach, while EGC-like AGCs predominate in the proximal part. When evaluating the depth of a gastric cancer, care should be taken not to underestimate measurements in proximal gastric cancers since they tend to be poorly-differentiated adenocarcinomas, in Lauren's diffuse type, and invade deeper than their endoscopic appearance might suggest.

Association of family history with cancer recurrence and survival in patients with gastric cancer

PURPOSE

Family history of gastric cancer is a major risk factor for the disease. In this study, we investigated the prognoses of patients with gastric cancer with a family history.

PATIENTS AND METHODS

We retrospectively reviewed data from 1,273 patients with gastric adenocarcinoma who had undergone gastrectomy between 2001 and 2005 at a tertiary cancer center hospital. A positive family history was defined as a self-reported history of cancer in first- or second-degree relatives. Patients were followed up until December 2009 for death or recurrence. Clinicopathologic characteristics were compared by family history. Kaplan-Meier plots and Cox proportional hazards regressions were applied for disease-free survival (DFS), recurrence-free survival (RFS), and overall survival (OS).

RESULTS

Of 1,273 patients, 263 patients (20.6%) had first-degree relatives with a history of gastric cancer. First-degree family history of gastric cancer was associated with better DFS, RFS, and OS (P = .012, .006, and .005, respectively). In patients with stage I or II gastric cancer, first-degree family history was not associated with survival. However, it was associated with a reduced risk of recurrence or mortality in patients with stage III or IV gastric cancer. Compared with patients without a family history, the adjusted hazard ratios for those with a first-degree family history of gastric cancer were 0.49 (95% CI, 0.29 to 0.84) for DFS, 0.51 (95% CI, 0.30 to 0.87) for RFS, and 0.47 (95% CI, 0.26 to 0.84) for OS in patients with stage III or IV gastric cancer.

CONCLUSION

A first-degree family history of gastric cancer is associated with improved survival after curative-intent surgery in patients with stage III or IV gastric cancer.

Clinical impact of microsatellite instability in colon cancer following adjuvant FOLFOX therapy

PURPOSE

Colon cancer with DNA mismatch repair (MMR) defects reveals indistinguishable clinical and pathologic aspects, including better prognosis and reduced response to 5-fluorouracil (5-FU)-based chemotherapy. There has been no consensus for p53 as a prognostic marker in colorectal cancer. This study investigated the clinical implication of MSI-H/MMR-D and p53 expression in R0-resected colon cancer patients who received adjuvant oxaliplatin/5-FU/leucovorin (FOLFOX) therapy.

EXPERIMENTAL DESIGN

We analyzed 135 patients, who had been treated by adjuvant chemotherapy containing 5-FU and oxaliplatin (FOLFOX) after curative resection (R0) for colon adenocarcinoma between May 2004 and November 2007. Tumor expression of the MMR proteins, MLH1 and MSH2, was detected by immunohistochemistry (IHC) in surgically resected tumor specimens. MSI was analyzed by polymerase chain reaction (PCR) amplification using fluorescent dye-labeled primers specific for microsatellite loci. Tumors with MMR defects were defined as those demonstrating loss of MMR protein expression (MMR-D) and/or microsatellite instability high (MSI-H) genotype. Expression patterns of p53 were determined in a semiquantitative manner by light microscopy.

RESULTS

There were 13 (9.6%) patients with stage II, 108 (80%) with stage III, and 14 (10.4%) with stage IV. Fourteen patients with stage IV (10.3%) had metastases to liver only, all of whom underwent complete metastasectomy for liver metastases. In total, 134 tumor specimens were genotyped, 115 specimens were tested by IHC and 113 cases had both genotyping and IHC results available for analysis. Genotyping results demonstrated that 12 (9.0%) cases were MSI-H and 122 (91.0%) were MSI-L/S. By IHC, 11 (9.6%) patients were MMR-D and 104 (90.4%) were MMR-I. The methods were in agreement in 108 patients (94.7%). We assessed 114 patients for p53 expression by immunostaining. MMR status was not significantly associated with DFS (P = 0.56) or OS (P = 0.61) in patients with colon cancer (n = 135) receiving adjuvant FOLFOX. According to p53 status, there was also no significant difference for DFS (P = 0.11) and OS (P = 0.94). For patients with genotyping/IHC agreement (n = 108), there was no difference in DFS (P = 0.57) and OS (P = 0.98) between patients with MSI-H/MMR-D and MSI-L/S/MMR-I tumors.

CONCLUSION

The MMR status or p53 positivity was not significantly associated with outcomes to FOLFOX as adjuvant chemotherapy in colon cancer patients with R0 resection. Adding oxaliplatin in adjuvant chemotherapy may overcome negative impact of 5-FU on colon cancers with MSI-H/MMR-D.

The effect of DNA mismatch repair (MMR) status on oxaliplatin-based first-line chemotherapy as in recurrent or metastatic colon cancer

Colon cancer with DNA mismatch repair (MMR) defects reveals distinct clinical and pathologic features, including a better prognosis but reduced response to 5-fluorouracil (5-FU)-based chemotherapy. A current standard treatment for recurrent or metastatic colon cancer uses capecitabine plus oxaliplatin (CAPOX), or continuous-infusion fluorouracil plus oxaliplatin (FOLFOX). This study investigated the effect of MMR status on the treatment outcomes for CAPOX and FOLFOX as first-line combination chemotherapy in recurrent or metastatic colon cancer. We analyzed 171 patients who had been treated with CAPOX or FOLFOX as first-line combination chemotherapy in recurrent or metastatic colon adenocarcinoma between February 2004 and July 2008. Tumor expression of the MMR proteins, MLH1 and MSH2, was detected by immunohistochemistry (IHC) in surgically resected tumor specimens. The microsatellite instability (MSI) was analyzed by polymerase chain reaction (PCR) amplification, using fluorescent dye-labeled primers specific to microsatellite loci. Tumors with MMR defect were defined as those demonstrating a loss of MMR protein expression (MMR-D) and/or a microsatellite instability-high (MSI-H) genotype. In all, 75 patients (44%) received FOLFOX, and 96 patients (56%) received CAPOX as first-line combination chemotherapy. The incidence of colon cancer with MMR defect was 10/171 (6%). Colon cancers with MMR defect (MSI-H and/or MMR-D) are more commonly located in proximal to the splenic flexure (p=0.03). The MMR status did not significantly influence the overall response (p=0.95) to first-line CAPOX or FOLFOX treatment in patients with recurrent or metastatic colon cancer. According to the MMR status, there was no significant difference for PFS (p=0.50) and OS (p=0.47) in patients with recurrent or metastatic colon cancer treated with first-line CAPOX or FOLFOX. In colon cancers with MMR defect, there was no significant difference for PFS (p=0.48) and OS (p=0.56) between CAPOX and FOLFOX as first-line combination chemotherapy. However, in MMR intact, there was significant difference for OS between CAPOX and FOLFOX (p=0.04). OS was significantly better in patients treated with CAPOX when compared to patients with FOLFOX. The MMR status does not predict the effect of oxaliplatin-based combination chemotherapy as 1st line in recurrent or metastatic colon cancers. CAPOX in the first-line treatment of recurrent or metastatic colon cancer with MMR intacts showed a superior OS compared with FOLFOX unlike colon cancer with MMR defects.

Clinicopathologic characteristics and outcomes of gastric cancers with the MSI-H phenotype

OBJECTIVES

We examined the correlation between microsatellite instability (MSI) status and the clinicopathological features and prognostic value in gastric cancer and compared the efficacy of immunohistochemical staining for hMLH1 and hMSH2 with a polymerase chain reaction (PCR)-based test.

METHODS

MSI status was examined in 328 consecutive gastric adenocarcinomas using tissue preserved in paraffin blocks. DNA extracted from tumor sections and the corresponding normal tissue was analyzed using PCR at the five microsatellite loci recommended by the National Cancer Institute (NCI). Immunohistochemical staining for hMLH1 and hMSH2 was performed and the results were compared with the MSI status measured using PCR. The relationship of the clinicopathologic variables to MSI status was analyzed.

RESULTS

Of the gastric cancers, 8.2% (n = 27) contained MSI-H and this was associated with older age (>70 years), distal tumor location, tumor size, and intestinal subtype. Lymphatic and vascular invasion were associated with the disease-free survival. On immunohistochemical staining, the loss of expression of hMLH1 or hMSH2 was observed in 11% (n = 36). The sensitivity, specificity, positive predictive value, negative predictive value, and accuracy of immunohistochemical staining were 63.0%, 93.7%, 47.2%, 96.6%, and 91.2%, respectively.

CONCLUSIONS

Gastric cancers with MSI-H have specific clinicopathologic characteristics, such as older age at diagnosis, distal tumor location, increased tumor size, and intestinal histologic type. However, immunohistochemical staining for hMLH1 and hMSH2 is not as accurate as the PCR-based MSI test.

Stage IV early gastric cancer: two cases with microsatellite instability

BACKGROUND

We experienced two rare cases of stage IV early gastric carcinoma with extensive lymph node metastasis (pT1N3) and microsatellite instability caused by methylation of the MLH1 gene.

MATERIALS AND METHODS

The clinicopathological features of patients with stage IV EGC were examined. Microsatellite instability (MSI) was analyzed using five microsatellite markers and MLH1 gene promoter methylation patterns were determined by methylation specific polymerase chain reaction (PCR) from paraffin-embedded tissue samples. Loss of hMLH1 was identified by immunohistochemical study.

RESULTS

In both cases, the carcinomas were located in the antrum of the stomach, confined within the submucosa (SM3) and accompanied by endolymphatic tumor emboli. Immunohistochemical analysis for hMLH1 showed negative nuclear staining in the carcinoma cells. The tumor demonstrated methylation of the MLH1 gene and MSI-H because they manifested instability in three and two of the five markers tested. One patient is alive without any clinical, radiological, or pathological evidence of recurrence or metastasis at 37 months, while the other patient died after a cerebrovascular accident 5 months after surgery.

CONCLUSION

Our rare cases support that MSI caused by MLH1 promoter methylation and the loss of hMLH1 protein play an important role in stage IV EGC development.

Mutations in Exons 6 and 7 of TP53 Gene Correlate Positively with Serum Tumor Necrosis Factor Alpha Independent of Microsatellite Instability in BAT26 Gene in Egyptian Patients with Endometrial Carcinoma

Abnormalities in the TP53 gene are the most frequent genetic alterations in human cancers. The role and mechanism of TP53 mutations have been well studied in many types of human cancer. Similarly, the presence of microsatellite instability (MSI) in the DNA mismatch repair system (hMSH2) may provide evidence of faulty DNA mismatch repair. One of the most important locations of MSI is the BAT26 gene. In addition, deranged serum cytokines, especially elevated levels of the tumor necrosis factor (TNF) alpha, have been found in many gynecological conditions.

Aims

The current study aimed at evaluating mutations in exons 6 and 7 of TP53 and the presence of microsatellite instability in BAT26 of the hMSH2 system in Egyptian patients with endometrial carcinoma. The study also evaluated whether there was a correlation between any of these genetic mutations/instability and the tissue expression of estrogen and progesterone receptors and the serum TNF-alpha level.

Patients and methods

The current study included 2 groups: a control group comprising 20 healthy women aged 52.21 ± 5.80 years attending the clinic for routine checkups and 40 patients with endometrial cancer aged 55.30 ± 6.21 years. Mutations in TP53 and BAT26 were evaluated using polymerase chain reaction–single-strand conformational polymorphism (PCR-SSCP) and automated sequencing while serum TNF-alpha was measured using an ELISA technique. Estrogen and progesterone receptor expression in biopsy tissue was evaluated using immunohistochemical staining.

Results

Seven of the 40 patients (17.5%) were positive for TP53 gene alterations in exon 6, while 9 patients (22.5%) were positive for TP53 alterations in exon 7. Cases positive for TP53 mutations had higher tumor stages. Ten patients (25%) showed MSI in BAT26. Nearly all patients with mutations in BAT26 had a strong family history for endometrial cancer (χ2=13.33, p<0.05). There was no positive correlation between the presence of MSI in the BAT26 gene and mutations in the TP53 gene or high serum TNF-alpha levels. Cases positive for TP53 mutations had a significantly higher level of TNF-alpha than cases negative for TP53 mutations (p<0.05). Cases showing mutations in exon 6 or 7 of TP53 showed a significantly higher intensity of immunohistochemical staining for estrogen and progesterone receptor expression in biopsy tissue than cases negative for mutations. (χ2=8.11, p<0.05).

Conclusion

Our results suggest that the development of endometrial carcinoma is probably mediated through a multi-step carcinogenesis pathway and mutation of TP53 does not necessarily result from the presence of microsatellite instability in BAT26. The high serum TNF-alpha levels detected in our patients may represent an immunological antitumor response that was particularly evident in cases positive for TP53 mutations.