Unique Genomic Alterations and Microbial Profiles Identified in Patients With Gastric Cancer of African, European, and Asian Ancestry: A Novel Path for Precision Oncology

OBJECTIVE

Here, we characterize differences in the genetic and microbial profiles of GC in patients of African (AFR), European, and Asian ancestry.

BACKGROUND

Gastric cancer (GC) is a heterogeneous disease with clinicopathologic variations due to a complex interplay of environmental and biological factors, which may affect disparities in oncologic outcomes..

METHODS

We identified 1042 patients with GC with next-generation sequencing data from an institutional Integrated Mutation Profiling of Actionable Cancer Targets assay and the Cancer Genomic Atlas group. Genetic ancestry was inferred from markers captured by the Integrated Mutation Profiling of Actionable Cancer Targets and the Cancer Genomic Atlas whole exome sequencing panels. Tumor microbial profiles were inferred from sequencing data using a validated microbiome bioinformatics pipeline. Genomic alterations and microbial profiles were compared among patients with GC of different ancestries.

RESULTS

We assessed 8023 genomic alterations. The most frequently altered genes were TP53 , ARID1A , KRAS , ERBB2 , and CDH1 . Patients of AFR ancestry had a significantly higher rate of CCNE1 alterations and a lower rate of KRAS alterations ( P < 0.05), and patients of East Asian ancestry had a significantly lower rate of PI3K pathway alterations ( P < 0.05) compared with other ancestries. Microbial diversity and enrichment did not differ significantly across ancestry groups ( P > 0.05).

CONCLUSIONS

Distinct patterns of genomic alterations and variations in microbial profiles were identified in patients with GC of AFR, European, and Asian ancestry. Our findings of variation in the prevalence of clinically actionable tumor alterations among ancestry groups suggest that precision medicine can mitigate oncologic disparities.

Establishment and characterization of a new intrahepatic cholangiocarcinoma cell line derived from a Chinese patient

Patients with intrahepatic cholangiocarcinoma (ICC) require chemotherapy due to late detection, rapid disease progression, and low surgical resection rate. Tumor cell lines are extremely important in cancer research for drug discovery and development. Here, we established and characterized a new intrahepatic cholangiocarcinoma cell line, ICC-X1. STR testing confirmed the absence of cross-contamination and high similarity to the original tissue. ICC-X1 exhibited typical epithelial morphology and formed tumor spheres in the suspension culture. The population doubling time was approximately 48 h. The cell line had a complex hypotriploid karyotype. The cell line exhibited a strong migration ability in vitro and cell inoculation into BALB/c nude mice led to the formation of xenografts. Additionally, ICC-X1 cells were sensitive to gemcitabine and paclitaxel but resistant to 5-fluorouracil and oxaliplatin. RNA sequencing revealed that the upregulated cancer-related genes were mainly enriched in several signaling pathways, including the TNF signaling pathway, NOD-like receptor signaling pathway, and NF-κB signaling pathway. The downregulated cancer-related genes were mainly enriched in the Rap1 signaling pathway and Hippo signaling pathway among other pathways. In conclusion, we have created a new ICC cell line derived from Chinese patients. This cell line can be used as a preclinical model to study ICC, specifically tumor metastasis and drug resistance mechanisms.

The Association of Race With Adequate Lymph Node Evaluation for Gastric Cancer

BACKGROUND

National studies have reported racial and socioeconomic disparities in gastric cancer (GC) care. The current study evaluated adequate lymph node (LN) assessment (≥16 LNs) during resection for GC within a healthcare system servicing a socioeconomically disparate, mostly non-White population in the Southeast United States.

METHODS

A retrospective cohort study of patients undergoing resection for GC between 2003-2019 was performed. Factors associated with adequate LN assessment including patient and tumor characteristics were analyzed.

RESULTS

Among 202 patients, adequate LN assessment was performed in 97 (48%) patients. On univariable analysis, younger age, non-White race, lower Charlson Comorbidity Index (CCI), Medicaid or no insurance, D1+/D2 lymphadenectomy, clinical evidence of regional LN metastases, total gastrectomy, and receipt of neoadjuvant therapy were associated with adequate LN assessment. On multivariable analysis, non-White race (OR 2.79, 95% CI 1.38-5.65), CCI <4 (OR 2.14, 95% CI 1.15-3.96), and D1+/D2 lymphadenectomy (OR 3.63, 95% CI 1.96-6.74) were the only factors independently associated with adequate LN evaluation.

CONCLUSIONS

In the current study, non-White race, independent of socioeconomics, was significantly associated with adequate LN assessment. Future work is necessary to improve standardization and achieve higher rates of adequate LN assessment for all patients during resection for GC.

It's more than just cancer biology: Health disparities in patients with pancreatic neuroendocrine tumors

BACKGROUND AND OBJECTIVES

Pancreatic neuroendocrine tumors (PNETs) represent a rare form of pancreatic cancer. Racial/ethnic disparities have been documented in pancreatic ductal adenocarcinoma, but health disparities have not been well described in patients with PNETs.

METHODS

A retrospective review of patients with PNETs in the National Cancer Database was performed for 2004-2014. Approximately 16 605 patients with PNETs and available vital status were identified. Survival was compared by race/ethnicity and socioeconomic status using Kaplan-Meier methods and Cox regression.

RESULTS

There were no significant differences in survival between Non-Hispanic, White; Hispanic, White; or Non-Hispanic, Black patients on univariate analysis. Kaplan-Meier analysis showed that patients from communities with lower median household income and education level had worse survival (p < 0.001). Patients age less than 65 without insurance, similarly, had worse survival (p < 0.001). Multivariable modeling found no association between race/ethnicity and risk of mortality (p = 0.37). Lower median household income and lower education level were associated with increased mortality (p < 0.001).

CONCLUSIONS

Unlike most other malignancies, race/ethnicity is not associated with survival differences in patients with PNETs. Patients with lower socioeconomic status had worse survival. The presence of identifiable health disparities in patients with PNETs represents a target for intervention and opportunity to improve survival in patients with this malignancy.

The Survival Advantage of Females at Premenopausal Age Is Race Dependent in Colorectal Cancer

Background

A female prognostic advantage in younger individuals has been demonstrated in various cancers. Several large-scale analyses based on different racial backgrounds have reported inconsistent results in colorectal cancer. The aim of the present study was to evaluate the prognostic value of sex and age in patients with colorectal cancer of different ethnic groups.

Methods

We identified 71,812 eligible patients from the Surveillance, Epidemiology and End Results database. According to age at diagnosis, the patients were categorized into premenopausal age (≤45 yrs), menopausal age (46–54 yrs), and postmenopausal age (≥55 yrs) subgroups for further analysis.

Results

Multivariate analysis identified the female survival advantage to be significant in the premenopausal age subgroup (P = 0.002, HR (95% CI): 0.73 (0.60–0.89)), diminished in the menopausal age subgroup (P = 0.09), and absent in the postmenopausal age subgroup (P = 0.96). Furthermore, the female survival advantage at premenopausal age was significant only in white patients (P = 0.001, HR (95% CI): 0.68 (0.54–0.87)) and not in either American Indian/Alaska Native or Asian or Pacific Islander patients. There was a trend of better survival of females in black patients (P = 0.07).

Conclusions

Sex was a major prognostic factor in colorectal cancer patients, especially premenopausal women, and the difference was also associated with race.

Multidisciplinary Approach in Improving Survival Outcome of Early-Stage Gastric Cancer

BACKGROUND

The necessity of extensive lymph node (LN) dissection/examination and adjuvant therapy for patients with early gastric cancer (EGC, Tis-T1, any N) remains controversial. We aim to refine treatment recommendations for patients with EGC through a reflective analysis for the survival gap between Eastern and Western countries.

METHODS

EGC patients diagnosed between 2004 and 2014 were identified from the National Cancer Database (NCDB) and a large medical center in China. Adequate LN yield was defined as ≥25 LNs examined.

RESULTS

In the US cohort, 14.4% of (1104/7641) patients with EGC had ≥25 LNs examined. The 5-y overall survival (OS) was significantly better than those with <25 LNs (78.9% versus 68.5%, P < 0.001). Examination of ≥25 LNs was an independent predictor of better OS after adjusting all known prognostic factors. Patients with ≥25 LNs examined had significantly higher chance of having LN-positive disease compared to patients with <25 LNs (14.9% versus 10.7%, P < 0.001). A similar stage migration phenomenon was observed in Chinese cohort (LN positive: 25.2% versus 18.4% in ≥25 LNs and <25 LNs examined group, respectively, P = 0.02). In the US cohort, adjuvant therapy was associated with a significant survival benefit for LN-positive patients (5-y OS: 71.0% versus 43.0% for with/without adjuvant therapy, respectively, P < 0.001) but not in LN-negative patients (5-y OS: 71.2% versus 71.5%, P = 0.90).

CONCLUSIONS

Adequate lymphadenectomy and LN examination are critical components of EGC management. Adjuvant therapy should be strongly encouraged for all EGC patients with LN-positive disease in the United States.

Socio-Demographic Disparities in Gastric Adenocarcinoma: A Population-Based Study

Background: Gastric cancer is one of the leading causes of cancer-related mortality worldwide, accounting for 8.2% of cancer-related deaths. The purpose of this study was to investigate the geographic and sociodemographic disparities in gastric adenocarcinoma patients.

METHODS

We conducted a retrospective study in gastric adenocarcinoma patients between 2004 and 2013. Data were obtained from the National Cancer Data Base (NCDB). Univariate and multivariable analyses were performed to evaluate overall survival (OS). Socio-demographic factors, including the location of residence [metro area (MA) or rural area (RA)], gender, race, insurance status, and marital status, were analyzed.

RESULTS

A total of 88,246 [RA, N = 12,365; MA, N = 75,881] patients were included. Univariate and multivariable analysis showed that RA had worse OS (univariate HR = 1.08, p < 0.01; multivariate HR = 1.04; p < 0.01) compared to MA. When comparing different racial backgrounds, Native American and African American populations had poorer OS when compared to the white population; however, Asian patients had a better OS (multivariable HR = 0.68, p < 0.01). From a quality of care standpoint, MA patients had fewer median days to surgery (28 vs. 33; p < 0.01) with fewer positive margins (6.3% vs. 6.9%; p < 0.01) when compared to RA patients. When comparing the extent of lymph node dissection, 19.6% of MA patients underwent an extensive dissection (more than or equal to 15 lymph nodes) in comparison to 18.7% patients in RA (p = 0.03).

DISCUSSION

This study identifies socio-demographic disparities in gastric adenocarcinoma. Future health policy initiatives should focus on equitable allocation of resources to improve the outcomes.

The impact of race and socioeconomic status on the presentation, management and outcomes for gastric cancer patients: Analysis from a metropolitan area in the southeast United States

BACKGROUND

Socioeconomic disparities in gastric cancer have been associated with differences in care and inferior outcomes. We evaluated the presentation, treatment, and survival for patients with gastric cancer (GC) in a metropolitan setting with a large African American population.

METHODS

Retrospective cohort analysis of patients with GC (2003-2018) across a multi-hospital system was performed. Associations between socioeconomic and clinicopathologic data with the presentation, treatment, and survival were examined.

RESULTS

Of 359 patients, 255 (71%) were African American and 104 (29%) Caucasian. African Americans were more likely to present at a younger age (64.0 vs 72.5, P < .001), have state-sponsored or no insurance (19.7% vs 6.9%, P = .02), reside within the lowest 2 quintiles for median income (67.4% vs 32.7%, P < .001), and have higher rates of Helicobacter pylori (14.9% vs 4.8%, P = .02). Receipt of multi-modality therapy was not impacted by race or insurance status. On multivariable analysis, only AJCC T class (HR 1.68) and node positivity (HR 2.43) remained significant predictors of disease-specific survival.

CONCLUSION

Despite socioeconomic disparities, African Americans, and Caucasians with GC had similar treatment and outcomes. African Americans presented at a younger age with higher rates of H. pylori positivity, warranting further investigation into differences in risk factors and tumor biology.

Evaluating Dissemination of Adequate Lymphadenectomy for Gastric Cancer in the USA

BACKGROUND

Adequate lymphadenectomy (AL) of 15+ lymph nodes comprises an important component of gastric cancer surgical therapy. Despite endorsement by the National Comprehensive Cancer Network and the Committee on Cancer, initial adoption of this paradigm has been relatively slow. The current analysis sought to perform an adjusted time-trend evaluation of the factors associated with AL and its dissemination.

METHODS

Utilizing the 2004-2015 National Cancer Database, 28,985 patients were identified who underwent gastrectomy for adenocarcinoma. An adjusted time-trend analysis was performed to estimate the adoption of AL overall. Multivariable logistic regression was utilized to assess factors associated with these observed trends. Interactions and stratified models determined disparate effects in vulnerable populations (older adults, ethnic minorities, low socioeconomic status).

RESULTS

The adjusted time-trend analysis demonstrated an overall 30% increase (28.8 to 58.7%) in receipt of AL (OR 1.10 increase/year; 95%CI 1.09-1.10) from 2004 to 2015. This trend persisted even after stratifying the models by age, race/ethnicity, and income (OR 1.07-1.12; p < 0.05). Slowest rates of adoption were seen amongst hospitals in the Midwest census region (OR 1.08, CI 1.06-1.90) and comprehensive community hospitals (OR 1.08, CI 1.06-1.91) and with African-American patients (OR 1.09, CI 1.06-1.11) (all p < 0.05).

CONCLUSION

This multi-center evaluation demonstrates increased adoption of AL during gastric cancer surgery in the USA overall and amongst vulnerable populations, although regional and racial disparities were observed. Future studies are needed to investigate reasons underlying racial and regional differences in receipt of AL.

Nature versus nurture: the impact of nativity and site of treatment on survival for gastric cancer

BACKGROUND

The prognosis of gastric cancer patients is better in Asia than in the West. Genetic, environmental, and treatment factors have all been implicated. We sought to explore the extent to which the place of birth and the place of treatment influences survival outcomes in Korean and US patients with localized gastric cancer.

METHODS

Patients with localized gastric adenocarcinoma undergoing potentially curative gastrectomy from 1989 to 2010 were identified from the SEER registry and two single institution databases from the US and Korea. Patients were categorized into three groups: Koreans born/treated in Korea (KK), Koreans born in Korea/treated in the US (KUS), and White Americans born/treated in the US (W), and disease-specific survival rates compared.

RESULTS

We identified 16,622 patients: 3,984 (24.0%) KK, 1,046 (6.3%) KUS, and 11,592 (69.7%) W patients. KK patients had longer unadjusted median (not reached) and 5-year disease-specific survival (81.6%) rates than KUS (87 months, 55.9%) and W (35 months, 39.2%; p < 0.001 for all comparisons) patients. This finding persisted on subset analyses of patients with stage IA tumors, without cardia/GEJ tumors, with > 15 examined lymph nodes, and treated at a US center of excellence. On multivariable analysis, KUS (HR 2.80, p < 0.001) and W (HR 5.79, p < 0.001) patients had an increased risk of mortality compared to KK patients.

CONCLUSIONS

Both the place of birth and the place of treatment significantly contribute to the improved prognosis of patients with gastric cancer in Korea relative to those in the US, implicating both nature and nurture in this phenomenon.

Development and validation of a nomogram to individually predict survival of young patients with nonmetastatic gastric cancer: A retrospective cohort study

BACKGROUND/AIMS

Evidence regarding gastric cancer (GC) patients <40 years old is limited. The aim of the study was to identify risk factors affecting overall survival (OS) of young patients with nonmetastatic GC and to establish a nomogram for prognostic prediction using data from the Surveillance, Epidemiology and End Results (SEER) database. Furthermore, this study sought to externally validate this nomogram in an independent patient cohort.

PATIENTS AND METHODS

In this retrospective cohort study, the records of patients aged <40 years with nonmetastatic GC (n = 559), from the SEER database, between 2006 and 2015, were examined. The nomogram was established based on the Cox proportional hazards regression model using the SEER dataset. Patients with nonmetastatic GC (n = 201) in our department between 2009 and 2015 were selected as an external validation set. Discrimination and calibration were performed in both cohorts.

RESULTS

The multivariate Cox model identified race, tumor subsites, tumor size, depth of invasion, lymph node metastasis, number of examined lymph nodes, and surgery as independent covariates associated with OS. The nomogram exhibited superior discriminative power than the eighth tumor, node, metastasis (TNM) staging system in both the training set [Harrell's concordance index (C index): 0.762 vs. 0.635,P < 0.001] and validation set (C index: 0.805 vs. 0.712,P= 0.176). Calibration of the nomogram was good in both cohorts.

CONCLUSIONS

We developed a nomogram predicting 3- and 5-year OS rates in young patients with nonmetastatic GC. Both the training set and validation set showed good discrimination and calibration, suggesting good clinical applicability.

Adjuvant Therapy is Associated with Improved Survival in pT1N1 Gastric Cancer in a Heterogeneous Western Patient Population

BACKGROUND

Two recent South Korean studies showed adjuvant therapy (AT) was not associated with improved survival in pT1N1 gastric adenocarcinoma (GAC). We established the prognostic utility of lymph node status, determined the pattern of use of AT, and compared survival stratified by type of AT in pT1N1 GAC in a Western patient population.

METHODS

We identified patients with pT1N0 and pT1N1 GAC using the National Cancer Database from 2004 to 2012. Clinicopathologic variables, treatment regimens, and overall survival (OS) were compared.

RESULTS

We compared 4516 (86.6%) pT1N0 to 696 (13.4%) pT1N1 patients. pT1N1 tumors were larger (median size 2.5 vs. 1.8 cm, p < 0.001), more often poorly differentiated (56.2% vs. 39.6%, p < 0.001), and had higher median retrieved lymph nodes (RLN) (14 vs. 12, p < 0.001) compared with pT1N0. pT1N1 was associated with worse median overall survival (OS) (6.9 vs. 9.9 years for pT1N0, p < 0.001). pN1 was independently associated with worse OS (hazard ratio [HR] 2.17, 95% confidence interval [CI] 1.84-2.56). Increased RLN was associated with improved OS (HR 0.73, 95% CI 0.65-0.83). Among pT1N1 patients, 330 (47.4%) had observation (OBS), 77 (11.1%) received adjuvant chemotherapy (ACT), 68 (9.8%) received adjuvant radiation therapy (ART), and 221 (31.8%) received adjuvant chemoradiation therapy (ACRT). ACT and ACRT were independently associated with improved OS (HR 0.37, 95% CI 0.22-0.65 and HR 0.40, 95% CI 0.28-0.57).

CONCLUSIONS

pN1 was associated with worse survival and RLN ≥ 15 was associated with improved survival in pT1 GAC. ACT and ACRT were independently associated with improved survival in pT1N1 gastric cancer suggesting a valuable role in Western patients.

Ramucirumab for the treatment of metastatic gastric or gastroesophageal junction adenocarcinoma following disease progression on first-line platinum- or fluoropyrimidine-containing combination therapy in Japanese patients: a phase 2, open-label study

BACKGROUND

Ramucirumab, a monoclonal antibody vascular endothelial growth factor receptor-2 antagonist, given as monotherapy improved survival in a global phase 3 study (REGARD) of patients with gastric cancer. However, REGARD did not include Japanese patients. This study evaluated the efficacy and safety of ramucirumab monotherapy in Japanese patients with advanced gastric cancer.

METHODS

This multicenter, open-label, nonrandomized phase 2 study (Clinicaltrials.gov: NCT01983878) was performed at 16 Japanese sites. Patients with advanced gastric or gastroesophageal junction cancer after disease progression following first-line chemotherapy received intravenous ramucirumab 8 mg/kg every 2 weeks. Primary efficacy outcome: 12-week progression-free survival rate (PFS).

RESULTS

Thirty-six patients were enrolled. The 12-week PFS rate was 23.8% [90% confidence interval (CI) 12.4-37.2); the primary outcome was not met as the lower limit of the CI was outside the threshold of 16%. Median PFS was 6.6 weeks (90% CI 6.1-7.1). No patients achieved an objective response, and 11 (31%) patients achieved disease control. Median overall survival was 8.6 months (90% CI 5.7-10.7). The most frequent treatment-emergent adverse events (TEAEs) were diarrhea (9/36; 25%) and decreased appetite (8/36; 22%). Three patients reported Grade ≥ 3 ileus; all other Grade ≥ 3 TEAEs were reported by ≤ 2 patients. The most frequent adverse events of special interest (AESIs) were hypertension (10/36; 28%), bleeding/hemorrhage (7/36; 19%), and proteinuria (7/36; 19%). All Grade ≥ 3 AESIs were reported by ≤ 2 patients.

CONCLUSIONS

These findings suggest that ramucirumab monotherapy has clinical activity and a manageable safety profile in Japanese patients with gastric cancer after disease progression following first-line chemotherapy.

Rates of TP53 Mutation are Significantly Elevated in African American Patients with Gastric Cancer

BACKGROUND

Gastric adenocarcinoma is a heterogenous disease that results from complex interactions between environmental and genetic factors, which may contribute to the disparate outcomes observed between different patient populations. This study aimed to determine whether genomic differences exist in a diverse population of patients by evaluating tumor mutational profiles stratified by race.

METHODS

All patients with gastric adenocarcinoma between 2012 and 2016 who underwent targeted next-generation sequencing of cancer genes by the Memorial Sloan Kettering-Integrated Mutation Profiling of Actionable Cancer Targets platform were identified. Patient race was categorized as Asian, African American, Hispanic, or Caucasian. Fisher's exact test was used to examine differences in mutation rates between racial designations for the most common mutations identified. The p values in this study were adjusted using the false discovery rate method.

RESULTS

The study investigated 595 mutations in 119 patients. The DNA alterations identified included missense mutations (66%), frame-shift deletions (13%), and nonsense mutations (9%). Silent mutations were excluded. The most frequently mutated genes were ARID1A, CDH1, ERBB3, KRAS, PIK3CA, and TP53. Of these, TP53 was the most frequently mutated gene, affecting 50% of patients. The proportion of patients with TP53 mutations differed significantly between races (p = 0.012). The findings showed TP53 mutations for 89% (16/18) of the African American patients, 56% (10/18) of the Asian patients, 43% (9/21) of the Hispanic patients, and 40% (25/62) of the Caucasian patients.

CONCLUSIONS

Significantly higher rates of TP53 mutations were identified among the African American patients with gastric adenocarcinoma. This is the first study to evaluate tumor genomic differences in a diverse population of patients with gastric adenocarcinoma.

Differential networking meta-analysis of gastric cancer across Asian and American racial groups

Background

Gastric Carcinoma is one of the most lethal cancer around the world, and is also the most common cancers in Eastern Asia. A lot of differentially expressed genes have been detected as being associated with Gastric Carcinoma (GC) progression, however, little is known about the underlying dysfunctional regulation mechanisms. To address this problem, we previously developed a differential networking approach that is characterized by involving differential coexpression analysis (DCEA), stage-specific gene regulatory network (GRN) modelling and differential regulation networking (DRN) analysis.

Result

In order to implement differential networking meta-analysis, we developed a novel framework which integrated the following steps. Considering the complexity and diversity of gastric carcinogenesis, we first collected three datasets (GSE54129, GSE24375 and TCGA-STAD) for Chinese, Korean and American, and aimed to investigate the common dysregulation mechanisms of gastric carcinogenesis across racial groups. Then, we constructed conditional GRNs for gastric cancer corresponding to normal and carcinoma, and prioritized differentially regulated genes (DRGs) and gene links (DRLs) from three datasets separately by using our previously developed differential networking method. Based on our integrated differential regulation information from three datasets and prior knowledge (e.g., transcription factor (TF)-target regulatory relationships and known signaling pathways), we eventually generated testable hypotheses on the regulation mechanisms of two genes, XBP1 and GIF, out of 16 common cross-racial DRGs in gastric carcinogenesis.

Conclusion

The current cross-racial integrative study from the viewpoint of differential regulation networking provided useful clues for understanding the common dysfunctional regulation mechanisms of gastric cancer progression and discovering new universal drug targets or biomarkers for gastric cancer.

Electronic supplementary material

The online version of this article (10.1186/s12918-018-0564-z) contains supplementary material, which is available to authorized users.

Increased survival rates in gastric cancer, with a narrowing gender gap and widening socioeconomic status gap: A period analysis from 1984 to 2013

BACKGROUND AND AIM

Gastric cancer (GC) has the fifth highest incidence rate of all cancers and has a poor prognosis. However, no recent large-scale and long-term studies have evaluated the incidence and survival rates of individuals with GC.

METHODS

In order to explore the change of GC incidence and survival rates by age, gender, race, and socioeconomic status (SES), incidence data and survival status of patients with GC between 1984 and 2013 were abstracted from the Surveillance, Epidemiology, and End Results database. Totally, 87 242 cases of GC were exported and were analyzed.

RESULTS

During these three decades, the incidence of GC was 7.4, 6.8, and 5.5 per 100 000 individuals in each decade. The 1-year relative survival rates (RSRs) improved from 42.4% to 44.3% to 49.0% (P < 0.0001), with a larger increase seen in the third decade. However, the long-term survival rates remained low (from 17.8% to 20.3% to 22.9% for the 5-year RSRs, P < 0.0001; from 14.1% to 16.4% to 18.6% for the 10-year RSRs, P < 0.0001).

CONCLUSION

Our analysis demonstrated the decreased incidence and increased survival rate of GC. In addition, lower SES was associated with lower survival rates. It is notable that others (primarily for Asians) had the highest incidence rate but had better outcomes than Whites and Blacks.

Racial disparities in preoperative chemotherapy use in gastric cancer patients in the United States: Analysis of the National Cancer Data Base, 2006-2014

BACKGROUND

No studies have investigated whether race/ethnicity is associated with the recommended use of preoperative chemotherapy or subsequent outcomes in gastric cancer. To determine whether there is such an association, analyses of patients with gastric cancer in the National Cancer Data Base (NCDB) were performed.

METHODS

Patients with clinical T2-4bN0-1M0 gastric adenocarcinoma, as defined by the eighth edition of the American Joint Committee on Cancer staging manual, who underwent gastrectomy from 2006 to 2014 were identified from the NCDB. Multiple logistic regression was conducted to examine factors associated with preoperative chemotherapy use.

RESULTS

This study identified 16,945 patients who met the criteria, and 8286 of these patients (49%) underwent preoperative chemotherapy. The use of preoperative chemotherapy remarkably increased over the study period, from 34% in 2006 to 65% in 2014. Preoperative chemotherapy was more commonly used for cardia tumors than noncardia tumors (83% vs 44% in 2014). In a multivariable analysis, races and ethnicities other than non-Hispanic (NH) white race were associated with less frequent use of preoperative chemotherapy in comparison with NH whites after adjustments for social, tumor, and hospital factors. The insurance status and the education level mediated an enhanced effect of racial/ethnic disparities in preoperative chemotherapy use. The use of preoperative chemotherapy and radiation therapy was associated with reduced racial/ethnic disparities in overall survival.

CONCLUSIONS

Racial/ethnic disparities in the use of preoperative chemotherapy and in outcomes exist among patients with gastric cancer in the United States. Efforts to improve the access to high-quality cancer care in minority groups may reduce racial disparities in gastric cancer in the United States. Cancer 2018;124:998-1007. © 2018 American Cancer Society.

Development and external validation of a prognostic nomogram for gastric cancer using the national cancer registry

A nomogram based on both western and eastern populations to estimate the Disease Specific Survival (DSS) of resectable gastric cancer (RGC) has not been established. In current study, we retrospectively analyzed 4,379 RGC patients who underwent curative resection from the Surveillance, Epidemiology, and End Results (SEER) database. Patients diagnosed between 1998 and 2009 were assigned as training set (n= 2,770), and the rest were selected as SEER validation set (n= 1,609). An external validation was performed by a set of independent 1,358 RGC patients after D2 resection from Sun Yat–sen University Cancer Center (SYSUCC) in China. The nomogram was constructed based on the training set. The multivariate analysis identified that patient's age at diagnosis, race, tumor location, grade, depth of invasion, metastatic lymph node stage (mLNS) and total number of examined lymph node (TLN) were associated with patient's DSS. The discrimination of this nomogram was superior to that of the 7th edition of AJCC staging system in SEER validation set and SYSUCC validation set (0.73 versus 0.70, p=0.005; 0.76 versus 0.72, p=0.005; respectively). Calibration plots of the nomogram showed that the probability of DSS corresponded to actual observation closely. In conclusion, our nomogram resulted in more–reliable prognostic prediction for RGC patients in general population.

Examining the gastric cancer survival gap between Asians and whites in the United States

BACKGROUND

Globally, Asian countries bear a disproportionate gastric cancer burden. Asian Americans, the fastest growing minority population in the US, have higher gastric cancer survival than non-Hispanic whites (NHWs) despite higher incidence. Benefitting from uniform cancer registry standards within the US, we examine for the first time the heterogeneity in the Asian American population, which may elucidate the causes of these disparities.

METHODS

SEER gastric cancer data from 2000 to 2012 were used to calculate 5-year survival estimates for NHWs and the six largest Asian ethnicities. Multivariate analyses were performed to identify critical prognostic factors and survival disparities between Asian groups and NHWs.

RESULTS

We analyzed 33,313 NHW and 8473 Asian gastric cancer cases. All Asian groups had significantly higher 5-year survival than NHWs, at 29.8%. Among Asians, Koreans and Vietnamese had the highest and lowest survival, at 45.4% and 35.7%, respectively. The Korean survival advantage was largely attributable to relatively high proportions of localized stage and low proportions of cardia tumors. After adjusting for major prognostic factors, the survival disadvantage of NHWs, while attenuated, remained significant in comparison to all Asian groups (HR: 1.33, 95% CI: 1.24-1.43; reference: Korean). The survival disparities within the Asian groups vanished with adjustment.

CONCLUSIONS

This study characterizes distinctive gastric cancer survival patterns among the six major Asian groups and NHWs in the US. The favorable survival for Koreans is largely attributable to specific clinical factors, particularly stage at diagnosis. The causes of the survival disadvantage for NHWs remain elusive.

Stage-Specific Prognostic Effect of Race in Patients with Resectable Gastric Adenocarcinoma: An 8-Institution Study of the US Gastric Cancer Collaborative

BACKGROUND

Gastric cancer constitutes a major public health problem. This study sought to evaluate the relevance of race in gastric cancer and its prognostic effect in the overall outcomes of patients with gastric adenocarcinoma.

STUDY DESIGN

Patients who underwent curative intent resection of gastric adenocarcinoma in 8 institutions of the US Gastric Cancer Collaborative were included, from 2000 to 2012. Nonparametric descriptive statistics were used to evaluate characteristics of standard demographic data. Multivariate Cox proportional hazards regression was used to identify factors associated with recurrence-free survival and overall survival.

RESULTS

There were 1,077 patients included in the study, the majority of whom were of Caucasian race (n = 698, 68%), followed by African-American (n = 164, 15%), Asian (n = 132, 12%), Hispanic (n = 34, 3.2%), and other (n = 49, 4.5%). Clinicopathologic data were similarly distributed among the 5 groups. Mean follow-up was 27.1 months. By multivariate, stage-specific analysis, Asian race was a significant predictor of recurrence (all stages hazard ratio [HR] 0.45 95% CI [0.23, 0.97], p = 0.041) and of overall survival (all stages HR 0.35 95% CI [0.18, 0.68], p = 0.002). Recurrence-free survival was significantly increased in the Asian population compared with the non-Asian population (25th percentile: 38.6 vs 17.7 months, p = 0.0096), as was overall median survival (141 vs 38.8 months, p < 0.001).

CONCLUSIONS

Patients of Asian race undergoing curative gastrectomy for gastric adenocarcinoma appear to have a better prognosis stage for stage. Further studies are required to elucidate the underlying etiology of this phenomenon.