Race and correlations between lymph node number and survival for patients with gastric cancer

Updates on global epidemiology, risk and prognostic factors of gastric cancer

Gastric cancer (GC) is defined as the primary epithelial malignancy derived from the stomach, and it is a complicated and heterogeneous disease with multiple risk factors. Despite its overall declining trend of incidence and mortality in various countries over the past few decades, GC remains the fifth most common malignancy and the fourth leading cause of cancer-related death globally. Although the global burden of GC has shown a significant downward trend, it remains severe in certain areas, such as Asia. GC ranks third in incidence and mortality among all cancer types in China, and it accounts for nearly 44.0% and 48.6% of new GC cases and GC-related deaths in the world, respectively. The regional differences in GC incidence and mortality are obvious, and annual new cases and deaths are increasing rapidly in some developing regions. Therefore, early preventive and screening strategies for GC are urgently needed. The clinical efficacies of conventional treatments for GC are limited, and the developing understanding of GC pathogenesis has increased the demand for new therapeutic regimens, including immune checkpoint inhibitors, cell immunotherapy and cancer vaccines. The present review describes the epidemiology of GC worldwide, especially in China, summarizes its risk and prognostic factors, and focuses on novel immunotherapies to develop therapeutic strategies for the management of GC patients.

Importance of Examined Lymph Node Number in Accurate Staging and Enhanced Survival in Resected Gastric Adenocarcinoma-The More, the Better? A Cohort Study of 8,696 Cases From the US and China, 2010-2016

Background

While most guidelines advocate D2 lymphadenectomy for non-metastatic gastric adenocarcinoma (nmGaC), it is not always performed as standard of care outside East Asia. The recommended minimal examined lymph node (ELN) count in nmGaC to stage cancer accurately varies largely across guidelines, and the optimal count to satisfactorily stratify patient survival has yet to be determined. This large cohort study aimed at robustly defining the minimal and optimal thresholds of examined lymph node (ELN) number in non-metastatic gastric adenocarcinoma (nmGaC).

Methods

Data on nmGaC patients operated in 2010–2016 and surviving ≥3 months were retrieved from the US SEER-18 Program and a Chinese multi-institutional gastric cancer database (MIGC). The correlation of ELN count with stage migration and patient survival were quantified with the use of the multivariable-adjusted logistic and proportional hazards Cox models, respectively. The sequences of odds ratios (ORs) and hazard ratios (HRs) for each additional ELN were smoothed, and the structural breakpoints were determined.

Results

Together 7,228 patients from the US and 1,468 from China were analyzed, encompassing 23,114 person-years of follow-up. The mean ELN count was 20 in the US and 30 in China. With more ELNs, both cohorts significantly showed proportional increases from lower to higher nodal stage (OR_SEER = 1.03, 95%-CI = 1.03–1.04; OR_MIGC = 1.02, 95%-CI = 1.02–1.03) and sequential enhancements in postoperative survival (HR_SEER = 0.97, 95%-CI = 0.97–0.97; HR_MIGC = 0.98, 95%-CI = 0.97–0.99). Correlations for both stage migration and survival were still significant in most subgroups by patient, cancer, and management factors. Breakpoint analyses revealed a minimum threshold ELN count of 17 and an optimum count of 33, which were validated in both cohorts with good efficacy to differentiate probabilities of both stage migration and survival.

Conclusion

In resected nmGaC patients with anticipated survival ≥3 months, more ELNs are correlated with more accurate staging, which may partly explain the survival correlation. This observational investigation does not indicate causality. Our findings robustly conclude 17 ELNs as the minimum and propose 33 ELNs as the optimum thresholds, to assess the quality of lymph node examination and to stratify postsurgical survival.

Oncologic and surgical outcomes for gastric cancer patients undergoing gastrectomy differ by race in the United States

INTRODUCTION

Gastric adenocarcinoma lymph node retrieval during gastrectomy and survival differ significantly between Asian and Western studies. It is unclear whether such disparities are the result of surgical technique, patient population, or other factors. In this observational study, we aimed to determine whether lymph node retrieval and outcomes differ between White, Black, and Asian American patients undergoing gastrectomy for adenocarcinoma.

MATERIALS AND METHODS

47,217 cases of gastric resection for gastric adenocarcinoma and its subtypes were identified in the National Cancer Data Base (2000-2015). Differences in demographics, lymph node retrieval, operative outcomes, and survival were compared by self-reported race (White, Black, and Asian).

RESULTS

Asians had greater median lymph node retrieval (17) compared to White (15) and Black (16) patients, P < 0.001. Lymph node ratio was lowest in Asian (0.03) compared to White (0.05) and Black (0.09) patients, P < 0.001. Postoperative mortality was lowest in Asian patients on multivariable analysis (90-day mortality adjusted odds ratio of 0.54, P < 0.001). Median survival was not yet reached for Asian patients but was 39.5 months for White and 43.0 months for Black patients (P < 0.001). Differences in survival by race persisted on multivariable analysis (Asian adjusted hazard ratio was 0.64, 95% CI: 0.59-0.70, P < 0.001).

CONCLUSIONS

Asian-American patients with gastric cancer undergoing gastrectomy have greater lymph node retrieval, decreased lymph node ratio, decreased postoperative mortality, and increased long-term survival compared to White or Black Americans. Data suggest factors other than surgical technique and oncologic care may be responsible for gastric adenocarcinoma outcome differences seen between Asian and Western studies.

Implications of clinical research on adjuvant chemotherapy for gastric cancer: Where to go next?

Postoperative adjuvant chemotherapy (ACT) confers superior gastric cancer (GC) survival in the Eastern cohort. However, is the current standard of ACT already excessive, or is it still necessary to increase its intensity for specific subgroups? Tailored ACT strategies for GC depend on gradual exploration by clinical trials in selected patients. Thus, understanding the implications of previous and current research can help us respond wisely and design effective, rational trials, save medical resources and make better decisions in clinical practice. After reviewing and analyzing studies on ACT for GC patients undergoing curative resection, we found that research strategies for conducting “addition” ACT for specific stages of the disease have achieved great progress in making ACT more tailored and personalized in consideration of pathology stages. Furthermore, trials indicate that “addition” ACT strategies for GC patient subgroups based on histological characteristics might be helpful to move toward a more specific tailored and personalized management approach. Designing ACT research focused on different node statuses should also be conducted according to the biological specificity of lymph node (LN) metastasis. Therefore, future trials designed to determine tailored treatment based on histological and biological characteristics for specific subgroups are urgently needed and conducted as the theme of the 2019 American Society of Clinical Oncology (ASCO): Caring for Every Patient, Learning from Every Patient.

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.

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.

Molecular classification of gastric cancer

INTRODUCTION

Gastric cancer is among the most common cancers worldwide. Despite declining incidences, the prognosis remains dismal in Western countries and is better in Asian countries with national cancer screening programs. Complete endoscopic or surgical resection of the primary tumor with or without lymphadenectomy offers the only chance of cure in the early stage of the disease. Survival of more locally advanced gastric cancers was improved by the introduction of perioperative, adjuvant and palliative chemotherapy. However, the identification and usage of novel predictive and diagnostic targets is urgently needed. Areas covered: Recent comprehensive molecular profiling of gastric cancer proposed four molecular subtypes, i.e. Epstein-Barr virus-associated, microsatellite instable, chromosomal instable and genomically stable carcinomas. The new molecular classification will spur clinical trials exploring novel targeted therapeutics. This review summarizes recent advancements of the molecular classification, and based on that, putative pitfalls for the development of tissue-based companion diagnostics, i.e. prevalence of actionable targets and therapeutic efficacy, tumor heterogeneity and tumor evolution, impact of ethnicity on gastric cancer biology, and standards of care in the East and West. Expert commentary: The overall low prevalence of actionable targets and tumor heterogeneity are the two main obstacles of precision medicine for gastric cancer.

Rates of lymph node metastasis and survival in T1a gastric adenocarcinoma in Western populations

BACKGROUND AND AIMS

EMR and endoscopic submucosal dissection (ESD) are widely accepted in Asia for treatment of early gastric cancer (EGC). Few studies have examined lymph node (LN) metastasis of EGC in Western populations. We sought to examine EGC and LN metastasis in a heterogeneous Western population.

METHODS

Patients with surgically resected, histologically confirmed American Joint Committee on Cancer T1a gastric adenocarcinoma were identified in the Surveillance, Epidemiology, and End Results (SEER) database from 2002 to 2012. Patients were excluded if they had stage IV disease, had multiple primary cancers, or received neoadjuvant therapy. Rates of LN metastasis were calculated, and survival analyses were performed.

RESULTS

Of 923 patients in the cohort, 72 (7.8%) had at least 1 positive LN on final pathology. When stratified by race, Asian/Pacific Islanders (APIs) demonstrated the lowest rate of LN metastases (n = 17/327, 5.2%), followed by Hispanics (n = 12/171, 7.0%), whites (n = 27/278, 9.7%), and blacks (n = 16/147, 10.9%). The highest rates of stage IA disease were observed in API (93.9%) and Hispanic (92.4%) patients, followed by white (89.9%) and black (87.1%) patients (P = .04). Survival analysis of T1a gastric cancer patients by race/ethnicity showed that 5-year overall survival was highest for API patients (API, 88%; Hispanic, 81%; black, 79%; and white, 77%; P < .01).

CONCLUSIONS

The rate of LN metastasis in T1a gastric cancers in the United States is higher than the rates reported in Asia. Survival outcomes in T1a gastric cancers varied significantly by race, suggesting that definitive endoscopic treatment may not be appropriate for all patients in the United States.

Overall Survival Is Impacted by Birthplace and Not Extent of Surgery in Asian Americans with Resectable Gastric Cancer

Survival from gastric cancer in the USA still lags behind Asia. Genetic, environmental, and tumor biology differences, along with extent of surgery have been implicated. Our aim was to evaluate survival outcomes in Asian-American gastric cancer patients undergoing surgical resection by comparing place of birth and clinicopathologic characteristics (including evaluation of 15 lymph nodes).The Surveillance, Epidemiology, and End Results database was queried to identify patients treated surgically for gastric cancer with curative intent in the USA (2000-2010). US-born versus foreign-born Asian-American patients were analyzed for survival. Secondary comparison was made to non-Asian patients. Stage IV and non-surgical patients were excluded. Of 10,089 patients identified, 1467 patients were Asian: 271 were born in the USA, and 1196 were born outside the USA. Median survival was 32 months for non-Asians and 29 months for US-born Asians versus 61 months for Asian immigrants (p < 0.001). On multivariable analysis of overall survival in Asian patients, only US birthplace, older age, and higher stage yielded a significantly poorer outcome. Asian-American patients have a worse prognosis if born in the USA. Anatomic and surgical differences do not explain this disparity; environmental factors may be responsible.

Validating the prognostic and discriminating value of the TNM-classification for gastric cancer - a critical appraisal

AIM

We investigated the effect of the new tumour-, node-, metastasis- (TNM) classification on predicting and discriminating gastric cancer patient prognosis using the National Cancer Institute's Surveillance, Epidemiology and End Results (SEER) Program.

PATIENTS AND METHODS

From the SEER-database we retrieved gastric cancer patients with a primary adenocarcinoma, of Caucasian or Asian ethnicity and without distant metastases (M0). The pTNM-stage was determined according to the 7th edition of the union internationale contre le cancer (UICC) guidelines.

RESULTS

Spanning the period 2004-2010, 6136 patients fulfilled all inclusion criteria including 3424 (55.8%) men, 2712 (44.2%) women, 4629 (75.4%) Caucasian and 1507 (24.6%) Asian patients. 1524 (24.8%) patients underwent total gastrectomy and 4612 (75.2%) non-total gastrectomy. Only in 41.2% of the patients were >15 lymph nodes resected. 1857 (31.0%) patients received radiotherapy. Patient survival depended on ethnicity, type of surgery and radiotherapy. The discriminating value of the UICC-stage grouping could not be validated for Caucasian patients with >15 lymph nodes resected and who had not received radiotherapy: stage groups IIB, IIIA, IIIB and IIIC showed substantial overlap in survival ranges. In addition, the tumour specific survival of the different T-/N-combinations was significantly different in stage groups IIIB and IIIC, respectively.

CONCLUSIONS

Our retrospective analysis of the SEER-database does not validate the discriminating value of stage grouping of the 7th edition of the UICC-stage grouping. A revision should be considered and more reliable prognostic biomarkers are urgently needed.

Race/Ethnicity is predictive of lymph node status in patients with early gastric cancer

BACKGROUND

Race/ethnicity has long been suspected to affect survival in patients with gastric adenocarcinoma. However, the clinicohistopathological impact of race or ethnicity on early gastric cancer (EGC) is not known.

METHODS

From 2000 to 2013, 286 patients underwent gastrectomy and 104 patients had pathological confirmation of EGC. A retrospective analysis of pathological and clinical prognostic indicators was performed.

RESULTS

The study population consisted of 38 (37%) Asian Americans and 66 (63%) non-Asian Americans. Of these, 2 (5.3%) Asian Americans and 19 (28.8%) non-Asian Americans had pathological confirmation of lymph node metastasis (LNM) (p = 0.004). Univariate analysis comparing the clinicohistopathological characteristics in each group did not reveal significant difference regarding histotype, tumor size, grade, location, morphology, or lymphovascular invasion, except for the LNM rate and mean body mass index (23.2 versus 26.6, p < 0.001). Multivariate analysis showed that non-Asian race/ethnicity (odds ratio (OR), 9.09; 95% confidence interval (CI), 1.12-71.43; p = 0.038), younger age (OR, 1.11; 95% CI, 1.01-1.12; p = 0.046), and lymphovascular invasion (OR, 13.9; 95% CI, 2.40-79.99; p = 0.003) were significant predictors for LNM.

CONCLUSIONS

This study demonstrated that Asian American race in EGC is associated with a significantly decreased rate of LNM in comparison to non-Asian Americans, despite similar histopathological characteristics of each group.

Racial and ethnic disparities in gastric cancer outcomes: More important than surgical technique?

Racial and ethnic disparities in cancer care are major public health concerns and their identification is necessary to develop interventions to eliminate these disparities. We and others have previously observed marked disparities in gastric cancer outcomes between Eastern and Western patients. These disparities have long been attributed to surgical technique and extent of lymphadenectomy. However, more recent evidence suggests that other factors such as tumor biology, environmental factors such as Helicobacter pylori infection and stage migration may also significantly contribute to these observed disparities. We review the literature surrounding disparities in gastric cancer and provide data pertaining to potential contributing factors.