Abstract
Background
A questionnaire that distinguishes how variability in gastric cancer prevalence is associated with ethnicity/birth country/immigration/cultural diet along with known risk factors may improve targeting populations for gastric cancer screening in the United States.
Methods
Existing literature was used to identify the item pool. Cluster analysis, focus groups and cognitive interviewing were used to reduce collinear items and refine the questionnaire. Logistic regression analysis was used to determine which items distinguished gastric cancer cases from the primary care and community controls.
Results
Analysis of data from 40 cases and 100 controls (primary care=47; community =53) were used to reduce the 227 item pool to 12 items. After ranking these variables using model bootstrapping, a logistic regression model using the highest ranked 8 variables was chosen as the final model. Older age, foreign nativity, daily consumption of cultural food at ages 15 to 18, less than high-school education and greater acculturation were significantly associated with being a gastric cancer case compared to the controls.
Conclusions
An 8-item survey that addresses gastric cancer risk factors, ethnicity, cultural habits and immigration patterns has potential to identify high-risk persons from multicultural areas within the US, who might benefit from endoscopic screening for gastric cancer.
Keywords: Gastric Cancer Screening, Risk Prediction Model, Early detection of Gastric Cancer, Risk Assessment Questionnaire
Introduction
Gastric adenocarcinoma is the fifth most common cancer and third leading cause of cancer mortality in the world, with an estimated 723,000 deaths in 2012.1 In the United States (US), gastric cancer is one of the deadliest cancers ranking only behind lung, pancreas, and esophageal cancer.2 Screening for gastric cancer has been shown to be effective and attribute a 30-60% decrease in gastric cancer mortality in countries with national gastric cancer screening programs.3–5 Despite the success of gastric cancer screening programs in high-incidence countries, screening for gastric cancer is not performed in the US due to the low incidence rate of the disease (3.9 cases per 100,000 in the general population).1
In a low incidence region such as the US, screening persons at higher risk would make screening feasible.6 Methods to identify persons at risk should be easy to administer and applicable in both health care and community settings. There are many well known risk factors for gastric cancer, including diet, lifestyle, older age, gender, race, tobacco smoking, radiation, family history, Helicobacter pylori infection, low socioeconomic status, high intake of salty and smoked foods, low consumption of fruits and vegetables, obesity and gastroesophageal reflux disease (GERD).7,8 However, little is known about which of these variables will be most contributory in the discrimination of gastric cancer risk in the US with its extraordinary ethnic and racially diverse population.
Racial and ethnic minorities represent 38.3% of the total US population.9 Among these groups, there is large variation in gastric cancer incidence. African Americans, Hispanics, Asians, and Pacific Islanders have 1.7-2.0 fold higher incidence than Whites.10–12 Foreign-born immigrants from high-incidence countries continue to have a higher risk of gastric cancer even after immigration.13–16 Yet, few studies have examined gastric cancer risk factors across the various ethnicities and racial subgroups in the US. Additionally, there are few studies evaluating country of birth, immigration, and cultural dietary habits as risk factors among various ethnic subgroups in the US. These factors, in combination with known risk factors, may help identify a sub-population at elevated risk that might benefit from gastric cancer screening.
To this end, our ultimate long-term goal is to develop a short pre-screening questionnaire that can be used in both the community setting and health care settings to identify persons at high risk for gastric cancer so they can undergo screening endoscopy. As a preliminary step to a population–based, case-control study of gastric cancer risk factors in the US, we developed and pilot tested a risk assessment questionnaire. The aims of the present pilot case-control study were to 1) develop the item pool to assess gastric cancer risk in the US, 2) establish and test the procedures for optimal case and control ascertainment, and 3) analyze the pilot case-control data that were obtained in two health care sites serving racially and ethnically diverse patient populations.
Methods
Materials and process
Exposure was assessed through information collected from a comprehensive questionnaire created specifically for this purpose. The details of the questionnaire development process are provided in Appendix 1. A literature review was conducted to design a questionnaire to collect data on known risk factors for gastric cancer. A preliminary draft of the questionnaire was reviewed and modified through focus groups for the comprehensibility of survey questions. Risk factors assessed included demographics, race, socioeconomic status, food frequency, smoking and alcohol habits, family history, and Helicobacter pylori exposure, as well as less well studied factors that have potential to be highly discriminating in a multicultural country such as the US, including ethnicity, country of birth, acculturation index and lifetime ethnic dietary habits. A complete list of risk factors, references and questionnaires used to create the questionnaire is shown in table 1. The questionnaire then went through a process of translation and back-translation into Spanish, Mandarin Chinese and Korean. Cognitive interviews were used to test comprehension of the questionnaire in different ethnic populations and ensure items carried the same meaning across languages.
Table 1.
Gastric Cancer Risk Factors, Strength of Association and Questionnaires Used for development of gastric cancer risk questionnaire
| Strength of Association (OR Range) | Questionnaires Used | References | |
|---|---|---|---|
| Diet (129 questions) | |||
| Fruit intake | 1.1–1.65 | Nurses’ Health Study Questionnaire | [38–43] |
| Vegetable Intake | 1.25–1.65 | Nurses’ Health Study Questionnaire | [38–45] |
| Allium vegetable intake | 1.4–2.0 | ACS Cancer Prevention Study Questionnaire, based on questions asked in Gao 1999 and You 1989 (questionnaire not available) | [26] [46], [47] [48–50] |
| Red meat consumption | 1.4–1.7 | Hutchinson Cancer Center FFQ, ACS Cancer Prevention Study Questionnaire | [23][51–53] |
| Processed meats | 1.15–1.45 | Hutchinson Cancer Center FFQ, ACS Cancer Prevention Study Questionnaire | [23] [51–56] |
| Soy (low vs. high) | 1.4–3.3 | Ko 14-item FFQ, ACS Cancer Prevention Study Questionnaire | [26] [57] |
| Salt consumption | 1.4–2.2 | Ko 14-item FFQ | [23, 26, 39] |
| Pickled foods | 1.25–2.2 | Hutchinson Cancer Center FFQ | [42, 44, 53, 55, 58] |
| Chili consumption | 1.9 | Hutchinson Cancer Center FFQ, Ko 14-item FFQ, ACS Cancer Prevention Study Questionnaire, | [39], [59] |
| Fiber (low vs. high) | 1.65–2.0 | Hutchinson Cancer Center FFQ, ACS Cancer Prevention Study Questionnaire | [60, 61] |
| General dietary questions | - | Added by study team | - |
| Lifetime intake of fruits, vegetables, meat, bbq smoked foods, processed meats | - | ACS Cancer Prevention Study Questionnaire | - |
| Vitamins and supplements | 1.4–1.65 | Swedish Mammography Study Questionnaire, Hutchinson Cancer Center FFQ | [62–64], [65–67] |
| Lifestyle (12 Questions) | |||
| Physical Activity | 1.2–1.4 | NIH-AARP Baseline Questionnaire 1995 | [68],[69] |
| Smoking | 1.2 – 1.7 | NIH-AARP Baseline Questionnaire 1995 | [70–74],[75] |
| Alcohol Consumption | 0.9–1.4 | Million Women’s Health Study Questionnaire | [76–81],[82] |
| Lifetime exercise, smoking and alcohol habits | - | Added by study team | - |
| Quality of Health | - | Added by study team | - |
| Medical History (22 questions) | |||
| Body Mass Index | 1.05–1.2 | NIH-AARP Baseline Questionnaire 1995 | [83–86], [87] |
| Blood Type A | 1.1 | Added by study team | [88] |
| H. Pylori | 1.1–3.0 | Aklavik H. Pylori Project Clinical Questionnaire | [89–92], [93] |
| Antacids | 1.4 | NIH-AARP Risk Factor Questionnaire 1998 | [94] |
| NSAIDS (non-use) | 1.25–1.65 | NIH-AARP Risk Factor Questionnaire 1998 | [95–99], [100] |
| Family history of gastric cancer | 1.7–2.9 | Based on questions asked in Dhillon 2001 study (questionnaire not available) | [101–103] |
| Gastric-associated symptoms | - | Added by study team | |
| Prior medical care/screening | - | Added by study team | |
| Immigration/Acculturation | |||
| Country of origin | - | HCHS/SOL Personal Information Questionnaire | |
| Immigration history | - | Cha-Cha Demographic Questionnaire | |
| Vancouver acculturation scale (degree of agreement on scale of 1–9 with statements about American culture and own culture) | - | Vancouver Acculturation Index | |
| Ethnic food intake | 1.6 | Added by study team | [81] |
| Demographics (11 questions) | |||
| Gender | - | NIH-AARP Study Questionnaire 1995 | - |
| Marital Status | NIH-AARP Study Questionnaire 1995 | - | |
| Date of Birth | - | NIH-AARP Study Questionnaire 1995 | - |
| Low SES | - | HCHS/SOL Economic Questionnaire | [104] |
| Occupation | 1.25, N.S. | HCHS/SOL Occupation Classification and Exposures Questionnaire | [104] |
| Education | 4.3 | NIH-AARP Baseline Questionnaire 1995 | [104, 105] |
| Race/ethnicity | 3.0 | U. S. Census Bureau American Community Survey | - |
Case-control Selection
A pilot case-control study was conducted using the final version of the questionnaire to examine the feasibility of recruiting participants in primary care (PC-controls) and community settings (community control) and to identify questionnaire items that distinguish gastric cancer cases from non-cancer controls. A patient list of persons with gastric cancer and persons served in primary care clinics was obtained from two sites, a large urban academic medical center and a inner city public hospital. Both serve a large population of ethnic minorities. After excluding subjects who did not meet age and health-related eligibility criteria, invitation mailings were sent to eligible recruits providing study details and the opportunity to opt out if they did not wish to participate. Patients who did not opt out were contacted by phone for participation. PC-control phone recruitment proved problematic, and recruitment strategy was expanded to direct clinic recruitment for the remaining two-thirds of the PC-controls. Verbal or written informed consent was obtained from all study participants. Participants were initially asked to complete survey questions by telephone interview. This was modified to include paper survey administration about mid-way in the study. The study protocol was approved by the institutional review boards of each site.
Inclusion criteria for the cases and controls were as follows: 1) ages 40 to 85 years old, 2) mental and physical ability to participate, 3) no prior cancer diagnosis (other than gastric cancer or non-melanoma skin cancers), 4) no prior diagnosis that requires endoscopic surveillance (Barrett’s esophagus, esophageal or gastric adenoma, gastric ulcer, etc.), and 4) no known personal or family history of genetic syndromes associated with higher risk of gastric cancer (i.e. hereditary diffuse gastric cancer, Peutz-Jeghers syndrome, familial adenomatous polyposis, hereditary non-polyposis colorectal cancer, and Li-Fraumeni syndrome). Cases also needed to meet the following criterion: diagnosed with biopsy-proven gastric adenocarcinoma in the last five years.
A database was created for data input using SurveyMonkey® (San Mateo, CA). Interview staff entered phone interview responses directly into the database at the time of interview. Paper surveys were collected and separately entered into the database.
Statistical Analysis
Our primary goal of this pilot analysis was to see if it is feasible to develop a logistic regression model to distinguish cases from controls. The cognitive interview data (n=60) were combined with the pilot case-control data (n=90) for the analysis. This was acceptable given that interviews were conducted using translated versions of the completed comprehensive questionnaire, and the case and control selection generally followed the same protocol as the pilot case-control study.
Age was examined in 1-year increments for the model but presented as <55, 55-69 and greater than 70 in the descriptive tables. Race was categorized as non-Hispanic (NH) white, NH-Black, Hispanic and Asian/Pacific Islander (PI)/other. US generation was classified as US-born with one or both parents being US-born (3rd generation), US-born with both parents being foreign-born (2nd generation) and being foreign-born (1st generation). The incidence rate of gastric cancer in a given country where the participant was born as reported by the WHO GLOBOCAN [1] (IR_GCa) was categorized into 3 categories; <5, 5-<15 and 15 or more cases per 100,000. The frequency of cultural food consumption at ages 15 to 18 years was categorized as daily or more, less than daily and never or rarely. The Vancouver Index is a series of questions aimed at assessing a person’s level of acculturation. The questions are examined as heritage subscore and mainstream subscore [17]. Heritage subscore was grouped into tertiles. Alcohol consumption was ascertained as any frequency of any alcohol and aggregated as more than 4 times per week, 2-3 times per week and less than once per week. The frequency of barbequed foods (BBQ) was categorized as greater or less than once per week. PC-controls and community-controls were combined for the analysis.
Given the large number of items and limited sample size, we first underwent a process of item reduction. Items first underwent a quality check and were dropped if response sets were out of range or had inconsistent values and outliers. Cluster analysis was then performed for domains with large numbers of items, namely the food frequency items and acculturation items. The resulting items when checked and removed if found to be collinear. Due to the small sample size, we found the use of a single regression model to be unstable, so we used a bootstrapping technique of entering the items into a multivariable model with selection algorithms (backwards and stepwise elimination procedures) to rank the variables that most commonly pass the selection algorithms [18]. The top-ranked variables were then used to generate an adjusted regression model. The model with the least number of items, and with all individual variable chi-square p-values having values of <0.2 was chosen.
Information on the numbers of participants eligible, contacted, recruited and enrolled was collected at the time of recruitment. Information on difficulties encountered during survey administration and reasons for non-completion or withdrawal were collected and analyzed. All analysis was performed using SAS 9.4 (Cary, NC).
Results
Recruitment and participant characteristics
The recruitment process for the pilot case-control study is shown in Figure 1. Of 218 cases approached, 103 (47%) were unreachable and 30 (14%) were deceased. Of the 72 eligible cases that remained, 39 (54%) were recruited and 30 completed the survey. Of the 191 PC-controls that were approached, we found 96 (50%) were unreachable. Of 84 eligible persons, 61 (73%) refused participation. Reasons cited were lack of interest (38%), survey being too lengthy (18%), being too busy (18%), not being comfortable doing a phone interview (15%) and language barrier (13%). With a completion rate of only 5% using phone recruitment, we expanded the PC-control recruitment to direct recruitment in clinics. This had greater success with only 37% refusal rate and ultimate completion rate of 34%. Community control recruitment was fairly successful, with a recruitment rate of 52%, and a completion rate of 28%.
Figure 1.

Recruitment and Interview Flowchart of Pilot Study
Data from 40 cases, 47 PC-controls and 53 community controls were eligible for analysis using combined data from cognitive interviews and pilot study and after exclusion of persons obtained from outside of catchment areas (n=10).
A comparison of PC-controls and community-controls is shown in Appendix 2. There were more PC control participants that were older than 70 (17% vs. 6%), Black (40% vs. 26%), and education level > high school (HS) (47% vs. 64%) than community controls. PC controls had less participants that had IR_GCa >15 (4% vs. 19%). Most noticeably, PC-controls more often completed phone interviews (72% vs. 7%) while community controls generally completed paper surveys (93% vs. 28%).
Preliminary analysis of risk factors
The final survey questionnaire contained a pool of 227 items after the process of systematic review, focus groups and cognitive interviews. Appendix 3 describes the item reduction steps performed to identify the most predictive variable items with minimal collinearity. This resulted in the selection of 12 items. After ranking these variables using model bootstrapping, a logistic regression model using the highest ranked 8 variables was chosen as the final model.
In comparing gastric cancer cases to the controls (Table 2), gastric cancer cases were predominantly older (>55: 92% vs. 55%, p<0.01), male (50% vs. 24%, p<0.01) and Hispanic (60% vs. 28%, p<0.01) and were less well educated (education>HS 28% vs. 56%). Cases were more often foreign-born (85% vs. 54%, p<0.01), and born in countries with higher rates of gastric cancer (IR_GCa ≥ 5 per 100,000: 63% vs. 36%, p<0.01) and reported daily consumption of their cultural food at ages 15 to 18 (68% vs. 36%, p<0.01). Cases and controls appeared similar in frequency of family history, acculturation, alcohol, smoking, and BBQ_freq.
Table 2.
Descriptive Analysis of Cases and Controls (n=140)
| Variables | Categories | Cases N=40 |
Controls N=100 |
p-value Fisher’s exact |
|---|---|---|---|---|
| Age | age <55 | 3 (7.5%) | 45 (45.0%) | <0.01 |
| age 55–69 | 21 (52.5%) | 44 (44.0%) | ||
| age 70+ | 16 (40.0%) | 11 (11.0%) | ||
| US generation | US born, one or both parents US born (3rd) | 2 (5.0%) | 10 (10.0%) | <0.01 |
| US born, both parents foreign born (2nd) | 4 (10.0%) | 36 (36.0%) | ||
| Foreign born (1st) | 33 (85.0%) | 54(54.0%) | ||
| Cultural food consumption frequency at ages 15 to 18 | Never or Rarely | 2 (5.0%) | 13 (13.0%) | <0.01 |
| Less than daily | 7 (17.5%) | 35 (35.0%) | ||
| Daily or more | 27 (67.5%) | 36 (36.0%) | ||
| Missing | 4 (10.0%) | 16 (16.0%) | ||
| Education | Less than HS | 19 (47.5%) | 19 (19.0%) | <0.01 |
| High School | 10 (25.0%) | 25 (25.0%) | ||
| Greater than HS | 11 (27.5%) | 56 (56.0%) | ||
| Family History of Gastric | No | 32 (80.0%) | 92 (92.0%) | 0.07 |
| Cancer | Yes | 8 (20.0%) | 8 (8.0%) | |
| Race | NH-White | 4 (10.0%) | 17 (17.0%) | <0.01 |
| NH-Black | 10 (25.0%) | 33 (33.0%) | ||
| Hispanic | 24 (60.0%) | 28 (28.0%) | ||
| Asian/PI/Other | 2 (5.0%) | 22 (22.0%) | ||
| Acculturation (Heritage Subscore) | Upper Tertile (less acculturated) | 12 (30.0%) | 29 (29.0%) | 0.30 |
| Middle Tertile (moderately acculturated) | 17 (42.5%) | 28 (28.0%) | ||
| Lower Tertile (more acculturated) | 7 (17.5%) | 30 (30.0%) | ||
| missing | 4 (10.0%) | 13 (13.0%) | ||
| Gender | Male | 20 (50.0%) | 24 (24.0%) | <0.01 |
| Female | 20 (50.0%) | 76 (76.0%) | ||
| Alcohol | Less than once per week | 21 (52.5%) | 66 (66.0%) | 0.18 |
| 2–3 times per week | 6 (15.0%) | 16 (16.0%) | ||
| More than 4 time per week | 12 (30.0%) | 14 (14.0%) | ||
| Missing | 1 (2.5%) | 4 (4.0%) | ||
| Gastric Cancer Incidence | <5 | 15 (37.5%) | 64 (64.0%) | 0.02 |
| Rate of Country of Birth | 5-<15 | 16 (40.0%) | 24 (24.0%) | |
| 15+ | 9 (22.5%) | 12 (12.0%) | ||
| Smoking | Yes | 18 (45.0%) | 32 (32.0%) | 0.17 |
| No | 22 (55.0%) | 68 (68.0%) | ||
| BBQ frequency | 1 per week or more | 5 (12.5%) | 16 (16.0%) | 0.12 |
| Less than once per week | 5 (12.5%) | 25 (25.0%) | ||
| Never or rarely (ref) | 29 (72.5%) | 59 (59.0%) | ||
| missing | 1 (2.5%) | 0 (0%) |
Table 3 shows the results of 8-variable logistic regression. The model showed excellent discrimination (concordance index 0.941 95% CI 0.901-0.982) and calibration (Hosmer and Lemeshow Goodness-of-fit test p=0.8562). Increasing age (per year) (OR=1.14, 95% CI=1.07-1.22), being foreign-born (1st generation) (vs. one or both parents US-born [3rd generation])(OR=15.78 95% CI=2.02-123.13), daily or more frequent consumption of cultural food at ages 15 to 18 (vs. never or rarely) (OR=25.07 95% CI 2.04-308.20), having less than a high school education (vs. more than a high school education) (OR=4.85 95%CI=1.20-19.61), and being more acculturated (heritage subscore: lower vs. upper tertile) (OR=5.81 95%CI= 1.14-29.62) were associated with being a gastric cancer case compared to controls. A family history of gastric cancer (vs. none) (OR=3.37, 95%CI=0.78-14.50) and being male (vs. female) (OR=2.95, 95%CI=0.94-9.25) trended toward association with being a gastric cancer case.
Table 3.
Logistic Regression Models Predicting being a Gastric Cancer Case
| Cases vs All Controls (c-statistic 0.942) |
Case vs PC Controls (c-statistic 0.938) |
Cases vs Community Controls (c-statistic 0.969) |
||||||||
|---|---|---|---|---|---|---|---|---|---|---|
|
| ||||||||||
| OR | 95% CI | p-value | OR | 95% CI | p-value | OR | 95% CI | p-value | ||
| Age (per year) | 1.14 | 1.07–1.22 | <0.001 | 1.12 | 1.05–1.20 | <0.001 | 1.20 | 1.08–1.32 | <0.001 | |
| US generation | US born, one or both parents US born (3rd) (ref) | ref | - | 0.025 | ref | - | 0.045 | ref | 0.510 | |
| US born, both parents foreign born (2nd) | 7.66 | 0.51–114.09 | 9.49 | 0.41–220.54 | 3.11 | 0.17–57.85 | ||||
| Foreign born (1st generation) | 15.78 | 2.02–123.13 | 15.78 | 1.69–147.15 | 3.81 | 0.39–36.99 | ||||
| Consumption of Cultural Foods at ages 15 to 18 | Daily or more | 25.07 | 2.04–308.20 | 0.014 | 7.06 | 0.34–146.46 | 0.079 | 84.08 | 3.67–1925.05 | 0.023 |
| Weekly or more (less than daily) | 3.11 | 0.29–32.96 | 0.90 | 0.04–19.78 | 7.85 | 0.48–127.71 | ||||
| Less than once per week (Ref) | ref | - | ref | - | ref | - | ||||
| missing | 2.97 | 0.14–61.92 | 0.85 | 0.02–32.85 | 0.71 | 0.02–31.45 | ||||
| Education | Less than High school | 4.85 | 1.20–19.61 | 0.082 | 5.28 | 0.85–32.69 | 0.188 | 4.99 | 0.81–30.74 | 0.224 |
| High School | 1.92 | 0.47–7.85 | 2.01 | 0.33–12.24 | 2.05 | 0.38–11.16 | ||||
| Greater than high school (ref) | ref | - | ref | - | ref | - | ||||
| Family history of GCa | No (ref) | ref | - | 0.103 | ref | - | 0.249 | ref | - | 0.202 |
| Yes | 3.37 | 0.78–14.50 | 2.65 | 0.51–13.87 | 3.79 | 0.49–29.34 | ||||
| Race | NH-White (ref) | ref | - | 0.106 | ref | - | 0.281 | ref | - | 0.051 |
| NH-Black | 0.63 | 0.12–3.40 | 0.27 | 0.03–2.46 | 2.66 | 0.32–22.34 | ||||
| Hispanic | 1.77 | 0.34–9.13 | 0.84 | 0.09–8.18 | 4.56 | 0.56–37.23 | ||||
| Asian/PI/Other | 0.16 | 0.02–1.49 | 0.19 | 0.01–2.71 | 0.11 | 0.01–1.79 | ||||
| Acculturation (Heritage Subscore) | Upper Tertile (less acculturated) | ref | - | 0.051 | ref | - | 0.135 | ref | - | 0.138 |
| Middle Tertile (moderately acculturated) | 2.83 | 0.69–11.61 | 1.32 | 0.24–7.34 | 4.43 | 0.64–30.43 | ||||
| Lower Tertile (more acculturation) | 5.81 | 1.14–29.62 | 5.14 | 0.72–36.94 | 7.21 | 0.93–55.90 | ||||
| missing | 42.74 | 2.33–784.12 | 48.06 | 1.61–1438.90 | 76.92 | 1.20–4919.15 | ||||
| Gender | Male | 2.95 | 0.94–9.25 | 0.064 | 2.78 | 0.74–10.49 | 0.132 | 1.92 | 0.47–7.78 | 0.362 |
| Female (ref) | ref | - | ref | - | ref | - | ||||
Bolded denotes statistical significance
When cases were compared to PC-controls alone, we found increasing age (per year) (OR=1.12, 95% CI=1.05-1.20) and being foreign-born (1st generation) (vs. 3rd generation) (OR=15.78 95% CI=1.69-147.15) to be significantly different for cases. When cases were compared to community controls alone, we found increasing age (per year) (OR=1.20, 95% CI=1.08-1.32) and daily or more frequent consumption of cultural food at ages 15 to 18 (vs. never or rarely) (OR=84.08 95% CI 3.67-1925.05) to be significantly different for cases.
Discussion
In this study, we successfully developed an item pool that could be used to assess gastric cancer risk that was comprehensible, culturally sensitive and able to be translated into multiple different languages. Control ascertainment proved to be challenging through phone recruitment and procedure modification to direct recruitment in primary care clinics was necessary. We also found that expanding our survey administration options to include phone interview and paper format resulted in increased completion rates.
The questionnaire item pool was developed to assess gastric cancer risk factors that could subsequently be used to identify the key variables able to discriminate between persons at higher risk for gastric cancer. Questionnaire items combined conventional factors known to be associated with gastric cancer risk with less studied items including ethnicity, birth country, acculturation and ethnic diet. Though our pilot data, we were able to show that racial/ethnic variables were significant even with this small sample size and our findings showed promise that the addition of these variables will result in identifying a parsimonious list of risk factors that could be easily applied to multiple settings and used for public health initiatives to screen gastric cancer patients.
Given the diversity of the US population, these ethnic/cultural variables provide a straightforward and practical way of indirectly incorporating the genetic makeup and environmental exposures that underlie differences seen between countries, races and ethnicities in their gastric cancer incidence. While the US reports a low incidence rate of gastric cancer at 5-10 cases per 100,000.19 this aggregate incidence rate masks very large racial and ethnic disparities.20,21 Although overall rates for whites are low, among Blacks, Asians, and Hispanics, gastric cancer is one of the 10 most common cancers in the US.22 In studies examining SEER population-based registry data by race and ethnicity, Asians/Pacific Islanders, Blacks, and Hispanics were observed to have a two times higher incidence rate of non-cardia gastric cancer as compared with Non-Hispanic whites.11,20,21 In a retrospective cohort study in Southern California, Dong et al. found up to 50% increased gastric cancer incidence risk in racial minorities compared to Non-Hispanic whites.23 However, race alone is inadequate at characterizing gastric cancer risk.
Our study found US generation, cultural food consumption during ages 15 to 18 and acculturation to be risk factors for gastric cancer. Our finding is constant with other literature that shows variation in risk by birth country, ethnic origin and immigration generation. In a study of first-generation Hispanic males in Florida, gastric cancer rates were higher for men from Puerto Rico (21.3 per 100,000) than those from Mexico (14.0) or Cuba (9.7).15 In a study of Asians living in the US, gastric cancer was a top 5 cancer for Koreans, Chinese, Japanese, Laotian and Vietnamese, but not for Asian Indians, Pakistani and Kampucheans.24 The higher incidence observed among immigrants from specific countries, not just in Asia but in the Latin America and Eastern Europe, demonstrates the importance of country of birth in characterizing gastric cancer risk.25,26 Interestingly, we found that after adjusting for other variables in the model, greater acculturation appeared to have a higher risk of gastric cancer. When the acculturation variables were examined by US generation, we found that many 3rd generation participants declined to answer these questions, which may attribute to this finding (appendix 4). An alternative explanation may be that once generation status is accounted for, that following “American” habits, such as consuming a western diet, which is known to be a risk factor,27 becomes more pronounced. Given our small sample size, this would need to be tested in a larger sample.
Although rates are highest among foreign-born Koreans and Japanese, studies indicate the incidence of gastric cancer remains high in US-born Japanese-American and Korean-Americans as compared with non-Hispanic whites.13, 14 Similarly, in a study examining incidence patters among Hispanics in California, gastric cancer was higher in both foreign-born Hispanic men and US-born Hispanic women residing in high ethnic enclave neighborhoods with low socioeconomic status.28 While gastric cancer risk generally decreases with each generation’s length of time in the US, it’s not clear why this occurs.29 The shift from traditional to more acculturated/Western diets without high intake of pickled and salted foods, differences in lifestyle and exposures in the built environment may elucidate gastric cancer risk in immigrant subgroups.28,30,31 These findings suggest that immigrants have specific cancer risks of their native countries32,33 and continue to have a higher risk of gastric cancer in subsequent generations after immigration.13–16. As such, immigration generation, as well as their level of acculturation, should be considered when determining the risk of gastric cancer.6,29,34
The variation in incidence and mortality for gastric cancer among different racial and ethnic populations pose a challenge for management. While the American Society for Gastrointestinal Endoscopy (ASGE) recommends screening new US immigrants above the age of 40 from high-risk endemic regions, namely Japan, Korea, China, Russia and South America,35 there are no recommendations for other high-risk groups in the US, including future- generation immigrants from endemic regions or for high-risk racial groups, such as Hispanic/Latinos and Black Americans. In a survey of primary care providers and gastroenterologists, less than 30% of providers were able to correctly identify and categorize individuals from Black, Hispanic and Eastern European ethnicities as “high risk” for gastric cancer. Although 53% of providers believed screening for select populations, 85% of providers answered that they did not routinely test and treat for H. pylori in patients from endemic areas that were otherwise asymptomatic. The results of this survey indicate the providers have an insufficient understanding of gastric cancer risk36 and educating providers as to which individuals comprise high-risk in the US as well as developing methods that can be used to easily and objectively identify persons at risk should be made a priority.
Our study has the following limitations; first, this pilot study collected data from a small number of subjects and the derived model should not be taken as a definitive model for risk prediction. Second, the questions included in our item pool were specifically selected to be applicable for a future development of a gastric cancer risk questionnaire, and not designed to be used to identify new or novel risk factors. As such, we omitted risk factors that were burdensome to administer (e.g. food frequency questionnaires), inconstant (e.g. vitamin supplement consumption, presence of symptoms) or could not be assessable in questionnaire form and only assessable through invasive methods or specialized testing (e.g. H. pylori, serum-pepsinogen-levels). Third, while there is a potential for H. pylori or serum-pepsinogen testing to further specify the degree of an individual’s risk, a given the significant knowledge gap of health care providers36 and lack of awareness in the general population,37 make it imperative that a method to identify high-risk patients in the general population be developed and established into practice. Lastly, stage information had not been collected as part of this study. This information would have been beneficial to explore whether the cancer stage of persons included in this study were largely different than the overall stage distribution for gastric cancer. This provided us guidance that we will need to collect this information for the large case-control study being informed by this pilot study.
In summary, this pilot study found that a risk prediction model using a parsimonious set of items has the potential to identify persons at higher risk for gastric cancer for use in a targeted screening program for gastric cancer in the US. The findings of this pilot case-control study will be used to refine the methods for a future large case-control study of gastric cancer risk factors in the US. A proposal for a large scale case-control study aimed to fully develop and validate a risk prediction model that can identify high-risk persons is currently underway. Once developed, the model would need to be prospectively examined as a targeted screening program using the model to first identify persons at higher risk followed by endoscopy to detect gastric cancer. Our ultimate goal is to establish a targeted screening program for gastric cancer to decrease gastric cancer mortality in the US.
Supplementary Material
Acknowledgments
Support: Research reported in this publication was supported by the National Cancer Institute of the National Institutes of Health under the Award Number UG1CA189823 (Alliance for Clinical Trials in Oncology NCORP Grant). Partial support also provided by the Montefiore Medical Center (MMC) minority-based NCORP community site (UG1CA189859). The content is solely the responsibility of the authors and does not necessarily represent the official views of the National Institutes of Health.
Footnotes
Publisher's Disclaimer: This is a PDF file of an unedited manuscript that has been accepted for publication. As a service to our customers we are providing this early version of the manuscript. The manuscript will undergo copyediting, typesetting, and review of the resulting proof before it is published in its final citable form. Please note that during the production process errors may be discovered which could affect the content, and all legal disclaimers that apply to the journal pertain.
Author Contributions:
Analysis and interpretation of data – HI, ML, CS
Editing and drafting of the manuscripts – ALL
Conception and design of study, and/or acquisition of data – HI, MS, CS, JW, BR
All authors gave final approval for the manuscript to be published
Conflict of Interest: none
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