Data Version: 09/09/2026

There are 4 patients that did not consent and removed (not included in the total).

Note: Of 3046 total survey respondents, 2103 had complete data on 12 key variables (Consent, received germline genetic testing, genetic diagnosis, age at diagnosis (germline mutation), genetic test result, sex at birth, age range, cancer diagnosis, family history of stomach cancer, any gastric lesion, race/ethnicity, anti-acid medication/proton pump inhibitors). We proceed our analysis with n=2103 patients.

Figures

Self-reported cancer diagnosis. Note patients may indicate more than one cancer.

Self-reported race/ethnicity. Note patients may report more than one race/ethnicity.

Self-reported genes. Note patients may report more than one gene.

Self-reported genes among Stomach cancer patients. Note patients may report more than one gene.

Self-reported gastric lesions. Note patients may report more than one lesion.

Table 1. Overall demographics and health characteristics

Characteristic N = 2,1031
Baseline Age
    Less than 29 58 (2.8%)
    30-39 221 (11%)
    40-49 466 (22%)
    50-59 536 (25%)
    60-69 521 (25%)
    70 and over 300 (14%)
    Missing 1
Age at germline diagnosis (Median, IQRs) 48.0 (39.0, 57.0)
Sex
    Female 2,005 (95%)
    Male 98 (4.7%)
Race_Ethnicity
    American Indian, Alaska Native, or First Nations 1 (<0.1%)
    Asian or Asian American 30 (1.4%)
    Black or African-American 13 (0.6%)
    Hispanic White 21 (1.0%)
    Hispanic, Latino, or Latinx 47 (2.2%)
    Mixed race/ethnicity 35 (1.7%)
    Non-Hispanic White 1,936 (92%)
    Other 20 (1.0%)
Any_Gastric_Lesion 1,052 (50%)
H_pylori 145 (6.9%)
Fam_Hist_Stomach_Cancer
    Don't know 356 (17%)
    No 1,212 (58%)
    Yes 535 (25%)
Stomach_Cancer 54 (2.6%)
1 n (%); Median (Q1, Q3)

HR genes: ATM, BARD1, BRCA1, BRCA2, BRIP1, CHEK2, PALB2, RAD51C, RAD51D, NBN

Lynch genes: MLH1, MSH2, MSH6, PMS2, EPCAM

Hereditary Diffuse Gastric Cancer (HDGC) genes: CDH1, CTNNA1

Juvenile Polyposis Syndrome genes: SMAD4, BMPR1A

Peutz-Jeghers Syndrome gene: STK11 (also known as LKB1)

Li-Fraumeni Syndrome gene: TP53

Recessive cancer predisposition syndrome genes: MUTYH, NTHL1

All other genes not included: CDKN2A, ENG, NF1, PTEN

BRCA1/2 Subanalysis

Supplementary Table 1. Baseline characteristics of the BRCA1/2 carriers

Characteristic N = 9301
Age
    Less than 29 27 (2.9%)
    30-39 100 (11%)
    40-49 192 (21%)
    50-59 231 (25%)
    60-69 246 (26%)
    70 and over 133 (14%)
    Missing 1
Sex
    Female 888 (95%)
    Male 42 (4.5%)
Race_Ethnicity
    Asian or Asian American 16 (1.7%)
    Black or African-American 6 (0.6%)
    Hispanic White 8 (0.9%)
    Hispanic, Latino, or Latinx 26 (2.8%)
    Mixed race/ethnicity 10 (1.1%)
    Non-Hispanic White 861 (93%)
    Other 3 (0.3%)
Stomach_Cancer 13 (1.4%)
Colorectal_Cancer 11 (1.2%)
Breast_Cancer 297 (32%)
Ovarian_Cancer 45 (4.8%)
Fam_Hist_Breast_Cancer
    Don't know 23 (2.5%)
    No 154 (17%)
    Yes 753 (81%)
Fam_Hist_Stomach_Cancer
    Don't know 149 (16%)
    No 570 (61%)
    Yes 211 (23%)
Any_Gastric_Lesion 404 (43%)
Anti_acid_ever 543 (58%)
1 n (%)

Supplementary Table 2. Prevalence of H. pylori and gastric lesions among BRCA1/2 carriers

Characteristic Overall
N = 9301		 Both
N = 81		 BRCA1
N = 3571		 BRCA2
N = 5651		 p-value
H_pylori



0.42
    No 868 (93%) 7 (88%) 331 (93%) 530 (94%)
    Yes 62 (6.7%) 1 (13%) 26 (7.3%) 35 (6.2%)
Gastritis



0.82
    No 260 (64%) 4 (80%) 109 (65%) 147 (63%)
    Yes 144 (36%) 1 (20%) 58 (35%) 85 (37%)
    Missing 526 3 190 333
Gastric_Ulcer



0.72
    No 389 (96%) 5 (100%) 162 (97%) 222 (96%)
    Yes 15 (3.7%) 0 (0%) 5 (3.0%) 10 (4.3%)
    Missing 526 3 190 333
GERD



0.52
    No 100 (25%) 1 (20%) 37 (22%) 62 (27%)
    Yes 305 (75%) 4 (80%) 131 (78%) 170 (73%)
    Missing 525 3 189 333
Intestinal_Metaplasia



0.102
    No 393 (97%) 4 (80%) 164 (98%) 225 (97%)
    Yes 11 (2.7%) 1 (20%) 3 (1.8%) 7 (3.0%)
    Missing 526 3 190 333
Barretts_Esophagus



>0.92
    No 373 (92%) 5 (100%) 154 (92%) 214 (92%)
    Yes 31 (7.7%) 0 (0%) 13 (7.8%) 18 (7.8%)
    Missing 526 3 190 333
Pernicious_Anemia



0.132
    No 403 (43%) 5 (63%) 166 (46%) 232 (41%)
    Yes 527 (57%) 3 (38%) 191 (54%) 333 (59%)
Stomach_Cancer



>0.92
    No 917 (99%) 8 (100%) 352 (99%) 557 (99%)
    Yes 13 (1.4%) 0 (0%) 5 (1.4%) 8 (1.4%)
Colorectal_Cancer



0.0082
    No 919 (99%) 7 (88%) 350 (98%) 562 (99%)
    Yes 11 (1.2%) 1 (13%) 7 (2.0%) 3 (0.5%)
1 n (%)
2 Fisher’s exact test 
## # A tibble: 8 × 6
##   Q32               age_clean n_genes Any_Gastric_Lesion H_pylori Race_Ethnicity
##   <chr>                 <dbl>   <dbl> <fct>              <chr>    <chr>         
## 1 39                     39        14 Yes                No       Non-Hispanic …
## 2 18                     18         2 No                 No       Non-Hispanic …
## 3 37                     37         4 No                 No       Non-Hispanic …
## 4 52                     52         2 Yes                No       Non-Hispanic …
## 5 2005                   49.5       2 Yes                No       Hispanic, Lat…
## 6 between 30-40 yr…      35         2 No                 No       Non-Hispanic …
## 7 49                     49         2 Yes                No       Non-Hispanic …
## 8 28                     28         4 Yes                Yes      Asian or Asia…
## $`FALSE`
##    Min. 1st Qu.  Median    Mean 3rd Qu.    Max. 
##    16.0    37.0    45.0    45.3    54.0    79.0 
## 
## $`TRUE`
##    Min. 1st Qu.  Median    Mean 3rd Qu.    Max. 
##   18.00   33.25   38.00   38.44   49.12   52.00
## 
##  Wilcoxon rank sum test with continuity correction
## 
## data:  age_clean by is_both
## W = 4784.5, p-value = 0.1473
## alternative hypothesis: true location shift is not equal to 0
## 
##  No Yes 
##   3   5
##      
##       FALSE TRUE
##   No    523    3
##   Yes   399    5
## 
##  Fisher's Exact Test for Count Data
## 
## data:  table(dfbrca$Any_Gastric_Lesion, dfbrca$is_both)
## p-value = 0.3044
## alternative hypothesis: true odds ratio is not equal to 1
## 95 percent confidence interval:
##   0.4218716 14.1387603
## sample estimates:
## odds ratio 
##   2.182808
## 
##  No Yes 
##   7   1
##      
##       FALSE TRUE
##   No    861    7
##   Yes    61    1
## 
##  Fisher's Exact Test for Count Data
## 
## data:  table(dfbrca$is_both, dfbrca$H_pylori)
## p-value = 0.4254
## alternative hypothesis: true odds ratio is not equal to 1
## 95 percent confidence interval:
##   0.04402686 16.09117539
## sample estimates:
## odds ratio 
##    2.01435
## 
##     Asian or Asian American Hispanic, Latino, or Latinx 
##                           1                           1 
##          Non-Hispanic White 
##                           6
##                              
##                               FALSE TRUE
##   Asian or Asian American        15    1
##   Black or African-American       6    0
##   Hispanic White                  8    0
##   Hispanic, Latino, or Latinx    25    1
##   Mixed race/ethnicity           10    0
##   Non-Hispanic White            855    6
##   Other                           3    0
## 
##  Fisher's Exact Test for Count Data
## 
## data:  table(dfbrca$is_both, dfbrca$white)
## p-value = 0.1136
## alternative hypothesis: true odds ratio is not equal to 1
## 95 percent confidence interval:
##  0.04114899 2.43208733
## sample estimates:
## odds ratio 
##  0.2357337
## 
##  Fisher's Exact Test for Count Data
## 
## data:  table(dfbrca$Race_Ethnicity, dfbrca$is_both)
## p-value = 0.1287
## alternative hypothesis: two.sided
## $`FALSE`
##    Min. 1st Qu.  Median    Mean 3rd Qu.    Max. 
##   1.000   1.000   1.000   1.088   1.000   4.000 
## 
## $`TRUE`
##    Min. 1st Qu.  Median    Mean 3rd Qu.    Max. 
##       2       2       2       4       4      14
## 
##  Wilcoxon rank sum test with continuity correction
## 
## data:  n_genes by is_both
## W = 201, p-value < 2.2e-16
## alternative hypothesis: true location shift is not equal to 0