Identifying the Profile of -Negative Gastric Cancers: A Case-Only Analysis within the Stomach Cancer Pooling (StoP) Project.

BACKGROUND

The prevalence of -negative gastric cancer (HpNGC) can be as low as 1%, when infection is assessed using more sensitive tests or considering the presence of gastric atrophy. HpNGC may share a high-risk profile contributing to the occurrence of cancer in the absence of infection. We estimated the proportion of HpNGC, using different criteria to define infection status, and compared HpNGC and positive cases regarding gastric cancer risk factors.

METHODS

Cases from 12 studies from the Stomach cancer Pooling (StoP) Project providing data on infection status determined by serologic test were included. HpNGC was reclassified as positive (eight studies) when cases presented CagA markers (four studies), gastric atrophy (six studies), or advanced stage at diagnosis (three studies), and were compared with positive cases. A two-stage approach (random-effects models) was used to pool study-specific prevalence and adjusted odds ratios (OR).

RESULTS

Among non-cardia cases, the pooled prevalence of HpNGC was 22.4% ( = 166/853) and decreased to 7.0% ( = 55) when considering CagA status; estimates for all criteria were 21.8% ( = 276/1,325) and 6.6% ( = 97), respectively. HpNGC had a family history of gastric cancer more often [OR = 2.18; 95% confidence interval (CI), 1.03-4.61] and were current smokers (OR = 2.16; 95% CI, 0.52-9.02).

CONCLUSION

This study found a low prevalence of HpNGC, who are more likely to have a family history of gastric cancer in first-degree relatives.

IMPACT

Our results support that infection is present in most non-cardia gastric cancers, and suggest that HpNGC may have distinct patterns of exposure to other risk factors.