Is there an association between Helicobacter pylori cytotoxin Cag A seropositivity and risk for gastric cancer?
BACKGROUND
Since discovered in 1990, Cag A, a protein expressed by specific strains of Helicobacter pylori, was thought able to explain why only a few Helicobacter infected patients develop peptic diseases and gastric cancer. However, clinical trials provide discordant results.


METHODS
In this study we evaluate Helicobacter pylori and Cag A seropositivity in 35 cancer affected patients, in 36 gastritis affected patients and in 40 healthy blood donors by means of two commercially available fluorescence enzyme-immunoessay (ELISA).


RESULTS
Odds ratios determination strongly suggests that Cag A bearer Helicobacter strains play a pathogenetic role in gastric diseases (OR 4.23, 95% CI 3.22-5.24 for cancer versus healthy volunteers, OR 3.2, 95% CI 2.19-4.21 for gastritis versus asymptomatic patients), but is unable to demonstrate a direct carcinogenic activity (cancer-gastritis difference is not significant: OR 1.32, 95% CI 0.39-1.25).


CONCLUSIONS
Cag A seropositivity can be considered a risk factor for peptic disease, and only indirectly for gastric carcinoma. The paper also discuss some sampling, laboratory and statistical bias that can explain a wide eterogenity of the results reported in the literature.
Baiocchi
G L
GL
Department of Medical and Surgical Sciences, Surgical Clinic, University of Brescia, Italy.
Vettoretto
N
N
Colombrita
D
D
Giovanetti
M
M
Coniglio
A
A
Bonardelli
S
S
Pelizzari
A
A
Ronconi
M
M
Tiberio
G A
GA
Giulini
S M
SM
D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D000942:Antigens, Bacterial / Q000096:biosynthesis*; D001426:Bacterial Proteins / Q000096:biosynthesis*; D002277:Carcinoma / Q000453:epidemiology / Q000378:metabolism / Q000382:microbiology; D003603:Cytotoxins / Q000096:biosynthesis*; D004797:Enzyme-Linked Immunosorbent Assay; D005260:Female; D005753:Gastric Mucosa / Q000378:metabolism / Q000382:microbiology; D005756:Gastritis / Q000453:epidemiology / Q000378:metabolism / Q000382:microbiology; D016481:Helicobacter Infections / Q000453:epidemiology / Q000378:metabolism / Q000382:microbiology; D016480:Helicobacter pylori; D006801:Humans; D008297:Male; D008875:Middle Aged; D020133:Reverse Transcriptase Polymerase Chain Reaction; D012307:Risk Factors; D013274:Stomach Neoplasms / Q000453:epidemiology / Q000378:metabolism / Q000382:microbiology
D000942:Antigens, Bacterial; D001426:Bacterial Proteins; D003603:Cytotoxins; C080866:cagA protein, Helicobacter pylori