GASTRIC CANCER RISK WITH PERNICIOUS ANEMIA

Patients with pernicious anemia have an increased relative risk of developing gastric cancer, a meta-analytic review of relevant studies confirms.

The authors estimate a pooled gastric cancer incidence in pernicious anemia of 0.27% per person-years.

Although a risk of gastric cancer in relation to pernicious anemia is reported in the literature, the studies differ from each other in terms of sample size and methods for the identification of gastric cancer used during the follow-up period, said Dr. Bruno Annibale and colleagues from University Sapienza, Rome, Italy in a report online December 10 in Alimentary Pharmacology & Therapeutics.

"Gastric cancer is the most severe long-standing complication of pernicious anemia and, to our knowledge, this is the first systematic review on the estimate of gastric cancer incidence-rate," they note.

Through a literature search, the researchers identified 27 articles published between 1950 and 2011 that reported the incidence of gastric cancer in pernicious anemia.

In meta-analysis, the overall gastric cancer relative risk with pernicious anemia was 6.8 (95% CI 2.6 - 18.1).

Among a total of 22,417 patients, 417 new cases of gastric cancer were identified in 157,319 person-years of follow-up, corresponding to an overall pooled gastric cancer incidence-rate per person-year of 0.26%, with a range between 0% and 1.2%.

When the researchers considered only the six studies with active follow-up protocols involving gastroscopy and histology, the pooled gastric cancer incidence-rate per person-years was 0.27% (95% CI 0.25 - 0.29), corresponding to seven new gastric cancer cases observed in 2,563 person-years.

In their paper, the authors note that the range of annual incidence rates for gastric cancer in pernicious anemia overlaps that reported in the literature for patients with atrophic gastritis, which is between 0% and 1.8% per year.

In email to Reuters Health, study co-author Dr. Edith Lahner said an "important take home message is that patients with pernicious anemia should be considered patients with atrophic gastritis, a condition at higher risk for gastric cancer, in which regular endoscopic-histological monitoring seems to be of benefit."

She noted that an expert panel advised an interval of every three years, in a paper by Dinis-Ribeiro et al in Endoscopy this year.

"In other words, the atrophic gastritis associated with pernicious anemia seems not to be all that different from the atrophic gastritis without pernicious anemia," Dr. Lahner said.

In their paper, the authors point out that almost half of the studies they included in their analysis were of low or very low quality, based on the Newcastle-Ottawa Quality Scale for cohort studies, which permits a critical appraisal of data.

"Although the 27 included studies showed similar incidence rates for gastric cancer, clinical and methodological heterogeneity was present," they say. Ten studies were retrospective (37%), and hospital records were often the sources of patients for these studies. Nonetheless, they say the incidence-rates of gastric cancer were similar among the studies irrespective of the study design and the source of patients.

The overlap of the pooled gastric cancer incidence per person-year of 0.27%, calculated from the six studies with active follow up by gastroscopy and histology, and the overall estimate obtained by considering all studies supports the "robustness of our analysis," the authors say.

"Thus, the main finding of this systematic-review," they say, "is the similarity of the incidence-rates of gastric cancer, which are remarkably stable among all studies despite major heterogeneity between individual studies in terms of their design (country of study location, sources of selection of participants, sample size, type and methods of follow-up, methods for identification of gastric cancer)."

"At this point," Dr. Lahner said, "we need further studies to determine the extent of the gastric cancer risk and the usefulness and time scheduling of follow-up in patients with pernicious anemia."

In their paper, the authors say the increased risk for gastric neuroendocrine tumors in patients with pernicious anemia "could represent an additional potential rationale for endoscopic surveillance in these patients."

The study was supported by grants from the Italian Ministry for University and Research, PRIN 2007 and from University Sapienza of Rome 2010-2011 Italy. The authors have declared no conflicts of interest.