Studies Examine Incidence of Gastric Cancer, Benefits Associated With Chemotherapy Regimens

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The incidence of a certain type of gastric cancer has declined in the last 30 years for all age groups and races, except for whites 25–39 years of age, according to a study in the May 5 issue of JAMA. Another report in the same issue, based on an analysis of previous studies, finds that patients who receive chemotherapy after surgery for gastric cancer have a higher rate of survival compared with those patients who have surgery alone.

Although some tumors of the cardia may be related to gastroesophageal reflux, the majority of noncardia or distal gastric cancers are attributable to chronic infection by the bacterium Helicobacter pylori, according to a study by William R. Anderson, MD, of the National Cancer Institute (Rockville, Md), and colleagues.

“Overall, gastric cancer incidence has steadily declined in many countries over the past 50 years or longer. However, overall trends may mask important age-specific differences. Furthermore, the overall decline runs counter to the subsite-specific rise in cardia cancers that may be related to obesity and gastroesophageal reflux,” the authors write.

The researchers analyzed US population-based age-specific data for noncardia gastric cancer, using data from the National Cancer Institute's Surveillance, Epidemiology, and End Results program, which covers approximately 26% of the US population. From 1977 through 2006, there were 83 225 adults with new diagnoses of primary gastric cancer, including 39 003 noncardia cases.

The authors found that the overall, age-standardized annual incidence per 100 000 population declined during the study period from 5.9 to 4.0 in whites, from 13.7 to 9.5 in blacks, and from 17.8 to 11.7 in other races. “Age-specific trends among whites varied significantly between older and younger age groups: incidence per 100,000 declined significantly from 19.8 to 12.8 for ages 60 to 84 years and from 2.6 to 2.0 for ages 40 to 59 years but increased significantly from 0.27 to 0.45 for ages 25 to 39 years. Conversely, rates for all age groups declined or were stable among blacks and other races. Age-period-cohort analysis confirmed a significant increase in whites among younger cohorts born since 1952.”

In another study in the same issue of the journal, patients who underwent gastric cancer operations followed by chemotherapy were found to have a decreased risk of death and improved disease-free survival compared with patients who had surgery alone, according to an analysis of previous studies.

Xavier Paoletti, PhD, of the Institut National du Cancer (Boulogne, France) and colleagues with the Global Advanced/Adjuvant Stomach Tumor Research International Collaboration Group, assessed the benefit of adjuvant chemotherapy quantitatively through a meta-analysis based on individual patient data from all relevant trials. For this analysis, the researchers identified 31 eligible trials (6390 patients). As of 2010, individual patient data were available from 17 trials (3838 patients representing 60% of the targeted data) with a median (midpoint) follow-up of >7 years.

There were 1000 deaths among 1924 patients assigned to chemotherapy groups and 1067 deaths among 1857 patients assigned to surgery-only groups. The researchers found that there was a significant benefit from any chemotherapy compared with surgery alone, with the analysis indicating an overall 18% reduction in the risk of death with chemotherapy. The estimated median overall survival was 4.9 years in the surgery-only group versus 7.8 years in the group receiving adjuvant chemotherapy. An absolute improvement of approximately 6% in overall survival was observed after 5 years, and was maintained at 10 years. The 5-year overall survival increased from 49.6% to 55.3% with chemotherapy. Adjuvant chemotherapy was also associated with an 18% reduction in the risk of relapse, compared with surgery alone.

The authors conclude: “This patient-level meta-analysis shows that adjuvant fluorouracil-based chemotherapy, even in monotherapy, is associated with improvement in overall survival and is recommended for patients who have not received perioperative treatments after complete resection of their gastric cancer.” See: JAMA. 2010;303:1723–1728 and 1729–1737.