Reining in Gastric Cancer

As more has been learned about the biology of cancer, physicians have gradually begun to adopt an individualized approach to cancer treatment, using a tumor's genomic profile to guide therapeutic decisions when possible. Now, the results of a study reported in the Journal of the American Medical Association that examined factors associated with the eradication of bacteria linked to gastric cancer suggest that a more tailored approach to cancer prevention programs may be more effective as well.

However, “fine-tuning larger prevention efforts isn't something we usually do,” says Douglas Morgan, MD, MPH, an associate professor of medicine in the Division of Gastroenterology at Vanderbilt University in Nashville, TN, and the study's lead author.

Helicobacter pylori infection is the dominant risk factor for gastric cancer, a leading cause of cancer death globally. The number of deaths from the disease is expected to increase as aging populations grow in Latin America and eastern Asia, the 2 regions of the world with the highest incidence rates. Evidence suggests that eradication of H. pylori infection prevents carcinogenesis.

In the study, funded by the Bill & Melinda Gates Foundation and led by SWOG, 1,463 people were treated in 7 Latin American communities in which 80% of the population was known to be infected with H. pylori bacteria. The study participants were randomly assigned to receive 1 of 3 drug regimens: lansoprazole, amoxicillin, and clarithromycin (triple therapy) for 14 days; lansoprazole and amoxicillin for 5 days followed by lansoprazole, clarithromycin, and metronidazole for 5 days (sequential therapy); or lansoprazole, amoxicillin, clarithromycin, and metronidazole for 5 days (concomitant therapy).

Among the 1,091 participants who tested negative for H. pylori infection after treatment and were rechecked a year later, 11.5% tested positive for the bacteria again. Although the researchers reported in 2011 that the standard triple therapy initially proved significantly more effective at eradicating H. pylori than did the sequential and concomitant therapies, the drug regimen was not significantly associated with the risk of reinfection or eradication probability a year later.

However, being male, being older than 45, having fewer children in the household, and adhering to initial therapy were all significantly associated with reduced risk of recurrent infection. Because crowded households with younger children raise the risk of infection, caregivers, who are usually younger women, are prone to reinfection, explains Morgan. He also notes that certain geographic regions may have higher rates of antibiotic resistance than others do, perhaps accounting for the significantly higher risk of reinfection in 4 of the communities.

The results suggest that large-scale prevention efforts can be effective, but that “we may need to move away from a one-size-fits-all approach,” comments Morgan. For example, because women tend to develop gastric cancer 10 to 15 years later than men, and because younger women have a higher risk of recurrent infection, H. pylori eradication programs could treat men starting at age 30 and delay treatment for women until age 40.

“We also need continued efforts in basic science to better understand transmission, improve biomarkers to identify those at highest risk, and develop novel antimicrobial strategies,” Morgan adds.