February 28, 2013

Study offers insights into gastric cancer prevention

Gastric cancer is the second leading cause of cancer death worldwide, with a particular burden in Latin America and eastern Asia.

Gastric cancer is the second leading cause of cancer death worldwide, with a particular burden in Latin America and eastern Asia.

Chronic infection with a bacterium known as Helicobacter pylori (H pylori)is the dominant risk factor for this form of cancer.

Douglas Morgan, M.D., MPH

A new study in Latin America designed to examine the efficacy of antibiotic treatment regimens found that geography, age, gender and adherence to treatment may be as important as the choice of antibiotic therapy to eradicate H pylori in the design of primary prevention programs.

The study by co-lead author Douglas Morgan, M.D., MPH, associate professor of Medicine at Vanderbilt University Medical Center, and colleagues was published in the Feb. 13 issue of the Journal of the American Medical Association (JAMA).

H pylori is the most common chronic bacterial infection in the world and it is highly prevalent in developing nations.

In this H pylori eradication trial, the largest ever of its kind, investigators identified 1,463 infected patients ages 21 to 65 at seven Latin American sites in Mexico, Colombia, Chile, Honduras, Costa Rica and Nicaragua. Patients were randomly assigned to receive one of three antibiotic regimens and were evaluated post-treatment and one year later to determine recurrence of the infection and overall eradication.

The overall efficacy was 79.3 percent, with no significant difference among the three antibiotic treatment groups.

However, there was a marked difference among study sites, with an effectiveness rate of 87 percent to 90 percent in Costa Rica and Honduras, compared with 71 percent to 76 percent in Colombia, Nicaragua and two sites in Mexico.

Authors postulated that regional differences in antibiotic resistance may play a role.

Adherence to treatment, gender and age were also important factors in infection recurrence rates.

Young women ages 21-44 were the most likely to experience infection recurrence, which “makes sense,” notes Morgan, “since young children and crowded households raise the overall risk of infection.”

Since young women are also a lower risk for stomach cancer, a tailored approach may be warranted, wherein eradication interventions target men and women at different ages.

“Focused intervention in the highest risk communities is advocated, not a shotgun approach,” Morgan said. “We also need continued efforts in basic science: to better understand transmission; to improve biomarkers to identify those at highest risk; and to develop novel antimicrobial strategies.

The consortium looks forward to future trials and large scale interventions in Latin America.

The study was funded by the Bill & Melinda Gates Foundation, with leadership from the Southwest Oncology Group, Larry Baker, D.O., and Bob Greenberg, M.D. The Southwest Oncology Group is supported through a grant from the National Cancer Institute, a division of the National Institutes of Health (CA037429).

Three of the study sites have close ties to Vanderbilt — Colombia, led by co-author Pelayo Correa, M.D., who holds the Anne Potter Wilson Chair in Cancer Research at VUMC, as well as Honduras and Nicaragua (Morgan).