Asians May Have an Edge in Battling Prostate Cancer
A new study focusing on Asian-American men gives prostate cancer patients one more factor to ponder—on top of many well-established considerations—when selecting a treatment strategy. The data, which appear in the September issue of Cancer, highlight that the disease can follow significantly different courses in different ethnic groups.
Previous studies have shown that Asian-Americans get diagnosed with prostate cancer less frequently, while African-Americans get diagnosed more frequently and at an especially advanced and lethal stage in comparison with whites. (Consequently, early and frequent screening is particularly important in blacks.)
Now, researchers have found another advantage to being of Asian descent: Some factor seems to partially shield most groups even when they do develop the cancer. The study found that average survival time was longer in five of the six Asian ethnic groups that were analyzed than it was among whites, even though initial factors suggested the Asians might die first. The risk of a Japanese-American prostate patient dying, for example, is 34 percent lower than it is for a white patient, according to the study. An exception, however, highlights the limitations of clumping multiple Asian ethnicities into one group: South Asians have worse survival rates than whites by some 40 percent, the study found.
"For nearly all the groups we studied, being Asian seems to give you a favorable prognosis," says Anthony Robbins, a study author and epidemiologist with the California Cancer Registry in Sacramento. He and his colleagues hypothesize that Asian-American dietary patterns—which tend to include less fat, more soy, and more vegetables than a typical American diet—may play a role. Likewise, levels of testosterone, a hormone that aids prostate tumor growth, tend to be lower among Asians, according to some studies.
Mark Scholz, cofounder of the Prostate Cancer Research Institute in Los Angeles, subscribes to the view that diet is the critical factor, and he argues that the medical community has been slow to recognize that high-fat diets promote tumor growth. "In the United States, cancers grow better because we feed them better," he says. Scholz even recommends a vegetarian diet to his prostate cancer patients, though he cautions against overloading on soy.
Robbins's hunch, however, is that the "Asian edge" is primarily due to the fact that Asians tend to have good health overall when they're diagnosed with prostate cancer. He says they tend to suffer from fewer coexisting medical conditions, such as heart disease or obesity, which may make them more robust and able to withstand prostate cancer treatment.
Whatever the reason, a good prognosis might encourage a patient to turn down aggressive treatment—and thus avoid the high likelihood of suffering treatment-related side effects. But patients can't simply use their ethnicity to make treatment choices, Robbins cautions. "This is just one more piece of information that should go into the decision-making process," he says.