When Ohio State University cancer researchers first began studying a large sect of Amish living in Ohio, they theorized they would find higher incidence rates of cancer. Researchers hypothesized that because Amish religious beliefs and traditions limit contact with mainstream society, and because intermarriage within the relatively small population could increase the incidence of cancer-related gene mutations, cancer rates may be higher than in the general population.
Instead, “we found just the opposite,” said Dr. Judith Westman, division director of Human Genetics at The Ohio State University Comprehensive Cancer Center – Arthur G. James Cancer Hospital and Richard J. Solove Research Institute (OSUCCC-James).
The study of Amish suggests that clean living can lead to healthier life. Overall cancer rates in the studied population were 60 percent of the age-adjusted rate for Ohio and 56 percent of the national rate. The incidence of tobacco-related cancers in the Amish adults was 37 percent of the rate for Ohio adults, and the incidence of non-tobacco-related cancer was 72 percent.
“The Amish are at an increased risk for a number of genetic disorders but they probably have protection against many types of cancer both through their lifestyle – there is very little tobacco or alcohol use and limited sexual partners – and through genes that may reduce their susceptibility to cancer,” said Westman, who co-authored the study with OSUCCC-James researcher Amy K. Ferketich, who specializes in epidemiology.
The findings were reported in a recent issue of the journal Cancer Causes & Control. The study, which spanned 1996-2003 and is the first of its kind, looked at the incidence of 24 types of cancer in the Amish population. Of the 24 types of cancer studied, the incidence of seven of them – cervical, laryngeal, lung, oral cavity/pharyngeal, melanoma, breast and prostate – was low enough compared with the Ohio rate to be statistically significant.
Westman and Ferketich chose to study the Amish to gain a better understanding of the contributions of environment and genetics to developing cancer. Ohio is home to the largest Amish population in the world, and of the approximately 26,000 Amish living in Holmes County, all descended from the same 100 people who immigrated here 200 years ago.
Researchers interviewed 92 Amish families as part of a cross-sectional household survey and charted their family cancer histories obtaining cancer information on all relatives back three generations and as far forward as possible. For example, researchers interviewing a set of grandparents could gather cancer information on both their ancestors and descendants, said Ferketich.
The study population consisted of 9,992 Amish adults residing in the Holmes County area. Researchers also collected death certificates and cross-checked cancer cases reported to the Ohio Cancer Incidence and Surveillance System. Between 1996 and 2003, there were 191 incident cancer cases identified.
“Because this is a small, relatively closed population, we needed to interview just 92 families to cover 90 percent of the population in Holmes County,” said Ferketich.
The low cancer incidence in the Ohio Amish may be partially explained by lifestyle factors such as limited tobacco consumption and lack of sexual promiscuity. The Amish, as a whole, consume very little tobacco and alcohol, and they lead active, labor-intensive lives as farmers, construction laborers and factory workers.
“One of the things we can learn from the Amish is that they don’t typically smoke or use tobacco products,” Westman said. “They have limited sexual partners and monogamous relationships, so they don’t have some of the cancers that are related to sexual promiscuity.”
Even skin cancer rates are lower for Amish, despite the fact that many Amish make their living working outdoors where they are exposed to sunlight and UV rays. “They are typically covered and dress to work in the sun the way that is recommended by wearing wide-brimmed hats and generally wearing long sleeves to protect their arms,” Westman said.
Other Ohio State researchers involved in the study include Steven N. MacEachern, J.R. Wilkins III, Robert T. Pilarski, Rebecca Nagy, Stanley Lemeshow, Albert de la Chapelle and Clara D. Bloomfield.
The study was funded by the Ohio Division of the American Cancer Society, National Institutes of Health and the Leukemia Clinical Research Foundation.