Keck study shows cancer risk dependent on behavior

A study released by researchers at Keck School of Medicine of USC this August indicated that cancer cases in Los Angeles County lie along ethnic and gender lines. Dennis Deapen, a professor of clinical preventative medicine at USC, authored the study which tracked more than 1.3 million cancer diagnoses over the course of 37 years. The book Cancer in Los Angeles County: Trends by Race/Ethnicity 1976-2012 details cancer trends along racial and generational lines.

Lihua Li, an assistant professor of preventative medicine at Keck, who co-authored the study described stark differences between socioeconomic classes. Li described each type of cancer as having its own particular demographic breakdown.

“Our study is a report card for cancer trends along racial and generational lines. We found striking disparities between races, ethnicities and social classes,” Li said. “Cancer comes in many different forms and types, and each cancer has a unique racial, ethnic profile. For example, breast cancer is actually more common among upper-class white women.”

The study found that breast cancer was the most common diagnosis among women in Los Angeles County, followed by colorectal cancer. According to the report, breast cancer on the whole appears to be on the decline, except for in Korean women.

Reported trends also showed that black men were the most likely to diagnosed with cancer, especially prostate cancer, and black people across gender lines were at a higher risk of developing cancer of the pancreas, kidney and esophagus. For men, the most prevalent diagnoses were prostate and lung cancer, respectively. The only exception being Vietnamese men, who have the highest incidence of lung cancer in their population.

The researchers used data from USC Norris Comprehensive Cancer Center, which is considered one of 45 nationwide comprehensive cancer centers. When a person in Los Angeles County is diagnosed with cancer, they unknowingly contribute to the state-mandated Norris database.

Los Angeles County has provided a diverse group of samples for the report. Immigrant populations living in the county have allowed the researchers to study the effects of the Western lifestyle on cancer type and frequency. In a statement, USC described that the risks of certain cancers which are prevalent in immigrants’ home countries — such as stomach and liver cancer — decrease when immigrants live in the U.S. In fact, stomach cancer, a leading cause of cancer deaths in the world, has been on a steady decline for the at-risk Korean and Japanese populations. Yet, certain cancer risks may increase upon migration to the U.S., including breast cancer.

“Asian women living in Los Angeles experience higher and continuously rising breast cancer risk compared to their counterparts living in Asia. That’s because breast cancer is more prevalent in developed countries with Westernized lifestyles,” USC said in the statement.

A significant conclusion of the study was that cancer is based more on environmental choices than commonly believed. Li attributes a large proportion of cancer risks to tobacco use, drug use, poor diet and a lack of exercise.

“Cancer risks change so quickly that it’s difficult to keep track. But we do know that while genetic factors account for a small percentage of cancer risk, the larger issues are behavioral,” Li said. “Most of the cancer cases are non-genetically based conditions.”

Li advises that people focus on their personal health, rather than looking at hereditary causes of cancer.

“We hope that these findings will remind people that health is behavioral. If you want to beat cancer, it’s better to start with yourself,” Li said.