Vanderbilt Investigating Cancer Disparities
Researchers at Vanderbilt University Medical Center are making notable strides in the fight against cancer, with several recent studies focused specifically on minority ethnic groups.
Asian Americans & Stomach Cancer
According to a release from Vanderbilt, a study published recently in Gastroenterology found non-white Americans, especially Asian Americans, are at disproportionately higher risk for gastric cancer compared to non-Hispanic white Americans.
The study analyzed California Cancer Registry data for the seven largest Asian American populations (Chinese, Japanese, Korean, Filipino, Vietnamese, South Asian and Southeast Asian), as well as for non-Hispanic whites, non-Hispanic blacks and Hispanic populations. Worldwide, gastric cancer is the fifth most common cancer and third leading cause of cancer-related death. In the United States, gastric cancer ranks 15th among cancers, but it afflicts non-white and non-Hispanic population groups disproportionately.
Narrowing the Gap
"This is a primary interest of mine from a public health and advocacy standpoint," said Shailja Shah, MD, MPH, assistant professor of Medicine at Vanderbilt University School of Medicine, the study's lead author and corresponding author. "Gastric cancer has been under appreciated in the U.S. We have clear screening guidelines for colorectal and esophageal cancer and clear surveillance intervals for their respective precancerous stages," she said.
"Annually, there are 10,000 more cases of gastric cancer in Americans compared to esophageal cancer," Shah continued. "Upper endoscopy can similarly detect gastric cancer in an early, potentially curative, stage as well as diagnose gastric precancerous changes that might warrant surveillance and lead to improved patient outcomes. Yet, we still do not have gastric cancer screening recommendations in the U.S. for higher risk populations. Why aren't we doing anything about it?"
Shah hopes this study will move the needle forward towards developing guidelines surrounding gastric cancer screening for earlier, pre-symptomatic detection. Shah has also conducted two studies demonstrating that upper endoscopy for gastric cancer screening at age 50 is cost effective in non-white, non-Hispanic populations, but not in non-Hispanic white populations.
"We specifically chose to analyze the age group age 50 years and older since this is the population that undergoes average-risk colorectal cancer screening and in certain groups, esophageal cancer screening," she explained. According to Shah, there's a precedence for gastric cancer screening, including decades-old endoscopy screening guidelines in Japan and Korea.
Breaking it Down
The population-based study revealed that non-white race and ethnic groups had a several-fold higher risk of developing stomach cancer in the main area of the stomach (noncardia gastric cancer) compared to the non-Hispanic white population. This risk was most striking among Korean Americans age 50 and older, who demonstrated a 12-fold to 14.5-fold higher risk compared to non-Hispanic whites. This is the most common location for stomach cancer to develop. However, Asian Americans -- with the exception of Japanese American men -- had a lower risk than non-Hispanic whites of developing gastric cancer in the upper portion of the stomach where it joins the esophagus (cardia gastric cancer).
"Most Asians are lumped together in studies, but the aggregate 'Asian American' group represents at least 30 different countries with different diets, cultural beliefs and lifestyle factors," Shah said. "When we combine them, we potentially lose that differential aspect and might shroud important differences that can be leveraged for cancer reduction efforts."
The study revealed the incidence rate for Korean Americans was 49 cases per 100,000 people, 23.9 for Vietnamese Americans, 21.1 for Southeast Asian Americans (Cambodian, Laotian, Hmong and Thai), 19.2 for Japanese Americans, 17.6 for Chinese Americans, 14.0 for Hispanic Americans, 11.2 for non-Hispanic black Americans, 7.75 for South Asian Americans, 6.69 for Filipino Americans and 3.7 for non-Hispanic white Americans. According to the findings, men had significantly higher rates of gastric cancer compared to women. For instance, the rate for gastric cancer in the main area of the stomach was 70.0 per 100,000 for Korean American men compared to 33.5 for Korean American women.
Understanding Risks
Shah said the next step is exploring specific populations and understanding modifiable vs. non-modifiable risk factors. "We need more attention to these high-risk groups. Hand in hand with action right now with respect to screening and surveillance, we need to also explore how diet, lifestyle factors and H pylori affect risk," she said. "We need to educate patients about their individual risk so they can be the best advocates for themselves. The only way to move forward is to understand evidence and appreciate data, and take steps to implement early detection and prevention."
Rethinking Lung Cancer Screening Guidelines
In July, the U.S. Preventive Services Task Force recommended two changes that will nearly double the number of people eligible for lung cancer screening by lowering the age from 55 to 50 and reducing the number of smoking history pack years from 30 to 20. The recommendations were based partially on a 2019 study by Vanderbilt researchers published in JAMA Oncology, revealing a striking disparity in eligibility between races. A release from Vanderbilt University Medical Center stated that, among smokers diagnosed with lung cancer, 32 percent of African Americans versus 56 percent of whites were eligible for screening under the previous guidelines.
Appendiceal Cancer
Appendiceal cancer is a rare malignancy that is usually found during surgery for acute appendicitis. Although the rate of appendectomies has been stable over the last two decades, the incidence of malignant appendiceal cancer has increased 232 percent in the U.S.
Andreana Holowatyj, PhD, MSCI, and colleagues conducted the first study of appendiceal cancer patterns and survival by race/ethnicity among patients younger than 50 in the U.S. Reporting in the journal Gastroenterology, they found poorer disease outcomes among non-Hispanic blacks compared with non-Hispanic whites, and among men compared with women. However, they observed no differences in survival between young Hispanics and non-Hispanic whites with appendiceal cancer.
"Our discovery of disparities in survival across racial/ethnic groups and sex within this patient population noticeably parallels the unequivocal burden of COVID-19 by race or ethnicity and sex," said Holowatyj, assistant professor of Medicine in the Division of Epidemiology at VUMC. "These alarming healthcare realities heighten the need to understand the factors that contribute to disparities in disease susceptibility and prognosis in order to mitigate these differences, particularly for non-Hispanic black individuals."
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