Colorectal cancer incidence and mortality rates in California have decreased markedly for men and women in all major racial-ethnic groups since 1990, except for Hispanic men.
Colorectal cancer rates for Hispanic men have remained relatively the same, a disparity that can be improved by greater screening, a study of colorectal cancer trends from the UC Davis Institute for Population Health Improvement (IPHI) has found.
The study, "Colorectal Cancer Trends in California and the Need for Greater Screening of Hispanic Men," published online July 29 in the American Journal of Preventive Medicine.
"Routine screening for colorectal cancer enables physicians to identify and treat tumors and polyps early, reducing the incidence of invasive cancers and mortality," said IPHI Director Kenneth W. Kizer, senior author of the study. "But Hispanics are less likely to be screened, insured and use health care than other ethnic groups in California.
"In fact, screening rates among Mexican and South and Central American Hispanic men, the main Hispanic subgroups in California, are the lowest of any race/ethnic group in the country. Tailoring interventions to the needs of these specific populations are important to create effective prevention strategies and improve health," he said.
According to the National Cancer Institute, in 2014 only 46.2 percent of Hispanic men in the U.S. and 44.9 percent in California were screened, compared to 67.6 percent of white men in the U.S. and 72.4 percent in California.
For the study, IPHI researchers from the California Cancer Reporting and Epidemiologic Surveillance (CalCARES) program reviewed California Cancer Registry data for 23,157 Hispanic and 114,944 white men diagnosed with invasive colorectal cancer between January 1990 and December 2012. They identified trends in incidence, mortality and five-year relative survival by age, stage of diagnosis and tumor location.
The researchers found that while both groups experienced similar trends in survival and stage at diagnosis over time, white men had dramatically reduced colorectal cancer incidence and death across all age groups, particularly those over the age of 50. Colorectal cancer incidence among white men declined from 71.5 in 1990 to 49.1 in 2009, and to 41.3 in 2012, and overall mortality decreased 46 percent. By comparison, incidence rates among Hispanic men increased from 43.2 percent in 1990 to 49.1 in 2008, declining afterwards to 39.1 in 2012, and overall mortality decreased by only 3.5 percent.
Hispanic men also had a significantly higher proportion (65 percent) of tumors in the distal colon than white men (59 percent). Because colorectal screening is especially effective at identifying distal tumors, those located closer to the rectum, more Hispanic men could be benefitting from this well-established preventive test.
"While rates of screening among Hispanic men have increased in recent years, it remains to be seen if this trend continues," Kizer said.
The study also found that the number of both white and Hispanic men under the age 50 with colorectal cancer -- while small compared to the other age groups -- increased significantly. Current recommendations for screening do not begin until age 50, but these findings raise questions about whether screening for colon cancer, especially among higher risk groups, should begin earlier, Kizer noted.
Colorectal cancer is the third most common cancer in the U.S. and second leading cause of death from cancer that occurs in both men and women, according to the U.S. Centers for Disease Control and Prevention. In California, colorectal cancer mortality between 1990 and 2013 for all men decreased from 26.9 to 15.2 deaths per 100,000 and from 18.5 to 11.23 deaths per 100,000 women.
Other authors of the study include Cyllene R. Morris, Arti Parikh-Patel and Robert Martinsen from the CalCARES program at IPHI and Paulo S. Pinheiro from the University of Nevada, Las Vegas.
The collection of cancer incidence data used in this study was supported by the California Department of Public Health as part of the statewide cancer reporting program mandated by the California Health and Safety Code Section 203885; the National Cancer Institute's Surveillance, Epidemiology, and End Results Program, and the Centers for Disease Control and Prevention's National Program of Cancer Registries.