Study reveals increased risk for cancer among Latino populations

American Association for Cancer ResearchApr 19 2010

New findings from epidemiology and observational studies show an increased risk for cancer among Latino populations, but unique demographic characteristics suggest the problem may be worse than currently known.

"As we see the Latino population age, we are going to see the current disparity in knowledge and outcomes become an explosion," said Amelie G. Ramirez, Dr.P.H., director of the Institute for Health Promotion Research at the University of Texas Health Science Center at San Antonio.

Ramirez will receive the fifth annual AACR-Minorities in Cancer Research Jane Cooke Wright Lectureship at the 101st Annual Meeting 2010. She will deliver her lecture, "Networks in Acci-n for Latino Cancer Research," at 4:15 p.m. ET on Sunday, April 18, in room 143 of the Walter E. Washington Convention Center.

Currently, the rate of breast cancer among Latinas is lower than that in the general population, but the diagnoses are occurring earlier and the stage at presentation is becoming more severe. Latinos are already the largest minority population in the United States at 13 percent, and by 2050, one in every three individuals will be Latino, according to Ramirez.

"The challenge is that, as a group, Latinos have less education, higher poverty rates, less access to health care and lower rates of insurance. They also bring unique cultural customs that we need to understand to improve their access to care and response to treatment," she said. "We need to level the playing field to provide this population with better screening for early detection and better access to quality of care."

The challenges facing Latinos is an area of growing concern, and the AACR has highlighted the following studies in this arena, along with research facing other racial and socioeconomic groups:

Latina women who reside on either side of the U.S.-Mexico border are a study in contrasts when it comes to breast cancer screening.

In the United States, Latina women have a fairly high rate of receiving screening, such as a mammography or a clinical breast exam, but their knowledge about these practices is relatively low. By contrast, in Mexico the knowledge about the importance of such procedures is high, but actual rates of use are low.

"What this shows is that the Mexican government and other non-governmental organizations in Mexico, such as Fundacion CIM*AB, are doing a good job letting women know about these procedures, but the infrastructure is not there to support their use," said Matthew P. Banegas, a predoctoral research associate in the cancer prevention program of the public health sciences division at Fred Hutchinson Cancer Research Center, Seattle, Wash.

For Latina women residing in the United States, Banegas said the challenge is to get their knowledge and screening levels up to the overall levels seen among women of other ethnic populations who reside in the United States.

Banegas and colleagues interviewed 265 women, of whom 128 were Mexican and 137 were Latinas living in the United States.

Latinas living in the United States were 3.17-fold more likely to have received a mammography or breast ultrasound and 2.87-fold more likely to receive a clinical breast exam than Mexican women who lived in Mexico.

However, 55 percent of Mexican women living in Mexico were considered to have high levels of breast cancer knowledge, compared with 45 percent of Latinas living in the United States.

A smoking ban in bars and restaurants in Guatemala effectively reduced nicotine levels in these places, but not as much as hoped, which suggests the need for more rigorous enforcement.

"Levels dropped, but we want to see levels go down to zero. There should be no smoking following a ban," said Joaquin Barnoya, M.D., M.P.H., research assistant professor of surgery at Washington University in St. Louis and director of research at the Cardiovascular Institute in Guatemala.

Guatemala implemented its smoking ban in February 2009. Barnoya's research group measured air nicotine levels six months later and compared those levels with those found two years prior.

In 2007, nicotine levels were 4.57 mg/m3 in bars and 0.58 mg/m3 in restaurants.

Six months after the ban went into effect, nearly all bars still had nicotine levels that were measurable. However, the median levels had dropped to 0.32 mg/m3 (an 87 percent reduction). In restaurants, 24 percent had no detectable levels of nicotine. The median level of those restaurants that still registered nicotine levels was 0.03 mg/m3 (a 94 percent reduction).

"This study helps us to see that smoking bans, rather than just a response to popular opinion, have evidence-based results," said Barnoya. "With more commitment and enforcement, we could see these nicotine levels brought down to zero."

Barnoya's study showed that 81 percent of restaurant employees supported a smoke-free workplace, compared with 32 percent before the law was implemented.

"It is clear that pressure could be placed on Guatemalan officials to step up enforcement," said Barnoya.

Race may play a larger role than previously thought when it comes to optimal diagnosis and treatment of black women with breast cancer.

Researchers at The George Washington Cancer Institute, with funding from the National Cancer Institute, examined the effect of race and health insurance status on diagnostic and treatment delays over a 12-year period.

"We thought having health insurance would even the field. Insured black women should have had the same rapid evaluation as insured white women, but that was not the case in our study," said Heather Hoffman, Ph.D., assistant professor of epidemiology and biostatistics at The George Washington University School of Public Health and Health Services.

Hoffman and colleagues conducted a retrospective, cohort study of 581 women with breast cancer. Women were examined between 1997 and 2009 at seven hospitals and clinics in Washington, D.C.

Diagnostic delay time was defined as the number of days from abnormal screening to diagnosis, and treatment delay time was defined as the number of days from diagnosis to treatment initiation.

According to Hoffman, the goal was to identify risk factors associated with delays in diagnosis. They found the following:

• insured black women and uninsured white women waited more than twice as long to reach their definitive diagnosis than insured white women;
• lack of health insurance decreased the speed of diagnosis in white women, but having insurance did not increase the speed of diagnosis in black women; and
• overall, black women waited twice as long as white women for treatment initiation following definitive diagnosis.

Based on the results of this study, the researchers suggested that outreach focus on all black women and uninsured white women to improve their diagnostic time, and the importance of medical follow-up should be explained to patients.

"Black women should be the focus of breast cancer screening outreach and follow-up because they experience greater delays in diagnosis and in treatment than white women, regardless of insurance status," said Hoffman. "We need to determine those barriers in insured black women and all uninsured women."

In the Inland Empire locale of Southern California, failure to detect breast cancer in its early, more treatable stages is common among black women, and researchers have discovered that the cause may be a combination of incidence and mortality patterns, poverty, and a lack of medical insurance and education.

"Poverty and health care are intertwined, although large geographical areas such as San Bernardino County have the resources to effectively serve minority women," said Padma P.Tadi-Uppala, Ph.D., an associate professor in the department of environmental and occupational health at Loma Linda University, School of Public Health.

"The government and public health institutions should actively engage in identifying areas of need to serve minority women, reduce the breast cancer burden and ensure quality care regardless of race, ethnicity or socioeconomic status," she said.

While breast cancer mortality has declined by 31 percent overall in California, data for 2003 through 2007 indicated that mortality rates are significantly higher in women from the Inland Empire compared to the overall average in California.

About 2 million women live in the Inland Empire, an area that spans more than 27,000 square miles, according to the researchers. With funding from Susan G. Komen for the Cure, Inland Empire Affiliate, Tadi-Uppala and colleagues identified factors that may contribute to the unequal burden of breast cancer in the Inland Empire.

The mortality rate for breast cancer was 34.3 deaths per 100,000 non-Hispanic black women compared to 27 deaths per 100,000 non-Hispanic white women. Combining data for all race/ethnicity groups, the average annual age-adjusted mortality rate for breast cancer was 25.4 deaths in the Inland Empire compared to 22.8 deaths per 100,000 women statewide.

"Although this difference is slight, the higher risk of death from breast cancer in the Inland Empire is consistent with later detection of this screening-detectable cancer among these women," Tadi-Uppala said.

Non-Hispanic white women had a higher-risk of death from breast cancer than the statewide average. Results also showed the following:

• approximately 11.6 percent of homes had an income below poverty level;
• 24 percent of participants (mostly black and Latina) aged 16 to 64 years were uninsured;
• approximately 60 percent were not educated about breast health;
• 71 percent over 40 years of age did not have a mammogram in the last year; and
• nearly 80 percent were willing to participate in breast cancer clinical trials, but were not given opportunities to do so.

Tadi-Uppala and colleagues are currently working to educate minority women about the importance of participating in clinical trials, to recruit minority women into clinical trials, and to address lifestyle factors that affect breast cancer among minority women in the Inland Empire.

"We hope funding will be available to schools of public health such as ours that engage in community-based participatory research to reduce breast cancer incidence, morbidity and mortality among minority women who our research demonstrates currently experience an unequal burden of cancer," she said.

Socioeconomic status plays a role in colorectal cancer mortality rates by hindering health care interventions and/or restricting patient access to care, according to results of a retrospective cohort study.

"Those living in low socioeconomic status counties have yet to benefit from advances made in preventing colorectal cancer deaths more than 30 years ago, whereas those living in high socioeconomic status counties have seen a 33 percent to 50 percent reduction in mortality," said Andrew C. Wang, M.P.H., research assistant and student at Columbia University's Mailman School of Public Health, New York.

Colorectal cancer is a major cause of mortality; last year alone 16.2 people out of 10,000 died from this form of cancer, according to the researchers.

Experts believe that a few theories may help to explain why inequalities in colon cancer mortality rates exist. The first theory, fundamental cause theory, suggests inequalities exist because of the unequal access to resources. This theory works in part with access to health care. Diffusion of knowledge is the theory that the speed of new medical innovations may affect inequalities.

Wang and colleagues used administrative and U.S. census data from 2005 to pinpoint colon cancer mortality rates among whites and blacks from more than 3,000 counties.

Decreased mortality from colorectal cancer was associated with access to health care, living in states with histories of quicker uptake of new information and adoption of technology, and being in a higher socioeconomic county. Most importantly, Wang said, socioeconomic status acted as a form of a catalyst - access to health care and diffusion of knowledge made only a limited difference in low socioeconomic counties, but clearly lowered colorectal cancer mortality rates for high socioeconomic status counties.

Health care professionals are now faced with the challenge to ramp-up efforts to reduce colorectal cancer mortality rates among individuals in low socioeconomic status areas, according to Wang.

"The medical and non-medical communities are not doing enough to prevent colorectal cancer," he said. "Much more can be done for those who are disadvantaged."