Inaugural AACR Cancer Disparities Progress Report Spotlights Growing Concerns Around Racial Disparities

Antoni Ribas, MD, PhD, FAACR

The American Association for Cancer Research (AACR) revealed a comprehensive, first-of-its-kind AACR Cancer Disparities Progress Report, which highlights disparities in cancer incidence, diagnosis, treatment, and survival, along with a heavy emphasis on racial and ethnic disparities in cancer care.¹

“Research is driving tremendous progress against cancer and other diseases, but the grim reality is that these advances have not benefitted everyone equally,” said Antoni Ribas, MD, PhD, FAACR, 2020 to 2021 president of AACR and professor of medicine, surgery, and molecular and medical pharmacology at University of California, Los Angeles Jonsson Comprehensive Cancer Center. “Progress has come too slowly for people of color and the monumental cost of cancer health disparities in terms of health care inequalities, premature deaths, and the impact on communities must be immediately addressed.”

The annual progress report is 1 of 10 new initiatives being implemented by AACR in order to help strengthen its programs that are focused on minorities in cancer research and work towards health equity for all populations. In an exploration of the state of cancer health disparities in 2020, the report details the clear disparities in cancer burden experienced by different US racial and ethnic populations.²

Cancer Disparities in African Americans

In the report, African Americans, in particular, were noted as bearing a disproportionately high burden of overall cancer mortality in numerous tumor types compared with other racial and ethnic minority groups. It is estimated that approximately 202,260 African Americans were diagnosed with cancer in 2019, with 75,030 reported cancer-related deaths in the same year. African Americans were noted as having higher incidence and mortality rates connected to commonly diagnosed cancer types, such as breast, lung, prostate, and colorectal cancers, vs other racial and ethnic groups.

Prostate cancer was noted as being particularly lethal in African American men, with double the mortality rate and 1.5 times the incidence compared with other racial and ethnic subgroups. Disparities appeared to be greatest in those who were diagnosed with low-grade prostate cancer. Additional data indicate that African American men, while more likely to experience aggressive, fast-growing disease, are also less likely to receive optimal and newer therapies following a prostate cancer diagnosis.

This subgroup was also found to be double the mortality of White patients in regard to stomach cancer–related death, coupled with higher incidence rates. This higher burden of stomach cancer could be attributed to Helicobacter pylori, a cancer-causing bacterium that is twice as common in African Americans than in White individuals.

This isn't the only factor that may account for increased disease burden in African Americans. Higher rates of obesity in African American populations could account for high rates of multiple myeloma diagnoses and death within the population. Much like prostate cancer, African American patients with myeloma have poor access to novel treatments, which may contribute towards the high mortality rates.

This population also has notable disparities in incidence and death related to colorectal cancer, with higher rates of obesity in African American population being a likely factor. The report estimates that 42% of incidence and 19% of mortality disparities within this patient population could be attributed to difference in colorectal cancer screening rates.

“African Americans and Hispanics are more likely to be diagnosed with colorectal cancer before the age of 50 compared to Whites,” said Marcia R. Cruz-Correa, MD, PhD, AGAF, FASGE, executive director of the UPR Comprehensive Cancer Center and director of the GI oncology program, Oncologic Hospital, San Juan, Puerto Rico. “Unfortunately, screenings for colorectal cancer in US minorities tend to be lower compared with Whites. Multiple barriers to screenings have been identified, including lack of access to healthcare, poor knowledge of cancer risk, mistrust of the health care system, and, specifically for Hispanics, having English as a second language, [all of which] appear to be drivers of disparities in cancer screenings.”

Cancer Burden in Hispanic Populations

The United States Hispanic population has a 25% lower cancer incidence rate and 32% lower cancer mortality rate compared to whites overall. The subgroup is also noted as having lower incidence and death in the most commonly diagnosed cancer types, include breast, lung, prostate, colorectal, as well as melanoma. While this is seemingly positive, Hispanics have higher incidence and mortality rates in other tumor types compared with White patients, including stomach (4.9 vs 2.6), liver and intrahepatic bile duct (9.5 vs 6.3), and thyroid (0.7 vs 0.5).

The report notes there are differences in incidence and death based on country or region of origin, with Hispanics residing in Puerto Rico having a 60% higher incidence rate of prostate cancer compared with Hispanics living in the United States.

Liver cancer was noted as having the most notable disparities in incidence and mortality between Hispanics and Whites, with several studies indicating that Hispanic American men have double the incidence rate compared with those born outside of the United States. Rates were also determined to be comparable between Hispanic women who were born in the United States and outside the United States. It was additionally noted the Puerto Ricans living on the mainland United States have a higher incidence of liver cancer compared with those living in Puerto Rico. These disparities could be the result of exposure to certain liver cancer risk factors, including infection from hepatitis B or C virus, obesity, alcohol consumption, smoking,

and diabetes. The report notes the possibility that other risk factors may need to be identified in order to account for the disparities that cannot be explained by known risk factors.

Additionally, Hispanic women are noted as experiencing higher incidence and death related to stomach cancer; both incidence and mortality rates were found to be twice that of White women. Hispanic men also experience disparities in this space, having an incidence rate that's 61% higher and a mortality rate that's 98% higher than White men. Much like the African American population, Hispanic individuals are prone to chronic infection with Helicobacter pylori, as well as obesity, which may play a part in the disparities in stomach cancer seen within the Hispanic population.

Within the last 2 decades, cervical cancer incidence and death were noted as being significantly higher among Hispanic women compared with White females. One of the factors that may contribute towards these disparities are low screening rates.

"Cervical cancer is one of the most common cancers in Hispanic American women,” explained Cruz-Correa.” yet, they have [exceedingly] low cancer screenings compared to White women.”

American Indian and Alaskan Natives

Although overall incidence and mortality in American Indians and Alaskan Natives are 14% and 10% lower, respectively than that of White individuals, this population experiences higher rates in specific tumor types. Liver cancer, for example, disproportionately affects American Indians and Alaska Natives compared with White individuals, possibly due in part to higher rates of exposure to hepatitis B and C infection, chronic liver disease, obesity, alcohol consumption, smoking, and diabetes.

The report notes, however, that the those who reside within Indian Health Service regions have varied rates of incidence and mortality. Three of 6 Indian Health Service regions (Alaska, Northern Plains, and Southern Plains) were found to have higher rates of mortality compared with White individuals. Meanwhile, the Pacific Coast region was noted as having comparable overall cancer death rates and those in the East and Southwest regions have lower overall cancer death rates when compared with White populations.

Lung cancer incidence, both within American Indian men and Native Alaskan men, as well as those residing within Northern Plains, were noted as being 45% and 54% higher, respectively, when compared with White men. That being said, male Native Alaskans who reside within the Southwest were found to have a 65% lower incidence rate of lung cancer compared with White males.

References

1. AACR to unveil inaugural cancer disparities progress report at virtual congressional briefing today at noon et. News release. American Association for Cancer Research. September 16, 2020. Accessed September 16, 2020. https://bit.ly/37yPr0S.
2. American Association for Cancer Research. AACR Cancer Disparities Progress Report 2020. September 16, 2020. Accessed September 16, 2020. https://bit.ly/38jQYao