March 2018 Edition Vol.11, Issue 3

Demographic Studies Shed Light on Risks, Prevalence of Major Cancer Types

By Arlene Weintraub

A recently published analysis of breast cancer data reveals a persistent disparity in survival rates between Caucasian and African-American women: Although overall survival was high (88%) among women diagnosed in the 10 years ending in 2009, survival among African-American women was 10 percentage points lower than that of white women.1

The authors of the report, sponsored by the Centers for Disease Control and Prevention (CDC) and published in the journal Cancer in December 2017, called for more efforts by national and local health officials to address racial disparities in cancer survival.

It was the latest in a string of studies that examine how a variety of factors—ranging from race to co-existing health problems, such as obesity—are impacting diagnosis rates and outcomes of major cancer types such as breast and liver cancer. Although the research does reveal some progress has been made in addressing cancer disparities, there is still plenty of work to be done.

The CDC’s report on racial disparities in breast cancer came just a few months after the American Cancer Society (ACS) reported a 35-year drop in breast cancer death rates in its biennial “Breast Cancer Facts & Figures” report. According to the ACS report, death rates from the disease dropped 39% in the 35 years period, which ended in 2015.2

“This is the first time that we see the decrease among women across all racial and ethnic groups,” said Carol DeSantis, director of breast and gynecological cancer surveillance for the ACS.

That being said, death rates did decline faster in white women than in African-American women, DeSantis said. Yet mammography rates were similar across-the-board: 65% of non-Hispanic white women and 69% of non-Hispanic black women reported undergoing the screening test in the last two years.3 So why the disparity in death rates? According to DeSantis, lack of equal access to healthcare.

“We think that despite similar screening rates, black women still are more likely to be diagnosed at later stages,” when breast cancer becomes harder to treat successfully, she said.

Several states have undertaken concerted efforts to improve access to healthcare with initiatives such as expanding Medicaid under the Affordable Care Act, which is helping to narrow racial disparities in breast cancer diagnosis and treatment. As a result, seven states reported no racial disparities in breast cancer death rates, including Delaware, Connecticut, and Massachusetts.2

Improving Liver Cancer Outcomes

Several disparities are also evident in the diagnosis and treatment of liver cancer. The number of diagnosed cases in the U.S. doubled in the 25 years ending in 2015, and deaths from the disease grew 20%, according to the Global Burden of Disease study on liver cancer released in October 2017.4

The top three causes of the disease—hepatitis B, hepatitis C, and alcohol abuse—can all be prevented. Disparities among socio-economic groups showed some unevenness in public efforts to treat and prevent the viruses that cause liver cancer, as well as to address alcohol use, said lead author Christina Fitzmaurice, a hematologist at the Institute for Health Metrics and Evaluation at the University of Washington.

In the U.S., Fitzmaurice observed that “We see the highest liver cancer deaths in the southern states, and there are also high rates of hepatitis seen in southern states that have fairly high populations of Asian immigrants.”

The potential to significantly lower liver cancer incidence rates has been greatly enhanced by the recent regulatory approvals of antiviral drug cocktails that cure more than 90% of patients with hepatitis C. Treatments include Harvoni (ledipasvir/sofosbuvir) and Zepatier (elbasvir/grazoprevir).

It’s too early to measure the impact of these drugs on liver cancer prevalence, but in the report, Fitzmaurice and her co-authors urged health officials to focus on the accessibility and affordability of new medicines.

Still, the challenge of improving access to medicines that can lower the risk of liver cancer is evident in the hepatitis B vaccine. “The vaccine has been around since the early 1980s, but we still have a huge population that has not been vaccinated, and so those people are still at risk to get liver cancer,” said Fitzmaurice.

Tackling Obesity and Lifestyle Risks

Recent studies highlight a growing understanding of the link between obesity, lifestyle choices and some cancers. Mexican-Americans, for example, face a disproportionately high risk of developing liver cancer, according to a study reported at the 10th American Association for Cancer Research (AACR) Conference on the Science of Cancer Health Disparities in Racial/Ethnic Minorities and the Medically Underserved in September 2017.

A team led by the UCLA Cancer Prevention and Control Research Center reported that Mexican-American men and women were more likely to be obese, diabetic, and alcohol abusers than Mexican nationals. All of those characteristics raise the risk of liver cancer.5

Obesity is a growing concern among oncology researchers. In October 2017, the CDC published a report revealing a link between obesity and 13 cancer types, including liver and breast cancer. Most of the cancers that are associated with being overweight increased in the decade ended in 2014. (Figures 1 and 2)

Incidence rates were higher among males for more than half those cancers, including liver cancer. Among the cancers that affect only women, incidence rates were highest in postmenopausal breast cancer, but being overweight was also associated with endometrial and ovarian cancer.6

Co-author Lisa Richardson, MD, Director of CDC’s Division of Cancer Prevention and Control, says the agency was surprised by the finding that 630,000 Americans received a diagnosis in 2014 of a cancer associated with being overweight or obese.

“The big surprise was that the actual proportion of cancers that we can partially attribute to obesity was 40%, which is a huge number,” she said, adding that the trend in cancers associated with obesity is increasing among younger people.

A study published in the Lancet by British researchers in November 2017 echoed the CDC’s finding of a link between body weight and cancer. Those researchers reported that having a combination of a body mass index (BMI) above 25 and diabetes contributed to 5.6% of 14 million cancer cases reported to a worldwide registry, with the highest associations between those conditions and cancer diagnoses occurring in high-income western countries, including the U.S.

That research also uncovered regional disparities in the obesity-cancer link. In wealthy western countries, a high BMI accounted for 16% of cancer cases, vs. only 5% of diagnoses of the disease in high-income Asia-Pacific countries. The authors warned that without intervention to reduce obesity rates, the prevalence of BMI-associated cancers will grow by 30% in women and 20% in men by 2025. Liver cancer cases in men could grow as much as 47%.7

The AACR’s Cancer Progress Report, released in September, highlighted issues related to addressing cancer disparities, as well as risks such as obesity and poor lifestyle choices. There was some good news in the overall death rate from cancer—it dropped 35% for children and 25% for adults between 1991 and 2014. But the AACR reported a number of disparities. African-American men, for example, have a prostate cancer death rate that’s double that of any other racial group, and Hispanic children face a 24% higher risk of leukemia than their non-Hispanic counterparts.8

“The data suggest there’s excess mortality in rural and medically underserved populations, which is no doubt due to a lack of access and less care contributing to later diagnoses,” said Graham Colditz, M.D., associate director of prevention and control at Alvin J. Siteman Cancer Center in St. Louis and one of the authors of the AACR report.

He adds that significant progress has been charted in states that have increased access to healthcare, including Massachusetts. “In breast cancer, there is now no difference in mortality between black and white women with breast cancer in Massachusetts,” he said. “That shows the impact of statewide access to health insurance.”

The report also pointed out that half of all global cases of cancer can be tied to preventable causes such as obesity and lifestyle choices such as smoking. That underscores the themes of so many of the demographic studies on cancer that have been released of late, Colditz says. “One of the key priorities is to do rigorous work to help everyone get access to prevention strategies that we know will work,” he said.

References

  1. Jacqueline W. Miller, Judith Lee Smith, et al. Disparities in breast cancer survival in the United States (2001-2009): Findings from the CONCORD-2 study. http://onlinelibrary.wiley.com/doi/10.1002/cncr.30988/full.
  2. American Cancer Society. Report: breast cancer death rates down 39% since 1989. https://www.cancer.org/latest-news/report-breast-cancer-death-rates-down-39-percent-since-1989.html.
  3. American Cancer Society. Breast cancer facts & figures 2017-2018. https://www.cancer.org/content/dam/cancer-org/research/cancer-facts-and-statistics/breast-cancer-facts-and-figures/breast-cancer-facts-and-figures-2017-2018.pdf.
  4. Global Burden of Disease Liver Cancer Collaboration. The burden of primary liver cancer and underlying etiologies from 1990 to 2015 at the global, regional, and national level: results from the global burden of disease study 2015. https://jamanetwork.com/journals/jamaoncology/fullarticle/2656875.
  5. Yvonne N. Flores, Zuo-Feng Zhang, et al. Risk factors for liver disease/cancer among adults of Mexican descent in the United States and Mexico. The 10th AACR Conference on The Science of Cancer Health Disparities in Racial/Ethnic Minorities and the Medically Underserved. Abstract A 34.
  6. Centers for Disease Control and Prevention. Cancer and obesity. https://www.cdc.gov/vitalsigns/pdf/2017-10-vitalsigns.pdf.
  7. Jonathan Pearson-Stuttard, Bin Zhou, et al. Worldwide burden of cancer attributable to diabetes and high body-mass index: a comparative risk assessment. http://www.thelancet.com/journals/landia/article/PIIS2213-8587(17)30366-2/fulltext.
  8. AACR cancer progress report: harnessing research discoveries to save lives. http://cancerprogressreport.org/Pages/cpr17-harnessing-research-discoveries.aspx.

 

About the Contributor

Arlene Weintraub is a science writer and author of the book, Heal: The Vital Role of Dogs in the Search for Cancer Cures (ECW Press 2015), available at Amazon.

Post a Comment

OBR Archives

To view previous issues of OBR green contact you can visit our archives. The entire library of OBR green articles is searchable.