by Mass General Brigham
While cancer mortality rates in the U.S. have decreased, cancer remains the leading cause of death among Hispanic individuals, who generally having lower cancer incidence compared to non-Hispanic white individuals.
A new study by investigators from the Mass General Cancer Center, a member of the Mass General Brigham health care system, evaluated cancer mortality trends and identified disparities for Hispanic men and women by age group, cancer type, and United States region over two decades. They found that while cancer mortality rates overall declined, rates of liver cancer death among Hispanic men and women and rates of pancreatic and uterine cancer deaths among women increased from 1999 to 2020. Their results are published in JAMA Oncology.
"Despite the great strides in cancer screening, education and treatment advances, there are populations in the U.S. that haven't benefited from these improvements equally," said senior and corresponding author Sophia C. Kamran, MD, of the Department of Radiation Oncology at the Mass General Cancer Center. "Cancer incidence is fairly low among Hispanic populations, but it the leading cause of death. My team wanted to know which cancers might be driving this."
Kamran and colleagues used data from the Center for Disease Control and Prevention's public Wide-ranging ONline Data for Epidemiologic Research (WONDER) database to answer this question. The database captures the cause of every death in the U.S. from death certificates and is maintained by the National Center for Health Statistics. Data are disaggregated by sex, age of death, place of death, and more.
The researchers analyzed 690,677 cancer deaths among Hispanic individuals and found that, overall, cancer mortality decreased for Hispanic individuals from 1999 to 2020, with a larger decrease among men compared to women. One exception was an increase in cancer mortality rates among Hispanic men between the ages of 25 to 34 years. Upon further analysis, the team discovered that rates of colorectal and testicular cancer deaths were especially high for men in this group.
"This finding was pretty striking and may be driving the increase in overall cancer specific mortality in this particular age group," Kamran said. "There could be a lack of awareness, education, and screening since there is a stigma associated with testicular cancer. And we know colorectal cancer mortality is increasing among younger populations in general."
The team found additional cancer types where mortality also increased across all age groups from 1999 to 2020: liver cancer among men and liver, pancreatic, and uterine cancer among women. Liver cancer mortality rate also increased significantly in the West for Hispanic men and women compared to other regions of the U.S.
The authors have some hypotheses that may help explain these disparities: Hispanic immigrants may have less access to health care and insurance coverage, and Hispanic patients are more likely to be diagnosed at advanced cancer stages, which could drive poor survival. In addition, Hispanic patients are often not well-represented in cancer clinical trials.
Researchers did see substantially reduced lung cancer mortality rates among both Hispanic men and women.
"This might be pointing to the fact that there's been a lot of education about smoking cessation and improvement in screening and treatment for this cancer," Kamran said. "That was very encouraging."
Equipped with this information about cancer mortality trends, researchers, educators, and policymakers can identify populations and cancer types that require additional efforts to reverse increasing mortality trends.
Limitations of the study included potential for the WONDER database misclassifying cause of death. The study also does not include undocumented populations nor account for migration or changes in zip code over time. Further, data about stage of cancer, previous treatments, insurance status, education, employment, or language were not available so the analysis could not account for these factors that might affect cancer mortality rate.
More granular data collection and analysis could strengthen investigations and allow researchers to replicate results in similar studies for specific disaggregated Hispanic subpopulations. Still, current findings underscore unique disparities that exist for Hispanic individuals.
"Clearly, the Hispanic population can't just be lumped together with all other U.S. cancer patients," Kamran said. "We have to think a little bit differently and target specific cancer research, education, and treatments toward this population, so we are caring for these patients as best we can."
More information: US Cancer Mortality Trends Among Hispanic Populations From 1999 to 2020, JAMA Oncology (2023). DOI: 10.1001/jamaoncol.2023.1993. jamanetwork.com/journals/jama/ … /jamaoncol.2023.1993
Journal information: JAMA Oncology
Provided by Mass General Brigham
by Ananya Sen, University of Illinois at Urbana-Champaign
Most solid tumors become stiff as the cancer progresses. Although researchers recognize that the environment around the cancer cells influences their behavior, it is unclear how it does so. In a new paper, published in Scientific Data, researchers from the University of Illinois Urbana-Champaign have collected gene expression data in response to mechanical stiffness in tumors. Their work can help guide our understanding of the crosstalk between cancer cells and their surroundings.
Historically, researchers have focused on how cancer cell genes change their expression over time. Based on this information, scientists have developed several therapeutic strategies, and yet over 600,000 people die every year in the US alone.
"We haven't made as much progress as we would have liked against cancer," said Bashar Emon, a postdoctoral researcher of mechanical science and engineering in the Saif (M-CELS/RBTE) lab. "Even with all the advances, the patient survival rate has not improved proportionately, when you consider how much research and funding has gone into studying cancer."
As a result, there has been a recent push to understand the tumor environment holistically. Cancer cells are surrounded by non-cancerous stromal cells, the most abundant of which are the cancer-associated fibroblasts. Although researchers have recognized that CAFs play a role in metastasis, they do not understand which signals are involved in the process.
"In this paper we focused on the tumor microenvironment because it becomes stiffer with time and we know that CAFs can sense this change," Emon said. "We wanted to understand how they convey this information to cancer cells."
The researchers cultured human colorectal CAFs on gels that had increasing stiffness ranging from 1 kPa to 40 kPa. "One kPa is very soft, like Jell-O whereas 40 kPa is firmer, like rubber erasers. Imagine pressing your finger against a layer of Jell-O or rubber; one should feel like a normal tissue, while the other one is more like a tumor," Emon said.
After isolating and sequencing the RNA from the CAFS, the researchers were able to compare which genes were being expressed differently in response to the increasing stiffness. Furthermore, they were also able to decipher changes in signaling molecules and pathways, and observe which biological functions were being affected.
"A gradient of increasing pressures from 1 kPa to 40 kPa created dramatic changes in gene expression, indicating that these CAFs were able to sense changes in stiffness and adapt. Comparing 1 kPa to 40 kPa, which are similar to the pressure inside a solid tumor, showed differentially expressed genes and molecules that may be relevant for cancer progression," said You Jin Song, a graduate student of cell and developmental biology in the Prasanth lab.
The study looked at CAFs whereas other groups have looked at how cancer cells respond to different pressure conditions. In future studies, the authors would like to grow the two types of cells together and see how the crosstalk manifests. "Our study was a necessary step in this direction because we need to first understand the individual responses of each cell type before we study their interactions," Song said.
"The importance of our paper lies in the fact that it is an unbiased experiment that monitored the expression of several genes simultaneously. It could be a good resource for other researchers who want to see whether the genes that they are interested in change in response to stiffness," Song said.
More information: Bashar Emon et al, Mechanosensitive changes in the expression of genes in colorectal cancer-associated fibroblasts, Scientific Data (2023). DOI: 10.1038/s41597-023-02233-9
Journal information: Scientific Data
Provided by University of Illinois at Urbana-Champaign
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