U.S. death rates from cancer continued to decline from 2014 to 2018, driven mostly by drops in deaths from lung cancer and melanoma, according to a new report published Thursday.
But America's collective lack of exercise and poor diet may have driven increases in certain other cancers, including pancreatic cancer and breast cancer, the report found.
Overall deaths from cancer declined 2.2% in men and 1.7% in women over four years. Declines were consistent across all ethnicities and races, the Annual Report to the Nation on the Status of Cancer found.
Deaths from lung cancer and melanoma saw "accelerated" declines compared to other cancers. Researchers said the drop in lung cancer death rates drove the overall decline, and the melanoma decline represented a "substantial increase in survival for metastatic melanoma."
"The declines in lung cancer and melanoma death rates are the result of progress across the entire cancer continuum - from reduced smoking rates to prevent cancer to discoveries such as targeted drug therapies and immune checkpoint inhibitors," Karen Knudsen, chief executive officer of the American Cancer Society, said in a news release.
The survival rate for advanced melanoma cancer has "substantially" improved since 2009, said Farhad Islami, lead author on the report and scientific director for cancer disparity research with the American Cancer Society.
"The two-year survival rate for melanoma, advanced melanoma in 2009 was about 27%, this increased to about 44% in 2014, which is about a 60% increase in the survival rate," he said.
The report is put together by the American Cancer Society, the US Centers for Disease Control and Prevention, the National Cancer Institute, the National Institutes of Health and the North American Association of Central Cancer Registries. All data cover a time period prior to the Covid-19 pandemic.
But it wasn't all good news. For prostate, colorectal and female breast cancers, declines in death rates slowed or disappeared, the report found. Death rates rose for brain and nervous system cancers and pancreatic cancers.
While death rates declined for all groups, cancer death rates were still higher among Black people than in White people, even though incidence rates were lower in Black people than in White people.
"The continuing disparity largely reflects a combination of multiple intertwined factors of tumor biology, stage at diagnosis, receipt of timely and effective treatment, and systemic discrimination in cancer care delivery," the report reads. "Furthermore, largely owing to social determinants of health inequalities, Black persons and individuals of lower socioeconomic groups in general are more likely to have a higher exposure to some cancer risk factors and limited access to healthy food, safe places for physical activity, and evidence-based cancer preventive services."
Cancer incidence rates increased for pancreatic, kidney and female breast cancers, which researchers suggested may be linked to a "staggering" rise in obesity and total sitting time.
"We see that most of the cancer types that are increasing, those are obesity-related cancers," Islami said.
"We see that increasing trend for many of the obesity-related cancers in those younger ages," he said. "So we think that at least a proportion of the increase in rates are attributable to increases in excess body weight and obesity."