A report published on Wednesday shows good news for cancer in the US, but the picture can be mixed depending on gender, ethnicity, or the type and stage of cancer.
Overall, the cancer mortality rate — the number of deaths per 100,000 people — is dropping in the US, including most of the common cancers such as lung, colorectal, breast, and prostate, according to a report that is published each year by the American Cancer Society, the Centers for Disease Control and Prevention, the National Cancer Institute, and the North American Association of Central Cancer Registries.
The death rate is dropping in men, women, and children, and most racial and ethnic groups, declining 1.8% each year in men and 1.4% in women every year between 1999 and 2015. Overall, mortality rates have dropped for 11 of 18 cancer types in men and 14 of 20 cancer types in women between 2011 and 2015.
However, the mortality rate is rising for some cancer types, including liver, pancreatic, and brain and other nervous system cancers, according to the report published in the journal Cancer.
And the incidence — new cases of cancer per 100,000 people — has increased slightly for children, flatlined for women, and dropped for men. In general, men are still more likely to be diagnosed and die of cancer than women are.
A second report in the journal looked specifically at prostate cancer and found the incidence overall has declined but that cases of advanced prostate cancer have gone up. It's not clear why, but fewer men are getting tested for prostate specific antigen — the blood test is thought to sometimes lead to unnecessarily aggressive treatment for a usually slow-growing cancer.
"There is a lot of good news in the report — overall mortality is going down for all cancers combined," lead study author Kathy Cronin, the deputy associate directory of the surveillance research program at the National Cancer Institute, told BuzzFeed News.
Cancer mortality is thought to be declining for a number of reasons including less smoking (which reduces the risk of lung, colorectal, and other cancers), earlier diagnoses, and better treatments. Smoking is still the cause of more than 25% of all cancer deaths in the US.
"The site that is going up the fastest as far as the annual percent change in mortality is liver, and that’s for both men and women," Cronin said. "Of course this is an observational study so you can’t really assign causality to it, but it’s believed to be due to hepatitis C."
Hepatitis C is a virus that infects the liver and is spread by shared or contaminated needles, being born to a hepatitis C-infected mother, and less often, sexual contact. A chronic infection can increase the risk of liver cancer. There are new treatments for hepatitis C, so in theory, liver cancer mortality might drop in the future.
Black men and women have the highest cancer mortality rates compared to other groups.
"Except for female lung cancer, black men and black women had the highest death rates for cancer sites with the highest mortality in the overall population: lung, prostate, female breast, colorectal, and pancreas," according to the report.
Hispanic men and women have a lower rate of cancer incidence and death than non-Hispanic people. And the cancer incidence for all different types of cancer combined is highest for black men and white women.
For all people, the largest increases in incidence were for liver cancer, myeloma, melanoma, thyroid cancer, and leukemia, and there were smaller rises in kidney and breast cancer.
Cancer diagnoses can increase for a number of reasons, including more people getting cancer or more cases of cancer being diagnosed due to screening.
For example, obesity has been linked to a higher risk of breast, pancreatic, uterine, and endometrial cancer. "It is estimated that obesity accounts for 25% and 68% of pancreas and uterus cancer deaths, respectively, in the United States," Cronin and her colleagues wrote.
And HPV, the common sexually transmitted infection that is know to cause cervical cancer, might be the reason for a rise in oral cancer mortality in men (although smoking and alcohol are also linked to oral cancer).
Thyroid cancer is thought to be on the rise due to more detection of cases, Cronin said.
"It’s thought that a lot of that is due to detection since most of the increase is small, very small tumors," she said. And melanoma incidence might be on the rise due to sun exposure and tanning bed use, as well as better detection, she said.
"I'd say we are making progress, but more work needs to be done," Cronin said.