April 15, 2021 -- The next 20 years will see a big shift in rankings of the most common kinds of cancers, researchers predict.
These predicted rankings of cancer types by their total number of annual cases were published online April 7 in JAMA Network Open.
The authors also rank cancer type by mortality. Currently, most cancer deaths are due to lung cancer, followed by colorectal, pancreatic, and breast cancers
By 2040, the most notable change in cancer deaths is that liver and bile duct cancer, currently sixth most-deadly, jumps up to third.
Two decades from now, the ranking in terms of cancer deaths will be lung, pancreatic, liver and bile duct, and colorectal.
"Our findings reflect the shifting dynamics of cancer screening and treatment," lead author Lola Rahib, PhD, a pancreatic cancer scientist at Cancer Commons, an advocacy nonprofit, commented in a press statement.
The new analysis used population-growth projections (based on 2010 US Census data) and current population-based cancer incidence and death rates (from SEER 2014-2016) to calculate the changes in incidences and deaths to the year 2040.
The projected, estimated numbers are not ironclad, the researchers acknowledged.
"Our projections assume that the observed rates and trends [from recent years] don't change over time," Rahib told Medscape, but she pointed out that change may indeed happen.
"Any long-term projections should be considered with a grain of salt," said
Kim Miller, MPH, a surveillance research scientist at the American Cancer Society, said in response to the study
Miller explained that "cancer trends can sometimes rapidly change within a few years." Projections just 2 to 4 years ahead are "extremely difficult" and those 20 years ahead are even more so, she said.
"We're encouraged to see the projected decreases in deaths from lung, colorectal, and breast cancer in the coming years," said co-author Lynn Matrisian, PhD, chief science officer at the Pancreatic Cancer Action Network. "It's time to shift focus to some of the less commonly diagnosed cancers with the lowest survival rates, like pancreatic and liver cancer."
Difference in Opinion on Prostate Cancer
Changes in prostate screening recommendations over the past 15 years will cause the huge fall in prostate cancer cases, they suggest.
"The most recent change in 2018 recommends that men aged 55-69 can make their own decisions regarding screening, but previous changes recommended against PSA screening," said Rahib.
"These changes in screening guidelines have influenced the number of diagnoses of prostate cancer in recent years and will continue to do so to 2040," Rahib commented.
For breast cancer, the authors highlight the fact that although the number of breast cancers will continue to increase, the number of breast cancer deaths will decrease. That ongoing trend is most likely attributable to increased screening and advancements in treatment, they say.