PHILADELPHIA – In the United States, breast, colorectal, endometrial, pancreatic, and kidney cancers are becoming increasingly common among people under age 50, according to a study published in Cancer Discovery , a journal of the American Association for Cancer Research (AACR).
The findings may have implications for early-onset cancer prevention and screening efforts, the researchers noted.
Early-onset cancers, defined in this study as those diagnosed in individuals under age 50, are rising in incidence for reasons that remain unclear, according to Meredith Shiels, PhD, MHS , the first author of the study and a senior investigator in the Infections and Immunoepidemiology Branch of the National Cancer Institute, part of the National Institutes of Health.
"The aim of this study was to carry out a comprehensive descriptive analysis of early-onset cancer incidence and mortality rates in the United States," she noted. "Understanding which cancers are increasing in younger age groups, and whether those cancers are also increasing among those at older ages, will inform future studies focused on identifying the drivers of rising rates."
Shiels and colleagues analyzed cancer incidence from 2010 to 2019 using data from the United States Cancer Statistics database and cancer mortality from 2010 to 2022 using national death certificate data from the National Center for Health Statistics. Early-onset age groups included ages 15-29, 30-39, and 40-49; late-onset age groups included ages 50-59, 60-69, and 70-79.
Among 2,020,829 cases of early-onset cancer diagnosed between 2010 and 2019, 63.2% were diagnosed in females. The most common early-onset cancer types during this period were breast cancer, thyroid cancer, and melanoma among female patients and colorectal cancer, testicular cancer, and melanoma among males.
Of the 33 cancer types included in the analysis, 14 cancer types had significantly increasing incidence rates in at least one early-onset age group. The incidence of five of these cancer types increased in at least one early-onset age group without corresponding increases in any late-onset age group: melanoma, plasma cell neoplasms, cervical cancer, stomach cancer, and cancer of the bones and joints.
The remaining nine cancer types had significantly increasing incidence in at least one early-onset and one late-onset age group: female breast cancer, colorectal cancer, kidney cancer, testicular cancer, uterine cancer, pancreatic cancer, precursor B-cell non-Hodgkin lymphoma, diffuse large B-cell lymphoma, and mycosis fungoides/Sézary syndrome.
The greatest increases in the number of early-onset diagnoses in 2019 compared to what was expected based on 2010 incidence rates were seen in female breast cancer, colorectal cancer, kidney cancer, and uterine cancer—together, these accounted for more than 80% of the additional cancer diagnoses in 2019 compared with 2010.
Four of the 14 cancer types with increasing incidence rates—testicular cancer, uterine cancer, colorectal cancer, and cancer of the bones and joints—also had increasing mortality rates in at least one age group. The remaining 10 cancer types exhibited increasing incidence without increasing mortality for any age group.
"Descriptive data like these provide a critical starting point for understanding the drivers of rising rates of cancer in early-onset age groups and could translate to effective cancer prevention and early detection efforts," said Shiels. "As one example, recent guidelines have lowered the age of initiation for breast and colorectal cancer screening based, at least partially, on observations that rates for these cancers are increasing at younger ages."
Shiels noted that an important feature of the analysis was the comparison of incidence trends between early-onset and late-onset age groups, which could provide clues about the factors that contribute to cancer development. "The increasing incidence of many cancer types in younger and older age groups suggests that there may be risk factors that impact cancer development across ages or advances in screening or imaging technologies that allow cancers to be detected more frequently than before," she said.
Other strengths of the analysis were the use of nationwide data, inclusion of mortality trends, and estimates of additional cancers diagnosed in 2019, which provided context not previously included in prior studies, according to Shiels.
A limitation of the study was the lack of information on each patient's cancer risk factors, screening uptake, or access to care, which prevented the researchers from examining potential drivers of increasing incidence.
The study was funded by the Intramural Research Program of the National Cancer Institute of the National Institutes of Health and the Institute of Cancer Research. Shiels declares no conflicts of interest.
