Many Early-Onset Cancers Increasing, Particularly in Women

Rates of certain cancers in the United States — including breast, colorectal, and thyroid cancers — increased between 2010 and 2019 among patients aged less than 50 years, while overall cancer incidence and mortality rates did not increase, a new study found. 

Among the more than two million cases of early-onset cancer diagnosed during this period, 63.2% were in women, researchers reported recently in Cancer Discovery.

Breast cancer, thyroid cancer, and melanoma were the most common early-onset cancers in women. Among men, the most common were colorectal cancer, testicular cancer, and melanoma. 

Researchers from the National Cancer Institute analyzed cancer incidence data from the United States Cancer Statistics database for 2010-2019 and national death certificate data from the National Center for Health Statistics from 2010 to 2022. The team excluded incidence data from 2020 and 2021, which was artificially low due to COVID.

The researchers divided the data according to age groups: The early-onset age groups were 15-29, 30-39, and 40-49 years, and the late-onset groups were 50-59, 60-69, and 70-79 years. The team also estimated the expected number of early-onset cases in 2019 by multiplying 2010 age-specific cancer incidence rates by population counts for 2019. 

First author Meredith Shiels, of the National Cancer Institute, and colleagues found that the largest absolute increase in incidence of early-onset cancers, compared with expected incidence, were for breast (n = 4834 additional cancers), colorectal (n = 2099), kidney (n = 1793), and uterine cancers (n = 1209). These diagnoses accounted for 80% of the additional cancer diagnoses in 2019 vs 2010.

Looking at increases by age group, Shiels and colleagues reported that 1.9% of all cancers occurred in overall early-onset cohort 15- to 49-year-olds (age-standardized incidence rate of 39.8 per 100,000), and the incidence was greater in the older cohorts: 3.6% for 30- to 39-year-olds (123.5 per 100,000) and 8.8% for 40- to 49-year-olds (293.9 per 100,000).

Overall, 14 of 33 cancer types significantly increased in incidence in at least one early-onset age group. Among these 14 cancer types, five — melanoma, plasma cell neoplasms, cervical cancer, stomach cancer, and cancer of the bones and joints — showed increases only in early-onset age groups, not in late-onset age groups. For example, between 2010 and 2019, cervical cancer rates increased by 1.39% per year among 30- to 39-year-olds, melanoma rates increased by 0.82% per year among 40- to 49-year-olds, and stomach cancer rates increased by 1.38% per year. 

The remaining nine cancer types increased in at least one early-onset and one late-onset group. These included female breast, colorectal, kidney, testicular, uterine, pancreatic cancers as well as precursor B-cell non-Hodgkin lymphoma, diffuse large B-cell lymphoma, and mycosis fungoides/Sézary syndrome.

For four of the 14 cancer types with increasing incidence rates — testicular cancer, uterine cancer, colorectal cancer, and cancer of the bones and joints — mortality also increased in at least one early-onset age group, whereas the remaining 10 cancer types increased in incidence without an increase in mortality for any age group.

Shiels and her colleagues aren’t the first to address the rising incidence of early-onset cancers. In a keynote lecture at the European Society of Medical Oncology (ESMO) 2024 Annual Meeting, Irit Ben-Aharon, MD, PhD, from the Rambam Health Care Campus in Haifa, Israel, noted that from 1990-2019, the global incidence of early-onset cancer increased by 79%.

Although the current study doesn’t identify drivers of rising cancer rates in younger patients, “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,” Shiels said in a press release. For instance, “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.”

This study is “a great step forward” toward understanding the increasing incidence of early-onset cancers, agreed Shuji Ogino, MD, PhD, from Harvard Medical School and Brigham and Women’s Hospital in Boston, who wasn’t involved in the research.

The investigators provide new details, particularly by breaking down the early- and late-onset age groups into subcategories and by comparing incidence and mortality rates, Ogino noted.

“Mortality is a great endpoint because if the increased in early incidence is just an effect of [increased] screening we won’t see a mortality increase,” Ogino said. But “we need more data and some way to tease out the screening effect.” Plus, he added, “we need more mechanistic studies and tissue-based analyses to determine if early-onset cancers that are increasing in incidence are a different beast, rather than just an earlier beast.”

This 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 declared no conflicts of interest.

Sharon Worcester, MA, is an award-winning medical journalist based in Birmingham, Alabama, writing for Medscape Medical News, MDedge, and other affiliate sites. She currently covers oncology, but she has also written on a variety of other medical specialties and healthcare topics. She can be reached at sworcester@mdedge.com or on X: @SW_MedReporter.