While cancer diagnosed before the age of 50 is generally uncommon, it’s becoming more common in the United States, prompting researchers to investigate the reasons behind this rise.
A recent government study offers the clearest view yet of early-onset cancers, revealing that the most significant increases are seen in breast, colorectal, kidney, and uterine cancers. Scientists from the National Cancer Institute analyzed data from over 2 million cancer cases diagnosed in individuals aged 15 to 49 between 2010 and 2019.
Out of 33 different cancer types, 14 have shown rising rates in at least one younger age group. Notably, around 63% of these early-onset cases occurred in women.
“Such trends usually indicate major underlying issues,” stated Tim Rebbeck from Dana-Farber Cancer Institute, who studies cancer risk but was not part of the study. “We need to support research that helps us understand these trends.”
The study’s findings were published in the journal Cancer Discovery, affiliated with the American Association for Cancer Research.
What are the numbers looking like?
The researchers assessed cancer rates in 2019 against what would have been anticipated based on 2010 figures.
Breast cancer accounted for the majority of the excess, with an estimated 4,800 additional cases. Colorectal cancers increased by around 2,000 cases compared to expectations from 2010, while kidney cancers saw an increase of 1,800 and uterine cancers added about 1,200 cases.
On a positive note, death rates for most cancers among young adults haven’t risen, though colorectal, uterine, and testicular cancers have seen increasing mortality rates.
What’s driving this increase?
Understanding the reasons behind these trends will require further study. The large databases utilized in the research lack details on risk factors and healthcare access. Various theories exist, and a major conference is scheduled for later this year to convene experts in this field.
“Some of the cancer types are linked to higher body weight, making rising obesity rates a plausible hypothesis,” noted lead author Meredith Shiels from the National Cancer Institute.
Similarly, advancements in cancer detection and shifts in screening recommendations might contribute to more cases being diagnosed earlier.
In the case of breast cancer, the trend of women delaying childbirth may offer an explanation, as pregnancy and breastfeeding are known to lower risk.
Not all cancers are following the same trend
This situation isn’t uniform across the board. For more than a dozen cancer types, rates in those under 50 are actually declining, with the most significant reductions seen in lung and prostate cancers.
Declining cigarette use over the years likely accounts for the dip in lung cancer among younger individuals.
Regarding prostate cancer, changes in guidelines that advise against regular PSA testing in younger men due to concerns about overtreatment appear to be influencing the decline.
