A worrying new study suggests one form of bowel cancer is increasingly striking young Americans.
While cases in older adults have fallen thanks to screening and awareness, diagnoses in younger people have continued to rise year after year.
Now researchers say rectal cancer appears to be driving much of that surge.
The disease is a type of colorectal cancer that develops in the final section of the large bowel, just above the anus.
The American Cancer Society estimates bowel cancer diagnoses in adults under 50 have risen by about three per cent a year over the past two decades. Nearly half of patients are now under 65.
Separate research has also found colorectal cancer is now the leading cause of cancer death in Americans under 50.
Using more than 20 years of CDC death records, researchers in New York found deaths from rectal cancer in people under 45 are rising up to three times faster than colon cancer in the same age groups.
Even more worrying, rectal cancer death rates are expected to keep climbing for at least another decade if current trends continue.
Researchers have found deaths from rectal cancer in people under 45 are increasing up to three times faster than colon cancer in every other age group (stock image)
The findings, due to be presented at next month’s Digestive Disease Week conference, follow another recent report that named rectal cancer as the biggest driver of the early-onset bowel cancer epidemic.
Experts said the results may support new screening approaches focused on the lower bowel and urged younger adults not to ignore warning signs such as bleeding, abdominal pain or changes in bowel habits.
In an announcement highlighting the worrying data entitled ‘Rectal cancer is striking earlier and killing faster’, the authors wrote: ‘Rectal cancer deaths among older millennials are accelerating, with growth in mortality far outpacing colon cancer.’
Mythili Menon Pathiyil, lead study author and a gastroenterology fellow at SUNY Upstate Medical University in New York said: ‘Colorectal cancer is no longer considered predominantly a disease of older adults.
‘Rectal cancer, especially, is becoming a growing problem in younger individuals, and we need to act early to reverse this trend.’
Across the US, bowel cancer cases in under-50s have been rising steadily, overturning the long-held belief that it is mainly an illness of old age.
The latest American Cancer Society figures show three in four younger patients are diagnosed only after the disease has already spread locally or to distant parts of the body – making treatment harder.
When caught early and still confined to the bowel, five-year survival rates are about 91 per cent. That falls to 74 per cent once it has spread nearby, and just 13 per cent once it has spread to distant organs.
Experts are still trying to pin down why rectal cancer is rising so sharply in younger adults. But growing evidence points to modern diets high in fat and low in fibre.
Marisa Peters, pictured above, was diagnosed with rectal cancer in her 30s after her symptoms were repeatedly dismissed
James Van Der Beek (pictured above) died earlier this year at age 48 from colorectal cancer
Low-fibre diets can slow digestion, meaning waste sits in the lower bowel for longer and potentially gives harmful bacteria and cancer-linked chemicals more time to damage cells.
Processed meats and environmental pollutants such as pesticides may also play a role by increasing exposure to substances that end up in the stool.
For the latest study, researchers analysed US death records from 1999 to 2023 covering adults aged 20 to 44 using the CDC WONDER database.
They then examined how death rates changed by age, sex, ethnicity and region, before using machine learning to predict trends through to 2035 if current patterns continue.
The full results have yet to be published, but early findings suggest bowel cancer death rates are rising overall – with rectal cancer deaths climbing between two and three times faster than colon cancer across every demographic studied.
The sharpest warning came for adults aged 35 to 44, where deaths from rectal cancer were projected to keep rising all the way to 2035. Colon cancer deaths in the same age group were increasing more slowly.
‘Our study shows that rectal cancer is driving much of the increase in colorectal cancers, and it’s most likely to worsen over time if we don’t change what we are doing right now,’ Pathiyil said.
Researchers also found Hispanic adults and people living in Western states saw the steepest rise in rectal cancer deaths.
Experts are not yet sure why, but CDC data shows Hispanic adults are less likely to undergo routine screening tests such as colonoscopies than white Americans. Language barriers and reduced access to care may also delay diagnosis and treatment.
Pathiyil said the findings could push doctors to consider earlier bowel cancer screening and greater use of sigmoidoscopy – a test that specifically checks the rectum and lower colon – in younger adults.
‘It’s less about just changing guidelines overnight and more about changing how we think about it, recognizing that colorectal cancer in young adults is no longer rare, and it needs earlier attention,’ she said.
