A new study published in a leading journal reports that rectal cancer appears to be rising among Americans under the age of 40, while colon cancer rates have remained steady for several decades; the study says more effort should go into diagnosing rectal cancer in young people.
The study, led by Dr Joshua Meyer, a radiation oncologist at Fox Chase Cancer Center, Philadelphia, Pennsylvania, is due to be published online today, 23 August, in Cancer, a peer-reviewed journal of the American Cancer Society.
Rectal cancer is thought to be rare among young people in the US, but Meyer and colleagues decided to do an analysis and check the extent to which this might be true, since such a belief, if widely held, might lead to missed or delayed diagnoses.
For their study, which took place when Meyer was at the New York-Presbyterian Hospital/Weill Cornell Medical Center in New York City, they examined data from the US Surveillance Epidemiology and End Results (SEER) cancer registry and compared trends in rectal cancer to trends in colon cancer between 1973 and 2005. SEER holds data on about 26 per cent of cancer cases in the US.
They found 7,661 people under the age of 40 who had been diagnosed with colon and rectal cancer during that period.
Their analysis showed that:
- Rates of colon and rectal cancer were low over those decades (1.11 and 0.42 cases per 100,000 of the population respectively).
- Rates of colon cancer have remained relatively flat over the period.
- However, rates of rectal cancer have been increasing steadily since 1984.
- Rectal cancer rates have gone up about 3.8 per cent per year between 1984 and 2005.
- The rates appear to be increasing across all races and in both sexes.
Meyer told the press that doctors should do an endoscopic evaluation when a young patient presents with rectal bleeding or other signs of rectal cancer, to rule out malignancy.
As well as rectal bleeding, other symptoms of rectal cancer include a change in bowel habits, diarrhea, anemia and weight loss.
Currently, what is often the case when a young person presents with these symptoms, is to assume they have hemorrhoids.
“More frequent endoscopic evaluation may be able to decrease the documented delay in diagnosis among young people,” urged Meyer.
However, the authors did not recommend routine screening of people under 40 for rectal cancer because the overall rates, despite the steady increase, are relatively low.
A person is at a higher risk for colorectal cancer if he or she has a family history of the disease, smokes, drinks a lot of alcohol, is obese, has a diet low in vegetables and high in red meat, and doesn’t get enough Vitamin D.
Meyer said they searched the medical literature to try and find an explanation for this rising trend, and also spoke to experts in the field, but found no clues.
“It’s a little bit puzzling,” said Meyer, according to a report in the Los Angeles Times.
Meyer and colleagues did not find any evidence that the rise in rectal cancer rates was associated with anal sex, which is typically linked to anal cancers caused by HPV, the human papillomavirus, which tend to be of the adenocarcinoma type while the rectal tumors are of the squamous cell carcinoma type.
“Increasing incidence of rectal cancer in patients under age 40: an analysis of the Surveillance, Epidemiology, and End Results database.”
Joshua E. Meyer, Tarun Narang, Felice H. Schnoll-Sussman, Mark B. Pochapin, Paul J. Christos, David L. Sherr.
DOI: 10.1002/cncr.25432.
Sources: American Cancer Society, Los Angeles Times.
Written by: Catharine Paddock, PhD