Colorectal cancer 'hype' suggests rates rising in under 50s

A new study of data from the EU and UK indicate that overall deaths from colorectal cancer are decreasing.

The research, published in the "Annals of Oncology," follows long-term trends that the disease is claiming fewer lives than it did 30 years ago.

According to the data, 6.2 million deaths from all cancers have been avoided in the EU since 1988, and 1.3 million death have been avoided in the UK.

The study used population data from the World Health Organization to predict cancer-related deaths for 2024 from all forms of cancer.

"The fall in mortality rates for colorectal cancers was 4.8% in men and 9.5% in women. The reason for the drop is a fall in smoking rates, along with better diagnosis and better treatment for cancers," Carlo La Vecchia, of the University of Milan in Italy, who led the study, told DW.

The largest declines in colorectal cancer mortality rates are for those over the age of 70. But there is an overall reduction in colorectal cancer incidence and mortality, which La Vecchia described as "grounds for optimism."

Michael Bretthauer, a professor of medicine at the University of Oslo, Norway, whom DW asked to comment on the findings, said: "Fatality rates for colorectal cancer used to be 50-60% but now they've dropped to 20-30%. This is a great achievement."

The reduction in mortality rates is due to better surgical techniques with colonoscopies, where the cancerous tissue in the lower intestines and rectum are removed surgically, along with better cancer treatment drugs, and better screening methods to catch the disease earlier.

Colorectal cancer mortality rising in young adults, but fewer get it

The study also found that colorectal cancer mortality rates are increasing in people below the age of 50.

 Mortality rates in younger people in Italy, Poland and Spain for men, and in Germany for women rose by 5-7%, while rates in the UK rose by 26%.

"We see a reversal of trends [of falling cancer mortalities] for those below 50. It's major in the UK and observed in other European countries. We can link this to both increased screening of colorectal cancers and higher rates of obesity, which is a risk factor," said La Vecchia.

However, Bretthauer said the absolute numbers of people below the age of 50 suffering from colorectal cancer were extremely low and little cause for concern.

"There has been a lot of media hype about increases in colorectal cancers in young people, but if you look at the absolute risk rather than relative risk, the rates are very low," he said.

Mortality rates in Germans under the age of 50, for example, are 2.53 per 100,000 people, compared to 164 per 100,000 people over the age of 70.

"Colorectal cancer is primarily a disease of old age. It's why we see lower incidences of the disease in developing countries with younger populations," said Bretthauer. "If you are 30 or 40 years old, [...] the risk is just so low."

What causes colorectal cancer?

Scientists understand "risk factors" that may influence the disease, said Bretthauer, but we don't fully understand how they cause cancer.

Smoking, obesity and diet are all well-established risk factors, for instance, but how they directly impact the disease is not well-known.

"Obesity is a major risk factor, but it's not as high as it is for smoking. Diet is also key, but the evidence is very mixed. For example, there's likely no association between red meat and colorectal cancers. But we don't really know the mechanisms behind how these factors might cause colorectal cancers," said Bretthauer.

Is alcohol a risk factor for colorectal cancer?

Stopping drinking could reduce the impact of colorectal cancers. A WHO report published in December concluded that alcohol consumption is a risk factor for colorectal cancers.

Beatrice Lauby-Secretan, who heads the WHO's IARC cancer prevention program and led the report, said there were direct links between alcohol consumption and colorectal cancer.

"Ethanol — the principal alcohol in alcoholic beverages — is transformed into acetaldehyde. Acetaldehyde is genotoxic and causes DNA damage, leading to carcinogenic mutations. Acetaldehyde alters the composition of the gut microbiome, which leads to intestinal permeability. This, in turn, triggers inflammation, which is known to increase the risk of cancer," Lauby-Secretan told DW in an email.

Reducing or stopping alcohol consumption can, then, reverse the long-term effects of alcohol on body, particularly by decreasing DNA damage within a few months of cessation, said Lauby-Secretan.

The burden of cancer is increasing in the world due to rising aging populations. Lauby-Secretan said the most effective way to counteract cancer burden is through lifestyle changes — "refraining from smoking, reducing alcohol consumption and keeping a healthy weight" — to reduce the risk of cancer developing.  

Edited by: Zulfikar Abbany