What explains the increase in bowel cancer among young Australians?

Bowel cancer mainly affects people over the age of 50, but recent data suggest that this phenomenon is on the rise among young Australians.

Our study, recently published in Cancer Epidemiology, Biomarkers and Prevention, found that the incidence of bowel cancer, which includes cancers of the colon and rectum, increased by 9% in those under 50 years between 1990 and today.

Our research examined all cases of intestinal cancer recorded in the last 40 years in Australians aged 20 years and older. Earlier studies evaluating the incidence of bowel cancer among young Australians have also highlighted an increase in the younger age group.

Read more:
Interactive Body Map: What is really giving you cancer?

This trend is also observed at the international level. An American study suggests an increase in the incidence of bowel cancer in people aged 54 years and under. Research shows that the incidence of rectal cancer increased by 3.2% per year between 1974 and 2013 among 20 to 29 year olds.

Bowel cancers should be the third most commonly diagnosed cancer in Australia this year. In 2018, Australians have a chance on 13 to be diagnosed with bowel cancer before the age of 85.

Our study also found that the incidence of bowel cancer was decreasing among older Australians. This probably reflects in part the effectiveness of the national intestinal cancer screening program for 50-74 year olds. Screening for bowel cancer helps reduce the incidence of cancer by detecting and eliminating precancerous lesions, as well as reducing mortality by detecting existing cancers at an early stage.

This is important because bowel cancer has a good cure rate if it is discovered early. From 2010 to 2014, a person with a bowel cancer had about 70% chance of surviving over the next five years. Survival is greater than 90% in people with bowel cancer detected at an early stage.

That's why screening is so effective – and we had previously predicted that if coverage rates of the national gut screening program could be increased to 60%, approximately 84,000 lives could be saved from 39, here 2040. This would represent an extraordinary success. In fact, intestinal screening can be one of the greatest public health successes ever achieved in Australia.

Why this increase among young people?

Our study was not designed to determine why bowel cancer is increasing in young people. However, certain factors could support our conclusions.

The increase in obesity is comparable to that of bowel cancer and extensive population-based studies have linked obesity to an increased risk of cancer.

Read more:
How obesity causes cancer and can make testing and treatment more difficult

Unhealthy lifestyles, such as increased consumption of highly processed foods (including meats), have also been badociated with an increased risk of bowel cancer. High quality studies are needed to further explore this role.

Alcohol is also thought to help increase the risk of bowel cancer.

So, should we lower the screening age in Australia to people under 50?

Evaluating a cancer screening program for the general population requires careful badysis of the benefits, harms and potential costs.

A recent Australian study modeled the benefits of reducing the age of screening to 45 years. She showed that more cancers could be detected. But there would also be more colonoscopy-related damage, such as perforation (tearing), in an extremely small proportion of people requiring further evaluation after screening.

A lower screening age would also increase the number of colonoscopies to be performed in the overburdened public health system and could therefore have the unexpected consequence of lengthening wait times for colonoscopy in high-risk individuals.

Read more:
Useless procedures: when is a colonoscopy necessary?

How to reduce the risk of cancer of the intestine

Rectal bleeding is one of the most common symptoms of bowel cancer. So, if you notice blood when you go to the bathroom, check with your doctor to have it checked.

A healthy lifestyle that includes proper exercise, avoiding smoking, limiting alcohol consumption and eating well is essential to reduce the risk of cancer.

Aspirin can also reduce the risk of cancer, but you should discuss it with your doctor because of the risk of side effects, including major bleeding.

More importantly, we need to ensure that eligible Australians participate in the current evidence-based screening program. Only 41% of the population in the target age group 50 to 74 completed their poop tests in 2015-2016. The test is free, delivered by mail and able to be self-administered.