Author Austin Ulmer
A concerning trend emerging in Australia, is the number of colorectal cancer cases increasing in younger adults. Colorectal cancer is the fourth most common cancer in Australia and has historically been diagnosed in adults over the age of 50. However, diagnosis rates in adults over 50 have been steadily decreasing over the years. This is largely due to the success of the National Bowel Cancer screening program. Alternatively, colorectal cancer is on the rise in those under 50 and is the deadliest cancer for Australians between the ages of 25 and 54 [1]. People under the age of 50 are generally not included as part of the National Bowel Cancer screening program, and so this may explain why their colorectal cancer is also reportedly being detected at a later stage. So, the important question remains, why is this?
Identifying the reasons for the rise in early-onset colorectal cancer is now a major focus of scientific investigations. The current evidence suggests that this increase is caused by a complex interaction between a person’s genes and their environment. A strong family history of colorectal cancer and inherited conditions, such as Lynch syndrome, is known to increase the risk of early-onset colorectal cancer. However, these known genetic contributions only make up around 30% of cases, meaning most occur in people without a known inherited cause [2]. Because of this, researchers are investigating other factors that may contribute to the rise in early-onset colorectal cancer.
Growing evidence suggests that obesity, inactivity, and elevated insulin are associated with increased risk of early-onset colorectal cancer [2]. A Western diet,  characterised by a diet  high in processed foods, refined sugars, salt and saturated fats, is also associated with an increased risk of colorectal cancer. Researchers believe this may be due to  negative effect on the gut microbiome, which plays a key role in regulating digestion, inflammation, and metabolism [2].
Other evidence suggests that overall dietary patterns may play a key role in disease prevention. The Mediterranean diet for example, which is rich in fruits, vegetables and whole grains, is associated with a decreased risk of early-onset colorectal cancer [3]. Beyond overall dietary patterns, researchers are investigating whether specific nutrients are important for disease prevention. One nutrient, folate, may be of particular interest as it plays a key role in DNA synthesis and repair. Studies have suggested that a higher folate intake may be associated with lower risk of early-onset colorectal cancer [3]. Although these findings are promising, there is limited literature on how personalised diet can help prevent and manage early-onset colorectal cancer. Understanding why colorectal cancer is becoming more common in younger adults is only part of the problem. It is also important to find ways to better support people living with the disease.
At NBRI, we are developing the DIGESTICS pilot study to explore whether personalised dietary intake  based on a person’s genetics, known as nutrigenomics, and full nutritional assessment added to standard medical care is feasible and can improve the management for colorectal cancer patients. The long-term goal of this study is to determine whether a tailored diet influences disease outcomes and quality of life. By improving our understanding of how genetics and diet interact, studies such as the DIGESTICS pilot study may lead to more individualised approaches to colorectal cancer care and improve quality of life for those living with the disease.