Colorectal cancer is a type of cancer that affects the colon (large bowel/large intestine) and/or rectum. According to the World Health Organisation, colorectal cancer is the third most common cancer worldwide, accounting for approximately 10% of all cancer cases and is the second leading cause of cancer-related deaths worldwide. While predominantly affecting older adults (50 + years), in recent years it has become more common in younger adults (i.e., those under 50 years), possibly due to changes in lifestyle over the past few decades. Modifiable risk factors include an unhealthy diet, sedentary lifestyle, smoking and excessive alcohol consumption. Unmodifiable risk factors include age, a family history of colorectal cancer and a genetic tendency to develop bowel polyps.
Like essentially all forms of cancer, early diagnosis, appropriate treatment, and regular follow-up care are important for improving survival rates and quality of life.
In its initial stages, colorectal cancer often has no symptoms, which is why regular screening after the age of 50 (after 45 in some countries like Australia) is recommended. In later stages, common symptoms include:
- changes in bowel habits such as diarrhoea, constipation, or narrowing diameter of the stool
- blood in the stool (rectal bleeding), either bright red or dark and tar-like
- abdominal cramps, pain or bloating
- unexplained sudden weight loss
- iron deficiency anaemia due to chronic bleeding, causing fatigue, weakness and paleness
- feeling constantly tired and lacking energy, even with enough rest
My mothers personal experience with colorectal cancer was literally lifechanging. She was diagnosed with bowel cancer in the late 1980’s when I was a university student studying Psychology and Communication Studies. She was in her early 50’s, and had recently been losing weight, was constantly tired, bloated and occasionally she found blood in her stools.
Diagnosis wasn’t straight forward for her, however – an abdominal ultrasound indicated that she had multiple cysts on her liver and kidneys, and the large lump on her ascending colon was originally thought to be a cyst. The cysts were thought to be benign, and not worth treating unless they physically blocked an organ. This led her to seek advice from a “complimentary therapist” to help her reduce the cysts, naturally. The person she saw had studied animal nutrition at university (he had two master’s degree’s in the area), but started advising people about nutrition after his wife was diagnosed with cancer.
My parents were both born and raised in England, and grew up during World War II. They lived with food rationing during the 1940’s and 50s, before moving first to Canada and then to Australia in the late 60’s. Their diet was probably quite typical for English people of their generation – Weetabix with cow’s milk and table sugar for breakfast, white bread sandwiches, buttered, with a simple filling (e.g., cheese and/or ham) for lunch, and meat (mostly beef and lamb, with the occasional chicken or fish) and 3 veg (potato (typically mashed), peas and carrots) for dinner – often as a stew, casserole, or in a home-made pie. Nutritionally, their diets would have been high in animal fat and protein, refined carbohydrates (i.e., starches and sugars) and relatively low in dietary fibre.
The “complimentary therapist” advised mum to eat less animal fat and protein, and to eat more seafood, fruit and vegetables. Plus, he prescribed quite a long list of vitamins, minerals, herbal teas, and other supplements. Her health did improve, but weight loss and abdominal pain continued, so she had further investigations and was eventually diagnosed with cancer of the ascending colon. Surgery was arranged promptly and was successful.
As I was a student, I had access to medical databases (microfiche!) through my university’s library. I found some evidence that poor diet increased the risk of developing bowel cancer. I also bought a number of popular “diet” books available at that time and came to the conclusion that not only was poor diet a likely cause of my mothers bowel cancer, but eating a healthy diet might help her prevent it re-occurring.
I raised this with my mother’s surgeon, and asked if she should follow a special diet after her surgery. He advised that diet had nothing to do with colorectal cancer, and that she could continue to eat what she liked. While I was definitely not an expert in the area, this advice was at odds with what I had read. I was living with my parents at that time, and the family drifted in to pescatarianism, then vegetarianism, and then briefly veganism (long-before it became trendy)! Based on my experiences, I decided that food and nutrition was probably more important for health and wellbeing than psychology and switched to studying Nutrition and Food Science (undergraduate), and finally Dietetics (post-graduate). My mother’s diagnosis of bowel cancer was also a life-changing event for me.
My mother is still alive – she turned 88 this year. She is still a pescetarian. As will be seen in this month’s edition of GI News, over the past few decades, research into the causes and treatment of colorectal cancer has increased dramatically. There is now evidence from systematic reviews and meta-analyses of observational studies that prudent/healthy dietary patterns are associated with lower all-cause mortality (deaths) in cancer survivors, with an average 27% risk reduction in people who have had colorectal cancer. I think its fair to conclude that prompt surgery and changing my mothers diet has helped her to live another ~35 years since she was diagnosed with colorectal cancer.
I am glad we didn’t listen to the surgeon’s dietary advice back then. Hopefully, it would be very different today…
- World Health Organisation. Colorectal cancer. July, 2023.
- Better Health Channel. Complementary therapies.
- Spei and colleagues. Post-Diagnosis Dietary Patterns among Cancer Survivors in Relation to All-Cause Mortality and Cancer-Specific Mortality: A Systematic Review and Meta-Analysis of Cohort Studies. Nutrients, 2023