Researchers have observed increases in early-onset colorectal cancer. In a recent study, they determine its relation to obesity.
Obesity is characterized by being overweight and specifically, having a BMI of 30 or greater. According to Obesity Canada, obesity is a chronic illness that resembles diabetes mellitus (type 1 diabetes) and high blood pressure. The effects of obesity can negatively impact one’s lifespan and lead to a vast number of lifestyle diseases.
Statistics show that obesity is a troubling disease as it impacts a large percentage of Canadians. Canada’s Community Health Survey in 2014 approximated the number of obese Canadians to exceed 5 million people; this means that 30% of Canada’s population is obese.
How is cancer related to obesity?
Cancer is a disease characterized by the abnormal and rapid production of cells that have no clear function in the body. Most cancers can be traced to DNA damage, including mutations (mistakes made during cell replication). Obesity is related to chronic inflammation in the body, which can over time, lead to DNA damage. This is one of the many ways obesity can increase the likelihood of developing cancer.
Individuals suffering from obesity possess more adipose tissue. Adipose tissue is the medical term for fat tissue; this tissue releases estrogen which can increase the probability of developing hormone-related cancers. Cancers like breast cancer, endometrial cancer and ovarian cancer among others are more common among obese women compared to women with low body fat percentages.
An additional impact of obesity on our biochemistry is that individuals who are obese often have elevated levels of insulin. This impacts an individual’s health by increasing the amount of IGF-1 or insulin growth factor-1 in the body. Insulin growth factor 1 has been linked to the development of colon, prostate and kidney cancer among others.
Researchers at the National Cancer Institute and National Institutes of Health in the United States were surprised when increases in early-onset colorectal cancer were being reported. They hypothesized that this was due to the obesity epidemic. In order to test their theory, they looked at the United States’ cancer registry system to assess cancer incidence in the past 50 years. They published their results in The Lancet Journal of Public Health.
Steady increase in obesity-related cancers over the past 50 years
Interestingly, researchers’ hypotheses were confirmed: obesity-related cancers steadily increased for younger adults over the past 50 years. Researchers assessed age groups ranging from 25 to 84 years of age and looked at changes in cancer incidence every year for age cohorts of 5 years
(ie. 25-29 year olds, 30-34 year olds, etc.). Specifically, there has been a 1.44% annual increase for multiple myeloma, obesity-related cancer. Myeloma cells are a type of white blood cell that produces antibodies that help provide immunity. Initially, few people experience symptoms, however, as the disease progresses, many people become anemic and therefore, experience frequent bleeding, bone pain and inability to fight infections.
Researchers found a 6.23% annual increase in kidney cancer, also known as renal cell carcinoma, in the age cohort of young adults aged 25-29 years old. One of the most common symptoms of renal cancer is fatigue, another common symptom is high blood pressure (this is because the kidneys lose their ability to properly filter the blood).
If the tumour is confirmed to be cancerous, patients can undergo a nephrectomy or removal of the kidney(s). This can be radical (to have the whole kidney removed) or it could be partial removal of the kidney (not all tissue is extracted).
This study revealed an overall increase for most cancers related to obesity for all age groups, however, the annual increase of cancer diagnoses seems to be must greater for younger generations. This is indicative that our government needs to focus on primary preventative measures to promote a healthy lifestyle from an early age for residents.
Today, 12 of the 30 recognized cancers are linked to obesity and these links are supported by clinical data. The investment in a healthier society will start at the community level by equalizing the opportunity to play sport and eat healthy, unprocessed foods. Hopefully, by adopting these changes, North Americans will notice a decrease in the incidence rates of obesity-related cancers.
Written by Nikki Khoshnood, BHSc Candidate
Reference: Sung, H., Siegel, L, R., Rosenberg, S, P., Jemal, A. (2019). Emerging cancer trends among young adults in the USA: analysis of a population-based cancer registry. The Lancet Journal of Public Health.