Scientists continue debate on finding causes for colon cancer

The number of colorectal cancer — sometimes called colon cancer — in adults below 55 years has been increasing in the US since the 1990s and the reason behind this is unknown, CNN reported.

Experts at Dana-Farber Cancer Institute are urging that there is much yet to be done to study, treat and prevent this cancer at a young age.

Dr Marios Giannakis and Dr Kimmie Ng in a research paper published in the journal Science suggested a plan to the experts to study the surge in the number of cancer diagnoses at a young age asking to set up specialised research centres focusing on the diverse number of diagnosed patients. They also hoped this will improve the outcomes for the young patients.

An estimate suggests that by 2030, the leading cause of cancer-related death among adults of 29 to 49 years would be colon cancer. A report by the American Cancer Society said in 1995, 11% of people were affected but in 2019 it went to 20%.

What are the symptoms of colon cancer?

The symptoms of colon cancer are rectal bleeding, blood in the stool, changes in bowel habits, abdominal pain, fatigue, and weight loss.

Dr Steven Lee-Kong, chief of colorectal surgery at Hackensack University Medical Center in New Jersey believes there is more than just one cause. He said he has witnessed an increase in rectal cancer patients and his youngest patient was 21.

He maintained that the cause of a general decrease in colon cancer patients because of screening of adults.

"But that doesn't really account for the overall increase in the number of patients younger than, say, 50 and 45 that are developing cancer," he noted

What are the causes of colon cancer

Rebecca Siegel, the lead author of the study, believes that the other factors which may cause cancer are consuming alcohol, obesity, smoking, family history, lack of physical activity and certain genetic mutations. However, no specific data is found that can show the cause of the cancer, she noted.

There are people who do not have excess weight but were diagnosed with cancer such as Broadway actor Quentin Oliver Lee who died last year at 34 after a stage IV diagnosis.

Siegel also said that I have heard people in conferences anecdotally that they have been healthy yet diagnosed with this cancer. Obesity may be a contributing factor.

The role of obesity

Dr Subhankar Chakraborty, a gastroenterologist with The Ohio State University Comprehensive Cancer Center, thinks that diet and lifestyle have a considerable role in cancer development.

He said that as the risk factors include obesity, eating processed meat, no physical activity, smoking, and alcoholic habits, it is evident that diet has a major role.

He maintained that though there are other factors causing the diseases, the major factor would be diet. He also said it is difficult to pinpoint one cause because of the time of years it takes to develop.

Researchers are also studying the link between childhood obesity with this cancer.

"The rise in young-onset colorectal cancer correlates with a doubling of the prevalence of childhood obesity over the last 30 years, now affecting 20% of those under age 20,” Dr William Karnes, a gastroenterologist and director of high-risk colorectal cancer services at the UCI Health Digestive Health Institute in California, told CNN.

Dr Shane Dormady, a medical oncologist from El Camino Health in California who treats colorectal cancer patients, also noted: "I think younger people are on average consuming less healthy food – fast food, processed snacks, processed sugars – and I think that those foods also contain higher concentrations of carcinogens and mutagens, in addition to the fact that they are very fattening."

Yet at the Center for Young Onset Colorectal and Gastrointestinal Cancers at Memorial Sloan Kettering Cancer Center, researchers and physicians are not seeing a definite correlation between the rise in colorectal cancer among their younger adult patients and a rise in obesity,

On the other hand, researchers at the Center for Young Onset Colorectal and Gastrointestinal Cancers do not see any concrete relation between obesity and cancer.

They believe that a lot of the patients that they saw are young and healthy and don’t really fit the obesity profile.

The role of genes

Some scientists are also studying the role of genetic mutation in the cause of cancer.

Karnes, from UCI Health, said “it is unlikely that there has been an increase in the genetic mutations that raise the risk of colorectal cancer, although, as expected, the percentage of colon cancers caused by such mutations, e.g., Lynch syndrome, is more common in people with young-onset colon cancer."

Lynch syndrome is hereditary cancer with 4,200 annual patients. Those having this syndrome are likely to develop cancer before 50.

Dormady said there is no clear relation between genes causing cancer. "I don't think the inherent frequency of those mutations is going up", he added.

The tumours of younger colon cancer patients are found similar to older ones, and if they're the same then why the surge is in young people, said Mendelsohn at Memorial Sloan Kettering Cancer Center.

She maintained: "About 20% may have a genetic mutation, so the majority of patients do not have a family history or genetic predisposition."

Mendelsohn also added that genetic mutation is not driving the rise in colorectal cancer in young adults.

How to check for colon cancer

Dr Shane Dormady said he is coming across an increased number of patients than 20 years ago because of the home testing kits, and the age reduction from 50 to 45 by US preventive Services Task Force.

He believed that as testing is improving, the diagnosis is the early detection of cancers.

Chakraborty maintained that "I think if we have that, then it would allow us hopefully, in the future, to provide some personalised recommendations on when a person should be screened for colorectal cancer and what should be the modality of screening based on their risk," he said.

Young adults develop cancer on the left side however, older people develop their right side. This can also be used to screen the younger adults versus the older ones, he added.