Unlikely factor that may increase risk of early colon cancer, new research finds
A unique study has found that older siblings carry a greater risk of early-onset colon cancer.
Researchers in New York found that people with older siblings were also more likely to develop the disease before age 50, regardless of other risk factors.
In the analysis of data from 500,000 adults, other variables known to increase the risk of colon cancer, such as family history of the disease, body weight and tobacco use, were excluded.
The study only shows a correlation and cannot say for sure that the two factors are linked. However, scientists say the ‘surprising’ connection is at least plausible.
Researchers in New York City found that people with two or more older siblings were 1.5 times more likely to develop colorectal cancer early than people who had no older siblings.
The graph above shows that the number of cases of bowel cancer among the over-50s has increased by more than 5,500 in 20 years. In 2020 there was a decrease, because the Covid pandemic caused fewer people to come forward for screenings.
One theory is that younger siblings are more likely to get childhood illnesses if there are many siblings around. Think of stomach flu, for example. This can cause inflammation and damage to the intestines at a young age or change the intestines in other ways.
You may also be more likely to be prescribed antibiotics, which are suspected of playing a role in the development of colon cancer, the researchers said.
Another hypothesis is that parents with multiple children are at greater risk of passing on genetic mutations that increase the risk of cancer.
The analysis was published in the journal Clinical Gastroenterology and Hepatology as a research article, so it is not a full study.
Therefore, other risk factors that can cause colon cancer, including diet and alcohol consumption, were not examined.
Researchers from three New York City institutions, including Memorial Sloan Kettering and Columbia University, collected data from 500,000 UK residents registered in the UK Biobank database.
In that group, there were fewer than 200 cases of colon cancer, which may also have influenced the findings.
But the team found that people with two or more older siblings were 50 percent more likely to develop colon cancer early than people who had no siblings.
People with an older brother or sister followed closely behind, with a 40 percent higher chance.
No association was found between colon cancer in people over 50 and the number of siblings they had.
The team said the “factors behind the observed association are unknown,” but suggested several theories.
They are particularly convinced that having multiple older siblings increases the risk of various childhood illnesses, such as flu, chickenpox and strep throat.
The team wrote: ‘Colorectal cancer (bowel cancer) can take decades to develop.
‘Therefore, it is important to understand the role of early-life factors such as socioeconomic status (SES), paternal age, genetics, and microbiome composition.
‘Older siblings can be direct sources of microbiota (bacteria). Recent data show that there is a positive association between the number of older siblings and greater diversity in the gut microbiome.’
The team further suggested that if their theory is correct, this would increase exposure to antibiotics used to treat bacterial infections.
Recent research suggests that these drugs are partly responsible for the increase in colorectal cancer cases.
Dr. Suneel Kamath, an oncologist specializing in colorectal cancers at the Cleveland Clinic, previously told DailyMail.com that overuse of these drugs can damage the gut microbiome, a network of healthy bacteria that helps regulate gut health and the immune system, among other things.
“What we suspect is that when there is overuse of antibiotics, there is a change in what was a normal, healthy microbiome, and then bad pathogens, if you want to call them that, move in,” he said.
‘These can cause inflammation or other things that cause mutations in cells.
“(These) can lead to an overdrive of the cell, which is sort of dividing and replacing itself. And if you do that faster than you should, that can lead to mutations and as a result tumors.”
In one Study 2021 Researchers examined the entire Swedish population from 2005 to 2016 and identified more than 40,000 cases of colorectal cancer (CRC), compared with a control group of 200,000 cancer-free Swedes.
Both women and men who took antibiotics for more than six months had a 17 percent higher risk of cancer in the ascending colon, the first part of the colon reached by food after the small intestine, than women who were not prescribed antibiotics.
Additionally, the researchers noted that people with more older siblings may be at greater risk because their parents were older when they had them compared to their siblings, as older populations are most likely to develop colorectal cancer. However, they noted that more research is needed to confirm this.
The team has not yet confirmed whether a full study will be released. “Findings warrant confirmation in other large study populations,” the team wrote.
Dr. Jen Dunphy, an oncologist at Wellness Innovation Network in California who was not involved in the study, told DailyMail.com that while the research seems bizarre, it is plausible.
She noted that one theory behind the findings is that older children bring more processed foods into the home.
“As children get older, they have more access to sugary drinks and processed foods, both at school from their peers and at home. Often, these snacks are also shared with siblings, exposing younger siblings to these dietary risk factors for colon cancer,” she said.
However, she indicated that research is needed to confirm this.
Data from JAMA Surgery shows that the number of colon cancer cases is expected to increase by 90 percent in people between the ages of 20 and 34.
Dr Kamath, who was not involved in the study, responded to the new findings, telling DailyMail.com that the research is “very surprising” and that “it’s difficult to say what the cause might be.”
He proposed a theory that younger siblings are born from older sperm and eggs than their older siblings. This increases the risk of genetic mutations, which “may persist in the child and potentially lead to cancer earlier in life.”
“I would add that this finding is not particularly useful, because we cannot go back in time and have older siblings ‘unborn’. I doubt that many people in the future would set a limit on the number of children they have based on these findings,” he said.
‘It may be useful for young people who have symptoms that suggest colon cancer. If their doctor is aware of these findings, they may be able to refer them for a colonoscopy sooner, if they are the youngest child in the family.’
‘Larger and better studies are needed to confirm whether these findings are true or not.’
While the findings may seem bizarre, the paper is part of a growing body of research showing that birth order and genetics may increase the risk of certain diseases.
A judgement For example, a study of more than 238,000 people in 17 countries found that children of overweight grandparents were twice as likely to be overweight or obese themselves than children with a normal BMI.
And a study in the Journal of Epidemiology and Community Health found that firstborn children were significantly more likely to be overweight or obese than their siblings.