Scientists have identified potential links between higher birth weight and paternal age as contributing factors to the rising rates of early-onset bowel cancer in young Australians. The findings, published by the Yale School of Public Health, offer insights into a trend that has baffled experts worldwide.
Bowel cancer is the deadliest cancer for Australians aged 25 to 54, with a significant surge in cases diagnosed in individuals under 50. While the exact causes for this increase have remained largely unknown, the new study suggests that excess weight at birth and having an older father may markedly increase the chances of developing the disease.
Key Findings on Risk Factors
The study found that newborns weighing 4kg (8lb 13oz) or more, a condition known as foetal macrosomia, were more likely to develop early-onset bowel cancer. This condition, thought to affect up to 10 percent of Australian babies, is commonly associated with parental obesity and diabetes. These parental health factors may, in turn, increase their children's risk of developing life-threatening diseases, including cancer.
Furthermore, the research indicated that young women whose fathers were 35 or older at the time of conception had a significantly higher risk of early-onset bowel cancer. Older paternal age has been linked to various birth defects, and some studies suggest it may also increase the risk of certain cancers. The researchers theorize that spontaneous genetic changes, known as de novo mutations, among children born to older fathers could be a contributing factor.
However, the study noted a difference in the birth weight association between sexes. For females, every half-kilogram difference in birth weight was linked to a 10 percent increased risk of bowel cancer, a pattern not observed in males. The reasons for these sex-specific differences remain unclear.
Rising Rates and Previous Research
Globally, Australia has the highest rate of early-onset bowel cancer among 50 surveyed countries. Rates are two to three times higher among Australians born in the 1990s compared to those born in the 1950s. Approximately one in eight Australians diagnosed with bowel cancer are under 50, and the risk of diagnosis before age 40 has more than doubled since 2000.
Previous research has already established that obesity, lack of exercise, and alcohol consumption are known risk factors for bowel cancer. The recent study builds upon this by highlighting potential prenatal and paternal influences on the disease's development in younger populations.
The findings come years after the death of BBC journalist and bowel cancer campaigner Dame Deborah James, who died from the disease at age 40 in 2022. Her advocacy brought increased attention to the disease, particularly its impact on younger individuals. The Bowel Babe fund, established in her honor, has raised significant funds for cancer research.
Understanding Bowel Cancer Symptoms
Bowel cancer can manifest with various symptoms, though not everyone experiences them, especially in the early stages. Common signs include blood in stool or rectal bleeding, persistent changes in bowel habits such as looser stools or constipation, a change in the shape of stool, frequent gas pain or bloating, unexplained anemia leading to fatigue, a feeling of incomplete bowel emptying, or pain or a lump in the anus or rectum.
Bowel Cancer Australia recommends that anyone experiencing such symptoms for two weeks or more should consult a general practitioner. Early diagnosis is crucial, as almost 99 percent of bowel cancer cases can be successfully treated when detected early. The organization also advises participation in screening appropriate to individual risk levels, with current medical guidelines recommending a faecal immunochemical test every two years from age 45 to 74 for those at average risk without relevant symptoms.