Groundbreaking research from Stanford University has uncovered a surprising revelation about ageing and cancer that challenges long-held medical beliefs. Contrary to conventional wisdom that cancer risk continuously increases with age, new evidence suggests that extreme old age might actually provide protective benefits against tumor growth.
Unexpected Findings in Ageing Mice
In a comprehensive study using genetically engineered mice, researchers made a startling discovery. Very old mice developed significantly fewer and smaller tumors compared to their younger counterparts. The study specifically examined lung cancer development, with young mice aged four to six months developing multiple large lung tumors, while older mice aged 20 to 21 months showed far fewer and considerably smaller tumors.
Dr. Monte Winslow, PhD, associate professor of genetics and pathology at Stanford, expressed surprise at these results. "We would expect older animals to develop more and worse cancers, but that is not what we observed," he stated. "Understanding how molecular changes associated with ageing suppress cancer is the next challenge."
Why Cancer Risk Plateaus in the Elderly
This research provides a potential explanation for observations in human populations where cancer incidence plateaus or even declines after approximately 85 years of age. While it's well-established that cancer risk generally increases with age due to accumulated DNA mutations during cell division, data consistently shows that this risk stabilizes or decreases in the very elderly.
Dr. Emily Shuldiner, PhD, lead author of the study, explained that introducing identical cancer-causing mutations in both young and old mice revealed striking differences. Young mice developed rapidly growing tumors, while older mice demonstrated slower tumor development and reduced tumor size.
Dr. Dmitri Petrov, PhD, professor of biology, commented on the significance: "After a certain point, ageing appears to act as a form of cancer suppression."
Implications for Cancer Treatment and Research
The study, published in Nature Aging, highlights critical gaps in current cancer research methodologies. Most laboratory studies use young animals, potentially overlooking age-related biological mechanisms that influence tumor formation and treatment response.
Researchers discovered that when they inactivated 25 tumor suppressor genes, tumor formation increased in both young and old mice, but the impact was significantly more pronounced in younger animals. PTEN, a crucial tumor suppressor gene, showed particularly strong age-dependent effects, suggesting that targeted therapies might work differently in younger versus older patients.
Dr. Winslow emphasized the practical implications: "If we want animal models to inform patient therapies accurately, we must include ageing as a factor. Otherwise, important biological differences in older patients may be missed."
The research team also found that older mice maintained signatures of ageing even in rapidly dividing cancer cells, indicating that cellular ageing processes might inherently inhibit cancer development through changes in DNA methylation, genome stability, and chromosomal structures.
This pioneering research opens new possibilities for cancer treatment strategies that could harness the body's natural protective mechanisms activated during advanced ageing. As Dr. Petrov optimistically noted, "This research suggests that ageing may have beneficial aspects that could be harnessed for more effective cancer treatments in older adults."
