Can Growing Old Save You From Cancer? New Stanford Study Reveals A Surprising Finding

Last Updated:November 18, 2025, 11:42 IST

The unexpected link between extreme age and declining cancer risk, backed by a new study published by Stanford University, from genetically engineered mice.

For as long as medicine has existed, one assumption has gone largely unquestioned: the older a person gets, the higher the risk of developing cancer. The logic has always seemed simple, as many studies have shown that every year our cells accumulate mutations, and the cancer risk increases with age due to the accumulation of DNA mutations during cell division.

In a series of experiments, a new study published by Stanford University on November 12, 2025, challenges this long-held belief. The study involved genetically engineered mice, and researchers discovered that extreme age may actually protect against the formation of tumours.

Older mice developed fewer and smaller lung tumours than younger ones, despite being exposed to the exact same cancer-causing mutations. One striking phenomenon in the study was that the protective effect seen in mice is similar in humans. Cancer rises sharply from around the age of 50, peaking between 70 and 80 years. However, data show that after the age of 85, the risk of cancer often plateaus or even declines.

“It’s a striking finding,” said Dr Monte Winslow, associate professor of genetics and pathology at Stanford. “We would expect that older animals would get more and worse cancers, but that’s not at all what the study found.”

Link Between Age And Cancer

To explore the relationship between age and tumour development, “Dr Emily Shuldiner, a former Stanford graduate student, genetically engineered mice to develop fluorescently tagged lung cancers when exposed to an inhaled gene delivery system.” She compared the tumour growth in young mice and older mice.

• Young mice: 4-6 months old (similar to a human in their 20s-30s)
• Old mice: 20-21 months old (roughly comparable to a human aged 70-80)

“We would expect older animals to develop more and worse cancers, but that is not what we observed. Understanding how molecular changes associated with ageing suppress cancer is the next challenge,” said Dr Monte Winslow.

Results Of The Research

15 weeks after inducing cancerous tumours, the younger mice had roughly three times more tumours, which were large and more aggressive. “In every way we could measure, the younger animals had worse cancers,” Shuldiner said.

The cancer risk in older mice revealed a striking difference – it showed slower tumour development and smaller tumour size.

Why Cancer Risk Plateaus After Age 85

For years, scientists have proposed alternative explanations, like reduced screening in the very elderly, individuals who are more resistant to disease surviving to older ages (survivor bias), and Immune systems in long-lived people may be “stronger than average,” but the Stanford mouse findings challenge the idea that this pattern is simply statistical.

Dmitri Petrov, professor of biology at Stanford and senior author of the study, explained: “The standard model of cancer says that as you age, you accumulate bad things in your DNA, and eventually cancer happens. But after a certain point, ageing instead appears to be a general form of cancer suppression.” In simple words, after a lifetime of accumulating damage, the biology of ageing may actually make the tissue environment less hospitable to cancer.

Ageing Changes The Rule Of Cancer Development

Ageing alters every cellular process, from DNA repair to metabolism. One of the most revealing observations from the Stanford study was that cancer cells in older mice still retained molecular signatures of ageing, even in rapidly dividing cancer cells. “We found that patterns known to be associated with ageing were still present in the cancer cells from old mice,” Shuldiner said. “It was surprising to see those signatures persist.”

Researchers inactivated 25 suppressor genes, which prevent cancer development, including a major cancer gene called PTEN, to identify whether age changes how cancers respond to genetic damage. Tumour formation increased significantly in both groups when these genes were inactivated, but the impact was greater in young mice. When PTEN was inactivated in old mice, their cancer cells began behaving like young cancer cells again.

This suggests that ageing changes how cancer mutations behave and may even influence the effectiveness of targeted therapies. “It suggests that the effect of any given mutation, or the efficacy of therapies targeting that mutation, might differ between young versus old people,” Shuldiner explained.

Why Most Cancer Research Misses This Entire Phenomenon

Nearly all cancer mouse models use young animals and may overlook critical ageing-related mechanisms. “If animal models are going to inform patient therapies accurately, we must include ageing as a factor,” Winslow said. “Otherwise, critical age-related differences in cancer biology may be missed.” These findings highlight the importance of developing cancer that accounts for age.

Petrov added, “This research suggests that ageing may have beneficial aspects that could be harnessed for more effective cancer treatments in older adults.”

A Global Perspective: Ageing, Cancer, and Prevention

Age remains a leading cancer risk factor, but it is not the only one. According to the World Health Organisation, 30-50% of cancers are preventable through lifestyle change.

Major risk factors include:

• Tobacco and alcohol use
• HPV and hepatitis infections
• Obesity and diet
• Air pollution and radiation
• Occupational exposures

The Stanford study has raised both urgency and hope since it reveals that ageing may naturally suppress cancer growth in ways that were not discovered. As Winslow puts it, “We develop these animal models of cancer with an eye to developing new treatments for patients. But for this to work, the models have to be correct.” The study has offered new strategies that may help prevent or treat cancer in the ageing population.

Older mice developed fewer and smaller lung tumours than younger ones, despite being exposed to the exact same cancer-causing mutations. One striking phenomenon in the study was that the protective effect seen in mice is similar in humans. Cancer rises sharply from around the age of 50, peaking between 70 and 80 years. However, data show that after the age of 85, the risk of cancer often plateaus or even declines.

“It’s a striking finding,” said Dr Monte Winslow, associate professor of genetics and pathology at Stanford. “We would expect that older animals would get more and worse cancers, but that’s not at all what the study found.”

Link Between Age And Cancer

To explore the relationship between age and tumour development, “Dr Emily Shuldiner, a former Stanford graduate student, genetically engineered mice to develop fluorescently tagged lung cancers when exposed to an inhaled gene delivery system.” She compared the tumour growth in young mice and older mice.

• Young mice: 4-6 months old (similar to a human in their 20s-30s)
• Old mice: 20-21 months old (roughly comparable to a human aged 70-80)

“We would expect older animals to develop more and worse cancers, but that is not what we observed. Understanding how molecular changes associated with ageing suppress cancer is the next challenge,” said Dr Monte Winslow.

Results Of The Research

15 weeks after inducing cancerous tumours, the younger mice had roughly three times more tumours, which were large and more aggressive. “In every way we could measure, the younger animals had worse cancers,” Shuldiner said.

The cancer risk in older mice revealed a striking difference – it showed slower tumour development and smaller tumour size.

Why Cancer Risk Plateaus After Age 85

For years, scientists have proposed alternative explanations, like reduced screening in the very elderly, individuals who are more resistant to disease surviving to older ages (survivor bias), and Immune systems in long-lived people may be “stronger than average,” but the Stanford mouse findings challenge the idea that this pattern is simply statistical.

Dmitri Petrov, professor of biology at Stanford and senior author of the study, explained: “The standard model of cancer says that as you age, you accumulate bad things in your DNA, and eventually cancer happens. But after a certain point, ageing instead appears to be a general form of cancer suppression.” In simple words, after a lifetime of accumulating damage, the biology of ageing may actually make the tissue environment less hospitable to cancer.

Ageing Changes The Rule Of Cancer Development

Ageing alters every cellular process, from DNA repair to metabolism. One of the most revealing observations from the Stanford study was that cancer cells in older mice still retained molecular signatures of ageing, even in rapidly dividing cancer cells. “We found that patterns known to be associated with ageing were still present in the cancer cells from old mice,” Shuldiner said. “It was surprising to see those signatures persist.”

Researchers inactivated 25 suppressor genes, which prevent cancer development, including a major cancer gene called PTEN, to identify whether age changes how cancers respond to genetic damage. Tumour formation increased significantly in both groups when these genes were inactivated, but the impact was greater in young mice. When PTEN was inactivated in old mice, their cancer cells began behaving like young cancer cells again.

This suggests that ageing changes how cancer mutations behave and may even influence the effectiveness of targeted therapies. “It suggests that the effect of any given mutation, or the efficacy of therapies targeting that mutation, might differ between young versus old people,” Shuldiner explained.

Why Most Cancer Research Misses This Entire Phenomenon

Nearly all cancer mouse models use young animals and may overlook critical ageing-related mechanisms. “If animal models are going to inform patient therapies accurately, we must include ageing as a factor,” Winslow said. “Otherwise, critical age-related differences in cancer biology may be missed.” These findings highlight the importance of developing cancer that accounts for age.

Petrov added, “This research suggests that ageing may have beneficial aspects that could be harnessed for more effective cancer treatments in older adults.”

A Global Perspective: Ageing, Cancer, and Prevention

Age remains a leading cancer risk factor, but it is not the only one. According to the World Health Organisation, 30-50% of cancers are preventable through lifestyle change.
Major risk factors include:

• Tobacco and alcohol use
• HPV and hepatitis infections
• Obesity and diet
• Air pollution and radiation
• Occupational exposures

The Stanford study has raised both urgency and hope since it reveals that ageing may naturally suppress cancer growth in ways that were not discovered. As Winslow puts it, “We develop these animal models of cancer with an eye to developing new treatments for patients. But for this to work, the models have to be correct.” The study has offered new strategies that may help prevent or treat cancer in the ageing population.

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