Your Risk Of Getting Cancer Declines As You Age, According To This Study
It’s long been thought that age is the most significant risk factor for cancer since, over time, genetic mutations accumulate in cells, and this gradual buildup can eventually lead to cancer development.
However, a new study conducted using a mouse model of lung cancer by Memorial Sloan Kettering Cancer Center (MSK) researchers suggests cancer risk actually declines in older age.
Dr. Xueqian Zhuang, the study’s first author, detailed how lung cancer, like many cancers, is most commonly diagnosed around age 70. Yet, its occurrence tends to decline by age 80 or 85.
“Our research helps show why. Aging cells lose their capacity for renewal and therefore for the runaway growth that happens in cancer,” Dr. Zhuang said.
The team set out to understand why cancer rates peak in early senior years and then decline. They used a genetically modified mouse model of lung adenocarcinoma, a common lung cancer type that’s responsible for approximately 7% of global cancer deaths.
The study of aging in lab models is challenging because it takes two years for mice to reach an age that’s equivalent to between 65 and 70-years-old among humans. Despite the process being time-consuming and requiring a lot of resources, the researchers found it worthwhile.
It was discovered that as mice age, they produce more NUPR1, a protein that causes lung cells to behave as though they are deficient in iron.
This is strange since, according to Dr. Zhuang, the aging cells actually contain more iron. It’s unclear why they act as if they’re iron deficient.
Nonetheless, this perceived lack of iron in older mice resulted in their cells losing some regenerative ability. Given that this ability is closely tied to cancer growth, older mice develop significantly fewer tumors than younger ones.
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It was also uncovered that this effect was reversible. Providing the older mice with extra iron or lowering the levels of NUPR1 in their cells restored their regenerative capacity.
“We think this discovery may have some immediate potential to help people. Right now, millions of people, especially following the COVID-19 pandemic, live with insufficient lung function because their lungs didn’t fully heal from an infection or for some other reason,” explained senior study author Dr. Tuomas Tammela.
“Our experiments in mice showed that giving iron can help the lungs regenerate, and we have really good ways of delivering drugs directly to the lungs, like asthma inhalers.”
Nonetheless, restoring the regenerative ability of lung cells can also enhance their potential to develop cancer. That’s why Dr. Tammela stated that it may not be suitable for individuals who are at high risk of cancer.
The study’s results may also impact therapies that target ferroptosis, a form of cell death driven by iron that was discovered in 2012. Several ferroptosis-inducing compounds and FDA-approved drugs are being explored for their potential to kill cancer cells.
Younger cells aren’t as resistant to ferroptosis as older cells due to the fact that older cells act as if they lack sufficient iron.
This suggests that ferroptosis-targeting treatments may be less effective in older patients compared to younger ones.
Dr. Tammela says the research showed that ferroptosis is tumor-suppressive, but especially among younger animals.
So, as cells age, their biology changes, as does their sensitivity to drugs. Dr. Zhuang believes doctors should carefully evaluate the effects of treatments on both older and younger patients during clinical trials.
“What our data suggests in terms of cancer prevention is that the events that occur when we’re young are probably much more dangerous than the events that occur later. So, preventing young people from smoking, or tanning, or from other obvious carcinogenic exposures is probably even more important than we thought,” Dr. Tammela concluded.
To read the study’s complete findings, which have since been published in Nature, visit the link here.
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