Cancer begins when cells in the body start to grow out of control. This usually happens after changes, called mutations, build up in a cell’s DNA. DNA is the instruction book inside every cell that tells it how to grow, divide, and repair itself.
Some DNA changes are harmless, but others can damage important genes that normally keep cell growth under control. When enough harmful changes collect over time, cancer can develop.
A new study from Yale University gives scientists a clearer picture of where many of these DNA mutations come from.
The research helps explain which cancers are strongly linked to things people can avoid, such as smoking or too much sunlight, and which cancers are mostly caused by natural changes that happen as people grow older. The findings were published in the journal Molecular Biology and Evolution.
To reach their conclusions, the research team studied DNA mutations found in 24 different types of cancer. Every cancer carries a pattern of genetic changes that acts like a fingerprint. By carefully examining these patterns, the scientists estimated how much damage came from outside the body and how much came from normal biological processes that happen during aging.
The study showed that some of the most common cancers are strongly connected to preventable causes. Skin cancers, including melanoma, basal cell carcinoma, and squamous cell carcinoma, were among the clearest examples.
Ultraviolet (UV) rays from the sun and tanning beds can damage DNA inside skin cells. Over many years, this damage builds up and can lead to cancer. This is one reason health experts recommend using sunscreen, wearing protective clothing, seeking shade during the hottest part of the day, and avoiding indoor tanning.
Lung cancer was another cancer that was found to be heavily influenced by preventable exposures. Tobacco smoke contains many chemicals that can damage DNA.
People who never start smoking, or who stop smoking, can greatly reduce their risk of developing lung cancer. Bladder cancer also showed links to harmful chemical exposure, including chemicals found in tobacco smoke and some workplace environments.
The researchers said these findings are encouraging because they show that many cancers are not simply a matter of luck. Healthy choices and public health measures can lower the number of DNA mutations caused by preventable exposures. This means fewer people may develop certain cancers in the future.
However, the study also found that not every cancer can be prevented in the same way. Some cancers appear to be influenced much more by natural changes that occur inside the body over time.
Prostate cancer and gliomas, which are tumors that begin in the brain, were among the cancers that seemed to be driven mainly by age-related DNA changes rather than lifestyle or environmental factors.
This does not mean that healthy living is unimportant. Instead, it shows that some cancers may develop even when people make good choices because cells naturally collect genetic changes as people get older.
The researchers believe their work could help improve cancer prevention in several ways. By understanding which cancers are strongly linked to preventable exposures, governments and health organizations can continue promoting smoking prevention, sun safety, and safer workplaces.
The findings may also help scientists identify groups of workers who are regularly exposed to cancer-causing chemicals and develop better ways to protect them.
The study may also help researchers discover new causes of cancer. Some mutation patterns could point to harmful exposures that scientists have not yet recognized. Finding these hidden risks could lead to better safety rules and new ways to reduce cancer cases.
The team also noted that their study does not explain every genetic change found in cancer. Some cancers contain large DNA changes, including extra copies of genes or even whole chromosomes. These complex genetic events were not fully included in the current analysis, so more research is needed to understand their role.
Although no one can completely eliminate the risk of cancer, this research offers an important message. Many cancer risks are within our control, while others are not.
People should focus on the steps they can take, including avoiding tobacco, protecting their skin from too much sunlight, maintaining a healthy weight, staying physically active, limiting alcohol, eating a balanced diet, and following recommended cancer screening programs.
These actions cannot guarantee that cancer will never develop, but they can lower the risk of many common cancers and improve overall health.
The study was led by Jeffrey Townsend from Yale University and published in Molecular Biology and Evolution. As scientists continue learning more about how cancer develops, research like this gives people clearer information about which risks they can change and which are simply part of the natural aging process.
Better knowledge helps individuals, doctors, and public health experts make smarter decisions that may save lives in the years ahead.
If you care about cancer, please read studies that a low-carb diet could increase overall cancer risk, and berry that can prevent cancer, diabetes, and obesity.
For more health information, please see recent studies about how drinking milk affects the risks of heart disease and cancer and results showing vitamin D supplements could strongly reduce cancer death.
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