Many people know that smoking can cause lung cancer and that spending too much time in the sun without protection can increase the risk of skin cancer. These are well-known examples of how everyday choices can affect health.
However, scientists have long wondered how much of a person’s cancer risk comes from preventable habits and environmental exposures compared with natural aging and random genetic changes that happen over time.
Cancer develops when changes, called mutations, build up in a cell’s DNA. Some of these mutations are caused by harmful exposures such as tobacco smoke, ultraviolet (UV) rays from the sun, or certain chemicals. Others happen naturally as cells divide and people grow older, even when they live a healthy lifestyle.
A new study from Yale University has taken a closer look at this question. The research was led by Jeffrey Townsend and published in the journal Molecular Biology and Evolution. The scientists analyzed DNA changes in tumors from 24 different types of cancer to better understand what had driven each cancer to develop.
The researchers searched for patterns of genetic mutations that are known to be linked with specific environmental exposures. For example, UV light leaves a different pattern of DNA damage than tobacco smoke.
By measuring how much each pattern contributed to tumor growth, the researchers could estimate whether a cancer was mainly driven by preventable factors or by natural biological processes.
The results showed that the causes of cancer can vary greatly depending on the type of cancer. Bladder cancer and skin cancer were found to be strongly influenced by environmental and lifestyle factors. This suggests that reducing harmful exposures, such as avoiding excessive sunlight or limiting contact with cancer-causing substances, could help prevent many of these cancers.
In contrast, prostate cancer and gliomas, a type of brain cancer, appeared to be influenced much more by aging and normal biological processes inside the body. This does not mean these cancers cannot be treated or detected early. Instead, it suggests that healthy habits alone may not prevent every case because some genetic changes happen naturally throughout life.
The researchers believe their method could also help uncover hidden environmental dangers. If workers in a particular industry or people living in a certain community develop unusually high rates of cancer, scientists may be able to use these genetic clues to identify harmful substances responsible for the disease.
This information could help governments and public health officials reduce dangerous exposures before more people become ill.
The study does have some limitations. The researchers focused on many common DNA mutations but did not include every possible genetic change involved in cancer. More complex changes, such as duplicated genes or extra chromosomes, were not fully examined, meaning the complete picture of cancer development is still being explored.
Even with these limitations, the findings provide valuable new insights into how different cancers begin.
Understanding which cancers are mainly driven by preventable exposures and which are more closely linked to aging could improve cancer prevention strategies, workplace safety, and public health policies. It may also help doctors identify people who would benefit most from screening and early detection.
The study reminds us that cancer is usually caused by a combination of factors rather than a single event. Healthy lifestyle choices such as avoiding smoking, protecting the skin from excessive sunlight, maintaining a healthy weight, and following recommended screening programs remain some of the best ways to lower cancer risk.
At the same time, ongoing research continues to improve our understanding of the causes of cancer and may lead to better prevention strategies in the future.
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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