Chronic inflammation may create lasting cellular changes that promote cancer.
New research suggests that long-lasting effects from chronic inflammation may help explain why some people develop cancer years after an illness appears to heal. Scientists studying intestinal disease found that inflammation can leave behind lasting biological changes in cells, creating conditions that make tumors more likely to form later in life.
The study, conducted by researchers at the Broad Institute of MIT and Harvard, explored how inflammation in the digestive system affects cells even after visible recovery. Chronic inflammation has long been linked to cancer risk, but the exact process connecting the two has remained unclear. The new findings provide evidence that inflammation may leave a form of biological memory inside cells that continues to influence how they behave long after symptoms disappear.
Researchers focused on colitis, a condition marked by ongoing inflammation of the colon. Using animal models, scientists triggered inflammation in gut tissue and then allowed the tissue to recover. Under a microscope, the tissue appeared normal once healing occurred. However, deeper analysis revealed that some cells still carried hidden changes affecting how genes could be activated.
These changes occurred not in the DNA sequence itself but in what scientists call the epigenome. The epigenome controls which genes are switched on or off without altering the genetic code. Chemical markers and structural shifts around DNA can make certain genes easier or harder to activate. According to the study, inflammation changed these controls in lasting ways, leaving what researchers described as molecular scars.
Even after inflammation ended, certain regions of DNA remained unusually accessible. This meant genes linked to cell growth and survival could be activated more easily in the future. When researchers later introduced a cancer-related mutation, tissues that had experienced earlier inflammation developed larger and faster-growing tumors compared with tissues that had never been inflamed.
The findings suggest cancer development may occur through a two-step process. First, inflammation reshapes how genes are regulated, creating a vulnerable environment. Later, a genetic mutation acts as a trigger that pushes those altered cells toward tumor formation. Both steps together appear to increase cancer risk more than either factor alone.
Scientists also discovered that stem cells played an important role in preserving this memory. Stem cells divide repeatedly to replace older cells in the intestine. When these stem cells carried epigenetic changes caused by inflammation, they passed those changes to future generations of cells. Over time, entire groups of cells inherited traits that made them more sensitive to cancer-promoting signals.
The research may help explain why colorectal cancer rates have risen among younger adults despite little change in inherited genetics. Lifestyle factors such as diet, environmental exposures, or repeated inflammation may leave lasting marks that influence health decades later. Experiences early in life may shape disease risk long after circumstances change.
Another important finding is that many people carry cancer-related mutations without ever developing cancer. The study suggests that mutations alone may not determine outcomes. Instead, the history of a cell’s exposures and stressors may decide whether those mutations remain harmless or become dangerous.
Researchers are now exploring ways to detect these molecular scars in humans. One possibility involves identifying biological markers in stool samples that signal increased cancer risk before disease develops. Early detection could allow doctors to monitor higher-risk individuals more closely or intervene before tumors form.
Future treatments may also focus on reversing harmful epigenetic changes rather than targeting tumors after they appear. If scientists learn how to reset or repair these cellular memories, it may become possible to lower cancer risk linked to chronic inflammation.
Although the study was conducted in animals, it adds to growing evidence that long-term health is shaped not only by genetics but also by past biological experiences. Inflammation, once viewed mainly as a temporary response to injury or illness, may leave lasting effects that shape how cells function for years.
The findings encourage further research into how preventing or reducing chronic inflammation could lower cancer risk over time. Understanding how cells remember past stress may open new paths for prevention, earlier screening, and treatments designed to stop cancer before it begins.
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Chronic inflammation leaves epigenetic scars that increase future cancer risk
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