Chronic inflammation is the body’s mechanism for injury, but did you know that it can lead to tumor progression? Rather than fighting it, long-lasting inflammation acts as a constant irritant that quietly fuels normal tissue into tumor growth. It provides the environment necessary for tumor growth as well as progression.

The basics of chronic inflammation 

Chronic inflammation is a state of incomplete immune response. Acute responses, such as redness and swelling from a cut, are temporary. Chronic inflammation is the continuous presence of immune cells and inflammatory molecules without any effective resolution. It can be caused by underlying issues like persistent infections, environmental toxins, obesity, or autoimmune disorders. This state of alert creates a basic instability that is necessary for cancer growth.

How does it damage cells?

Immune cells like macrophages and neutrophils keep releasing ROS and RNS when they remain at a chronic inflammation site. This constant oxidative and nitrosative stress damages the DNA of the nearby cells. Repeated cycles of damage and repair overwhelm cell mechanisms, and genetic mutations can easily form and persist. This increases the conversion of normal cells to malignant ones, making way for uncontrolled cell growth.

Creating a home for the tumor

After nascent tumor formation, chronic inflammation shifts from a cause to a collaborator. The inflammatory environment then becomes an important part of the tumor microenvironment (TME). Within the TME, immune cells release a host of signalling molecules—cytokines, chemokines, and growth factors that support the survival and growth of cancer. The molecules promote proliferation, inhibit programmed cell death, and stimulate the formation of new blood vessels. The inflammation-driven blood supply secures cancer growth and its expansion by supplying it with essential nutrients and oxygen.

Impact on immune defense

Chronic inflammation has a significant impact on the immune defense. The continuous inflammatory signals cause exhaustion and dysfunction of cytotoxic T-lymphocytes and natural killer (NK) cells, which are the immune cells that help the body fight cancer. The immune signaling within TMe pushes the immune cells into a pro-tumor phenotype, where they can secrete growth factors instead of killer signals. By creating an immunological tolerance, the immune suppression allows the tumor to avoid detection and elimination. This results in a weaker tumor control and accelerates cancer progression

Why does it matter?

Chronic inflammatory conditions are linked to specific cancers, including gut cancers, liver cancers, lung cancer, and pancreatic cancers. By understanding the mechanism, inflammation reduction through targeted therapies, lifestyle changes, and infection control is an important strategy to lower long-term cancer risks and improve therapeutic outcomes. 

Chronic inflammation is a partner in cancer progression; it causes DNA damage, creates a permissive tumor microenvironment, and actively suppresses the body’s anti-tumor defenses. It transforms from a temporary immune response to a systemic disease catalyst. By addressing the roots of chronic inflammation, a powerful and preventative way can be found to stop this silent fuel source for cancer.