Cancer is a large group of diseases that causes cells to grow out of control. Researchers are working to develop a list of hallmarks of cancer that distinguish cancer cells from normal cells.

There is no single group of cancer symptoms that all people with cancer share. In fact, many people with cancer only learn of their diagnosis when they have a cancer screening or when a doctor discovers cancer while testing for something else.

Various cancer types affect people uniquely and have very different death rates.

In a paper from 2000, Douglas Hanahan and Robert A. Weinberg identified six hallmarks of cancer that cancer cells share. In 2011, the researchers updated their paper to add two additional hallmarks. Since then, other researchers have expanded upon their research, and studies of potential new hallmarks are ongoing.

Identifying the hallmarks of cancer can help scientists understand what makes cancer cells different from other cells. This could, over time, lead to new treatments.

Read on to learn more about the hallmarks of cancer.

Cancer is a disease where the cells in the body grow uncontrollably. Normal, healthy cells grow and develop according to a predictable schedule, and eventually, they die.

On the other hand, cancer cells may grow faster or longer than normal cells. They may not die as soon, or they may not respond to the body’s signals to die. Unlike normal, healthy cells, the body does not need cancer cells.

Cancer cells may damage healthy cells. Over time, they can also spread throughout the body via a process doctors call metastasis. This can damage organs, organ systems, and the entire body. It can ultimately be fatal.

In 2000, Douglas Hanahan and Robert Weinberg originally proposed six hallmarks of cancer. These hallmarks appear to distinguish cancer cells from healthy cells and may help researchers better understand how and why cancer behaves the way it does.

The original six hallmarks include:

Evading cell death signals

Programmed cell death — or apoptosis — is the process by which typical cells of the body die. It allows new, healthy cells to replace older ones. Apoptosis also prevents cells from growing out of control or harming healthy cells.

Cancer cells can evade signals for programmed cell death, allowing them to live longer and potentially grow larger.

Self-sufficient growth signals

Healthy cells rely on specific signals from the body to grow. For example, hormonal signals tell the female body when to produce a new egg follicle during ovulation.

Cancer cells do not need growth signals. They continue growing, even without specific signaling from the body.

Insensitive to anti-growth signals

Just as cancer cells do not require signals to grow, they also do not respond well to signals telling them to stop growing.

This makes them less sensitive to the processes the body uses to prevent harmful cell growth.

Limitless potential for replication

Healthy cells typically have a limit on how often, or how extensively, they replicate.

Cancer cells are often capable of limitless replication. This allows them to grow faster and larger, potentially overtaking healthy cells and invading nearby tissues and organs.


Angiogenesis is the ability to produce new blood vessels.

Cancer cells send out chemical signals that create new blood vessels. This allows tumors to grow larger and potentially spread through the bloodstream.

Invasion of tissue and metastasis

A key reason cancer can be so dangerous is that it can spread from its original location. Cancer can invade tissues and organs, disrupting their ability to function correctly.

The ability to invade tissue and spread can help distinguish cancerous tumors from benign tumors.

Since their original 2000 paper, Hanahan and Weinberg have proposed two additional hallmarks. They argue that the research is sufficient to support these additional hallmarks of cancer, bringing the total number to eight.

Immune system evasion

Cancer cells cause several issues that would normally attract responses from the immune system. But cancer cells often fully or partially evade the immune system. This allows the cells to continue growing unchecked, even as they cause significant harm.

Deregulated metabolism

Cancer cells metabolize energy differently, and often more effectively, than other cells. This allows them to grow faster and larger. They may also metabolize drugs differently, making them resistant to drugs designed to cause cell death.

The pair also argue that two enabling characteristics help cancer develop its eight hallmarks. These are:


Inflammation may increase the risk of developing cancer. For example, a chronic infection in an area could give rise to cancer.

The research also suggests that chronic inflammation may help with the creation of new blood vessels that nourish cancer cells.

Genome instability

Cancer cells often have genetic abnormalities. These unstable genes tend to mutate and change as cancer progresses. Genetic mutations also tend to contribute to the development of cancer, including cancer’s hallmarks.

Different types of cancer may appear to be very different diseases. For example, the behavior of a skin cancer tumor is different from that of pancreatic cancer. Moreover, cancer cells do not behave like normal cells. Their growth, death, and movement can be unpredictable.

The hallmarks of cancer are traits different types of cancer tend to share. Identifying these traits may have the following benefits:

  • making it easier to predict cancer growth
  • helping develop treatments that can slow or reverse cancer growth
  • detecting risk factors or early signs of cancer

However, not all researchers support the notion of unique cancer hallmarks. For example, most of the hallmarks, except for metastasis and invasion, are also hallmarks of benign tumors. Currently, no conclusive data supports the idea that all cancers share distinct hallmarks that they also do not share with noncancerous cells.

The hallmarks of cancer are a group of characteristics researchers have used to help them distinguish cancerous cells from noncancerous cells. These hallmarks describe the behavior and characteristics of cancer, but critics argue that benign growths also share some of these characteristics.

Despite these challenges, attempts to identify unique cancer hallmarks could eventually help researchers understand more about when, why, and how cancer develops. This project is ongoing though, with continual revisions to potential hallmarks.