Cancer is a group of diseases characterized by the uncontrolled growth of abnormal, mutated cells that can spread throughout the body.

Metastasis: When cancer cells begin to travel through the body

Metastatic cancer starts in one part of the body and moves to another over time. This is known as metastasis. Such cancers are much more harmful since they attack multiple parts of the body, adapting new metabolic changes to suit the various environments found throughout a body.

Cancer is typically broken down into four stages influenced by tumor size, the presence of cancerous cells in the lymph nodes, and the extent to which the malignancy has spread to other organs in the body.

The immune system is in a constant fight to detect and eliminate cellular mutations.

How does cancer spread through the body?

Cancer usually begins with one tumor, but it can spread to other organs if not removed. This video breaks down how cancer moves to these new areas and why some organs are more likely to get infected than others.

Cells become cancerous if checkpoints in the cell cycle are damaged

Before cells divide, a protein called p53 can halt the cell cycle if damaged DNA is identified, preventing the fault from propagating to daughter cells. If p53 and other tumor-suppressing molecules cannot function due to mutations or other instabilities, damage can accumulate over successive generations until nothing stops cells from dividing uncontrollably, creating tumors.

There are hundreds of subtypes of cancer, making a universal cure nearly impossible.

Why don't we all have cancer?

The creation of a single cell produces 120,000 genetic mutations that can lead to cancer. This video investigates how our bodies proofread and autocorrect those mistakes.

Immunotherapy focuses on boosting the immune system to fight cancer

The immune system detects and destroys abnormal cells, curbing the growth of many cancers. Immunotherapy works to boost the body’s immune system to target and kill cancer cells. There are many ways to accomplish this, including adaptive cell therapy, checkpoint inhibitors, vaccines, and monoclonal antibodies.

Many cancers arise from genetic mutations inherited from your parents

These mutations may happen in response to environmental or lifestyle factors, or may be passed down through family members. Genetic testing can be important in catching certain family cancers early and ensuring patients receive the right treatment for their disease.

Large animals like giraffes and elephants have evolved unique cancer defenses.

Chemotherapy is a cocktail of powerful drugs that slows cancer by interfering with cell division.

The seven viruses that cause human cancers

Certain viruses have been linked to the development of human cancers. These viruses account for up to 20% of cancers worldwide, causing cancer by interacting with host proteins, proliferating within weak immune systems, and commandeering susceptible human cells. Unlike other viruses, human tumor viruses don't kill host cells, allowing them to establish persistent infections. The seven viruses include the Epstein-Barr Virus, the Human Papillomaviruses, and more.

The term 'cancer' is roughly 3,000 years old and derives from the Greek word for 'crab,' which may refer to how a malignant tumor can feel like a hard shell.

Chronic inflammation can cause cellular damage and could lead to cancer

Over time, this cellular defense system can inadvertently damage cells and tissues when it's in this heightened alarm mode over a prolonged period. This occurs because, when immune cells are sent somewhere without a true target, they may attack healthy cells and tissues.

How does cancer actually kill someone?

While the emotional and physical tolls of cancer are often clear, the innerworkings of how cancer kills can be confusing — and terrifying to discuss. Here, oncologists explain how cancer can progress.

What is cancer bioengineering?

While new treatments for cancer are under continuous development, researchers are increasingly using engineering principles to find wholly new strategies to combat the disease. Directions include nanoparticle drug delivery, advanced imaging tools, developing new materials to interact with cells, tissue engineering, robotic surgeries, and more. Such interdisciplinary efforts are expected to unlock new tools and therapies beyond traditional drug formulation.

Explore global maps of cancer prevalence, with incidences that reflect various risk factors, including smoking rates, HPV infections, sunscreen use, and alcohol consumption.

Explore the differences between healthy and cancerous cells using a DNA microarray

In this simulation, you will learn how scientists use microarrays to experiment on thousands of genes at the same time. By determining which genes are on or off, users can identify those that contribute to cancer formation.

mRNA vaccines alter immune response, not DNA, to combat diseases like cancer.

Changing a single letter in DNA can permanently alter an organism

Genetic mutations occur when cells replicate, which requires a copy of DNA to be created, and involve substituting, deleting, or inserting letters in a cell's genetic code. Mutations can be caused by normal cellular processes, chemical exposure (e.g., carcinogens), or radiation and may result in genetic disorders or genetic variations that drive evolution.

Roughly 1 in 5 cancers are caused by viruses

About 20% of cancers are caused by viruses, with seven specific oncoviruses causing between 10% and 15% of cancers worldwide. These include human papillomavirus and hepatitis B and C viruses, which can lead to diseases such as cervical and liver cancer. Understanding the mechanisms of these viruses is crucial for prevention and treatment strategies.

Patients are a part of the progress

Navigating a cancer diagnosis can be terrifying and overwhelming. There is a robust community of patient advocates dedicated to prevention and diagnosis, research and clinical trials, legislation, needs of individual cancer types, among others. See how patient advocacy improves cancer research leading to improved treatment options and patient care.

Breast, prostate, and lung cancer are the most common forms of cancer.

Teaching immune cells to fight cancer

CAR T-cell therapy is a type of immunotherapy, which involves strengthening the immune system to attack cancer cells. Patient T cells, which manage immune responses and are responsible for killing pathogen-infected cells, are collected and re-engineered to produce surface-level proteins called chimeric antigen receptors. These CARs, now able to bind to specific proteins on cancer cell surfaces, are multiplied into the millions and infused back into the patient.

Low cell division rates in heart cells make heart cancer particularly rare

The heart's location in the chest also offers protection from external cancer-causing factors. The disease affects about 3 in every 10,000 people, though most cases arise from metastasis from other body parts.

About 40% of cancer cases are linked to preventable risk factors

Maintaining a healthy weight, engaging in regular physical activity, and consuming a balanced diet can lower cancer risk. Research indicates that about 40% of US cancer cases are linked to preventable factors, including poor diet and inactivity. Understanding these mechanisms empowers individuals to adopt healthier lifestyles for cancer prevention.

Organisms can possess multiple unique sets of DNA in one body

Genetic chimeras can result when cells with different DNA combine, such as when two sperm cells fertilize two egg cells, creating two embryos that then merge. In mosaicism, mutations arise within an organism after conception and can spread through cell division, resulting in diseases and forming genetically distinct anatomy.

Explore the National Cancer Institute's archive on cancer treatments, including complementary and alternative medicine.

Necrosis is the unplanned death of cells and the tissue they comprise

If cells die prematurely due to a lack of blood flow, injury, or disease, they and their organelles can swell, leading to rupture of the surrounding cell membrane. This releases the cell's contents into the surrounding tissue, causing inflammation and damage to neighboring cells.

Alcohol may be responsible for about 5% of cancer cases and 4% of cancer deaths in the US.

How autoimmune diseases, which attack your own tissues and cells, work in the body

These diseases remain some of medicine's thorniest problems because the immune system can mistakenly attack almost any tissue in the body, resulting in myriad diseases, including lupus (numerous tissues affected), Hashimoto's (thyroid), and MS (the nervous system).

The spread of fraudulent stem cell treatments

All the coverage of research into promising (but often unproven) medical treatments involving stem cells has created conditions allowing some people to engage in activities regulators describe as scams. As this news article explains, attorneys general in at least seven states have taken legal action against businesses that promised (costly) stem cell treatments but allegedly engaged in fraud.

A computer virus is a type of malware that self-replicates and spreads

Spread through emails, downloads, messaging services, and outdated software, viruses attach to programs, self-replicate, and infect other systems. They can delete files, steal data, and cause performance issues as they spread.

Visualize how CRISPR-Cas9—a type of immune system used by single-celled organisms to attack invasive viruses—targets and makes precise changes to a gene's DNA.

Computer viruses' hijacking abilities led them to be named after biological viruses

Just as their counterparts infect cells and take control of cellular processes to replicate endlessly, computer viruses cannot replicate on their own and must copy their code into host software before duplicating when the program or file is opened. The term "virus" comes from the Latin word for "venom."

Stem cells become specialized cells through the activation or silencing of specific genes

After fertilization, when a sperm cell fuses with an egg, the resulting stem cell is described as totipotent—capable of transforming into any type of body cell or embryonic structures (e.g., placenta). Once differentiated into multipotent cells, they can only specialize further within specific cell type families, such as hematopoietic cells that become platelets and red and white blood cells.

Learn how monoclonal antibodies, which mimic the body's antibodies, can fight diseases like Ebola.

Explore this interactive tool from the National Cancer Institute to calculate your risk of dying from various causes, including cancer.

Symptoms of DNA loss may mimic those seen in mushroom poisoning or chemotherapy

Although no organism has ever lost all its DNA, the destroying angel mushroom contains amatoxin, which disrupts DNA transcription and is known to cause death via liver and kidney failure in three days. Doxorubicin, which tangles DNA to disrupt cellular replication, compromises a person's immune system.

These cells 'taste' danger, trigger immune responses

Taste receptor-coated tuft cells are found throughout the body, where they communicate with and take part in a growing list of biological processes. In the intestines, these taste receptor-studded cells can sense byproducts of parasite metabolisms. This causes the taste receptors to release chemicals that alert the immune system, order nearby goblet cells to produce mucus, and trigger muscle contractions in attempts to launch the parasites from the intestines.

Stem cells have the ability to self-renew

Stem cells have remarkable potential for new medical therapies. But to understand what makes stem cells so special, you must understand exactly what they are, and what they’re capable of doing. This page offers an accessible introduction to stem cell biology and their unique properties.

Measles attacks the body’s immune system, leaving it vulnerable to secondary complications

A measles infection begins in the lungs, where it hijacks cells known as macrophages and begins to replicate itself. It then uses a Trojan horse method to enter the lymph nodes, where it attacks vulnerable T and B cells. Symptoms include fever and rashes.

How do stem cells actually work?

Stem cells are unspecialized cells that can develop into various cell types while also making exact replicas of themselves. This amazing ability has made stem cells a candidate to treat a wide variety of diseases and conditions—though the vast majority of potential therapies remain in the research stage.

Rheumatoid arthritis occurs when the immune system attacks cells within joints

Rheumatoid arthritis is a specific type of arthritis that occurs when the body's immune system attacks normal cells within the connective tissues of the joint and degrades them. This sets off a painful cycle of inflammation and joint destruction that often requires lifelong medication to control.

Candida albicans is a natural body-dwelling yeast, but it can cause yeast infections

This fungus is naturally occurring on the body, but C. albicans can become a problem when the natural balance of bacteria on the body is off-kilter, allowing this yeast to spread. It can cause anything from diaper rash to a yeast infection in the throat or vagina. It’s typically treated with doctor-prescribed antifungal medications.

An interactive dive into the immune system

Our bodies are equipped with an incredible system able to fight off invasive pathogens to protect us from illness. The complicated system includes lymph nodes, the spleen, bone marrow, and even the tonsils. But this same system can turn against itself, a condition known as autoimmune disorders. Follow along with this thorough, engaging explainer on the human body's defense system.

Exposure to ionizing radiation from nuclear accidents can damage DNA

The damage can increase the risks of cancer, cataracts, heart disease, and other illnesses based on exposure times and intensities. Contaminated food, water, air, or soil from near nuclear accidents can further prolong one's exposure.

Zoonotic diseases: Pathogens that jump from animals to humans

Such diseases may be caused by a variety of pathogens—viruses, bacteria, fungi, or parasites—and can originate in creatures ranging from ticks and mosquitoes to pigs and bats. Because they develop in animals and are often new to human immune systems, zoonotic diseases have severe consequences for public health.

Diabetes is a hormonal disorder that occurs when the pancreas does not produce enough of a hormone that regulates blood glucose, called insulin, or when the body cannot effectively use the insulin it produces.

Diabetes is a chronic disease linked to insulin production and high blood sugar

Diabetes is a chronic, progressive disease caused by a lack of, or problems processing, the hormone insulin, leading to persistently high blood sugar. Around 90 to 95% of cases are Type 2 (chronic and caused by factors like diet and environment). The remainder are Type 1 diabetes (an autoimmune disorder).