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.

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

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.

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.

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

Timeline of cancer research milestones

While cancer remains incurable, there's been so much progress in its treatment over the last two decades. Nature provides an abridged history of milestones and major triumphs in cancer research and treatment. Start in the year 2000, and see how much has changed in the first quarter of the new millennium

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

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.

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.

Explore more statistics about cancer

The American Cancer Society's Cancer Statistics Center estimates there will be more than 2 million new cancer cases and almost 620,000 cancer deaths in the US during the course of 2025. Breast, prostate, and lung cancers remain the most prevalent. This interactive tool provides detailed statistics on cancer incidence, mortality, and survival rates, allowing users to explore data by state, cancer type, demographics, and risk factors.

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

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.

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

Lung cancer advances are making a big difference

Lung cancer deaths are declining faster than new cases due to advances in treatment. The progress illustrates what is possible, even for a cancer that has long had a poor prognosis.

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

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.

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.

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.

Tumor genetic profiling can lead to targeted treatments

Genetic profiling of tumors—based on a sample from the tumor, a patient's blood, or both—can help clinicians determine if targeted therapies known to block the growth of certain types of tumors would be appropriate for specific patients.

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

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.

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.

Prostate cancer is both manageable and the second-deadliest cancer for men

One in 44 men in the US will die from prostate cancer, while one in eight will be diagnosed with it. Commonly viewed as the safest cancer to have, screenings can save lives—but they can also cause complications for otherwise benign cases of the disease.

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

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.

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.

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.

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.

A snapshot of progress in cancer treatments

The American Association for Cancer Research's "Snapshot of a Year of Progress" offers an overview of significant advancements in cancer research and treatment over the past year. Take a quick look at the rapid pace of scientific discovery and the translation of research findings into clinical practice. In 2024 alone, health regulators approved 15 new anticancer therapies alone.

The difference between standard cancer treatments and emerging immunotherapies

If you've ever wondered what the difference was between immunotherapy and chemotherapy, this short video takes you through the steps. Briefly, chemotherapy attacks cancer in tumor cells directly, while immunotherapy encourages your immune system to fight it. There's more to it than that, but this delightful two-and-a-half-minute video provides a good primer.

Late-onset menopause lowers osteoporosis risks, but heightens the risks for certain cancers

Defined as when a woman starts to experience perimenopause after age 55, this delayed menopause onset is linked to elevated risk of developing breast, ovarian, and uterine cancers.

Cells are categorized by the presence of contained genetic material and other organelles

While prokaryotes contain one or more cells with free-floating genetic material in a region called the nucleoid, eukaryotes possess a nucleus specialized for DNA storage. Plant cells possess cell walls—a reinforced structure surrounding their membrane—made of cellulose, while fungal cell walls contain chitin. Animal cells have lysosomes housing enzymes that break down biomolecules. (Some readers may experience a paywall.)

Based on its varied symptoms, scientists think that long COVID-19 is not a single disease, but rather a group of different conditions triggered by COVID-19 infection.

Understanding the stages of sleep

Do you have trouble keeping the different stages of sleep straight and organized in your mind? Us too. Sometimes it helps to have a straightforward listing of what each stage is and why it’s important. Look no further than this resource from Lumen. It is a basic outline of the four stages of the sleep cycle, along with the brainwaves and attributes that characterize each. If you’re brave enough, test yourself on the built-in quiz!

What conditions can be treated with stem cells?

Stem cell research is a global enterprise, and much of the work is being done in Europe. This page gives readers a good sense of the medical conditions stem cell researchers in Europe focus on, and the specific research challenges they address. This page also offers links to in-depth information about many of the research projects.

An estimated 2 million brain cells die each minute a stroke goes untreated

Modern stroke treatment is a delicate balance between obtaining an accurate diagnosis and delivering treatment quickly. Each stroke has its own cause, and the appropriate treatment must be paired with the correct diagnosis to prevent further harm. Typical treatments pair emergency surgery to relieve the affected area and long-term regimens to avoid recurrence.

Symptoms of extreme radiation exposure may take hours to manifest

Large doses of ionizing radiation can damage the body within minutes, particularly in the bone marrow and inner layer of the digestive tract. Victims may briefly seem fine before rapidly deteriorating as immune failure, infection and organ collapse set in.

There are three types of stem cells, each with different properties

Embryonic stem cells are "blank slates" that can change into any other type of cell. Adult stem cells can become specialized cells to replenish the supply or repair injury, while induced pluripotent cells are "reset" by scientists and used in clinical and medical applications.

Postmenopause is a stage lasting roughly a third of a woman's life

Postmenopause is the final stage of menopause, occurring once a woman hasn't had any bleeding for a full year. She is then considered postmenopausal for the rest of her life. While some of the intense symptoms she might experience during perimenopausal will decline, her risk for certain conditions and diseases will increase.

Early menopause, occurring before age 45, can be triggered by certain risk factors

Some potential causes of early menopause include autoimmune disorders, chemotherapy, smoking, and certain surgeries that cause the body to produce lower levels of estrogen and progesterone.

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.

Using stem cells for bone marrow transplants

Stem cells hold promise for many future medical applications, but only one type of stem cell is currently approved for use. This page offers a clear description of adult stem cells called hematopoietic stem cells, which create the full range of blood cells and are approved for use in treatments such as bone marrow transplants.

Organoids: 3D organs grown from stem cells in the lab

An organoid is a three-dimensional construct composed of multiple cell types that originate from stem cells that can simulate the architecture and functionality of native organs. One big benefit of these lab-grown organs is that drug candidates can be tested in model systems without needing live patients.

Health problems are being misdiagnosed as perimenopause symptoms

Symptoms of menopause and perimenopause (the premenopause period) can be varied enough that clinicians dismiss them in patients in their mid-30s and onward as just a symptom of hormone level change. In this story, a woman's itching was dismissed as a hormonal change, but after two years and 11 separate doctor consultations, was diagnosed as cancer. (Some users may experience a paywall.)

Cryptococcus neoformans, a growing threat, causes infections in the brain and lungs

This inhalable, microscopic pathogen is found worldwide. It rarely causes illness, but it can take root in those with compromised immune systems, including people with advanced HIV/AIDS. Symptoms of cryptococcal infection—such as a stiff neck, vomiting, and confusion—can begin weeks or months after breathing in spores, though sometimes symptoms won’t appear for years. There are no known cases of transmission between people or between people and animals.

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.

Someone suffers from a stroke every 40 seconds

Every 40 seconds, someone in the US experiences a stroke—and every minute without treatment destroys millions of brain cells. This explainer breaks down the two main types of strokes, their risk factors, and how early detection could change outcomes in the future.

Sclerosis is the technical term for the lesions or plaques that form without myelin

In the absence of myelin, the body forms scar tissue called sclerosis. That scar tissue hampers nerve's abilities to transmit nerve impulses, essentially acting as a roadblock to speedy communication.

Around 5 million of our 3 billion DNA letters differ between individuals

Genetic testing examines gene variants to help explain disease symptoms. It explores how genetic differences between individuals can be used to understand risks of developing diseases like Huntington's Disease or passing variants linked to disease onto offspring.

This 2022 study is one of the findings that prompted WHO to label aspartame as 'possibly carcinogenic'

This French study analyzed online periodic self-reported food journals from more than 100,000 people for a median of almost eight years and linked aspartame consumption to a roughly 15% increased cancer risk. It found that the people who consumed higher levels of aspartame had elevated cancer numbers—particularly breast and obesity-related cancers.