Cancer

Sometimes cells in our body grow too fast.

They can make a little lump. This lump is called a tumor.

Some lumps stay in one place. Other lumps can spread to new parts of the body.

Many things can cause this to happen. Some people get it from things they eat. Others get it from things in the air. Some people get it from tiny germs.

Doctors use tests to find these lumps. They can use special tools to look inside. Then, they can use medicine to help.

We can help our bodies stay strong. Eating fruit and vegetables is good. Being active is also good for us.

Staying healthy is a great way to live.

Cancer is a group of diseases. It happens when cells grow out of control.

These cells can make a lump called a tumor. Some tumors are benign, which means they do not spread. Other tumors are malignant. These can spread to other parts of the body. This spreading is called metastasis.

Most cancers come from changes in a cell's genes. These changes are called mutations. Many things can cause these changes. Using tobacco is a big risk. Not eating enough fruit or vegetables can also help cause it. Some cancers come from tiny germs like viruses.

Doctors find cancer with screening tests. They might use medical imaging to look inside. They also use a biopsy. This is when they check a small piece of the tissue. Doctors treat cancer with surgery or radiation. They may also use chemotherapy. This is a type of medicine. Some new treatments use immunotherapy. This helps the body's own immune system fight the disease.

Cancer is a large group of diseases involving uncontrolled cell growth.

Usually, this growth results in tumors that can invade other body parts. Some tumors are benign, which means they do not spread. Other tumors are malignant and have the potential to spread. This spreading is called metastasis.

Most cancer deaths happen because the disease has metastasized. The original site is called the primary tumor. The new sites are called metastatic tumors. This process often happens through the blood or lymphatic system.

Cancer works through a series of steps in the cells. It often starts with genetic mutations, which are changes to a cell's instructions. Many changes are usually required before cancer develops. These changes can make cells grow even when they should stop. They can also help cells avoid programmed death. Malignant cells even build new blood vessels to help them grow.

This process is called angiogenesis. The cells can then move into nearby tissues. Eventually, they may enter the blood to travel far away.

People have studied these diseases for a very long time. The word comes from the ancient Greek word "karkinos," meaning crab.

Ancient Greek doctors like Hippocrates and Galen noticed this name. They thought some tumors looked like crabs with swollen veins. The word entered the English language around the year 1600. Today, we know cancer is a complex family of diseases. We now understand how many different types exist in humans.

There are many facts about how cancer affects the world.

In 2015, about 90.5 million people worldwide had cancer. In 2019, annual cases grew by 23.6 million people. There were 10 million deaths worldwide that year. For children under 15, the five-year survival rate is about 80% in developed countries. In the United States, the average survival rate is 66% for all ages. Many cancers are caused by lifestyle, like tobacco use or diet.

We can link cancer to things we see in our daily lives. For example, smoking is linked to lung cancer.

Using sunscreen helps protect against UV radiation from the sun. Eating plenty of fruits and vegetables is also helpful. Vaccines can even protect against viruses like hepatitis B. These vaccines can nearly eliminate certain cancer risks. Doctors use tools like surgery and chemotherapy to treat the disease. New treatments called immunotherapy help the body's own immune system fight back.

Cancer is a large group of diseases defined by uncontrolled cell growth.

This growth often leads to the formation of tumors. A tumor is a mass of cells that has undergone unregulated growth. Some tumors are benign, meaning they do not spread to other parts of the body. Other tumors are malignant, which means they have the potential to invade nearby tissues. Malignant tumors can also spread to distant locations through a process called metastasis.

This process is why cancer is such a complex medical challenge.

To become malignant, cells must undergo several specific changes known as hallmarks. These hallmarks allow cancer cells to bypass the body's normal rules. First, cells grow and divide even when they do not receive the proper signals. They also continue to divide even when they receive signals to stop. Malignant cells also avoid programmed cell death, which is a natural process for removing old cells. They can divide a limitless number of times. Furthermore, they promote angiogenesis, which is the construction of new blood vessels to supply the tumor. Finally, they gain the ability to invade local tissue and form metastases.

Metastasis follows a specific sequence of steps to move through the body. It begins with local invasion into the surrounding area. Next, cells undergo intravasation, where they enter the blood or the lymphatic system. The cells then circulate through the body to reach new locations. Once they reach a new site, they perform extravasation to exit the blood or lymph vessels. After entering the new tissue, the cells begin to proliferate, or multiply. They may also trigger further angiogenesis to support their new home. While cancers can spread anywhere, they often move to the lungs, liver, brain, or bones.

Humans have studied these growths for thousands of years. The term originates from the ancient Greek word *karkinos*, which means crab.

Ancient physicians like Hippocrates and Galen observed tumors with swollen veins. They thought these shapes resembled the legs of a crab. The word entered the English language in a modern medical sense around the year 1600. Today, scientists recognize that there are over 100 different types of cancers affecting humans. This variety makes finding a single cure very difficult.

Many factors contribute to the development of cancer. About 90% to 95% of cases are caused by genetic mutations from environmental and lifestyle factors. These factors can change the genes of a cell. Common environmental contributors include tobacco use, which accounts for about 25% to 30% of cancer deaths. Diet and obesity contribute to 30% to 35% of deaths. Infections from viruses, bacteria, and parasites cause approximately 16% to 18% of cancers worldwide. For example, hepatitis B and HPV are infectious agents linked to cancer. Only about 5% to 10% of cancers are due to inherited genetic defects.

Cancer affects millions of people and has a massive global impact.

In 2015, roughly 90.5 million people worldwide had cancer. By 2019, annual cases grew by 23.6 million people. There were 10 million deaths worldwide in 2019, a 21% increase over the previous decade. The economic cost of cancer is estimated at US$1.16 trillion per year. However, survival rates can be high with early detection. In the developed world, the five-year survival rate for children under 15 is about 80%. In the United States, the average five-year survival rate for all ages is 66%.

Different types of cancer are more common in specific groups. In males, the most frequent types are lung, prostate, colorectal, and stomach cancers. In females, the most common are breast, colorectal, lung, and cervical cancers. In children, acute lymphoblastic leukemia and brain tumors are the most common. However, in Africa, non-Hodgkin lymphoma occurs more often.

If non-melanoma skin cancers were included in annual totals, they would account for about 40% of all new cases. Risk also increases significantly as people age.

Medical science offers several ways to manage and treat these diseases. Doctors may use surgery to remove tumors or radiation therapy to target cells. Chemotherapy uses drugs to kill cancer cells, though some chemotherapy drugs are themselves carcinogens. Targeted therapy focuses on specific mechanisms within the cancer. A newer field called immunotherapy harnesses the patient's own immune system to fight the disease. For advanced cases, palliative care helps manage pain and symptoms.

Early screening is also vital for detecting cervical and colorectal cancers early.