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What is Cancer?

Cancer is a disease that happens when cells inside the body start multiplying out-of-control and turn into lumps called tumorsthat kill healthy neighboring cells. Some examples are kidney cancer, skin cancer, lung cancer, colon cancer, and lymphoma.

However, cancers of the blood such as leukemia do not form tumors. No matter the type of cancer, the effects are the same. First, cancerous cells DO NOT function the same as regular cells therefore, they don’t contribute to your survival. Second and most importantly, cancer cells inhibit the function of healthy cells, stopping them from working property.

But not all tumors cause cancer!

There are two types of tumors:

  1. Benign tumors: Do not grow forever and do not move around in the body. They form lumps but are not normally dangerous and can usually be taken out by surgery.

  2. Malignant tumors: Are made from cancerous cells that can divide forever. These cells can move in the blood to different parts of the body (a process called metastasis)where they divide and grow, making more secondary tumors. These tumors destroy healthy tissues around them. When metastasis happens, the cancer becomes very serious and difficult to treat. 

Benign tumor– A tumor that doesn’t kill healthy tissues around it and doesn’t normally cause cancer.

Malignant tumor– A tumor that kills healthy tissues around it. It causes cancer.

Metastasis– The process of formation of a secondary tumor.

Secondary tumor – A tumor that forms when one or more cancerous cells from another tumor travel in the blood and divide to make a new tumor.

What causes cancer?

Normal cells divide to make more copies but eventually stop. This is because they have DNA inside that tells them to stop. However, the DNA of cancer cells isdamagedand so they don’t give the instructions to stop growing and instead, the cells will divide forever, forming tumors. There are three main causes of cancer.

  1. Hereditary: Some types of cancer are inherited, meaning that if someone in a family had or has cancer like a grandparent or parent for example, then there is a chance that the damaged DNA will be passed on to their children.

  2. Carcinogens: Are thingsthat we either ingestor are exposed to that damage our DNA and cause cancer. These include tobacco (smoking), asbestos, radiation such as gamma and x-rays, the Sun, and chemicals in car exhaust.

  3. Viruses such as HPV, hepatitis B and C, and Epstein-Barr virus have been linked to different types of cancer.

Signs and Symptoms

You should always pay attention to the health of your body! If someone sees or feels something new like a lump or a patch of skin with a weird shape and color, they should speak to their doctor! A tumor can affect different parts of the body so how you feel depends on the location of the tumor.

For example:

Brain Tumor Symptoms: Since your brain controls how you see, hear and walk, some common symptoms of brain tumors are:

  • vision, hearing and balance problems.

  • changes in mental ability.

  • seizures, nausea and changes in your ability to smell.

Carcinogens –Something that can cause cancer.

Heredity - The passing of traits like hair color, height, etc. from parent to child.

Ingest – something you eat, drink, or breathe into your body.

Nausea –The feeling that you want to throw up.

Lung Tumor Symptoms: Since your lungs control your breathing and breathing allows you to be active, some common symptoms of lung tumors are:

  • a cough that won’t go away or brings up blood.

  • chest pain that gets worse with deep breathing, laughing or exercise.

  • shortness of breath.

  • feeling weak.

Diagnosing Cancer

There are different steps to diagnose cancer. First a doctor will ask to know about the patient’s family medical history. Then a patient will do a physical exam and lab tests. A doctor will use imaging tests like X-rays, computed tomography (CT), magnetic resonance imaging (MRI) or other tests to see the exact location and size of the tumor. Then a biopsy is performed, which means a sample of the cells is removed from the tumor and studied under a microscope to check for cancerous cells. These tests will determine whether the tumor is benign or malignant and what stage the cancer is at.


There are three main treatments for cancer including: chemotherapy, radiation and surgery. Chemotherapy and radiation are meant to kill the cancerous cells while surgery is physically cutting them out of the body. Almost all cancer treatments use a combination of the three to ensure all the cancerous cells are eliminated.

The earlier the disease is discovered and treated, the higher the chance of curing the disease and the person surviving.The stages of cancer go from 0 to 4, with higher stages being more difficult to cure. Stage 1 tumors are mostly curable with surgery and treatment while stage 4 cancer is usually not treatable.

Biopsy – A small amount of tissue is removed and looked at under a microscope.

Chemotherapy–Using chemicals to poison and kill the cancer cells.

Radiation – High-energy rays are used to kill cancer cells.


To reduce your risk of getting cancer, make sure to avoid carcinogens as much as possible! This means always using sunscreen when you are exposed to the sun, and never smoking! Also, make sure you are always aware of your body and attend your yearly checkups so that you can detect the cancer early. Lastly, ask your parents about your family medical history, this information is important for your doctor to know!


Reading Comprehension Questions:

  1. What is cancer?

  2. What is a tumor?

  3. What are the two types of tumors? Are they both cancerous?

  4. What is it called when cancerous cells spread to different parts of the body?

  5. Why do cancer cells divide and multiply uncontrollably?

  6. What are the three main ways that DNA can become damaged and causes cancer?

  7. What kind of treatment will a doctor recommend for cancer?

  8. Why is it important to discover cancer early?

Extension Questions:

  1. Why do cancer treatments usually use two or three treatments and not just one?

  2. All cancer treatments come with side effects. Research a) the main side effects people suffer from during cancer treatment. b) what causes these side effects.

  3. Summarize what you have learned about Cancer in 150-200 words.


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Bianconi E, P. A.-A. (2013, December). An estimation of the number of cells in the human body. Annal of Human Biology, 40(6), 471. Retrieved February 26, 2016, from

Cancer Research UK. (2015, March). Can Cancer Be Prevented? Retrieved February 26, 2016, from

How Stuff Works Science. How MRI works.Retrieved February 26, 2016, from

Medical News Today (2015, September, 2015). Cancer: Facts, Causes, Symptoms and research. Retrieved February 26, 2016, from

National Cancer Institute. (2015, February). What Is Cancer? Retrieved February 26, 2016, from

Style Pinner. List Of Top Cancer Cell Division Images. Retrieved February 26, 2016, from

Torpy JM, Lynm C, Glass RM. Brain Tumors. JAMA. 2005;293(5):644.Retrieved February 26, 2016, from

WebMD. Cancer Health Center. Retrieved February 26, 2016,

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