What is Cancer?

Cancer is the term for a group of diseases where abnormal cells grow and multiply out of control. The abnormal cells—cancer cells—can invade nearby tissues, and may also travel to other parts of the body (also called metastatic cancer). Cancer can happen almost anywhere in the body.

Also see: Breast Cancer, Chronic Myeloid Leukemia, Leukemia, Osteosarcoma, Ovarian Cancer

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Types of Cancer

There are more than 100 different types of cancer. Usually, cancer is named according to the organ where it starts, for example lung cancer, breast cancer, prostate cancer, kidney cancer. Cancer can also be described by the type of cell where it begins. Examples include:

  • Carcinomas: cancers that arise from epithelial cells, which are the cells that line the inside and outside of the body
  • Sarcomas: cancers that form in bone and soft tissues
  • Osteosarcoma is the most common type of bone cancer
  • Leukemias: cancers that begin in the blood-forming cells of the bone marrow
  • Lymphomas: cancers that begin in lymphocytes, the white blood cells of the immune system

Many cancers form a mass of tissue called a tumor; however, not all tumors are cancer. Cancerous tumors are malignant, which means they can invade surrounding tissue, unlike benign (noncancerous) tumors.

How Common is Cancer?

In 2018, it is estimated that 1,735,350 new cases of cancer will be diagnosed in the US each year. Currently, the most common cancer is breast cancer, followed by lung, prostate, and colorectal cancer.

There are more than 15 million cancer survivors in the US.

Cancer in Children and Young Adults

Cancer occurs less frequently in children than in adults. The most common types of childhood cancers are leukemia, brain and other central nervous system tumors, and lymphoma.

Leukemia, lymphoma, testicular, and thyroid cancer are the commonest types of cancer in those aged 15 to 24.

Approximately 70,000 young people (15-39) are diagnosed with cancer in the US each year. This accounts for about 5% of all cancer diagnoses.


Leukemia is cancer of the body's blood cells. There are different types, depending on which cells are involved, and whether the leukemia progresses slowly or quickly. Leukemia is most common in those over 55 years. However, it is also the most common cancer in children under the age of 15.

Brain and Other Central Nervous System Tumors

Together, the brain and the spinal cord make up the central nervous system.

Brain tumors are one of the commonest cancers that affect children. In the US, almost 5,000 children are diagnosed with a brain tumor every year. Brain and other central nervous system tumors can be benign or malignant.


Lymphomas are a type of cancer that starts in white blood cells called lymphocytes. Lymphocytes are part of the immune system, which helps the body fight infections and other disease.

Our Cancer Resources

Jumo Health strives to empower and support those living with cancer by arming children and families with the knowledge to understand the condition—in an accurate, understandable, and relatable way.

The cancer portfolio consists of a series of titles:

  1. Childhood cancers:
    1. Childhood cancer (a general overview)
    2. Chronic myeloid leukemia
    3. Leukemia
    4. Osteosarcoma
  2. Adult cancers:
    1. Breast cancer
    2. Lung cancer
    3. Ovarian cancer

Additional resources on cancer-related topics:

  1. Chemotherapy
  2. Meet the Hospital Team
  3. PICC lines
  4. Palliative Care

Causes of Cancer

Cancer happens as a result of gene changes or mutations that lead to uncontrolled cell growth.

Gene mutations can be:

  1. Present at birth. These are inherited mutations and account for a small number of cancers.
  2. Acquired after birth. These gene changes can develop over a lifetime. Often, there is no clear cause, although the following are risk factors for the development of cancer in some people:
    1. Obesity
    2. Alcohol use
    1. Smoking and tobacco use
    2. Lifestyle
    3. Sun and Radiation
    4. Viruses and other infections
    5. Cancer-causing chemicals (carcinogens)

The causes of childhood cancer remain largely unknown. A gene mutation is inherited in about 5% of cases. Environmental triggers for children are harder to determine as cancer is less frequent in this population, and it is also more difficult to establish exactly what children were exposed to in early life.

Symptoms of Cancer

Different cancers present in different ways. The following may be symptoms of cancer, but more commonly these changes are not caused by cancer. Any change that persists needs to be checked by a doctor.

  • Skin - changes in an existing mole or the appearance of a new one
  • Breast - changes in texture or nipple
  • Lump on or under the skin
  • Unexplained changes in weight
  • Problems eating
  • Abdominal pain
  • Unexplained bleeding or discharge
  • Unexplained night sweats
  • Tiredness and weakness
  • Persistent hoarseness or cough


There are many different types of treatments, depending on what type of cancer it is and where it is in the body. Some people will have one type of treatment, others will need a combination.


Surgery involves removing the cancer, or part of it. It works best for solid tumors that are confined to one place. It is not suitable for leukemia, and also generally not for cancers that have spread.

Radiation Therapy

Radiation therapy means using high doses of radiation to kill cancer cells.


Chemotherapy means using strong medicine to slow down the growth of cancer cells.


Immunotherapy is a type of biological therapy that helps your immune system fight the cancer cells.

Targeted Therapy

Targeted medicine is a type of precision or personalized medicine. It works by targeting the mechanisms within the cancer cells that help them to grow and multiply.

Hormone Therapy

Hormone therapy is used for cancers that use hormones to grow, for example some types of breast cancer.

Palliative Care

Some people with cancer may benefit from palliative care, which aims to improve the quality of life of those with a serious illness such as cancer. Palliative care focuses on the person as a whole rather than just the disease.

Living With Cancer

Being told that you have cancer can be a life-changing moment. Different people react differently to the diagnosis. You might feel angry, frightened, sad, confused—all these emotions are normal. Coping with cancer treatment brings challenges, time spent in the hospital, treatment side effects, and not being able to do the things you normally do. Even after treatment has ended, there are ongoing challenges, including the fear of cancer recurrence.

It’s important to always make sure you have the information and support that you need. Ask your hospital team about anything you are confused or concerned about. Cancer is common, and many people are going through the same experience as you—this applies to caregivers as well as those with a cancer diagnosis. There are many advocacy and support groups that can help all members of families affected by cancer. Your hospital team will be able to help you get in touch with any additional support you might need.

Additional Resources