Cancer is a group of diseases characterized by uncontrolled cell division that leads to abnormal tissue growth. Many a times, people often use the terms cancer and tumor synonymously. But all tumours are not cancerous.

There are two main types of tumors: malignant tumours and benign tumours.

Malignant tumours: These are the cancerous cells that can invade and destroy surrounding healthy tissue, including organs. The cancer can spread to distant parts of the body through the lymphatic system or bloodstream. Not all tumours are cancerous.

Benign tumours:  These types of tumours do not grow uncontrollably or do not invade neighboring tissues. They do not spread throughout the body.

There are over 200 different known cancers that affect humans. Most of the cancers are named from where they start. For example, lung cancer starts in the lung, and breast cancer starts in the breast. The spread of cancer from one part of the body to another is called metastasis. Symptoms and treatment depend on the cancer type and how advanced it is. Most treatment plans may include surgery, radiation and/or chemotherapy.

National Institute of Cancer Prevention and Research (NICPR)

Symptoms of cancer, are usually caused by the effect of cancer on the part of body where it is growing. Although symptoms of cancer may appear in the form of general debility including weight loss or tiredness, yet it is generally advised that if anyone is experiencing unusual symptoms for more than a few weeks than he/she should seek medical attention.

Local symptoms: Local symptoms generally occur due to the mass of tumour or its ulceration. For example:
Esophageal cancer can cause narrowing of the esophagus, making it difficult or painful to swallow, Colorectal cancer may lead to narrowing or blockages in the bowel, resulting in changes in bowel habits.

Systemic symptoms: General symptoms occur due to distant effects of the cancer that are not related to direct or metastatic spread. These may include:

  • Unintentional weight loss
  • Fever
  • Getting extremely tired easily (Fatigue)
  • Changes in the skin color/ appearance

Various causes of cancer are:

  • Genetic mutations 
  • Harmful rays due to exposure to sun/ radiation
  • Diet and physical activity
  • Hereditary
  • Environmental factors
  • Idiopathic/unknown


Cancers can generally be recognized by appearance of signs and symptoms through screening.

Screening: Screening tests help in detecting cancer at an early stage (before the symptoms appear). When abnormal tissue or cancer is found early, it is easy to treat or cure. By the time symptoms appear, the cancer might have grown and spread. This can make the cancer harder to treat or cure. It is important to remember that when a doctor suggests any screening test, it does not always mean  that there is a  cancer. People with suspected cancer are investigated with medical tests. These tests include Blood tests, X-rays, MRIs, Biopsy, Pap-smears, CT scans and Endoscopy and many more.

Remedial treatment: Remedial treatment refers to treatment which seeks to make the patient feel better and may or may not be combined with an attempt to attack the cancer. Treatment includes action to reduce the physical, emotional, spiritual, and psycho-social agony experienced by people with cancer.

Surgery: Surgery is the fundamental method of treatment of most isolated cancers and may play a role in remedial measure and prolongation of survival. Biopsy is normally required. It is typically an important part of establishing the definitive diagnosis and staging the tumour required. Localized cancer surgery typically attempts to remove the entire mass along with the lymph nodes in the region (in some cases).

Radiation: Radiation therapy involves the use of ionizing radiation in an attempt to either cure or ameliorate the symptoms of cancer. It is used in about half of the cases and can be either from internal sources in the form of brachytherapy or external therapy.

Chemotherapy: Chemotherapy in addition to surgery has proven to be useful in a number of different cancer types including: breast cancer, colorectal cancer, pancreatic cancer, osteogenic sarcoma, testicular cancer, ovarian cancer, and some lung cancers.

Stem cell transplants for treating cancer: Sometimes very high doses of chemotherapy are used, often with radiation therapy, in order to destroy the cancer cells. This treatment also kills the stem cells in the bone marrow. Soon after treatment, stem cells are replanted to replace those that were destroyed. These stem cells are given into a vein, much like a blood transfusion. Over time they settle in the bone marrow and begin to grow and make healthy blood cells. This process is called engraftment.


Cancers are classified based on the nature of cells that the tumor cells resemble and are therefore classified as :

  • Carcinoma: Cancers that are derived from epithelial cells are known as carcinomas. This group of cancer is most common, especially in the older people, and includes nearly all cancers developing in the breast, prostate, lung, pancreas, and colon.
  • Sarcoma: These cancers are derived from connective tissues (i.e. bone, cartilage, fat), each of which develop from cells originating in mesenchymal cells outside the bone marrow.
  • Lymphoma and leukemia: These two classes of cancer arise from hematopoietic (blood-forming) cells that leave the marrow and tend to mature in the lymph nodes and blood, respectively. Leukemia is the most common type of cancer in children.
  • Germ cell tumor: Cancers derived from pluripotent cells ( refers to a stem cell that has the potential to differentiate into any of the three germ layers: endoderm (interior stomach lining, gastrointestinal tract, lungs), mesoderm (muscle, bone, blood, urogenital), and ectoderm (epidermal tissues and nervous system), most often presenting in the testicle or the ovary (seminoma).
  • Blastoma: These types of cancers are derived from immature "precursor" cells or embryonic tissue. Blastomas are more common in children than in older adults.


  • Cancer is contagious: Cancer is not contagious and does not spread like "catching" the flu or a cold. It is not classified as an infectious or communicable disease.
  • Cancer is hereditary: Generally, cancer is a lifestyle disease. The factors responsible for causing cancer could be alcohol, tobacco, certain chemicals, toxins and hormonal disturbances etc.
  • Regular checkups & today's medical technology can detect all cancers early: Although regular medical care can indeed increase the ability to detect cancer at an early stage, it can't guarantee it. Most cancers are detected early but some still remain undetected till date.
  • A needle biopsy or biopsy can disturb cancer cells, causing them to travel to other parts of the body: For most types of cancer, there is no conclusive evidence that needle biopsy (a procedure used to diagnose many types of cancer) causes cancer cells to spread.
  • Everyone who has cancer has to have treatment: An individual can decide about the treatment after consulting with the doctor and learning about the options. Some people with cancer might not have any signs or symptoms or some might be at a terminal stage where doctor might just prescribe pain relievers.
  • Cancer is always painful: Some cancers never cause pain and are completely painless. For people who do experience cancer pain, especially people with advanced cancer, doctors have become more aware of the need to control such pain and have learned better ways to manage it. Although all pain may not be eliminated, it may be controlled so that it has little impact on the daily routine of a cancer patient. 
  • Most breast lumps are cancerous: Most breast lumps are not cancerous, but should be checked by a doctor. Women should not shy away and should report any changes at all that they find, because catching breast cancer early is beneficial. Your doctor may recommend a mammogram, ultrasound, or biopsy to determine whether a lump is cancerous or not.
  • Breast implants can raise cancer risk: Women with breast implants are are not a greater risk of getting breast cancer. Standard mammograms might not work well but additional X-rays are sometimes needed to fully examine the breast tissue.
  • Negative mammography means not to worry about cancer: Mammography can often detect breast cancer before it can be felt or before it produces symptoms. Overall, mammograms will pick up 80-90% of cancers but there are still 10-20% of cancers that will not be detected.
  • We don't need to talk about cancer: Cancer can be a difficult topic to address, particularly when you don't know what to share and how the other person would react. Talking about cancer to partners, family members, friends and colleagues can help to alleviate these feelings and at the same time dealing with the disease openly can improve outcomes and you will feel relieved.
  • There is nothing that can be done for treatment of cancer: This is a myth which needs to be debunked, there is a lot that can be done if cancer is detected at an early stage, and with the right strategies, one-third of the most common cancers can be prevented. 
  • There are no signs or symptoms of cancer: It is true that early signs and symptoms are not known for all cancers, but for many cancers, including breast, cervical, skin, oral and colorectal cancers, and some childhood cancers, the benefits of early detection are indisputable. Awareness is the first step to early detection and it is important for individuals, health professionals and policy makers to be aware and educated in recognizing the signs and symptoms for cancer.


  • LAST UPDATED ON : Apr 07, 2017


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The content on this page has been supervised by the Nodal Officer, Project Director and Assistant Director (Medical) of Centre for Health Informatics. Relevant references are cited on each page.