According to the World Health Organization, cancer is one of the leading causes of death globally. In 2020, nearly 10 million people died due to cancer.
Cancer is a group of diseases in which there is the development of abnormal cells that grow and divide uncontrollably in the body. In a normal person, there is constant wearing and tearing of cells. This is balanced by new cells that replace the old ones. Various sets of genes control this whole process of destruction of old cells and formation of new cells. Sometimes, due to mutation or deletion of these genes, the control over cell growth is lost. This leads to infinite production of cells resulting in tumour development and organ infiltration. This phenomenon is called cancer.
The ability of the malignant tumour cells to go to distant locations of the body and cause other organ involvement is called metastasis. Cancer includes all types of malignancies in the human body. The malignancies are usually named after the organs or tissues where they originate and the type of cells they are made up of. For example, breast cancer, lung cancer, bone cancer, osteosarcoma, etc.
Symptoms of Cancer
The symptoms depend on the organ which is infiltrated. However, some of the general symptoms are:
- Unintentional weight loss
- Lumps or masses
- Fever and night sweats
- Altered bowel and bladder habits
- Pain in the involved organ
- Paraneoplastic symptoms
The organ-specific symptoms include dysfunction of that particular organ along with pain and lump development. For instance, in lung cancer, there is difficulty in breathing, chronic cough, hemoptysis etc.
Similarly in bone cancer, there is bone pain, fractures, difficulty in movements etc.
Paraneoplastic symptoms: This is a group of symptoms seen primarily as a result of the immune response of the body against a tumour. Autoantibodies are developed against malignant cells, which start attacking the body or an unrelated organ.
For example, neurological abnormalities due to breast cancer, excessive ADH secretion in lung cancer, etc.
Causes and Risk Factors
Mutations or deletions of the following gene can lead to cancer development:
- Loss of apoptotic or cell deletion gene: The process of destruction of old and damaged cells is hampered due to which they cannot be eliminated from the body.
- Mutation in a growth-promoting gene causes uncontrolled cancer cell multiplication.
- Mistakes in DNA repair lead to altered genome and cell properties.
The aforementioned gene mutations can be caused due to any of the following reasons:
- Genetic history
- Radiation exposure
- Exposure to carcinogenic compounds
- Excessive alcohol and smoking
- Poor nutrition
- Sunlight (UV rays)
- Chronic inflammatory diseases like GERD (Gastro-oesophageal reflux disease), IBD (Inflammatory Bowel Disease)
Types of Cancer
There are many types of cancer depending on the type of tissue where the malignancy originates:
- Carcinoma: This type of cancer occurs in the epithelial tissue that forms the covering of glands and all the surfaces of our body. For example, breast cancer, lung cancer, prostate cancer, etc.
- Sarcoma: This type of cancer affects the connective tissues in the body like muscles, bones, cartilages, etc. For example, rhabdomyosarcoma, leiomyosarcoma, liposarcoma, etc.
- Leukaemia: This type of cancer affects the blood-forming tissues in the bone marrow. For example, Acute Lymphoblastic Leukaemia, Acute Myeloid Leukaemia, Chronic Lymphoblastic Leukaemia, Chronic Myeloid Leukaemia, etc.
- Lymphoma: Cancer of lymphocytes (a type of WBC). For example, B cell lymphoma, T cell lymphoma, Burkitt’s lymphoma etc.
- Other types: These include all the other malignancies like melanoma, germ cell tumours, etc.
Stages of Cancer
The staging differs between tumours but the general stages are as follows:
- Stage 0: The tumour is in-situ at this stage, which means that it does not breach the basement membrane of the involved organs and can be treated with risk of distant spread or lymph node involvement.
- Stage 1: The tumour breaches the basement membrane but does not involve any lymph nodes or distant structures.
- Stages 2 and 3: The size of the tumour enlarges, and infiltration takes place in the surrounding structures with local lymph node involvement, but distant structures are not affected.
- Stage 4: This is the last stage with the worst prognosis, where the cancer cells metastasise to distant organs with distant lymph node involvement.
- Physical examination: Any lump, organ enlargement, signs and symptoms are noted here.
- Laboratory tests: Blood tests for various tumour markers and blood cell counts in leukaemia and urine tests are done
- Imaging procedures: CT scan, PET-CT scan, and MRI are done to see the infiltration of the tumour cells.
- Endoscopy of the involved organ may be performed
- Biopsy: This is the confirmatory test where a small part of the tissue is taken out from the affected organ and then stained and visualised under a microscope. If malignant transformation is seen, then this not only confirms malignancy but also tells us the stage of cancer.
The aim of the treatment is to remove all the malignant cells from the body by opting for one or more of the following treatment options:
- Chemotherapy: Strong chemicals targeted against the highly dividing malignant cells are injected into the blood.
- Radiotherapy: Targeted radiations are used on the affected part. The high energy in the rays causes the death of the malignant cells.
- Surgery: The affected part or organ as seen under the imaging procedures is surgically cut out along with the nearby involved lymph nodes.
- Immunotherapy: A part of biological therapy, the immune system’s functions are used against malignant cells
- Bone marrow transplant: It is done in the cases of blood cancers where the bone marrow cells are destroyed and have to be replaced with new ones for survival.
- Hormone therapy: Medications are given in this treatment procedure, which alters the levels of hormones in the body that are important for the survival of some cancer cells in cases like breast cancer, prostate cancer, etc.
- Healthy lifestyle choices including the consumption of fresh fruits and vegetables and less processed and packaged food.
- Regular physical activity
- Avoiding consumption of alcohol and tobacco
- Usage of sunscreen and sunglasses when out in the sun
- Vaccinations against cancer-causing viruses like HPV, Hep B
- Frequent check-ups if there is a history of cancer in the family
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