CANCER: Types, Causes, Treatment, Cancer detection, Preventions.

CANCER

ABOUT

# What is Cancer ?

• Cancer is the uncontrolled growth of abnormal cells in the body.
• These abnormal cells crowd the normal cells, making it difficult for the body to function properly.
• Eventually, those abnormal cells can form into big mass, called tumors.
• These tumours can either be non-cancerous (Benign) or cancerous (Malignant).

Malignant tumor:  The word "Cancer" itself refers to malignant tumors.

•  As the more dangerous of the two tumor types, malignant tumors multiply before penetrating, and harming the body's tissues, leading to serious health issues and possibly premature death.
•  Receiving regular medical check up is incredibly important, so that potential malignancies can be spotted and treated as early as possible.

Benign tumor:  Unlike malignant tumors, benign tumors will not invade neighbouring tissues. But they can also grow in size and cause various health problems.

•  Eventually l, a benign tumor may press against vital structures in your body, including the nerves and blood vessels .
•  In these type of cases benign tumor will require treatment.

Types

Each type of cancer merits a different form of treatment. Depending on the type we have:-

1. Bladder Cancer: About 81,000 new cases occur annually making it the fourth most common cancer types in men, with slightly fewer cases diagnosed in women .
2.  Brain Cancer:  A Brain cancer can arise from many different types of brain cells (primary brain cancer) or occur when cancer cells from other parts of the body spread (metastasize) to the brain. True brain cancers are those that arise in the brain itself. About 100,000 and 200,000 people in the United States are affected by this disease.
3. Breast Cancer: Breast cancer is cancer that forms in the cells of the breasts. These form a form of lump in the breasts. Every 2 minutes, another woman in the United States is diagnosed with breast cancer.
4. Cervical Cancer: Cervical cancer is a type of cancer that occurs in the cells of the cervix — the lower part of the uterus that connects to the vagina.Various strains of the human papillomavirus (HPV), a sexually transmitted infection, play a role in causing most cervical cancer. Cervical cancer is one of the most treatable form of cancer.
5. Colon Cancer : Colon cancer is a type of cancer that begins in the large intestine (colon). The colon is the final part of the digestive tract.
6. Esophageal Cancer: The Esophageal cancer usually begins in the cells that line the inside of the esophagus. Esophageal cancer can occur anywhere along the esophagus. More men than women get esophageal cancer. The two most common forms are Adenocarcinomas(AC) and squamous cell carcinomas(SCC).
7. Fallopian-tube cancer: Fallopian tube cancer starts in the fallopian tubes, which connect a woman's ovaries to their uterus. Each month, an ovary releases one egg into the fallopian tube. The egg either gets fertilized by sperm, or it passes out of the body during a menstrual period. Fallopian tube cancer is very rare. Only about 1% of all reproductive cancers in women start in    the fallopian tubes.
8. Head and neck cancers Cancers that are known collectively as head and neck cancers usually begin in the squamous cells that line the mucosal surfaces of the head and neck (for example, those inside the mouth, throat, and voice box). These cancers are referred to as squamous cell carcinomas of the head and neck. Head and neck cancers can also begin in the salivary glands, sinuses, or muscles or nerves in the head and neck, but these types of cancer are much less common than squamous cell carcinomas.
9. Kidney Cancer: In adults, renal cell carcinoma is the most common type of kidney cancer. Other less common types of kidney cancer can occur. Young children are more likely to develop a kind of kidney cancer called Wilms' tumor. Kidney cancer occurs in more than 60,000 people annually, but is highly treatable.
10. Leukemia: Leukemia is different from other cancers and is generally called as cancer of blood cells, because it affects the blood, bone marrow, and potentially the lymph glands.
11. Liver Cancer: Several types of cancer can form in the liver. The most common type of liver cancer is hepatocellular carcinoma, which begins in the main type of liver cell (hepatocyte). Other types of liver cancer, such as intrahepatic cholangiocarcinoma and hepatoblastoma, are much less common.
12. Lung Cancer: Lung cancer is a type of cancer that begins in the lungs. Lung cancer is the leading cause of cancer deaths worldwide.People who smoke have the greatest risk of lung cancer, though lung cancer can also occur in people who have never smoked. The risk of lung cancer increases with the length of time and number of cigarettes you've smoked. If you quit smoking, even after smoking for many years, you can significantly reduce your chances of developing lung cancer.
13. Lymphoma: A common form of cancer, also known as blood cancer. Lymphoma is a cancer of the lymphatic system, which is part of the body's germ-fighting network.The lymphatic system includes the lymph nodes (lymph glands), spleen, thymus gland and bone marrow. Lymphoma can affect all those areas as well as other organs throughout the body.
14. Carcinoma: Carcinoma is the most common type of cancer. It begins in the epithelial tissue of the skin, or in the tissue that lines internal organs, such as the liver or kidneys. Carcinomas may spread to other parts of the body, or be confined to the primary location.
15. Melanoma: It is the cancer of melanocytes of skin.
16. Sarcoma: It is cancer of Mesodermal tissue.
17.  Pancreatic cancer: Pancreatic cancer begins in the tissues of your pancreas — an organ in your abdomen that lies behind the lower part of your stomach. One of the most difficult cancers to detect and manage, requiring aggressive treatment.
18. Ovarian cancer: Ovarian cancer is a growth of cells that forms in the ovaries. The cells multiply quickly and can invade and destroy healthy body tissue. Woman with ovarian cancer may develop epithelial, germ cell, stromal tumors.
19. Skin Cancer: Skin Cancer arises when DNA damage in skin cells triggers genetic mutations.
20. Stomach Cancer: Stomach cancer is an abnormal growth of cells that begins in the stomach. Stomach cancer, also known as gastric cancer, can affect any part of the stomach. In most of the world, stomach cancers form in the main part i.e. stomach body.
21. Thyroid Cancer: Thyroid cancer occurs in the cells of the thyroid — a butterfly-shaped gland located at the base of your neck, just below your Adam's apple.Thyroid cancer might not cause any symptoms at first. But as it grows, it can cause pain and swelling in your neck.
22. Uterine Cancer: Uterine cancer is a type of cancer that begins in the uterus. The uterus is the hollow, pear-shaped pelvic organ where fetal development occurs.

SYMPTOMS

Sign and symptoms caused by cancer will  highly depend on what part of the body is affected.

                      

                                  Some general symptoms associated with cancer include :-

1. Fatigue
2. Weight changes, including unintended loss or gain .
3. Lump or area thickening that can be felt under the skin .
4. Skin changes, such as yellowing darkening or redness of the skin, sores that won't heal, or changes to existing moles .
5. Persistent cough or terrible breathing.
6. Changes in bowel habits.
7. Hoarseness.
8. Persistent, indigestion or discomfort after eating.
9. Difficulty in swallowing.
10. Persistent, unexplained muscle or joint pain. 
11. Unexplained bleeding or bruising.
12. Persistent, unexplained fever or night sweats.

Causes of cancer

The cancer causing agents are called carcinogens.

They are of following types:-

1. Chemical agents:- Aniline dyes, N-nitrosolime-thylamine, benzopyrene. Ex:- Chemicals in cigarette smoke.
2. Physical agents:- Raising radiations like X-ray and r-rays, non- raising radiations like UV rays, damage DNA causing neoplastic transformation.
3. Biological agents:- Oncogenic viruses, some parasites.           

• Generally, cancer is caused by changes (mutations) to the DNA within cells.
• The DNA inside a cell is packaged into a large number of individual genes, each of which contain a set of instructions telling the cell what functions to perform as well as how to grow and divide.
• Errors in the instructions can cause the cell to stop it's normal function and may allow a cell to become cancerous.

Affect Of Gene Mutations

A gene mutation can instruct a healthy cell to :-

• Allow rapid growth => A gene mutation can tell a cell to grow and divide more rapidly. This creates many new cells that all have that same mutations.
• Fail to stop uncontrolled cell growth => Normal cells know when to stop growing so that you have just the right number of each type of cell. Cancer cells loose the controls (tumour suppressor gene) that tell them when to stop growing. A mutation in a tumour suppressor gene allows cancer cells to continue growing and accumulating.
• Make mistakes when repairing DNA errors => DNA repairs gene look for errors in a cell DNA and make corrections. A mutation in a DNA repair gene may mean that the other errors aren't corrected, leading to cells to become cancerous.

                               These mutations are the most common one found in cancer. But many other mutation can contribute to causing cancer.

# What causes Gene Mutations? 

Gene Mutations can occur for several reasons for instance :-

• Gene mutations at person's birth => A person may be born with a genetic mutation that you inherited from his parents. This type of mutations accounts for a small percentage of cancer.
•  Gene Mutations that occur after birth=> Most gene mutations occur after a person is born and isn't inherited. A number of forces can cause gene mutations, such as smoking, radiations, viruses, cancer-causing chemicals(carcinogens), obesity, hormones, chronic inflammations and a lack of exercise.

     => Gene mutation occur frequently during normal cell growth.

    => However cell contain a mechanism that recognises when a mistake occurs and repairs the mistake.

    => Ocassionally, a mistake is missed. This could cause a cell to become cancerous.

# Complications 

Cancer and it's treatment can cause several complication, including:-

• Pain- Pain can be caused by cancer or by cancer treatment, though not all cancer is painful.
• Fatigue- Fatigue in people with cancer has many causes, but it can often be managed. Fatigue associated with chemotherapy or radiation therapy treatments in common but temporary.
• Difficulty in breathing- Cancer or cancer treatment may cause a feeling of being short of breath. Treatments may bring relief.
• Nausea- Certain cancers and cancer treatments can cause nausea.
• Diarrhoea or constipation- Cancer and cancer treatment can affect the bowels and cause diarrhoea or constipation.
• Weight loss- Cancer and it's treatment may cause weight loss. Cancer steals food from normal cells and deprives them of nutrients.
• Chemical changes in the body- Cancer can upset the normal chemical balance in the body and increase risk of serious complications.
• Brain and Nervous system problems- Cancer can press on nearby nerves and cause pain and loss of function of body parts.
• Cancer that spreads- As cancer advances, it may spread (metasize) to other parts of the body, where cancer spreads depends on the type of cancer.
• Cancer that returns- Cancer survivors have a high risk of cancer recurrence. Some cancers are more likely to recurr than others.

Cancer Detection  

A) Blood and bone marrow tests are done for increased cell count in case of leukemia.

B) Histopathological study of biopsy:- In biopsy, piece of the suspected tissue cut into thin sections is stained and examined under microscope by a pathologist.

C) Radiography:- X-rays are used to detect cancer of the internal organs.

D) Computed Tomography:- Computed Tomography or CT scan uses X-rays to generate a 3-D image of the internal organs of a body.

E) Magnetic Resonance Imaging (MRI) :- Non-Ionising radiation and strong magnetic field are used in MRI to accurately detect pathological and physiological changes in living tissue.

F) Techniques in Molecular Biology:- These techniques are used to detect genes in individuals with inherited susceptibility to certain Cancers. Identification of such genes help in prevention by advising to avoid exposure to particular carcinogen to which they are susceptible like tobacco smoke for lung cancer.

Cancer Treatment

The common approaches for treatment of cancer are:- 

A) Surgery- The tumour cells are removed with the help of surgery to check the spread of cancerous cell

B) Radiation therapy:- A lethal irradiation of tumour vells is done, taking proper care of the normal tissues surrounding the tumour mass.

C) Chemotherapy:- Cancerous cell are killed by several chemotherapeutic drugs. These drugs exhibit side-effects like hair loss,  anaemia.

D) Immunotherapy:- In yjis method biological modifiers like Alpha-Interferons are used whicj activate the immune system and help in destroying the tumour as tumour cells avoid detection and destruction by immune system.

Majority of treatments require combination of surgery, radiotherapy and chemotherapy.

Prevention Of Cancer

Doctors have identified several ways to reduce the risk of cancer such as:- 

•  Stop smoking=> If a person quits smoking or doesn't smoke either actively or passively he is safe from not just lung cancer, but several other diseases. Smoking is linked to various types of cancers and diseases. Stopping now will reduce the risk of cancer in the future.
• Avoid excessive sun-exposure:- Harmful UV(ultraviolet) rays from the sun can increase the risk of skin cancer. So using a sunscreen can reduce fbe changes to a great extent.
• Rat a healthy diet:- A balanced and healthy diet including lots of fruits and green vegetables prevent from the risk of many types of cancers.
• Exercise daily.
• Maintain a healthy weight:- Maintaining a normal weight is best. Being overweight or obese may increase the risk of cancer.
• Immunizations:- Certain viruses increases the risk of cancer. Immunizations may help prevent those viruses, including, Hepatitis-B, which increases the risk of lung cancer.