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Cancer | main causes | symptoms of cancer |main hallmarks | types of mutation cancer cell

Updated: Aug 9





Human’s life span is about 80 years. However, the cells that make up our body have much shorter lifespans (for example, skin cells 2 weeks, liver cells 400 days). Old cells are dying and they are replacing by new cells.


Cancer can start any place in the body. It starts when cells grow out of control and crowd out normal cells. This makes it hard for the body to work the way it should. Cancer can be treated very well for many people. In fact, more people than ever before lead full lives after cancer treatment. Here we will explain what cancer is and how it’s treated. You’ll find a list of words about cancer and what they mean at the end of this booklet.

The genetic changes that contribute to cancer tend to affect three main types of genes proto-oncogenes, tumor suppressor genes, and DNA repair genes. These changes are sometimes called “drivers” of cancer.

Symptoms and signs depend on the specific type and grade of cancer; although general signs and symptoms are not very specific the following can be found in patients with different cancers: fatigue, weight loss, pain, skin changes, change in bowel or bladder function, unusual bleeding, persistent cough or voice change, fever, lumps, or tissue masses.

The TNM system of staging is a method of classifying tumors based on the size of the primary tumor (T), the extent to which cancer has spread to lymph nodes (N), and the presence or absence of metastasis (M). The combination of scores for T, N and M will tell the doctor which stage the cancer is at. A cancer’s stage does not change, even if the cancer gets worse – the stage always refers to the characteristics of the cancer when it was diagnosed. The TNM staging

The reason cancer is often a slow, insidious disease, is because these mutations accumulate not in a single original cell all at once, but rather in a cell lineage over time.

You might have one cell that gets a single mutation, all its offspring will have that mutation. Then one of those cells gets another mutation, all of that cell's offspring now have two mutations! And so onuntil you end up with cell offspring with enough mutations to bypass your body’s numerous control systems and divide rapidly. This is the clonal evolution of cancer cells.






There are 6 main hallmarks commonly associated with cancerous cells;

· They can provide their own growth signals and are insensitive to anti-growth signals.

· They evade programmed cell death ('apoptosis') that normal cells undergo when their DNA is damaged.

· They have replicative immortality (normal cells have a set number of replications before they can no longer divide and cancer cells can bypass this via production of certain enzymes),

· They can influence the production of new blood vessel branches to supply them with nutrients.

· Malignant cancer cells have the ability to metastasise - to spread to and invade other tissues

· Cancerous cells acquire these abilities through slow accumulation of faults/mutations in cell DNA.

Generally you have two main types of mutation.

A gain-of-function mutation will grant a cell extra function. For example; growth factor receptors on cells wait for an external signal from the cell's environment. When they're activated, they tell the cell it can proceed through the cell cycle and divide. Cancerous cells sometimes acquire a mutation in this receptor which causes it to always be switched on, meaning they can continuously move through the cell cycle and divide rapidly.

We call normal genes that contribute to growth and development of a cell proto-oncogenes, and when they get gain-of-function mutations, we call them oncogenes. We have 2 copies of each gene, and it only takes a gain-of-function mutation in a single copy of a proto-oncogene to turn it into an oncogene.

We also have genes specifically meant to prevent cells from growing uncontrollably, these are called tumor suppressor genes and they stop changes that lead to cancer growth by detecting DNA damage, stopping the cell cycle and repairing the damage, or causing the cell to commit suicide if the damage is too severe to repair. Cancer cells have mutations that 'knock out' these tumor suppressor genes by inactivating them. These mutations are known as loss-of-function mutations, and when a tumor suppressor gene is no longer active, it can no longer stop a cell from growing uncontrollably.

You need two loss-of-function mutations (one in each copy of the tumor suppressor gene) to knock it out, since a single mutation will only knock out one copy of the gene, meaning the other copy will still work and be able to repair DNA damage.

System is used for all cancers except lymphoma, cancers of the brain, and non-Hodgkin’s lymphoma.

The major causes of DNA mutation could be radiation, or exposure to mutagens. Another major concern which is leading to cancer is the lifestyle of the people. Smoking, eating habits, environmental conditions - anything could trigger up a mutation. But then it depends on you, and the strength of your DNA repair system to fix it. Mutation in the oncogenes or tumor-suppressor genes usually renders the body more prone to mutations.

There are more than 100 types of cancer and are classified on the basis of origin: 1. Leukemia (blood cells) 2. Lymphoma (cells and organs of the immune system) 3. Sarcoma (connective and supportive tissues) 4. Carcinoma (epithelial cells)

The different types of cancers belong to two main groups:

1. solid tumors

2. Blood cancers (also called haematological cancers).

· Solid tumors

Solid tumors include many common cancers like breast cancer, bowel cancer and lung cancer.

A tumour is a lump or swelling, but not all tumours are cancers:

· Benign tumours are not cancers: they can cause problems if they press on nearby tissues or organs, but they don’t spread to other parts of the body.

· Malignant tumours are cancers: they can spread into nearby tissues or to other parts of the body.

Blood cancers (also called haematological cancers).

Your blood is made up of different cell types including red blood cells for carrying oxygen, platelets to help blood clot and white blood cells that fight infections. They all originally come from stem cells, which have the potential to develop into any type of blood cell as they divide and mature. Problems in this process, known as ‘differentiation’, are at the route of all blood cancers. Different types of blood cancer depend on when and how these problems occur.

What causes cancer?

For most people with cancer, specific reasons are rarely known. However, we do know some things or causes which may increase the risk of developing cancer.

Some aspects such as lifestyle can be monitored to decrease the risk. Others, such as our genes, we may not be able to change.

Making some simple changes to your lifestyle can greatly reduce your risk of developing cancer. For example, healthy eating, taking regular exercise and not smoking will all help lower your risk.

physiotherapy helps cancer patients?

Physiotherapist are experts in finding the best ways for cancer patients to be active. This may involve exercise programmes or advice on everyday activities, such as climbing stairs or getting dressed.Physiotherapists

With some cancers, research has shown that exercise can reduce the risk of it coming back and increase your chances of surviving. Specialist physios can also help with problems and possible treatment of side effects such as tiredness, osteoporosis and lymphoedema.

Physios also support cancer patients with managing pain. This is important, as pain can make you feel afraid to move or walk. Managing pain can also improve your quality of life. For cancer patients of working age, physiotherapy can help you gain enough strength and mobility to return to work.

Some common symptoms that may occur with cancer are as follows:-

1) Persistent cough or blood-tinged saliva. These symptoms usually represent simple infections such as bronchitis or sinusitis. They could be symptoms of cancer of the lung, head, and neck. Anyone with a nagging cough that lasts more than a month or with blood in the mucus that is coughed up should see a doctor.

2) A change in bowel habits. Most changes in bowel habits are related to your diet and fluid intake. Doctors sometimes see pencil-thin stools with colon cancer. Occasionally, cancer exhibits continuous diarrhea. Some people with cancer feel as if they need to have a bowel movement and still feel that way after they have had a bowel movement. If any of these abnormal bowel complaints last more than a few days, they require evaluation. A significant change in bowel habits that cannot be easily explained by dietary changes needs to be evaluated.

3) Blood in the stool. A doctor always should investigate blood in your stool. Hemorrhoids frequently cause rectal bleeding, but because hemorrhoids are so common, they may exist with cancer. Therefore, even when you have hemorrhoids, you should have a doctor examine your entire intestinal tract when you have blood in your bowel movements. With some individuals, X-ray studies may be enough to clarify a diagnosis. Colonoscopy is usually recommended. Routine colonoscopy, even without symptoms, is recommended once you are 50 years old. Sometimes when the source of bleeding is entirely clear (for example, recurrent ulcers), these studies may not be needed.

4) Unexplained anemia (low blood count) Anemia is a condition in which people have fewer than the expected number of red blood cells in their blood. Anemia should always be investigated. There are many kinds of anemia, but blood loss almost always causes iron deficiency anemia. Unless there is an obvious source of ongoing blood loss, this anemia needs to be explained. Many cancers can cause anemia, but bowel cancers most commonly cause iron deficiency anemia. Evaluation should include endoscopy or X-ray studies of your upper and lower intestinal tracts.

5) Breast lump or breast discharge. Most breast lumps are noncancerous tumors such as fibroadenomas or cysts. But all breast lumps need to be thoroughly investigated.A negative mammogram result is not usually sufficient to evaluate a breast lump. Your doctor needs to determine the appropriate X-ray study which might include an MRI or an ultrasound of the breast. Generally, diagnosis requires a needle aspiration or biopsy (a small tissue sample). Discharge from a breast is common, but some forms of discharge may be signs of cancer. If discharge is bloody or from only one nipple, further evaluation is recommended. Women are advised to conduct monthly breast self-examinations.

6) Lumps in the testicles. Most men (90%) with cancer of the testicle have a painless or uncomfortable lump on a testicle. Some men have an enlarged testicle. Other conditions, such as infections and swollen veins, can also cause changes in your testicles, but any lump should be evaluated. Men are advised to conduct monthly testicular self-examinations.

7) A change in urination. Urinary symptoms can include frequent urination, small amounts of urine, and slow urine flow or a general change in bladder function. These symptoms can be caused by urinary infections (usually in women) or, in men, by an enlarged prostate gland.Most men will suffer from harmless prostate enlargement as they age and will often have these urinary symptoms.These symptoms may also signal prostate cancer. Men experiencing urinary symptoms need further investigation, possibly including blood tests and a digital rectal exam. The PSA blood test, its indications, and interpretation of results should be discussed with your health care provider. If cancer is suspected, a biopsy of the prostate may be needed. Cancer of the bladder and pelvic tumors can also cause irritation of the bladder and urinary frequency.

8) Blood in the urine. Hematuria or blood in the urine can be caused by urinary infection, kidney stones, or other causes. For some people, it is a symptom of cancer of the bladder or kidney. Any episode of blood in the urine should be investigated.

9) Hoarseness. Hoarseness not caused by a respiratory infection or that lasts longer than three to four weeks should be evaluated. Hoarseness can be caused by simple allergy or by vocal cord polyps, but it could also be the first sign of cancer of the throat.

10) Persistent lumps or swollen glands. Lumps most frequently represent harmless conditions such as a benign cyst. A doctor should examine any new lump or a lump that won't go away. Lumps may represent cancer or a swollen lymph gland related to cancer. Lymph nodes swell from infection and other causes and may take weeks to shrink again. A lump or gland that remains swollen for three to four weeks should be evaluated.

11) Obvious change in a wart or a mole. Multicolored moles that have irregular edges or bleed may be cancerous. Larger moles are more worrisome and need to be evaluated, especially if they seem to be enlarging. Removing a mole is usually simple. You should have your doctor evaluate any suspicious mole for removal. The doctor will send it for examination under a microscope for skin cancer.

12) Indigestion or difficulty in swallowing. Most people with chronic heartburn usually do not have serious problems. People who suffer from chronic or lasting symptoms despite using over-the-counter antacids may need to have an upper GI endoscopy. A condition called Barrett esophagus, which can lead to cancer of the esophagus, can be treated with medication and then monitored by a doctor. Difficulty swallowing is a common problem, especially in elderly people, and has many causes. Swallowing problems need to be investigated, because nutrition is always important.Difficulty swallowing solids can be seen with cancer of the esophagus.

13) Unusual vaginal bleeding or discharge. Unusual vaginal bleeding or bloody discharge may be an early sign of cancer of the uterus. Women should be evaluated when they have bleeding after intercourse or bleeding between periods. Bleeding that comes back, that lasts two or more days longer than expected, or that is heavier than usual also merits medical examination. Postmenopausal bleeding, unless expected on hormone therapy, is also worrisome and should be evaluated. Usually, the evaluation will include an endometrial biopsy, in which a doctor takes a small tissue sample from inside the uterus for testing. A Pap smear should be part of every woman's routine medical care.

14) Unexpected weight loss, night sweats, or fever. These nonspecific symptoms might be present with several different types of cancer. Various infections can lead to similar symptoms (for example, tuberculosis).

15) Continued itching in the anal or genital area. Precancerous or cancerous conditions of the skin of the genital or anal areas can cause persistent itching. Some cancers cause skin color changes. Several infections or skin conditions (for example, fungal infections or psoriasis) also can cause these symptoms. If itching does not stop with over-the-counter topical medications, your doctor should inspect the area.

16) Non-healing sores. Sores generally heal quickly. If an area fails to heal, you may have cancer and should see a doctor. Non-healing sores in your mouth or persistent white or red patches on your gums, tongue, or tonsils are also should raise concerns. Some non- healing sores may be due to poor circulation (for example, diabetic foot ulcers).

17) Headaches. Headaches have many causes (for example, migraines, aneurysms) but cancer is not a common one. A severe unrelenting headache that feels different from usual can be a sign of cancer, but aneurysms may present in the same way. If your headache fails to improve with over-the-counter medications, see a doctor promptly.

18) Back pain, pelvic pain, bloating, or indigestion. These are common symptoms of daily life, often related to food intake, muscle spasms or strains, but they also can be seen in ovarian cancer. Ovarian cancer is particularly difficult to treat, because it is frequently diagnosed late in the course of the disease.

 https://www.cancer.gov/

https://www.quora.com/What-is-cancer-3

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