Cancer has been known since human societies first learned to record their activities. It was well known to peoples of ancient civilizations. The word CANCER means CRAB in the Greek language. The founder of modern medicine, Hippocrates, likened the spreading of a cancerous tumor to the shape of the claw of a crab. This description best describes cancer even today. Cancer is a disease involving dynamic changes in the genome. The pathway to tumor formation is a multi-step journey involving the accumulation of genetic alteration along the way. Mutations are responsible for oncogenes with dominant gain of function and tumor suppressor gene with recessive loss of function; both classes of cancer genes have been identified through their alteration in human and animal cancer cell and by the elicitation of cancer phenotype in experimental models.
In normal life, cells are always exposed to carcinogens in one form or the other, but they don't always turn cancerous. These carcinogens because they can repair the damage do this. Faulty genes are repaired and it takes more than just a single gene to cause cancer. Also, the body's immune system (the body's defense mechanism) destroys any abnormal cell, thus preventing its multiplication. As we age, our defense system weakens and thus cancer is more common in the elderly. There is also accumulation of enough number of faulty genes to cause damage. Undiagnosed cancers also reach their peak during old age and hence we see more cases of cancer in older people.
What causes cancer ?
Cancer is caused by several factors. These can be classified into the following:
- Tobacco smoking
- Spicy diet
- Occupational hazards like chimney sweepers
- Hormone producing tumors
Formation of a cancerous tumor
The single cell containing the abnormal oncogene multiplies quickly. It divides to form two cells, which in turn divides to form four cells, then eight and so on. Each and every cell of the tumor then has the ability to turn cancerous. Tumor growth is measured by the time taken for the number of cells in a tumor to double. This period usually varies from about 1 month to 2 years. A patient usually detects a solid tumor after 25 to 30 such doublings. In this phase the tumor contains approximately billion cells and has a diameter of half an inch.
What is a cancerous tumor?
A cancerous tumor is a collection of many abnormal cells, most of which divide without any control. This tumor spreads to neighboring tissues by forcing its way between normal cells. The abnormal cells of the tumor bear little or no resemblance to the cells of their origin. They are irregular in size and shape.
What does the cancerous tumor consist of ?
The cancer cell has a large nucleus. They may also consist of calcium deposits that can be seen on an X-ray. These characteristic coupled with the irregular appearance of the cells are often the diagnostic feature of the detection of cancer.
How does cancer spread?
A cancerous tumor spreads not only locally but also migrates to different sites in the body by a process called as metastasis.
The tumor cells multiply and proliferate to form outgrowths from the original tumor. These cells then spread to the surrounding tissue. The involvement of nerve fibers near the spreading tumor causes pain. The spread of cancer can be considered in the blood as well as the lymphatic fluid. Spread of cancer in the lymphatic fluid. As the tumor grows it spreads into the neighboring lymphatic vessels. The cancer cells detach from the primary tumor and are carried by the lymphatic flow until they settle in a lymph node. In the lymph node the cancer cell again starts dividing to form another tumor. The tumor then remains in the node. It is temporarily stopped from spreading by the immune cells in the lymphatic system. The tumor soon overcomes the immune system and may spread throughout the body in the same manner.
Spread of cancer in the blood
Cancer cells mostly spread to organs having a good blood supply. These organs are the liver, lungs, bones and brain. The growing tumor invades nearby blood vessels by growing into their walls. A cancer cell detaches itself from the primary tumor. This cancer cell flows with blood until it lodges itself in a very small blood vessel called as a capillary. Here it starts forming a secondary tumor.
The spread of the cancer from one site to a distant site is by a process called as metastasis. Cancerous cells become detached from the primary tumor. The blood or lymphatic system carries these to distant sites like the liver, lungs, bones and brain. The cancer cell then proliferates as these sites to form secondary tumors or secondaries.
What are the symptoms of cancer?
At times cancer is detected while investigating for some other disease. But usually it is detected when symptoms gradually develop and become noticeable over a period of weeks or months. The symptoms of cancer are:
- A lump, which is often firm or painless, present beneath the skin
- Non-healing wounds.
- Blood in the urine, sputum or in the vomitus.
- Changes in bowel movements.
- Constant pain in the abdomen.
- Weight loss, which is significant in a short period of time.
- Loss of appetite.
- Long standing hoarseness of voice.
These are the most common symptoms of cancer and if you present with any of these symptoms, do consult your doctor immediately.
How are cancers diagnosed ?
Cancers can be diagnosed in various ways. Emphasis should be laid on the detection of cancer at an early stage. Detection of late stage of cancers is no doubt easier, but it serves no purpose, as treatment of terminal stage cancers is difficult and survival rates are low.
Cancers can be detected by the following methods:-
This type of screening is improving the early diagnosis of cancer. Screening is a procedure to detect cancers before it presents with any symptoms. Cancers that can be diagnosed with this method are:
- Breast cancer, which is detected by a procedure called as mammography.
- Cancer of the large intestine, which is detected by colonoscopy, or a simple rectal examination.
- PAP smear, which is the screening-test for cancer of the cervix of the uterus.
The three main techniques to treat cancer are surgery, chemotherapy and radiation therapy. Other treatments include hormonal and biological therapies.
Surgical treatment involves removal of the tumor. Usually some normal tissue surrounding the cancerous tissue is also removed. This ensures maximal removal of cancerous cells from the tumor site. The lymph nodes surrounding the tumor are also removed to prevent the tumor from spreading. Rarely surgery may be performed to remove tumor growth from remote sites where the cancer has spread. Cancer surgery is not useful if the tumor site is deep within the body and is inaccessible for surgery. It is also not advisable in old patients and in those in whom the cancer has spread extensively.
Treatment of cancers with anticancer drugs is called as chemotherapy. These drugs can be taken orally, but can be given as injection into a vein. This therapy is used when the cancer is widespread throughout the body, such as in leukemia. It can also be used to arrest the spread of cancers by metastasis. The drawback of chemotherapy is its side effects. These include nausea, vomiting, temporary hair loss, constipation, diarrhea, fatigue, kidney damage and anemia. The duration of treatment depends on the type of cancer and the purpose of the treatment.
In this procedure, focused radioactive rays are used to destroy or slow the growth of cancerous tissue. This therapy can however have severe side effects. They include reddened or painful skin, loss of appetite, vomiting, nausea, and fatigue.
Therapy with hormones plays a major part in cancer treatment. For example, estrogens are responsible for stimulating growth of most breast cancers. They are also responsible for suppressing the growth of prostate cancer in men. Treatment with sex hormones plays a vital role in these types of cancers.
These drugs involve the latest in the treatment of cancers. They are called as cancer vaccines. They are interferon like drugs. Interferon is a substance present in the body that offers resistant to foreign agents like viruses. These drugs produce an interferon like substance, which stimulates the white blood cells of the body to engulf abnormal cells.
The many treatment modalities of cancer treatment include surgery chemotherapy, radiotherapy, immunotherapy, and gene therapy, are all directed towards killing tumor cells or preventing cell proliferation. Although conventional chemotherapies have traditionally been used to treat patients with various types of cancer, their side effects and damage to normal cells have been of monumental concern. Blood-forming bone marrow cells are the first cells to be adversely effected by chemotherapy, leading to a decline in the number of peripheral blood cells. It is therefore highly desirable to search for alternative chemical agents that can effectively destroy cancer cells but have minimal or no side effect on normal cells.
Complementary and Alternative cancer therapy
Complementary and alternative medicine (CAM) refers to a broad range of healing philosophies, approaches, and therapies that exist largely outside the institutions where conventional health care is taught and provided. However, some of these therapies are now making way to the mainstream medicine. Use of CAM is widespread among cancer patients. Throughout the world cancer patients try many forms of questionable or unproven treatment methods. The reasons for adopting these therapies most certainly are complex and are related to the social and cultural contexts. In case of severe illness, the hope to leave no stone unturned is a powerful motivator. In developing countries factors like ignorance, socioeconomics, and inadequate access to mainstream medical facilities are some major factors that play an important role for patients to opt alternative therapies that are replacement for, rather than adjunct to, mainstream therapy. Whereas in developed countries a significant proportion of cancer patients try complementary therapies viz. acupuncture, relaxation therapy and massage for anxiety as adjuncts to mainstream care for management of symptoms and to improve quality of life. Evidence from randomized trial supports the value of hypnosis for cancer pain and nausea.