What is Cancer
Know Your Cancer
Cancer can originate in any cell of the body. The human body is made up of trillions of cells categorized into different divisions. Any of these cells can turn cancerous at any time due to a malfunction in the DNA.
Every cell in the body contains strains of DNA that act as the control center for the cell. It’s the DNA that regulates the life-cycle of a cell. Usually, normal cells follow a pre-programmed cycle of growth, division, and death. Cell-death happens, when the cells get old or damaged, through a process called ‘cellular suicide’ or apoptosis.
But sometimes, a mutation in the DNA can induce the cells to evade the process of apoptosis or self-death. These cells continue to grow abnormally and uncontrollably thus turning into malignant cancerous cells. These cells often accumulate to form a tumor.
Information About Cancer
Cancer refers to a large cluster of diseases characterized by the development of abnormal cells that divide uncontrollably and have the ability to infiltrate and destroy normal body tissue.
One certain cause of cancer is genetic. The malfunction in the genetic programming can be inherited from parents, but genetic reasons contribute to only 5- 10% of all cancer cases around the world.
In most cases, these mutations arise due to errors in cell division caused by environmental exposure or lifestyle factors.
Some common causes of cancer are:
- Tobacco and alcohol
- Exposure to carcinogens
- Obesity
- Poor nutrition
- Hormones
- Sexually transmitted diseases
- UV rays of the sun
Most cases of cancer are preventable. In fact, researchers claim 50 % of cancer cases can be prevented by adopting a healthy lifestyle.
In all cancers there is one basic similarity – they occur due to a mutation in the DNA. But each cancer in each patient is different from the other and that makes the treatment and management of cancer so complex.
Cancers may be aggressive or slow in nature. They respond to treatment in different ways. Some cancers are more likely to recur than another. For some the fatality rate is high and for some the survival rate is high!
Thus, depending on several such factors cancers are categorized into more than 200 types.
Some malignant cancers are aggressive and they have the capability to spread to distant organs of the body, these cancers are called metastatic cancer and the process by which these cells spread out is termed as metastasis.
Usually, this happens at a much later stage when the cancer grows beyond the site of origin. Metastasized cancers are difficult to treat and in most cases of metastasized cancers the doctors target to inhibit the growth and relieve the symptoms.
Let’s understand what happens in metastasis.
As the cancerous cells continue to grow uncontrollably, some cells may travel to other parts of the body through blood stream or lymphatic system. These cells continue to grow resulting in new tumors. This is called metastasis of cancer.
Tumors formed in distant sites are also named after the area of origin. E.g. if breast cancer spreads to the lungs then cancer in the lung is called metastatic breast cancer, not lung cancer.
This is because the metastatic cancer cells generally look the same as cells of original cancer. In almost all cases, they have similar molecular features and the cells replicate specific chromosome changes.
Usually, metastasis occurs at an advanced stage of cancer. In some cases, treatment can prolong life expectancy, but in others, it helps to control the growth of cancer or relieve the symptoms caused by it.
Depending on the site of origin, type of cells or nature of the cancer, cancer is categorized into several types. Most cancer types are named after the organs or tissues they arise from. For example, lung cancer begins in the cells of the lungs, pancreatic cancer arises from the cells of the pancreas.
(Read more about different cancer types)
Some of the categories of cancer are:
1. Carcinoma
Carcinomas are the most common type of cancers. They begin in the cells of skin or tissues covering the surface of internal organs and glands. Most carcinomas form solid tumors. Depending on the cell type, they are further divided into –
- Adenocarcinoma is cancer that originates in the epithelial cells of the body. Cancers of the breast, colon, and prostate are adenocarcinomas.
- Basal cell carcinoma begins in the basal (base) layer of the epidermis, the outer layer of skin.
- Squamous cell carcinoma forms beneath the outer surface of the skin. These cells are also present in the stomach, intestines, lungs, bladder, and kidneys.
- Transitional cell carcinoma occurs in the linings of the bladder, ureters, and part of the kidneys and a few other organs.
2. Sarcoma
Sarcomas begin in the cells that connect or supports the body. They are found in the cells of bone and soft tissues, like muscle, fat, blood vessels, lymph vessels, cartilage, tendons and ligaments.
3. Leukemia
Leukemia is the cancer of the blood. It forms in the cells of the blood-forming bone marrows. Leukemias do not form solid tumors but they are malignant and dangerous.
There are four main types of leukemia – acute lymphocytic leukemia, chronic lymphocytic leukemia, acute myeloid leukemia, and chronic myeloid leukemia.
4. Lymphomas
Lymphoma arises in the lymphatic system, it’s a network of vessels and glands that help fight infection. Lymphomas are of 2 types: Hodgkin Lymphoma and non-Hodgkin Lymphoma.
Other Types of Tumors:
§ Germ Cell Tumors – They begin in the cells of sperms or eggs. These tumors can be benign or malignant and can occur at any site.
§ Neuroendocrine Tumors – These tumors form in the cells that release hormones into the blood.
§ Carcinoid Tumors – these are slow-growing tumors usually found in the gastrointestinal system.
A malicious mutation in the gene can instruct the cell to
- Grow rapidly
- Lose control over cell death
- Make mistakes when repairing DNA errors
Benign and Malignant Tumors
Not all tumors are cancerous and neither all cancers form tumors.
Tumors that do not spread or invade nearby tissues are referred as benign tumors. They are usually not life-threatening; they do not usually recur after removal and they never spread to other parts of the body. It’s a hard mass of cells that can sometimes grow large enough to press against other body parts.
However, the malignant or cancerous tumors have the capability to grow and spread to distant organs in the body. They can be aggressive, invasive and life-threatening. Malignant cancer cells can reappear in any part of the body even after complete treatment.
Several risk factors of cancer are now identified. Scientists have labeled many substances as carcinogens (cancer-causing agents) and many are categorized as probable carcinogens. Some of the common risk factors cited by doctors are –
- Age – For most cancers, the risk increases with age. However, there are some cancers that are more common in children and adults.
- Lifestyle – Unhealthy sedentary lifestyle is a major risk factor for cancer.
- Family history – Genetic mutations can be inherited from parents.
- Medical conditions – Medical conditions like diabetes, PCOD, can increase cancer risk.
- Environment – Carcinogens like asbestos, benzene, passive smoking etc. are risk factors for cancer.
Depending on the site of origin, type of cells or nature of the cancer, cancer is categorized into several types. Most cancer types are named after the organs or tissues they arise from. For example, lung cancer begins in the cells of the lungs, pancreatic cancer arises from the cells of the pancreas.
(Read more about different cancer types)
Some of the categories of cancer are:
1. Carcinoma
Carcinomas are the most common type of cancers. They begin in the cells of skin or tissues covering the surface of internal organs and glands. Most carcinomas form solid tumors. Depending on the cell type, they are further divided into –
- Adenocarcinoma is cancer that originates in the epithelial cells of the body. Cancers of the breast, colon, and prostate are adenocarcinomas.
- Basal cell carcinoma begins in the basal (base) layer of the epidermis, the outer layer of skin.
- Squamous cell carcinoma forms beneath the outer surface of the skin. These cells are also present in the stomach, intestines, lungs, bladder, and kidneys.
- Transitional cell carcinoma occurs in the linings of the bladder, ureters, and part of the kidneys and a few other organs.
2. Sarcoma
Sarcomas begin in the cells that connect or supports the body. They are found in the cells of bone and soft tissues, like muscle, fat, blood vessels, lymph vessels, cartilage, tendons and ligaments.
3. Leukemia
Leukemia is the cancer of the blood. It forms in the cells of the blood-forming bone marrows. Leukemias do not form solid tumors but they are malignant and dangerous.
There are four main types of leukemia – acute lymphocytic leukemia, chronic lymphocytic leukemia, acute myeloid leukemia, and chronic myeloid leukemia.
4. Lymphomas
Lymphoma arises in the lymphatic system, it’s a network of vessels and glands that help fight infection. Lymphomas are of 2 types: Hodgkin Lymphoma and non-Hodgkin Lymphoma.
Other Types of Tumors:
§ Germ Cell Tumors – They begin in the cells of sperms or eggs. These tumors can be benign or malignant and can occur at any site.
§ Neuroendocrine Tumors – These tumors form in the cells that release hormones into the blood.
§ Carcinoid Tumors – these are slow-growing tumors usually found in the gastrointestinal system.
- Benign: non-cancerous tumor.
- Malignant: cancerous tumor.
- Cancer: cells growing abnormally and uncontrollably.
- Metastasized: Cancer spread to distant organs.
- Biopsy: scraping some cells to check cancerous changes.
- Chemotherapy: the use of drugs to treat cancer.
- Oncologist:a doctor who treats cancer.
- Radiation therapy: using high-energy x-rays to treat cancer.
- Remission: re-occurrence of cancer cells.
- Stage: the severity and spread of cancer.
- Adjuvant therapy: Post-treatment cancer care.
Cancer Care
Cancer is a complex cluster of diseases that presents unique features in each patient. With years of research and studies, doctors are able to understand a lot about this disease, yet a lot remains unknown.
The current knowledge of cancer enables us to treat, manage, and even cure several cancer types. But further studies are being conducted to understand the causes, preventives, risk factors, and less invasive treatment procedures.
10 Facts About Cancer
- 20% of all cancers worldwide is caused by chronic infections like HPV or HBV.
- About 77% of cancers are diagnosed in people who are 55 years old or older.
- Tobacco is the largest preventable cause of cancer in the world causing 22% of cancer deaths.
- Cancer patients in need of pain relief can be helped with the current knowledge about pain control and palliative care.
- There is a steady drop in cancer mortality mostly due to advances in early detection and treatment.
- Currently, Cancer is one of the leading causes of death across the world.
- Most of these deaths by cancer could have been prevented.
- About 70% of all cancer deaths are recorded in low and middle-income countries.
- Less than 30% of low-income countries have access to cancer treatment services.
- Only 14% of cancer patients have access to palliative care.