About Cancer
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Understanding Cancer
The DNA Control Center:
Every human cell contains DNA, which acts as the instruction manual regulating the cell’s life cycle, including growth, division, and death.
Normal Cell Behavior:
Under healthy conditions, cells follow a strict program. When they become damaged or aged, they undergo a natural process of self-destruction known as apoptosis.
How Cancer Develops:
When DNA mutations occur, they can override this "cellular suicide" program. Instead of dying, these damaged cells continue to divide and grow uncontrollably. These malignant cells often cluster together to form tumors.
What is Cancer?
Cancer is a broad group of illnesses defined by the growth of dysfunctional cells that multiply without restraint, often invading and damaging healthy bodily structures.
What causes cancer?
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
How are cancers different?
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.
Metastasis of cancer: How cancer spreads
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.
Categorization of cancers
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.
Effects of gene mutation that causes cancer
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.
Am I at risk of cancer?
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.
Treatment of 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.