Cancer

Cancer is an abnormal and uncontrolled division of cells that invade and destroy the surrounding tissues. In our body, cell growth and differentiation are highly controlled and regulated, however, in cancer cells, there is a breakdown of these regulatory mechanisms. Normal cells possess a characteristic property of contact inhibition using which contact with other normal cells stops their uncontrolled growth, cancer cells have lost this property of contact inhibition. As a result of this, cancerous cells continue dividing to give rise to masses of cells referred to as tumors. Cells released from tumours reach distant sites through blood and wherever they get accumulated in the body, they start a new tumor formation there. This property is known as metastasis is the most dreadful property of malignant tumours. 

The infection by Human Immunodeficiency Virus (HIV) causes AIDS (Acquired immunodeficiency syndrome). AIDS is a disorder of the cell-mediated immune system of the body. This disorder results in a reduction in helper T-cells which stimulate antibody production via B-cells. Resulting in the loss of natural defense against infections. The incubation period of ALDS is between 6 months to 10 years.

Types of Tumours

There are two categories of tumours:

• Benign Tumours: normally remained confined to their original location and do not spread to other parts of the body and cause little damage. They can cause serious problems when they grow near vital organs, or restrict blood flow

• Malignant Tumour: these are a mass of proliferating cells known as neoplastic or tumour cells. These cells grow continuously, invading and damaging the surrounding normal tissues. As these cells actively divide and grow, they also starve the normal cells by competing  for vital nutrients

Types of Cancer

There are various types of cancer. Cancers are generally named after the organs or tissues where it is originated. For example, skin cancer starts in the skin, and brain cancer starts in the brain. Cancers may also be defined by the type of cells that forms them, such as an epithelial cell or a squamous cell.

Carcinoma

Carcinomas are formed via epithelial cells, these are the cells that cover the inside and outside surfaces of the body. There are many types of epithelial cells, which generally have a column-like shape when viewed under a microscope. 

Sarcoma

These are the cancers that develop from bones or soft tissues, such as fat, muscles, etc. Since bone and soft tissues can be found nearly everywhere in the body, a sarcoma can develop in any part of the body.

Lymphoma

The lymph system refers to a series of lymph nodes and vessels that helps in the movement of lymph fluid through the body.  Thus, lymphoma refers to a general term used for cancer that starts in the lymph system.  

Leukemia

It is also referred to as blood cancer. It usually affects the tissues present in the bone marrow, which are responsible for blood production. Lymphoma is caused by the uncontrolled growth of white blood cells. It is found to be the fatal form of cancer. These abnormally growing white blood cells damage the bone marrow tissues and surround the normally growing cells. Rapid destruction of normal cells via white blood cells replaces all normal cells from abnormal cells.

Causes of Cancer 

• Transformation of normal cells into cancerous neoplastic cells which can be induced by physical, chemical, or biological factors called carcinogens 

• Ionising Radiations like X-rays and gamma rays and non-ionizing radiations like UV rays cause DNA damage leading to neoplastic transformations

• Several genes known as cellular oncogenes (c-onc) or proto-oncogenes is identified in normal cells which when activated under certain conditions can lead to the oncogenic transformation of cells

Cancer Detection and Diagnosis

• Cancer detection is based on biopsy and histopathological studies of the tissues and blood and bone marrow tests for increased cell counts in case of leukemia

• In a biopsy, a piece of suspected tissue is cut into thin sections and then it is stained and examined under a microscope (histopathological studies) by a pathologist

• Techniques like radiography (use of rays), CT (computed tomography), and MRI (magnetic resonance imaging) are very useful to detect cancers of the internal organs. Antibodies against cancer-specific antigens can also be used for the detection of certain cancers

Treatment of Cancer

• The common methods for treatment of cancer are surgery, radiation therapy, chemotherapy, and immunotherapy (these methods are either used singly or are used in combination)

• In radiotherapy, tumor cells are irradiated lethally, taking care of the normal surrounding tissues of the tumor mass

• Many chemotherapeutic drugs are used to kill cancerous cells 

• Tumor cells have been shown to avoid detection and destruction by the immune system. Therefore, the patients are given substances known as biological response modifiers such as a-interferon which activate their immune system and help in destroying the tumor

Infection by HIV

A virus enters the body of a person and reaches the macrophages. Once the virus gains entry into the macrophage its viral RNA is converted into viral DNA with the help of enzyme reverse transcriptase. Viral DNA is then incorporated into the host cell DNA. On entering the host DNA the viral DNA the.  replicates along with infected host cell. Hence, the infected macrophages act as an HIV factory. The viral proteins formed get accumulated to form new viral particles which are released from the infected cells. They mature and target T-cells of the body and destroy them. 

As the number of helper T lymphocytes decreases in the body of the person, they become susceptible to infections of bacteria especially Mycobacterium, Viruses, Fungi, and even parasites like Toxoplasma. The patient gets immune-deficient and they are unable to protect themselves against these infections.

Transmission of AIDS Virus 

• Use of contaminated syringes

• From infected mother to child through the placenta

• Use of contaminated utensils

• Prevent the use of razors

Symptoms of AIDS

•  Fever  

• Lethargy 

• Pharyngitis

•  Nausea

Prevention of AIDS

In India, the NACO ( National AIDS Control Organisation) and various other NGOs are helping to educate people about AIDS infection and transmission.

WHO started several AIDS programs to prevent the spreading of HIV infection.

Treatment of AIDS 

 The use of antiretroviral drugs for the treatment of AIDS patients has proven to be an effective way of treatment, its only drawback is that it cannot prevent the death of a person, but it can only prolong their lives.

Conclusion

Uncontrolled growth of cells refers to cancer. It can occur in any part of the body. Cancers can be treated via various methods such as radiography, chemotherapy, etc. There are two types of tumors causing cancer benign and malignant. AIDS is an immunodeficiency disorder caused by HIV. ELISA is a method used to detect AIDS.