Chemotherapy

Overview of Chemotherapy in India

Chemotherapy involves a category of treatment that acts on cancer cells. Chemotherapy agents kill cancer treatment through causing damage to them or limiting their growth. Chemotherapy can be administered orally or by injection. In both circumstances, chemotherapy enters the bloodstream and exerts its effects on tumor cells throughout the body. The class of chemotherapy agents used is typically determined by the type of cancer for which chemotherapy has been recommended or sometimes, the stage of cancer at diagnosis. Chemotherapy can also be administered pre-operatively to shrink tumor size and post-operatively to kill remaining cancer cells.

Chemotherapy is the most beneficial treatment for cancers that have also widely disseminated to other locations in the body. Chemotherapy is beneficial but can also cause harm to the body. However, advanced therapies have enabled the side effects to be reduced, resulting in better efficacy of killing cancer cells. Across the globe, there are many health care systems with systems, cancer centers, and health care providers who provide specialized consultants for treating and managing cancer treatment, including chemotherapy.

What Is Chemotherapy?

Chemotherapy is a form of cancer therapy. This treatment, sometimes referred to as 'chemo', is one of several different types of cancer therapy using drugs to fight cancer. Other types of drug therapies include: 

• Hormone therapy: Medications that block certain cancers from receiving the hormones they need to develop. 
• Immunotherapy: Medications that assist your immune system in combating cancer. 
• Targeted therapy: Medicines that change how the cancer cells grow and behave. 

A medical oncologist supervises the treatment. These are healthcare providers who specialise in chemotherapy and other cancer-fighting medications. 

Chemotherapy may be combined with surgery or radiation therapy to heal cancer.

How Does Chemotherapy Work?

Cancer cells are able to develop and grow without restraint, and chemotherapy kills cancer cells or inhibits them from multiplying.

Your oncologist may use chemotherapy in many ways: 

• Adjuvant therapy: Chemotherapy kills cancer cells just after surgery or radiation therapy. 
• Curative therapy: Chemotherapy (may include radiation and/or surgery) eliminates the cancer and it does not come back. 
• Neoadjuvant therapy: Chemotherapy kills a tumor before surgery or radiation therapy. 
• Palliative therapy: Chemotherapy kills a tumor and reduces symptoms, but it does not cure the cancer.

Types of Chemotherapy:

Alkylating Agents 

These agents injure the DNA of cancer cells thereby preventing them from matruing. These agents injure the main source which controls the cancer cell growth. Some examples are: 

• Cyclophosphamide 
• Cisplatin 
• busulfan 

Antimetabolites 

These agents injure or prevent the DNA or RNA synthesis of cancer cells and don't allow them to generate proteins which are necessary for cancer cell growth, so in a way, these agents drive growth.  Some examples are: 

• Methotrexate (MTX) 
• 5-fluorouracil (5-FU) 
• gemcitabine

Anthracyclines

These drugs prevent the synthesis of DNA and RNA and also disrupt DNA structure. Examples include: 

• Doxorubicin 
• Daunorubicin
• Epirubicin.

Topoisomerase Inhibitors

These drugs inhibit the enzymes called topoisomerases, which allow for organised conditions of normal synthesis of DNA strands during the division of cells. When the vital enzyme called topoisomerase is absent or blocked, the DNA that resides within those classic cancer cells would degrade and die. Examples include: 

• Etoposide
• Topotecan 
• Irinotecan

Mitotic Blockers

The use of these medications inhibit or block mitosis, or cell division, by disrupting the structural elements that facilitate chromosome partitioning. Examples include: 

• Paclitaxel
• Docetaxel
• Vinblastine

Hormonal Therapy

This includes chemotherapy in which drugs inhibit hormone production, or block hormone receptors that these hormones act on. Examples of hormonal therapies include:

• Tamoxifen
• Letrozole
• Bicalutamide

Immunotherapy 

These medications activate the immune system to attack the malignant cells. Examples of immunotherapy include: 

• interleukin-2 (IL-2) 
• interferon-alpha 
• pembrolizumab. 

Target drug therapies 

These medications target specific proteins that regulate cancer growth and persistence. They can inhibit angiogenesis and cause cancer cell death. Some examples are: 

• tyrosine kinase inhibitors 
• monoclonal antibodies 
• proteasome inhibitors

Procedure:

Depending on the specific type of cancer and the chemotherapy medications being used, chemotherapy may be given in a variety of ways.

• Chemotherapy is generally administered through a vein (intravenously) and is commonly referred to as intravenous chemotherapy.
• Some chemotherapy drugs are given in the form of a tablet or capsule (oral chemotherapy).
• Some chemotherapy drugs may be given by intramuscular injection into a muscle.
• Some may be administered by subcutaneous injection into the area just under the skin.

Methods of administration listed above allow for chemotherapy to be transported into the bloodstream and spread throughout the body to enable drugs to reach cancer cells. In some cases, chemotherapy may be administered intrathecally, or injected into the fluid surrounding the spine for specific cancer types. Chemotherapy is sometimes delivered in a body cavity, such as the pelvic cavity or bladder, also referred to as intracavity chemotherapy.

Drugs that are administered via these methods tend to stay at the site of administration and typically do not affect cells in other tissues of the body. In some cases, particularly skin cancer, chemotherapy creams may also be used in which they only affect cells locally in the area where the cream is applied to the skin.