Cancer is characterized by rapid growth of cancer cells in some part of the patient’s body. Habitually the normal cells in our body tend to grow and divide by mitosis to form the new cellular structure. Normal cells are controlled from dividing abnormally as they are responsive to the phenomenon called ‘Contact Inhibition’. In case of cancer cells, contact inhibition does not counter their outgrowth; hence they grow at a higher rate.

Chemotherapy aims at arresting the cell division by deactivating cellular RNA and DNA. RNA and DNA signal cells to divide and copy themselves. Thus disengaging them would oppose the cell division amongst cancer cells and this conclusively shrinks the size of tumor. The rate of cancer cells’ division is directly proportional to the efficacy of chemotherapy drugs. Based on the stage at which a chemotherapy drug targets to attack the cancer cells chemotherapy drugs are categorized in two types.

1. Chemotherapy drugs that kill cancer cells only when they are in the process of rapid cellular division; these are called chemotherapy cell cycle specific drugs

2. Chemotherapy drugs which kill cancer cells when they are at rest and not dividing rigorously; these are called chemotherapy cell cycle non specific drugs

Chemotherapy drugs recognize any cancer cells by perceiving their cell division thus they invariably and unknowingly end up damaging some normal cells which divide continually. Some normal cells which are likely to be harmed by chemotherapy are hair follicle cells, cells lining our skin and intestine and the bone marrow cells which form our blood. The damage done to these normal cells could make the patient experience some common side effects like loss of hair, anemia, low immunity, nausea, diarrhea and excessive bleeding. Though patients often have a bad memory of the side effects associated with chemotherapy, these side effects disappear once the treatment is over.

Chemotherapy has undergone many spells and bounds. Researchers are coming up with new cutting edge technologies to directly target the cancer cells thereby restoring the normal cells or not allowing the chemotherapy drugs to harm the normal cells. The newer mechanism of chemotherapy is called targeted therapy. Targeted therapy identifies some unique features of the cancer cells that are unlikely in any normal cell. Targeted therapy involves the use of monoclonal antibodies and anti angiogenesis.

1. Monoclonal Antibodies based Targeted Therapy: Antibodies are the chemicals formed in our body as a response to any foreign particle or germs called as an ‘antigen’. Scientists test many cancer cells in laboratory and find out some common antigens present in them. Some antibodies are synthetically prepared to increase their efficiency. These are then clinically tested, approved and then given to the patient. These antibodies are meant to travel to the antigens, through the bloodstream, and kill the specific cancer cell.
2. Anti Angiogenesis based Targeted Therapy: Angiogenesis is the process by which cells lining our blood cells form new blood vessels to supply nutrients to the surrounding tissues. This usually occurs during pregnancy, when the damaged cells are repaired. Cancer cells also form new blood vessels. These are formed using the neighboring normal cells. Anti angiogenesis chemotherapy stops the growth of new blood vessels in the targeted region. Being deprived of the necessary nutrients and oxygen, the cancer cells undergo a process of self destruction.

Targeted chemotherapy cells thus do not render a lot of side effects, which the patients normally experience during conventional chemotherapy. Hence this mode of chemotherapy has an added advantage as it causes fewer side effects. Apart from targeted chemotherapy, other methods like, heated chemotherapy, combination chemotherapy, ozone treatment for cancer, gene treatment for cancer, etc., are being researched for. Some of these have also proved to show good results in some cases.