Question

We know the HPV (human papilloma virus) vaccine & that it helps prevent cervical cancer. While this vaccine comes with its share of controversy, it illustrates a good point: vaccines can be useful to help prevent cancer. How do they accomplish this?

Please no picture or handwritten responses - only typed replies

Answer 1

Cancer vaccines or vaccines that prevent cancer are of 2 types

Prevention vaccines and treatment vaccines

Cancer prevention vaccines are for healthy people to keep certain cancers from developing. A person has to get the vaccine before the virus infects him or her. Otherwise, the vaccine will not work. Eg. HPV vaccines to prevent cervical cancer and HepB vaccines to prevent liver cancer.

Cancer treatment vaccines or therapeutic vaccines natural immune system of body to fight a cancer that the patent is diagnosed of. Doctors give treatment vaccines to people already diagnosed with cancer.

How do they work?

Immune system of human body works through two significant steps- antigen recognition and destruction. Antigens are present on cell surfaces that the immune system recognise as not it's own and attacks them. This process creates a memory whuch helps the system to recognise it and deal effectively later. Cancer treatment vaccines boost immune system and bring about better responses. Some vaccines contain cancer specific antigen presesent on cancer cells. Such vaccines create a memory of the antigen and the response to it thus eliminating cancer cells.

Virus like HPV, EBV, HepB etc have antigenic substances on their surface. These substances are isolated in vitro and introduced into an individual of identified risks. This creates a minor reaction whose memory is retained. Subsequent infection of this virus and carcinogenic reactions are prevented due to early activation by this memory component and effective elimination by immune system.