Infectious agents and cancer
10.29.09 by Sharmila Pejawar-Gaddy
Several cancers have been attributed to infectious agents. It is estimated that approximately 18% of all cancers worldwide are caused by infectious agents. 26% of these are in developing countries and 8% in developed countries. These figures and discrepancies between the developed and developing worlds point to differences in disease prevalence, either due to sanitary conditions or shortage of vaccines. Infectious agents can be classified as indirect or direct carcinogens. Indirect carcinogenic agents are those that cause chronic infection and thus chronic inflammation, which then leads to the advent of cancer. Examples of these include, Helicobacter pylori infection that is the an attributing factor to a majority of stomach/gastric cancers, as well as chronic hepatitis B and C infections that are causally linked to a majority of liver cancers. On the other hand, direct carcinogenic agents are those that can incorporate oncogenes into the cell’s genome. Examples of these are human papillomavirus that causes a majority of cervical cancers, as well as in some cases, penile cancer, vaginal cancer and genital warts; Epstein-Barr virus linked to a majority of Naso-pharengeal carcinomas and human herpes virus-8 linked to Kaposi’s sarcoma. This list grows every day. The good news is this: most of these infections, and thus the advent of several cancers, can be prevented by vaccination.
Adapted from Parkin, DM. 2006. Int J Cancer. 118:3030 and Dr. Douglas Lowy
Related articles
- Parkin, DM. 2006. The global health burden of infection-associated cancers in the year 2002. Int J Cancer. 118:3030.
- Campbell, K. 2006. The infectious causes of cancer. Nurs Times. 102(33):28.
- FDA approves Gardasil to prevent genital warts in boys (ctv.ca)
- FDA Approves Merck’s Gardasil for Boys (abcnews.go.com)
Cancer vaccines: a brief introduction
05.8.09 by Sharmila Pejawar-Gaddy
From the time of the first documented vaccine against smallpox by Edward Jenner, developing an effective vaccine to prevent deadly disease caused by existing or newly emerging pathogens has been the goal of many microbiologists and immunologists. With a single exception, that of the rabies vaccine, all vaccines developed previously have been prophylactic, meaning that they are administered in order to prevent the onset of disease. The concept of a vaccine has slowly evolved to currently include a therapeutic vaccine, meant to ameliorate an existing disease state by potentially strengthening an ongoing but not fully effective immune response against a pathogen. Further broadening of the concept of a vaccine has come about with the realization that in addition to eliciting an immune response where there was none, a vaccine could also be designed to change an existing immune response from one type to another. Most recently, vaccines are being considered not only for elicitation of immunity but also potentially for induction of tolerance [1, 2]. This concept has also increased potential targets of vaccines from diseases caused by pathogens to any disease that involves the immune system, such as cancer, autoimmunity and graft rejection. [3-6].
Challenges facing cancer vaccines
Choosing the right antigen and adjuvant are the sine qua non of an effective vaccine.
The “right” antigen: Antigens used in cancer vaccines should preferably be molecules that are different between normal cells and tumor cells ensuring that the immune response generated by vaccination will target for destruction antigen-bearing tumor cells and not normal cells [7, 8]. This requirement is satisfied more easily in the case of vaccines against pathogens because their antigens are all foreign to the host and thus immunity generated against them, in most instances, does not cross-react with normal host tissues. In cancer, most antigens are derived from mutated or modified self-proteins against which there is often a certain level of immune tolerance. This creates particular challenges for the appropriate design of vaccines that have to overcome this tolerance in order to elicit anti-tumor immunity without autoimmunity [9].
The reason for FundScience
12.21.08 by Sharmila Pejawar-Gaddy
As a member of The American Association of Immunologists (AAI), I receive the monthly AAI newsletter that keeps me up-to-date on current happenings in the world of Immunology (and sometimes science in general). This month’s newsletter also included a letter to members from the Executive Director of AAI, where she was asking members to “continue their support to AAI by renewing their membership, which is so important specifically in this current economic climate, where a strong AAI voice in Washington is essential to Immunologists”. The letter continued to tell us, in actual numbers, what a hard hit science has taken in these last 8 years. According to this newsletter, the NIH has had a 14% loss in purchasing power since 2003. 14% in 5 years, think about it! Stepping out of my scientist-skin, I ask a serious, unbiased question: what type of a society takes money away from medical advancement? As a person who is witnessing this first-hand, I cannot tell you how many cases I have heard off in which brilliant scientists have lost their funding and have either had to leave research all together or move to another country like Singapore, which has realized that advancement in science and healthcare is the touchstone of any successful civilization. If history has taught us a few things it is that many ancient civilizations were wiped off the face of the earth due to their inability to deal with disease, famine and draught, all which can have solutions in science.
This is where non-profit organizations like FundScience come into play. The unique thing about FundScience is that the general public is put in direct access with the scientific method. This begins to disslove the misunderstandings about science, scientific techniques and the timeline from the advent of a thought/idea to the fruition of that idea.
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