Cancer Vaccine?

vaccination is one of the preventive medicine's weapon

In medical industry, recently ,new vaccine for cervical cancer is approved by FDA. So, it's interesting to know about the CANCER VACCINE

The term cancer vaccine refers to a vaccine that either prevents infections with cancer-causing viruses, or treats existing cancer.

Some cancers, such as cervical cancer and some liver cancers, are caused by viruses, and traditional vaccines against those viruses, such as HPV vaccine and Hepatitis B vaccine, will prevent those cancers.

Gardasil: cervical cancer vaccine

GARDASIL is the only cervical cancer vaccine that helps protect against 4 types of human papillomavirus (HPV): 2 types that cause 70% of cervical cancer cases, and 2 more types that cause 90% of genital warts cases. GARDASIL is for girls and young women ages 9 to 26.Anyone who is allergic to the ingredients of GARDASIL, including those severely allergic to yeast, should not receive the vaccine. GARDASIL is not for women who are pregnant. GARDASIL does not treat cervical cancer or genital warts.GARDASIL may not fully protect everyone, and does not prevent all types of cervical cancer, so it’s important to continue routine cervical cancer screenings. GARDASIL will not protect against diseases caused by other HPV types or against diseases not caused by HPV.The side effects include pain, swelling, itching, bruising, and redness at the injection site, headache, fever, nausea, dizziness, vomiting, and fainting. GARDASIL is given as 3 injections over 6 months.

Problems

melanoma and renal cancer have failed to be faced by the cancer vaccine, possible explanations include:

1) disease stage being treated was too advanced: it is difficult to get the immune system to fight bulky tumor deposits, because tumors actively suppress the immune system using a variety of mechanisms (e.g. secretion of cytokines that inhibit immune activity). The most suitable stage for a cancer vaccine is likely to be early disease, when the tumor volume is low, 

2) escape loss variants (cancer vaccines that target just one tumor antigen are likely to be less effective. Tumors are highly heterogeneous and antigen expression differs markedly between tumors (even within deposits in the same patient). The most effective cancer vaccine is likely to raise an immune response against a broad range of tumor antigens to minimise the chance of the tumor being able to mutate and become resistant to the therapy.)

3) prior treatments (numerous clinical trials in the past have treated patients who have received numerous cycles of chemotherapy. Chemotherapy is often myelosuppressive and destroys the immune system. There is little point giving a cancer vaccine to a patient who is immune suppressed).

4) some tumors progress very rapidly and/or unpredictably, and they can literally outpace the immune system. It may take two to three months for an immune response to a vaccine to mature, but some cancers (e.g. advanced pancreatic) can produce marked clinical deterioration, or even death, within this timeframe.

5) many cancer vaccine clinical trials examine immune responses by patients as their primary goal. Correlations are then made, typically showing that the patients who made the strongest immune responses were the ones who lived the longest, and this is taken as evidence that the vaccine is working. The alternative explanation, however, is that the patients who made the best immune responses were the healthier patients with the better prognosis, and they would have survived longest in any event, even without the vaccine. In other words, the immune responses may simply be a simple reflection of a better health status, not an indication that the vaccine had any beneficial effects. As such, these immune 'false friends' may have tempted some to embark on expensive phase III trials without a solid rationale.

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