Sunday, April 1, 2012

MEDICINE : Human Papilloma Virus



Here’s the scope of the problem, and let me tell you, it’s enormous
Throughout the world, 490,000 women each year receive a diagnosis of cervical cancer. Each year, 270, 000 women in the world will die of cervical cancer. It’s the second most common cancer among women worldwide. In the United States, despite the effectiveness of Pap smears (more about this in another article to come... stay tuned!), 11,000 women each year will be diagnosed with cervical cancer, and 3900 will die from this disease..

What is the connection between HPV and cervical cancer?
Virtually 100% of cervical cancers are caused by HPV! Nearly all! HPV is the most common sexually transmitted disease in the US. Most Americans, perhaps 80%, will be infected by HPV sometime during their lives. 25% of women between the ages of 14-19 are HPV positive and nearly double that are HPV positive in the 20-24 age group. Will all these progress to cancer? Absolutely not! The vast majority of HPV infections do not lead to cancer (read on-you’ll find out why).  It appears most infections cause no problems and are handled by our body’s immune system.

What exactly is the Human Papilloma Virus?
For you budding virologists, HPV is a double-stranded DNA virus, and there are many genotypes-- over 130. Of these, around 40 appear to cause problems in people.  There are two subtypes  (HPV11 and HPV6) that cause 90% of anogenital warts. HPV16, HPV18, and 6 other subtypes cause nearly all of cervical cancer. HPVs16 and 18 alone cause 70% of cervical cancers. 
Why all the numbers? When you read on, you’ll find that the vaccination will protect you against most, but not all, of the dangerous HPV strains.
When the epithelium of the cervix is infected by HPV, your immune response usually handles the infection, eradicating the virus. Sometimes, the viral DNA will integrate into the cell’s DNA, and this is when problems begin. Certain normal genes that regulate the cell are shutdown and precancerous changes occur.  Most (70-90%) of these early changes (Cervical Intraepithelial Neoplasia-1) will spontaneously go away, but if these changes progress to CIN 2 or 3, the likelihood of cervical cancer increases.

If you are not so interested in the science, here’s where you can start reading again!

How can you prevent cervical cancer?
Get the vaccination! Gardasil protects you against 4 types of HPV (HPV’s 6, 11, 16 and 18). For those who dozed during the science section, this means the vaccination will protect against 90% of anogenital warts and around 70% of cervical cancers. That’s fantastic! The vaccination is effective (97% seroconversion) and long lasting (so far, because it’s a new vaccination, at least 4 years). In studies, vaccinated women  (previously HPV negative) have reduced their risk of precancerous changes by 90%! But while it’s important to remember that the vaccination doesn’t protect against all dangerous strains of HPV, it does protect you against the most common ones.
The vaccination is not a live virus but a strand of an inactive viral protein that potently stimulates your body’s immune system. If you are immunocompromised, you can still get the vaccine. In fact, you need the vaccine (the risk of cervical cancer is greater in immunocompromised women)! The vaccination is not recommended if you are pregnant. If you are already HPV positive (remember that over 130 types exist), you still should be vaccinated since the vaccination will protect you against 4 different subtypes, including the two that cause 70% of the cancers. But if you’ve already been infected with HPV 16 or HPV 18, you probably will not be protected against the existing infection by the vaccine. In any case, since nearly 30% of cervical cancers might not be prevented by the vaccination, all women need to be screened for cervical cancer at appropriate intervals. That’s important to know!

The vaccination is safe with occasional mild side affects. Serious side affects are rare. Gardasil, which protects you against HPV 6, 11, 16 and 18, is available in the US and is administered in three courses over a 6-month period. It costs around 375 dollars. If you stopped partway, you can and should finish the protocol.
Proper condom use will provide some protection (studies show 70% reduction in infection) against HPV, but not the infection via oral sex. HPV causes about 12% of oral and throat cancers (smoking increases the risk of HPV-related throat cancers... yet another reason not to smoke!).  Abstinence is not a very sound option because of the prevalence of HPV. In a study of college women who had previously abstained from sex and then had only one partner, 30% were seropositive for HPV within a year after their first sexual intercourse. It’s just that HPV is so common and asymptomatic.

If you are female and between the ages of 9 to 26, you need to be vaccinated.
What about women older than 26? Although older women respond well to the vaccination, it’s not known whether it is cost-effective to recommend that all older women be vaccinated.
What about men? This is controversial. Although the vaccination is very effective in men too, it may not be cost effective to vaccinate all adolescent and young men. There may be certain groups, such as gay men, at high risk for anal cancer (90% of these are caused by HPV) that would benefit from HPV vaccination. But eventually, the recommendations might change to vaccinate all adolescent males as well.... wouldn't that be nice!

If you are pressed for time, read just this beginning:

-If you are a young woman (11-26 years old), get the HPV vaccination. It’s available at UC Berkeley’s Tang Center.

-Tell your friends and sisters that they should too.

-If you are a gay man, get the HPV vaccination.

-Practice safe sex, but remember, the virus can be transmitted by oral sex.

-If you are 21 or older, you need to get a Pap smear done at least every 3 years (more in a later article)

-If you are a woman between the ages of 11 to 26, you need to be vaccinated against Human Papilloma Virus (HPV).  It’s one of the most important things you can do for yourself.

The Doctor Behind the Medicine: 

Dr. Martin went to medical school at UCSF. He has now retired from his long and brilliant career as an anesthesiologist, now playing guitar and making bread on his spare time. Dr. Martin and three associates have started a delicious commercial wine, MC4. For those who are 21 and older, I advise you to check out MC4-- cheers!

No comments: