In clinical research trials, scientists study the safety of a drug, medical device or vaccine and its efficacy. Efficacy can be thought of this way:
Under the ideal situation where a specific type of person uses the drug/device exactly as the researcher/developer intended at exactly the right dose, efficacy measures the extent to which the medicine or device does what the developer thought it would do. Safety is more obvious. The goal in the safety trial is for the drug or device not to kill anyone. Nor should it cause serious harm or side effects that are greater than the positive benefit.
Clinical trials tell us a lot about both safety and efficacy. But they are better at uncovering side effects that the greater public might experience than at confirming effectiveness.
When you or I take the drug or use the device under less than ideal situations, its effectiveness is considered. Drugs and medical devices continue to be studied for several years after they come to market. They are studied in the overall population.
Last week I completed a short continuing medical education activity (CME) on HPV vaccines. It was offered through Medscape. I learned that the real life common side effects occur in a small number of persons and are not severe. They include same day fainting or dizziness and delayed skin rash. In the same activity, I learned that there is no evidence that one cervical cancer case has been prevented by this vaccine. That was a curious point to make and it wasn't followed up with a review of that research. However, Medscape is a peer reviewed website so I feel that the statement was true.
My take away was that the vaccine is not harmful, but also may not be effective. It is likely that the efficacy (confirmed in the clinical trial) was based on the age of the person receiving the vaccine and that they received all three doses.
Whether or not you choose to get this vaccine, if you are a woman, a pap smear every 3 to 5 years is necessary. The pap smear can detect changes in the cells around the cervix which might indicate a pre cancerous condition.
Showing posts with label HPV. Show all posts
Showing posts with label HPV. Show all posts
Thursday, October 25, 2012
Monday, September 17, 2012
EU Reccomendations on HPV Vaccines
Cervical cancer is most commonly, if not entirely, caused by the human papillomavirus (HPV). Forty of the 100 strains are transmitted through sexual contact, including oral, vaginal and anal intercourse. Of those strains, some cause genital warts (unsightly and uncomfortable but minor) and others are associated with cervical cancer. Having the human papillomavirus may increase the risk of penile cancer for men. There are other causes of penile cancer which itself is very rare. Conversely, cervical cancer is the second most common cancer for women. Breast breast cancer being the most common. There were just over 12,000 cases of cervical cancer in the US in 2008. Cervical cancer deaths are not common as the PAP smear is able to detect abnormalities and prevent the cancer.
It is estimated that at least 50 percent of all adults have been exposed to HPV at one time or another. The virus is usually cleared by the body's immune system, but can be a chronic condition in rarer cases. One can transmit the virus to others through sexual contact in the acute state and if they do not clear the virus they will continue to risk transmission through sexual activity. The lingering virus is a serious matter and transmission rates are very high. For this reason, the two vaccines that are available have an important role (only for those not previously exposed). Because so many sexually active people have been in contact with a person carrying the virus, the target of the vaccine is girls (maybe boys too) who have not yet begun sexual activity.
The two vaccines, Gardasil and Cervarix, only target the most important strains of the 100. Gardasil covers two that cause warts and two that cause HPV. Cerarix only covers the HPV strains, however, Cervarix has also been shown to have an impact on oral cancer and this is important. Most people think of smokeless tobacco as the main cause of oral cancer - actually it is smoking BUT the rise in new oral cancer cases is associated with HPV NOT tobacco at all.
Earlier this month, European health officials with information from the European Centers for Disease Control, made a recommendation that ALL girls in Europe (ages?) be vaccinated. Some countries in Europe have coverage rates as low as 17% while Portugal and Brazil had coverage rates as high as 80%. The recommendations include more promotion of the vaccines and steps to make vaccination easier (logistics). The article that I read did not indicate if the coverage rates 17-80% were for the full series (3 shots) or for any vaccination level.
In the USA, the issue of HPV vaccines became a political firestorm when a presidential candidate made some erroneous statements regarding side effects.
According to the US CDC, all girls AND boys ages 11-12 should be started on the series of shots. The coverage is low and more info about this can be found here.
It is estimated that at least 50 percent of all adults have been exposed to HPV at one time or another. The virus is usually cleared by the body's immune system, but can be a chronic condition in rarer cases. One can transmit the virus to others through sexual contact in the acute state and if they do not clear the virus they will continue to risk transmission through sexual activity. The lingering virus is a serious matter and transmission rates are very high. For this reason, the two vaccines that are available have an important role (only for those not previously exposed). Because so many sexually active people have been in contact with a person carrying the virus, the target of the vaccine is girls (maybe boys too) who have not yet begun sexual activity.
The two vaccines, Gardasil and Cervarix, only target the most important strains of the 100. Gardasil covers two that cause warts and two that cause HPV. Cerarix only covers the HPV strains, however, Cervarix has also been shown to have an impact on oral cancer and this is important. Most people think of smokeless tobacco as the main cause of oral cancer - actually it is smoking BUT the rise in new oral cancer cases is associated with HPV NOT tobacco at all.
Earlier this month, European health officials with information from the European Centers for Disease Control, made a recommendation that ALL girls in Europe (ages?) be vaccinated. Some countries in Europe have coverage rates as low as 17% while Portugal and Brazil had coverage rates as high as 80%. The recommendations include more promotion of the vaccines and steps to make vaccination easier (logistics). The article that I read did not indicate if the coverage rates 17-80% were for the full series (3 shots) or for any vaccination level.
In the USA, the issue of HPV vaccines became a political firestorm when a presidential candidate made some erroneous statements regarding side effects.
According to the US CDC, all girls AND boys ages 11-12 should be started on the series of shots. The coverage is low and more info about this can be found here.
Monday, August 27, 2012
Circumsicing Babies
The focus of this blog has included the application of research to real life and evaluating headlines that are in response to research. In other words, the "truthiness" of those headlines.
The American Academy of Pediatrics confirmed its stance and recommendation for male infant circumcision today. The rationale behind the recommendation is that there are lower rates of certain infections amongst males who have had the procedure. The outcome that shows a greater difference between circumcised and uncircumcised boys is urinary tract infections. UTI rate also seems to have the most evidence behind it- it has been studied the longest. Other outcomes that researchers associate with lack of circumcision are HIV, HPV, cancer, and sexually transmitted infections in general. (associated meaning the outcomes are higher in one group than the other)
If I had a male child I would have him circumcised, but not because I believe that it prevents sexually transmitted diseases. I believe that it may reduce infections in general and to tell you the honest truth - my decision is also aesthetic.
This morning I heard someone make an argument for circumcision as an HIV prevention strategy using the results of the change in HIV rates in African men, living in African countries who are circumcised as adults. The person who was using this evidence to support circumcision in infant American boys was challenged. Can you see why? How are these two groups similar? They are not. The results from the adult study in another country does not translate to these boys. Even if it makes biological sense, you can't extrapolate to such a different context.
Another point made in the discussion was that the rate of circumcision in the UK is much lower than that in the USA and UK men HIV is lower in the UK. This was countered by another who said that the number of new cases was much higher in the UK - or the rate vs the prevalence (chronically ill vs newly ill). Again - the two groups are not the same and a comparison is suspect. (what else protects against HIV? Maybe UK men have less sex? Maybe many are HIV and undiagnosed? Who knows, but you can't show cause and effect either way.)
My biggest issue however, is when any of them try to say that circumcision prevents the "disease in question" or that not being circumcised causes it. The only way to claim that direct link is to have some boys circumsized and others not and then make sure that they are exposed to the same conditions and risks throughout their lives and see if one groups gets more diseases than the others. That has not been done and it will not be done.
I imagine that instead, most of these studies are looking at the characteristics of men with a disease. To determine what those characteristics are, they have to ask questions - either of the men, their physicians or their partners. Or some combination. Whether or not they have been circumcised is observable but the number of sexual partners, the use of condoms with partners, consistent or occasional use of condoms, the risk behaviors of the people the men have sex with... all of those things have to be considered and all of those things have certain biases. For example, a person might not remember, might not know, or might not want to say. But, what if boys who are not circumcised have different kinds of sexual partners/experiences on average than the circumcised boys/men do? With all of these things impacting the risk of getting sick, how can one say that circumcision is the determinant? Maybe a question to ask is whether or not condoms are more or less protective based on circumcision status.
I am not at all speaking out against the procedure - just the use of studies to make a link between the penis status and the diseases. I am especially suspect of the circumcision - HPV link.
Today I heard someone say that HPV causes penile cancer (they were claiming that circumcision prevents HPV and thus can prevent penile cancer). That got a reaction from me! I feel certain that if HPV caused a cancer in men Merck (drug company with the HPV vaccine) would be all over it. Unless of course, the association is real but the actual cancer incidence is extremely low.
I have not reviewed any of the studies, my main point is that there is a great deal to consider and just because someone says it on the radio, doesn't make it true.
Here is a link to the actual statement from the pediatric organization as published in their leading journal.
The American Academy of Pediatrics confirmed its stance and recommendation for male infant circumcision today. The rationale behind the recommendation is that there are lower rates of certain infections amongst males who have had the procedure. The outcome that shows a greater difference between circumcised and uncircumcised boys is urinary tract infections. UTI rate also seems to have the most evidence behind it- it has been studied the longest. Other outcomes that researchers associate with lack of circumcision are HIV, HPV, cancer, and sexually transmitted infections in general. (associated meaning the outcomes are higher in one group than the other)
If I had a male child I would have him circumcised, but not because I believe that it prevents sexually transmitted diseases. I believe that it may reduce infections in general and to tell you the honest truth - my decision is also aesthetic.
This morning I heard someone make an argument for circumcision as an HIV prevention strategy using the results of the change in HIV rates in African men, living in African countries who are circumcised as adults. The person who was using this evidence to support circumcision in infant American boys was challenged. Can you see why? How are these two groups similar? They are not. The results from the adult study in another country does not translate to these boys. Even if it makes biological sense, you can't extrapolate to such a different context.
Another point made in the discussion was that the rate of circumcision in the UK is much lower than that in the USA and UK men HIV is lower in the UK. This was countered by another who said that the number of new cases was much higher in the UK - or the rate vs the prevalence (chronically ill vs newly ill). Again - the two groups are not the same and a comparison is suspect. (what else protects against HIV? Maybe UK men have less sex? Maybe many are HIV and undiagnosed? Who knows, but you can't show cause and effect either way.)
My biggest issue however, is when any of them try to say that circumcision prevents the "disease in question" or that not being circumcised causes it. The only way to claim that direct link is to have some boys circumsized and others not and then make sure that they are exposed to the same conditions and risks throughout their lives and see if one groups gets more diseases than the others. That has not been done and it will not be done.
I imagine that instead, most of these studies are looking at the characteristics of men with a disease. To determine what those characteristics are, they have to ask questions - either of the men, their physicians or their partners. Or some combination. Whether or not they have been circumcised is observable but the number of sexual partners, the use of condoms with partners, consistent or occasional use of condoms, the risk behaviors of the people the men have sex with... all of those things have to be considered and all of those things have certain biases. For example, a person might not remember, might not know, or might not want to say. But, what if boys who are not circumcised have different kinds of sexual partners/experiences on average than the circumcised boys/men do? With all of these things impacting the risk of getting sick, how can one say that circumcision is the determinant? Maybe a question to ask is whether or not condoms are more or less protective based on circumcision status.
I am not at all speaking out against the procedure - just the use of studies to make a link between the penis status and the diseases. I am especially suspect of the circumcision - HPV link.
Today I heard someone say that HPV causes penile cancer (they were claiming that circumcision prevents HPV and thus can prevent penile cancer). That got a reaction from me! I feel certain that if HPV caused a cancer in men Merck (drug company with the HPV vaccine) would be all over it. Unless of course, the association is real but the actual cancer incidence is extremely low.
I have not reviewed any of the studies, my main point is that there is a great deal to consider and just because someone says it on the radio, doesn't make it true.
Here is a link to the actual statement from the pediatric organization as published in their leading journal.
Tuesday, November 29, 2011
Cervical Cancer Screening
When I have discussed my concerns about the HPV vaccine, it has had more to do with the implied message in the marketing campaign. The idea that the maker of the vaccine presents is that it could prevent cervical cancer (or now, oral cancer). But the vaccine does not prevent cancer, it can prevent some, if not most, of the strains of the humanpappiloma virus that leads to cancer.
It is the pap smear, the testing of cells from the cervix, that can prevent the cancer.
It seems that I started to hear conflicted recommendations on how often a woman should have a pap smear in recent years. What has remained consistent it that they are recommended to begin at age 18 or when a woman becomes sexually active. When I turned 18, the recommendation was for annual pap smears. Within the last 5 years or so, some professional organizations began to tweak recommendations so that three and five year tests were acceptable in some situations. It also was determined that after a certain age or a hysterectomy, the tests might not be necessary.
In the last year or two, another screening measure was tentatively and with some controversy, recommended.
This week the New England Journal of Medicine has a nice "perspective" piece on the varied recommendations.
I believe it is best that you read it yourself and it is available here for free. If nothing else, skip down to the table that makes suggestions based on the personal situation of the woman.
It is the pap smear, the testing of cells from the cervix, that can prevent the cancer.
It seems that I started to hear conflicted recommendations on how often a woman should have a pap smear in recent years. What has remained consistent it that they are recommended to begin at age 18 or when a woman becomes sexually active. When I turned 18, the recommendation was for annual pap smears. Within the last 5 years or so, some professional organizations began to tweak recommendations so that three and five year tests were acceptable in some situations. It also was determined that after a certain age or a hysterectomy, the tests might not be necessary.
In the last year or two, another screening measure was tentatively and with some controversy, recommended.
This week the New England Journal of Medicine has a nice "perspective" piece on the varied recommendations.
I believe it is best that you read it yourself and it is available here for free. If nothing else, skip down to the table that makes suggestions based on the personal situation of the woman.
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