Thursday, September 29, 2011

HPV infections findings of Thorough Research versus Inadequate Research

Below is a study from University of washington which found a slight but non-statistically significant higher HPV infection rate in circumcised men compared to intact men.  This contrasts with African research which found higher HPV infections in intact men.  However, when you look at the methodologies, you find the African researchers only tested for HPV at 1 site, the glans, versus the washington uni tested for HPV at multiple sites on the penis.  The more thorough investigation found a reported "no difference in HPV infections" using the more thorough methodology.  If you read the statistics circumcised men actually had had higher HPV rates with the ratio of 10 circumcised had infections versus 9 intact had HPV infections .


Circumcised men at equal risk of HPV infection

A large-scale study at the University of Washington has found no difference in the incidence of HPV infection between circumcised and uncircumcised male college students. HPV (Human Papilloma Virus) is a large group of viruses that may cause genital warts, and are implicated in the genesis of genital cancers. HPV is very common among the sexually active population. but most people never show any symptoms. The risk factors for the development of cancer have been shown to be numerous different sexual partners and smoking. The new study confirmed previous research which showed that the location of the virus differed between circumcised and uncircumcised men: circumcised men tend to carry the virus on the shaft skin of the penis, while intact men are more likely to carry it on the glans. The study also also found that circumcised men have more sexual partners. In a previous study the researchers found found that for college females the circumcision status of their partner was NOT a risk factor for HPV infection in women. The authors comment that the African Random Clinical Trials, which seemed to show that uncircumcised men were more likely to carry the HPV virus, were seriously flawed because they took samples only from the glans (not from the shaft skin, where the virus is concentrated in the circumcised).
Background: The role of circumcision in male HPV acquisition is not clear.
Methods: Male university students (aged 18–20 years) were recruited from 2003 to 2009 and followed up triannually. Shaft/scrotum, glans, and urine samples were tested for 37 human papillomavirus (HPV) genotypes. Cox proportional hazards methods were used to evaluate the association between circumcision and HPV acquisition. Logistic regression was used to assess whether the number of genital sites infected at incident HPV detection or site of incident detection varied by circumcision status.
Results: In 477 men, rates of acquiring clinically relevant HPV types (high-risk types plus types 6 and 11) did not differ significantly by circumcision status (hazard ratio for uncircumcised relative to circumcised subjects: 0.9 [95% confidence interval{CI}: 0.7–1.2]). However, compared with circumcised men, uncircumcised men were 10.1 (95% CI: 2.9 –35.6) times more likely to have the same HPV type detected in all 3 genital specimens than in a single genital specimen and were 2.7 (95% CI: 1.6–4.5) times more likely to have an HPV-positive urine or glans specimen at first detection.
Conclusion: We found no differences by circumcision status in overall HPV acquisition or in number of HPV types acquired. Findings held for all clinically relevant HPV types, as well as for the subgroups of high-risk types, high-risk -9 types, and HPV-16. This observation is consistent with findings from other longitudinal studies.
Bottom line: Circumcision does not lower the risk of infection with Human Papilloma Virus. People who claim that uncircumcised men are more likely to develop or communicate genital cancers are ignoring the facts and spreading misleading information.
Source: Kelley Van Buskirk et al, Circumcision and Acquisition of Human Papillomavirus Infection in Young Men, Sexually Transmitted Diseases 38 (12), December 2011.
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