A Retrospective Analysis of Pedicle Screw Placement Accuracy Using the ExcelsiusGPS Robotic Guidance System: Case Series

BACKGROUND

Robotic guidance has become widespread in spine surgery. Although the intent is improved screw placement, further system-specific data are required to substantiate this intention for pedicle screws in spinal stabilization constructs.

OBJECTIVE

To determine the accuracy of pedicle screws placed with the aid of a robot in a cohort of patients immediately after the adoption of the robot-assisted surgery technique.

METHODS

A retrospective, Institutional Review Board-approved study was performed on the first 100 patients at a single facility, who had undergone spinal surgeries with the use of robotic techniques. Pedicle screw accuracy was graded using the Gertzbein-Robbins Scale based on pedicle wall breach, with grade A representing 0 mm breach and successive grades increasing breach thresholds by 2 mm increments. Preoperative and postoperative computed tomography scans were also used to assess offsets between the objective plan and true screw placements.

RESULTS

A total of 326 screws were analyzed among 72 patients with sufficient imaging data. Ages ranged from 21 to 84 years. The total accuracy rate based on the Gertzbein-Robbins Scale was 97.5%, and the rate for each grade is as follows: A, 82%; B, 15.5%; C, 1.5%; D, 1%; and E, 0. The average tip offset was 1.9 mm, the average tail offset was 2.0 mm, and the average angular offset was 2.6°.

CONCLUSION

Robotic-assisted surgery allowed for accurate implantation of pedicle screws on immediate adoption of this technique. There were no complications attributable to the robotic technique, and no hardware revisions were required.

Factors Affecting the Accuracy of Pedicle Screw Placement in Robot-Assisted Surgery: A Multicenter Study

STUDY DESIGN

Retrospective multicenter.

OBJECTIVE

The aim was to investigate the factors involved in, and their relative contributions to, the overall accuracy of robot-assisted pedicle screw placement.

SUMMARY OF BACKGROUND DATA

Robot-assisted surgery has reportedly resulted in greater accuracy for placement of pedicle screws than conventional methods. There are many potential factors affecting the accuracy of pedicle screws placed with a robot. No study has investigated these factors in a robust way.

MATERIALS AND METHODS

Radiographic and clinical data of three centers were pooled. Preoperative and postoperative computerized tomographies were obtained by all three centers to assess the accuracy of the placed screws. The primary outcome measured was accuracy of pedicle screws placed with the robot. The authors performed a multivariate regression analysis to determine the significant patient-related and screw-related variables and their relative contribution to the overall accuracy. In addition, an ordinal regression analysis was conducted to investigate the effects of different variables on accuracy of robot-placed screws graded by Gertzbein-Robbins grading system (GRS).

RESULTS

The total contribution of all studied variables to overall accuracy variation as measured by offsets between the placed and planned screws was only 18%. Obesity, long constructs, female gender, surgeon, and vertebral levels were among the factors that had small contributions to the different screw offsets. For GRS grades, significant variables were gender (Log odds: 0.62, 95% CI: 0.38-0.85), age (Log odds: 0.02, 95% CI: 0.01-0.03), length of constructs (Log odds: 0.07, 95% CI: 0.02-0.11), screw diameter (Log odds: 0.55, 95% CI: 0.39-0.71), and length of the screws (Log odds: 0.03, 95% CI: 0.01-0.05). However, these variables too, regardless of their significant association with the accuracy of placed screws, had little contribution to overall variability of accuracy itself (only about 7%).

CONCLUSION

The accuracy of screws placed with robotic assistance, as graded by GRS or measured offsets between planned and placed screw trajectories, is minimally affected by different patient-related or screw-related variables due to the robustness of the robotic navigation system used in this study.

LEVEL OF EVIDENCE

Level III.

Male Circumcision Reduces Penile HPV Incidence and Persistence: A Randomized Controlled Trial in Kenya

BACKGROUND

Male circumcision reduces the risk of human immunodeficiency virus infection in men. We assessed the effect of male circumcision on the incidence and natural history of human papillomavirus (HPV) in a randomized clinical trial in Kisumu, Kenya.

METHODS

Sexually active, 18- to 24-year-old men provided penile exfoliated cells for HPV DNA testing every 6 months for 2 years. HPV DNA was detected via GP5+/6+ PCR in glans/coronal sulcus and in shaft samples. HPV incidence and persistence were assessed by intent-to-treat analyses.

RESULTS

A total of 2,193 men participated (1,096 randomized to circumcision; 1,097 controls). HPV prevalence was 50% at baseline for both groups and dropped to 23.7% at 24 months in the circumcision group, and 41.0% in control group. Incident infection of any HPV type over 24 months was lower among men in the circumcision group than in the control group [HR = 0.61; 95% confidence interval (CI), 0.52-0.72]. Clearance rate of any HPV infection over 24 months was higher in the circumcision group than in the control group (HR = 1.87; 95% CI, 1.49-2.34). Lower HPV point-prevalence, lower HPV incidence, and higher HPV clearance in the circumcision group were observed in glans but not in shaft samples.

CONCLUSION

Male circumcision reduced the risk of HPV acquisition and reinfection, and increased HPV clearance in the glans.

IMPACT

Providing voluntary, safe, and affordable male circumcision should help reduce HPV infections in men, and consequently, HPV-associated disease in their partners.

Incidence and clearance of penile human papillomavirus infection among circumcised Kenyan men

Prospective data are limited on human papillomavirus (HPV) acquisition and clearance among circumcised men from resource-limited geographical regions, particularly Africa. The goal of this study was to estimate incidence and clearance of type-specific genital HPV infection in men. Penile exfoliated cell specimens were collected from the glans/coronal sulcus and shaft of 1,037 circumcised Kenyan men at baseline and 6-, 12- and 18-month follow-up visits between 2003-2007. Specimens were tested with GP5+/6+ PCR to detect 44 HPV types. The median age of participants at baseline was 21 years (range 18-28). The 12- and 18-month incidence rates (IRs) for any HPV were 34.9/100 person-years (95% confidence interval [CI]: 31.2-39.0) and 36.4/100 person-years (95% CI: 32.9-40.2), respectively. The 18-month cumulative risk for high-risk HPV was 30% compared to 16% for low-risk HPV. Cumulative risk was not associated with age or anatomical site. The estimated probability of any HPV infection clearing by 12 months was 0.92. Time until HPV clearance was not associated with age, anatomical site, or whether HPV infection type was high-risk or low-risk. HPV IRs among circumcised men in this study were comparable to other circumcised populations.

Higher HPV16 and HPV18 Penile Viral Loads Are Associated With Decreased Human Papillomavirus Clearance in Uncircumcised Kenyan Men

BACKGROUND

Whether higher penile human papillomavirus (HPV) viral load is associated with a lower rate of HPV clearance remains unknown.

OBJECTIVES

We examined the association between penile HPV16 and HPV18 viral load and subsequent HPV clearance in uncircumcised Kenyan men.

STUDY DESIGN

Participants were human immunodeficiency virus (HIV)-seronegative, sexually active, 18- to 24-year-old men randomized to the control arm of a male circumcision trial in Kisumu, Kenya. Men provided exfoliated penile cells from two anatomical sites (glans/coronal sulcus and shaft) every 6 months for 2 years. GP5+/6+ polymerase chain reaction was used to identify 44 HPV-DNA types. Human papillomavirus viral load testing was conducted using a LightCyler real-time polymerase chain reaction assay; viral load was classified as high (>250 copies/scrape) or low (≤250 copies/scrape), for nonquantifiable values. The Kaplan-Meier method and Cox regression modeling were used to examine the association between HPV viral load and HPV clearance.

RESULTS

A total of 1097 men, with 291 HPV16 and 131 HPV18 cumulative infections over 24 months were analyzed. Human papillomavirus clearance at 6 months after first HPV detection was lower for high versus low viral load HPV16 infections in the glans (adjusted hazard ratio [aHR], 0.65; 95% confidence interval [CI], 0.46-0.92)] and shaft (aHR, 0.44; 95% CI, 0.16-0.90), and HPV18 infections in the glans (aHR, 0.05; 95% CI, 0.01-0.17).

DISCUSSION

High versus low HPV viral load was associated with a reduced HPV clearance for HPV16 infections in the glans and shaft, and for HPV18 infections in the glans, among young uncircumcised men. Reduced clearance of high viral load HPV16 and HPV18 infections in men may increase HPV transmission to their female partners as well as enhance the development of penile lesions in comparison to men with low viral load HPV infections.

Acquisition and persistence of human papillomavirus 16 (HPV-16) and HPV-18 among men with high-HPV viral load infections in a circumcision trial in Kisumu, Kenya

BACKGROUND

Circumcision and lower human papillomavirus (HPV) viral loads in men are possibly associated with a reduced risk of HPV transmission to women. However, the association between male circumcision and HPV viral load remains unclear.

METHODS

Swab specimens from the glans and shaft of the penis were collected from men enrolled in a circumcision trial in Kisumu, Kenya. GP5+/6+ polymerase chain reaction (PCR) was used to identify HPV DNA types. HPV-16 and HPV-18 loads were measured with a LightCycler real-time PCR and classified as high (>250 copies/scrape) or low (≤250 copies/scrape).

RESULTS

A total of 1159 men were randomly assigned to undergo immediate circumcision, and 1140 men were randomly assigned to the control arm (these individuals were asked to remain uncircumcised until the study ended). The hazard of acquisition of high-viral load infections in the glans was lower in the circumcision arm, compared with the control arm, for HPV-16 (hazard ratio [HR], 0.32 [95% confidence interval {CI}, .20-.49]) and HPV-18 (HR, 0.34 [95% CI, .21-.54]). The 6-month risk of HPV persistence among men with high-viral load infections in the glans at baseline was lower in the circumcision arm, compared with the control arm, for HPV-16 (risk ratio [RR], 0.36 [95% CI, .18-.72]) and HPV-18 (RR 0.34 [95% CI, .13-.86]). Weaker and less precise results were obtained for shaft samples.

CONCLUSIONS

Male circumcision could potentially reduce the risk of HPV transmission to women by reducing the hazard of acquisition, and the risk of persistence of high-HPV viral load infections in the glans in men.

Risk of HIV acquisition among circumcised and uncircumcised young men with penile human papillomavirus infection

OBJECTIVES

There are very few data from men on the risk of HIV acquisition associated with penile human papillomavirus (HPV) infection and no data on the potential modifying effect of male circumcision. Therefore, this study evaluated whether HPV is independently associated with risk of HIV.

DESIGN

A cohort study of HPV natural history nested within a randomized control trial of male circumcision to reduce HIV incidence in Kisumu, Kenya.

METHODS

Prospective data from 2519 men were analyzed using 6-month discrete-time Cox models to determine if HIV acquisition was higher among circumcised or uncircumcised men with HPV compared to HPV-uninfected men.

RESULTS

Risk of HIV acquisition was nonsignificantly increased among men with any HPV [adjusted hazard ratio (aHR) 1.72; 95% confidence interval (CI) 0.94-3.15] and high-risk HPV (aHR 1.92; 95% CI 0.96-3.87) compared to HPV-uninfected men, and estimates did not differ by circumcision status. Risk of HIV increased 27% with each additional HPV genotype infection (aHR 1.27; 95% CI 1.09-1.48). Men with persistent (aHR 3.27; 95% CI 1.59-6.72) or recently cleared (aHR 3.05; 95% CI 1.34-6.97) HPV had a higher risk of HIV acquisition than HPV-uninfected men.

CONCLUSIONS

Consistent with the findings in women, HPV infection, clearance, and persistence were associated with an increased risk of HIV acquisition in men. Given the high prevalence of HPV in populations at risk of HIV, consideration of HPV in future HIV-prevention studies and investigation into mechanisms through which HPV might facilitate HIV acquisition are needed.

Patterns of persistent genital human papillomavirus infection among women worldwide: a literature review and meta-analysis

Persistent high-risk human papillomavirus (HR-HPV) infection is the strongest risk factor for high-grade cervical precancer. We performed a systematic review and meta-analysis of HPV persistence patterns worldwide. Medline and ISI Web of Science were searched through January 1, 2010 for articles estimating HPV persistence or duration of detection. Descriptive and meta-regression techniques were used to summarize variability and the influence of study definitions and characteristics on duration and persistence of cervical HPV infections in women. Among 86 studies providing data on over 100,000 women, 73% defined persistence as HPV positivity at a minimum of two time points. Persistence varied notably across studies and was largely mediated by study region and HPV type, with HPV-16, 31, 33 and 52 being most persistent. Weighted median duration of any-HPV detection was 9.8 months. HR-HPV (9.3 months) persisted longer than low-risk HPV (8.4 months), and HPV-16 (12.4 months) persisted longer than HPV-18 (9.8 months). Among populations of HPV-positive women with normal cytology, the median duration of any-HPV detection was 11.5 and HR-HPV detection was 10.9 months. In conclusion, we estimated that approximately half of HPV infections persist past 6 to 12 months. Repeat HPV testing at 12-month intervals could identify women at increased risk of high-grade cervical precancer due to persistent HPV infections.

Mannose-binding lectin 2 gene and risk of adult glioma

BACKGROUND AND AIMS

The immune system is likely to play a key role in the etiology of gliomas. Genetic polymorphisms in the mannose-binding lectin gene, a key activator in the lectin complement pathway, have been associated with risk of several cancers.

METHODS

To examine the role of the lectin complement pathway, we combined data from prospectively collected cohorts with available DNA specimens. Using a nested case-control design, we genotyped 85 single nucleotide polymorphisms (SNPs) in 9 genes in the lectin complement pathway and 3 additional SNPs in MBL2 were tested post hoc). Initial SNPs were selected using tagging SNPs for haplotypes; the second group of SNPs for MBL2 was selected based on functional SNPs related to phenotype. Associations were examined using logistic regression analysis. All statistical tests were two-sided. Nominal p-values are presented and are not corrected for multiple comparisons.

RESULTS

A total of 143 glioma cases and 419 controls were available for this analysis. Statistically significant associations were observed for two SNPs in the mannose-binding lectin 2 (ML2) gene and risk of glioma (rs1982266 and rs1800450, test for trend p = 0.003 and p = 0.04, respectively, using the additive model). One of these SNPs, rs1800450, was associated with a 58% increase in glioma risk among those carrying one or two mutated alleles (odds ratio = 1.58, 95% confidence interval = 0.99-2.54), compared to those homozygous for the wild type allele.

CONCLUSIONS

Overall, our findings suggest that MBL may play a role in the etiology of glioma. Future studies are needed to confirm these findings which may be due to chance, and if reproduced, to determine mechanisms that link glioma pathogenesis with the MBL complement pathway.

Single-nucleotide polymorphisms of allergy-related genes and risk of adult glioma

Previous studies have shown an inverse association between allergies and glioma risk; however, results for associations between single nucleotide polymorphisms (SNPs) of allergy-related genes and glioma risk have been inconsistent and restricted to a small number of SNPs. The objective of this study was to examine the association between 166 SNPs of 21 allergy-related genes and glioma risk in a nested case-control study of participants from three large US prospective cohort studies. Blood collection took place between 1982 and 1994 among the 562 included Caucasian participants (143 cases and 419 matched controls) prior to case diagnosis. Custom Illumina assay chips were used for genotyping. Logistic regression analyses, controlling for age and study cohort, were used to determine associations between each SNP and glioma risk. Statistically significant associations were found between rs2494262 and rs2427824 of the FCER1A gene, which encodes the alpha chain of the high affinity immunoglobulin E receptor, and glioma risk (nominal trend p values 0.01 and 0.03, respectively). Significant associations were also found between SNPs in IL10, ADAM33, NOS1 and IL4R and glioma risk. However, our analyses were not corrected for multiple comparisons and need to be interpreted with caution. Our findings with FCER1A SNPs provide further support for the link between allergies and risk of glioma.

Sexual behaviour and less frequent bathing are associated with higher human papillomavirus incidence in a cohort study of uncircumcised Kenyan men

OBJECTIVES

Data on the acquisition of human papillomavirus (HPV) infection in men are limited, especially from developing regions including Africa. The objective of this study was to characterise and determine the risk factors of HPV acquisition among a cohort of uncircumcised men participating in a randomised controlled trial (RCT) of male circumcision in Kisumu, Kenya.

METHODS

Penile exfoliated cell specimens were collected at baseline, 6- and 12-month follow-up visits from the glans/coronal sulcus and shaft of men enrolled in the control arm of the RCT between 2002 and 2005. All participants were HIV seronegative, aged 17-24 years at baseline and remained uncircumcised over follow-up. Specimens were tested with GP5+/6+ PCR to detect 44 HPV types. Parametric frailty models were used to assess risk factors of HPV incidence.

RESULTS

The median age of 966 participants was 20 years. The median follow-up time was 12.1 months. The incidence rate (IR) of any HPV infection was 49.3/1000 person-months with HPV16 having the highest IR (10.9/1000 person-months). The strongest risk factors for overall HPV incidence were bathing less frequently than daily (adjusted HR=2.6; 95% CI 1.0 to 6.5) and having ≥ 2 female sexual partners in the past year (adjusted HR=1.6; 95% CI 1.2 to 2.1).

CONCLUSIONS

HPV IRs were notably high in this cohort of high-risk, uncircumcised men from Kisumu, Kenya, with the number of sexual partners and bathing frequency being the strongest risk factors.

Abstract 30: The epidemiology of triple-negative breast cancer: A review

Background: Molecular profiling of breast tumors has enhanced our knowledge of the heterogeneity of breast cancer, including the identification of subtypes associated with differences in prognosis. However, the etiology of these intrinsic subtypes remains unknown. The triple-negative subtype accounts for 10-25% of breast tumors and is most common among African-American and premenopausal women. The purpose of this review was to summarize the existing literature on the risk factors for triple-negative disease.

Methods: Epidemiologic studies published between January 2000 and December 2011 that reported subtype-specific effect measure estimates for hormonal and other breast cancer risk factors in case-only or case-control analyses were included. A total of 20 studies from 17 populations met our pre-specified inclusion criteria.

Results: Compared to luminal A, triple-negative cases were more likely to have younger age at menarche, higher parity, shorter duration of breastfeeding, and increased premenopausal body mass. Case-control data suggest that there may be positive associations between parity, premenopausal body mass and risk of triple-negative disease, while inverse associations were observed for age at first term full-term pregnancy.

Conclusions: Our review confirms that risk factor profiles may vary by subtype; although we were unable to draw definitive conclusions regarding all hormonal risk factors and risk of triple-negative disease.

Impact: Because this subtype represents a small proportion of tumors, collaborative efforts should be undertaken to precisely evaluate potential associations. In addition, future investigations should focus on enrolling a greater number of African-American participants, as this population is underrepresented in the majority of current studies.

Citation Format: Lauren E. McCullough, Leila Family, Katie M. O'Brien, Hilda Razzaghi, Danielle M. Backes, Irina Mordukhovich, Paul L. Reiter, Andrew F. Olshan. The epidemiology of triple-negative breast cancer: A review. [abstract]. In: Proceedings of the AACR Special Conference on Post-GWAS Horizons in Molecular Epidemiology: Digging Deeper into the Environment; 2012 Nov 11-14; Hollywood, FL. Philadelphia (PA): AACR; Cancer Epidemiol Biomarkers Prev 2012;21(11 Suppl):Abstract nr 30.

Vaccine-relevant human papillomavirus (HPV) infections and future acquisition of high-risk HPV types in men

BACKGROUND

Little is known about type-specific associations between prevalent human papillomavirus (HPV) infections and risk of acquiring other HPV types in men. Data on natural clustering of HPV types are needed as a prevaccine distribution to which postvaccine data can be compared.

METHODS

Using data from a randomized controlled trial of male circumcision in Kisumu, Kenya, adjusted mean survival ratios were estimated for acquisition of any-HPV, high-risk (HR) HPV, and individual HR-HPV types among men uninfected as compared to those infected with vaccine-relevant HPV types 16, 18, 31, 45, 6, or 11 at baseline.

RESULTS

Among 1097 human immunodeficiency virus-negative, uncircumcised men, 2303 incident HPV infections were detected over 2534 person-years of follow-up. Although acquisition of individual HR-HPV types varied by baseline HPV type, there was no clear evidence of shorter times to acquisition among men without vaccine-relevant HPV-16, -18, -31, -45, -6, or -11 infections at baseline, as compared to men who did have these infections at baseline.

CONCLUSIONS

These prospective data on combinations of HPV infections over time do not suggest the potential for postvaccination HPV type replacement. Future surveillance studies are needed to definitely determine whether elimination of HPV types by vaccination will alter the HPV type distribution in the population.

Male circumcision is associated with a lower prevalence of human papillomavirus-associated penile lesions among Kenyan men

Human papillomavirus (HPV)-associated penile lesions in men may increase the risk of HPV transmission to their female partners. Risk factor data on HPV-associated penile lesions are needed from regions with a high burden of cervical cancer. Visual inspection of the penis was conducted using a colposcope at the 24-month visit among participants in a randomized controlled trial of male circumcision in Kenya, from May 2006 to October 2007. All photos were read independently by two observers for quality control. Penile exfoliated cells sampled from the glans/coronal sulcus and the shaft were tested for HPV DNA using GP5+/6+ PCR and for HPV16, 18 and 31 viral loads using a real time PCR assay. Of 275 men, 151 were circumcised and 124 uncircumcised. The median age was 22 years. Circumcised men had a lower prevalence of flat penile lesions (0.7%) versus uncircumcised (26.0%); adjusted odds ratio (OR) = 0.02; 95% confidence interval (CI) = 0.003-0.1. Compared to men who were HPV negative, men who were HPV DNA positive (OR = 6.5; 95% CI = 2.4-17.5) or who had high HPV16/18/31 viral load (OR = 5.2; 95% CI = 1.1-24.4) had higher odds of flat penile lesions. Among men with flat penile lesions, HPV56 (29.0%) and 16 (25.8%) were the most common types within single or multiple infections. Flat penile lesions are much more frequent in uncircumcised men and associated with higher prevalence of HPV and higher viral loads. This study suggests that circumcision reduces the prevalence of HPV-associated flat lesions and may ultimately reduce male-to-female HPV transmission.

A review of African American-white differences in risk factors for cancer: prostate cancer

OBJECTIVE

African American men have higher prostate cancer incidence rates than White men, for reasons not completely understood. This review summarizes the existing literature of race-specific associations between risk factors and prostate cancer in order to examine whether associations differ.

METHODS

We reviewed epidemiologic studies published between January 1970 and December 2008 that reported race-specific effect estimates. We focused mainly on modifiable risk factors related to lifestyle and health. A total of 37 articles from 21 study populations met our inclusion criteria.

RESULTS

We found no evidence of racial differences in associations between prostate cancer and alcohol intake, tobacco use, and family history of prostate cancer. Research suggests that a modest positive association may exist between height and prostate cancer risk (all prostate cancer and advanced prostate cancer) among Whites only. No clear patterns were observed for associations with physical activity, weight/body mass index, dietary factors, occupational history, sexual behavior, sexually transmissible infections, and other health conditions.

DISCUSSION

Our results suggest few differences in prostate cancer risk factors exist between racial groups and underscore areas where additional research is needed. Future studies should enroll higher numbers of African American participants and report results for advanced prostate cancer.

Prevalence and risk factors of human papillomavirus infection by penile site in uncircumcised Kenyan men

Human papillomavirus (HPV) prevalence was estimated from 2,705 sexually active, uncircumcised, human immunodeficiency virus seronegative men aged 17-28 years in Kisumu, Kenya. HPV prevalence was 51.1% (95% confidence interval: 49.2-53.0%) in penile cells from the glans/coronal sulcus and/or shaft. HPV prevalence varied by anatomical site, with 46.5% positivity in the glans/coronal sulcus compared with 19.1% in the shaft (p < 0.0001). High-risk HPV was detected in 31.2% of glans and 12.3% of shaft samples (p < 0.0001). HPV16 was the most common type and 29.2% of men were infected with more than one HPV type. Risk factors for HPV infection included presence of C. trachomatis, N. gonorrhea, self-reported sexually transmitted infections, and less frequent bathing. Lifetime number of sexual partners and herpes simplex virus type-2 seropositivity were also marginally associated with HPV infection.

Systematic review of human papillomavirus prevalence in invasive penile cancer

OBJECTIVE

Type-specific prevalence data of human papillomavirus (HPV) DNA in penile carcinoma are needed to determine the potential impact of HPV prophylactic vaccines, assuming demonstrated efficacy in men.

METHODS

A review was conducted using search terms including HPV and penile cancer. Studies using polymerase chain reaction (PCR) assays for HPV DNA detection in invasive penile carcinoma were included.

RESULTS

A total of 1,266 squamous cell carcinoma (SCC) cases contributed data from 30 studies. The number of SCC was similar in Europe (28.2%), North America (27.6%), South America (23.9%) and Asia (20.4%). All SCC were histologically confirmed with biopsies for DNA detection. Most commonly used PCR primers were type-specific (35.2%), and combination PCR (18.2%). HPV prevalence was 47.9%, ranging from 22.4% in verrucous SCC to 66.3% for the basaloid/warty subtypes. HPV16 (30.8%), HPV6 (6.7%) and HPV18 (6.6%) were the most prevalent types. HPV16 and/or HPV 18 prevalence was 36.7%.

CONCLUSIONS

HPV DNA was detected in half of SCC, with HPV16 being the most common type. If proven efficacious in men, prophylactic vaccines targeting carcinogenic types HPV16 and 18 could potentially reduce approximately one-third of incident SCC.