Maaike C.G. Bleeker

Penile cancer: epidemiology, pathogenesis and prevention

ObjectivesPenile cancer is a disease with a high morbidity and mortality. Its prevalence is relatively rare, but the highest in some developing countries. Insight into its precursor lesions, pathogenesis and risk factors offers options to prevent this potentially mutilating disease. This review presents an overview of the different histologically and clinically identified precursor lesions of penile cancer and discusses the molecular pathogenesis, including the role of HPV in penile cancer development.MethodsA systematic review of the literature evaluating penile carcinogenesis, risk factors and molecular mechanisms involved.ResultsCareful monitoring of men with lichen sclerosis, genital Bowen’s disease, erythroplasia of Queyrat and bowenoid papulosis seems useful, thereby offering early recognition of penile cancer and, subsequently, conservative therapeutic options. Special attention is given to flat penile lesions, which contain high numbers of HPV. Their role in HPV transmission to sexual partners is highlighted, but their potential to transform as a precursor lesion into penile cancer has been unsatisfactorily explored.ConclusionsFurther research should not only focus on HPV mediated pathogenic pathways but also on the non-HPV related molecular and genetic factors that play a role in penile cancer development. Options for prevention of penile cancer include (neonatal) circumcision, limitation of penile HPV infections (either by prophylactic vaccination or condom use), prevention of phimosis, treatment of chronic inflammatory conditions, limiting PUVA treatment, smoking cessation and hygienic measures.

Determination of viral load thresholds in cervical scrapings to rule out CIN 3 in HPV 16, 18, 31 and 33‐positive women with normal cytology

An increased high‐risk human papillomavirus (hrHPV) viral load in cervical scrapings has been proposed as a determinant for high‐grade cervical intraepithelial neoplasia (CIN) and cervical cancer (≥CIN 2), but data so far for HPV types different from HPV 16 are limited and inconsistent. In addition, a viral load threshold to distinguish hrHPV positive women without ≥CIN 2 still has not been defined. Here, we used baseline cervical scrapings of women with normal cytology participating in a large population‐based cervical screening trial (i.e. POBASCAM) who were GP5+/6+‐PCR positive for 4 common hrHPV types, i.e. HPV 16, 18, 31 or 33, as a reference to arbitrarily define various viral load thresholds (i.e. 25th, 33rd, 50th, 67th and 75th percentiles of the lowest viral load values) for distinguishing women having single infections with these types without high‐grade CIN. Viral load assessment was performed by real time type‐specific PCR. The viral load threshold values were subsequently validated on abnormal cervical scrapes of 162 women with underlying, histologically confirmed CIN lesions containing 1 of these 4 hrHPV types. All 59 women with CIN 3 had viral load levels that were higher than those of 33% of the women with normal cytology containing the respective hrHPV type detectable by GP5+/6+‐PCR (i.e. higher than the 33rd percentile of viral load). By using this 33rd percentile viral load cut‐off, sensitivity for CIN 3 of 100% (95% CI 93.9–100) was obtained. Hence, application of this viral load threshold would increase the specificity of HPV testing for HPV 16, 18, 31 and 33‐associated prevalent CIN 3 without the cost of a marked reduction in sensitivity. In practice, on the basis of viral load analysis, a less aggressive management can be foreseen for 33% of the women with normal cytology participating in a population‐based screening program who are GP5+/6+‐PCR positive for HPV 16, 18, 31 or 33.

Concordance of Specific Human Papillomavirus Types in Sex Partners Is More Prevalent than Would Be Expected by Chance and Is Associated with Increased Viral Loads

BACKGROUND Genital human papillomavirus (HPV) infections are generally accepted to be sexually transmitted, but studies of HPV infections in sex partners are limited. We investigated HPV type-specific concordance and viral load in 238 heterosexual couples. Women with cervical intraepithelial neoplasia were the index patients in these couples. METHODS GP5+/6+ polymerase chain reaction (PCR), followed by reverse-line blot analysis, was used for the detection of 45 HPV types in cervical and penile scrape samples. Viral loads were subsequently determined in scrape samples positive for HPV types 16, 18, 31, and 33 by LightCycler-based real-time PCR assays. RESULTS A total of 89.9% of the women and 72.9% of their male partners were HPV positive. Predominantly high-risk HPV types were found in persons of both sexes, but infections with multiple and non-high-risk HPV types were more common in men. Of the HPV-positive couples, 57.8% of the men had the same HPV type as their partners; this rate was significantly higher than that expected by chance (P < .001). Moreover, these HPV-concordant men had higher penile scrape viral loads than did the non-HPV-concordant men. For HPV type 16-positive women, higher cervical viral loads were predictive of presence of HPV type 16 in their sex partners. CONCLUSIONS In sexually active couples, HPV type concordance was more prevalent than expected by chance and was associated with increased viral loads. These data provide biological support for HPV transmission between sex partners.

Condom use promotes regression of human papillomavirus-associated penile lesions in male sexual partners of women with cervical intraepithelial neoplasia.

Penile HPV‐associated lesions are frequently seen in male sexual partners of women with CIN. The natural course and clinical significance of these lesions are unclear. Women with CIN and their male sexual partners were randomized for condom use (condom group n = 68, noncondom group n = 68). Males were screened for the presence of penile lesions, i.e., flat lesions, papular lesions and condylomata acuminata, and of HPV in their penile swabs by PCR testing. Median follow‐up time was 13.1 months (range 2.9–57.4). The outcome of our study was clinical regression of penile lesions defined as disappearance of lesions at penoscopy. Potentially prognostic factors, i.e., HPV status, lesion type and age, were studied as well. Outcomes were assessed in 57 men of the condom group and in 43 men of the noncondom group. Condom use shortened the median time to regression of flat penile lesions (7.4 months condom group vs. 13.9 months noncondom group; HR = 2.1, 95% CI 1.2–3.7). This effect was not found for papular lesions (HR = 0.5, 95% CI 0.1–2.8). HPV‐negative men showed a significantly shorter median time to regression of flat lesions (3.8 months) compared to men with either HPV‐positive status (8.5 months; HR = 0.4, 95% CI 0.2–0.9) or inconsistent HPV status (13.1 months; HR = 0.2, 95% CI 0.1–0.6). Regression of flat penile lesions is HPV‐dependent and accelerated by condom use. This effect is probably the result of blocking viral transmission between sexual partners.

High-risk HPV type-specific clearance rates in cervical screening

We assessed clearance rates of 14 high-risk human papillomavirus (hrHPV) types in hrHPV-positive women with normal cytology and borderline/mild dyskaryosis (BMD) in a population-based cervical screening cohort of 44 102 women. The 6-month hrHPV type-specific clearance rates, that is, clearance of the same type as detected at baseline, in women with normal and BMD smears were 43% (95% confidence interval (CI) 39–47) and 29% (95% CI 24–34), respectively. Corresponding 18-month clearance rates were markedly higher, namely 65% (95% CI 60–69) and 41% (95% CI 36–47), respectively. The lowest clearance rates in women with normal cytology were observed for HPV16, HPV18, HPV31, and HPV33. Significantly reduced 18-month clearance rates at a significance level of 1% were observed for HPV16 (49%, 95% CI 41–59) and HPV31 (50%, 95% CI 39–63) in women with normal cytology, and for HPV16 (19%, 95% CI 12–29) in women with BMD. Among women who did not clear hrHPV, women with HPV16 persistence displayed an increased detection rate of ⩾CIN3 (normal P<0.0001; BMD, P=0.005). The type-specific differences in clearance rates indicate the potential value of hrHPV genotyping in screening programs. Our data support close surveillance (i.e. referral directly, or within 6 months) of women with HPV16 and are inconclusive for surveillance of women with HPV18, HPV31, and HPV33. For the other hrHPV-positive women, it seems advisable to adopt a conservative management with a long waiting period, as hrHPV clearance is markedly higher after 18 months than after 6 months and the risk for ⩾CIN3 is low.

Human Papillomavirus Type–Specific 18-Month Risk of High-Grade Cervical Intraepithelial Neoplasia in Women with a Normal or Borderline/Mildly Dyskaryotic Smear

Introduction: High-risk human papillomavirus (hrHPV) DNA testing is an increasingly used instrument in cervical cancer prevention along cervical cytology. The inclusion of hrHPV testing in cervical screening requires efficient management as many hrHPV infections are transient. We investigated the potential value of hrHPV genotyping in normal and borderline/mildly dyskaryotic (BMD) smears. Materials and Methods: From a screening population of 44,102 women in the Netherlands, we included hrHPV-positive women with a normal or BMD smear. We assessed the type-specific 18-month risk of high-grade cervical intraepithelial neoplasia (CIN). Results: In hrHPV-positive women, 18-month risk of CIN grade 3 or invasive cancer (≥CIN3) was 6% [95% confidence interval (95% CI), 4-9] after normal cytology and 20% (95% CI, 16-25) after BMD. If positive for HPV16, ≥CIN3 risks were 14% (95% CI, 9-21) and 37% (95% CI, 28-48), respectively. In the subset of hrHPV-positive women without HPV16, HPV18 was associated with an increased risk of high-grade CIN after normal cytology and HPV31 and HPV33 were associated with an increased risk, particularly after BMD. HPV16 and HPV18 were also associated with an increased risk of high-grade CIN in women with an hrHPV-positive normal baseline smear and a repeat normal smear at 6 months. Discussion: HrHPV-positive women without type 16, 18, 31, or 33 had a relatively low risk of high-grade CIN. Among women with baseline normal cytology and among women with a baseline and repeat normal smear, HPV16/18–positive women showed an increased risk of high-grade CIN. This warrants more aggressive management of HPV16/18–positive women compared with other hrHPV-positive women. (Cancer Epidemiol Biomarkers Prev 2006;15(7):1268–73)

Prevalence of types 16 and 33 is increased in high-risk human papillomavirus positive women with cervical intraepithelial neoplasia grade 2 or worse

High‐risk human papillomavirus (hrHPV) types are causally related to cervical cancer and its high‐grade precursor lesions. The risk posed by the different hrHPV types for the development of cervical intraepithelial neoplasia grade 2 or worse (≥CIN2) needs to be established. Here, we present the hrHPV type‐distribution in relation to cytology and histology for women participating in a cervical screening program. From 44,102 women who participated in a population‐based cervical screening program in the Netherlands, 2,154 hrHPV GP5+/6+ PCR positive women were recruited to determine the distribution of 14 hrHPV types by reverse line blotting of GP5+/6+ PCR products. For each HPV type, associations with cytology and histologically confirmed ≥CIN2 were measured by odds ratios. HPV types 16 and 33 were more prevalent in women, amongst those containing a single hrHPV type, with moderate dyskaryosis or worse (>BMD) than in women with normal cytology, but only in case of underlying ≥CIN2 (OR 4.10, 95%CI 2.98–5.64 and OR 2.68, 95%CI 1.39–5.15, respectively). Similar results were obtained for women with double infections (OR 3.29, 95% CI 1.61–6.75 and OR 4.37, 95% CI 1.17–16.34). Coexisting types did not influence the prevalence of ≥CIN2 in HPV 16 or 33 positive women. The increased prevalence of type 16 and 33 in hrHPV positive women with ≥CIN2, compared to women with normal cytology, suggests that infection with these types confers an increased risk for development of ≥CIN2. Distinguishing these types may therefore have implications for future cervical screening strategies.

Chromosomal Signatures of a Subset of High-Grade Premalignant Cervical Lesions Closely Resemble Invasive Carcinomas

Cervical cancer develops from precancerous high-grade cervical intraepithelial neoplasia (CIN) harboring a transforming infection with high-risk human papillomavirus, which is characterized by p16(INK4a) overexpression. Once such a lesion has developed, progression toward an invasive squamous cell carcinoma (SCC) may take one or more decades, underlining the heterogeneity of these lesions in terms of duration of existence and progression risk. We performed array-based comparative genomic hybridization (array CGH) on 46 p16(INK4a) immunopositive CIN2/3 lesions to determine whether this heterogeneity is reflected in their chromosomal profiles. Chromosomal profiles of CIN2/3 lesions were related to those of invasive cervical SCC and promoter methylation of CADM1, a tumor suppressor gene known to be functionally involved in the tumorigenic phenotype of cervical cancer cells. Frequent alterations found in CIN2/3 lesions included gains located at chromosome 1, 3, 7, and 20 and losses located at 4, 11, 16, 17, and 19. Unsupervised hierarchical clustering identified two subsets of CIN2/3 lesions, chromosomal profiles of one of which closely resembled invasive SCCs. Gains of 1, 3q, and 20 were characteristic for CIN2/3 lesions with chromosomal signatures resembling carcinomas. In addition, dense promoter methylation of the CADM1 gene was significantly more frequent in these CIN2/3 lesions (P = 0.004). No chromosomal alterations were detected in six CIN1 lesions, five of which were completely p16(INK4a) immunonegative. These findings suggest that biomarkers associated with gains at chromosomes 1, 3q, and 20 are potential hallmarks of advanced p16(INK4a)-positive CIN2/3 lesions with a high short-term risk of progression.

HPV type concordance in sexual couples determines the effect of condoms on regression of flat penile lesions

We earlier demonstrated, in a randomised clinical trial, that the regression time of flat penile lsions in male sexual partners of women with cervical intraepithelial neoplasia (CIN) was shorter in men who used condoms compared to those who did not. To further evaluate this finding, we examined whether the effect of condom use on the regression of flat penile lesions depends on the presence of human papillomavirus (HPV) type concordance in sexual couples, as determined in cervical and penile scrapes by GP5+/6+ PCR testing. A Cox model with time-dependent covariates showed a beneficial effect of condoms on regression of flat penile lesions in concordant couples (hazard ratio 2.63, 95% CI 1.07–6.48) but not in those who were nonconcordant. When both partners harboured different HPV types, no effect of condoms was found (hazard ratio 0.90, 95% CI 0.27–2.96). Delayed regression of flat penile lesions was associated with either stable lesions or with new penile lesions developing at sites surrounding pre-existing lesions suggesting reinfection of the penile epithelium. We conclude that condom use blocks sexual HPV transmission by preventing reinfection and development of new penile lesions in men who are susceptible to the same type as present in the female partner.

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.