MDACC 2018: HPV and Penile Cancer: Pathogenesis, Prevention, Prognosis and Therapy
Detection of HPV infection is most commonly performed through p16 staining by immunohistochemistry (IHC), although HPV PCR testing can be more specific. Among squamous cell carcinoma histologic variants, HPV is more commonly associated with the papillary, warty, or basaloid types. It is less common to find HPV-infection in the usual-type squamous cell carcinoma (accounting for only 10-20% of cases). HPV is not seen in verrucous or sarcomatoid variants.
If not all penile cancer cases are HPV-related, why would testing for HPV infection matter? Dr. Chahoud noted that in oropharyngeal cancers, the presence or absence of HPV infection has been shown to impact survival3; patients with HPV-positive oropharyngeal tumors had better 3-year rates of overall survival compared with those with HPV-negative tumors (82.4% vs. 57.1%, p<0.001). Though the same relationship has not been definitively established in penile cancer, the American Joint Committee on Cancer (AJCC) classifies p16 IHC and high-risk HPV PCR testing as emerging prognostic factors for clinical care4. Furthermore, knowledge of HPV status can be useful in assessing for clinical trial eligibility; among ongoing trials for penile cancer, at least two (NCI-2016-01170 and NCI-2015-01004) are specific for patients with HPV+ penile tumors. HPV testing may also be helpful for counseling or identifying a second HPV-related cancer. Dr. Chahoud presented data from Suk et al showing that the presence of persistent HPV infection can lead to a second primary HPV-associated malignancy5. For example, the risk of oropharyngeal cancer was significantly increased after an index penile cancer (standard incidence ratio 2.5; 95% CI 1.3-4.1). This finding has implications for patient counseling.
Since HPV is an acquired infection, HPV vaccination clearly plays a role in preventing HPV-associated malignancies. Vaccination against key HPV types is indicated in both boys and girls aged 9-45 years. Although adoption rates of HPV immunization are 94-98% in Australia and New Zealand, Dr. Chahoud noted that as of 2016, the rate of vaccination approaches only 50% in the US, with rates even lower in Texas.
Take-home messages: HPV testing in penile cancer can be beneficial for prognostication, clinical trial enrollment, and providing counseling for second HPV-related primary tumors in survivors and sexual partners. Currently, HPV status does not impact the staging and treatment of penile cancer.
Presented by: Jad Chahoud, MD, Hematology-Oncology Fellow, MD Anderson Cancer Center, Houston, Texas
References:
1. Miralles-Guri C, Bruni L, Cubilla AL, Castellsague X, Bosch FX, de Sanjose S. Human papillomavirus prevalence and type distribution in penile carcinoma. J Clin Pathol [Internet]. 2009 Oct 1;62(10):870–8.
2. Siegel RL, Miller KD, Jemal A. Cancer statistics, 2016. CA Cancer J Clin [Internet]. 66(1):7–30. Available from: http://www.ncbi.nlm.nih.gov/pubmed/26742998
3. Ang KK, Harris J, Wheeler R, Weber R, Rosenthal DI, Nguyen-Tân PF, et al. Human Papillomavirus and Survival of Patients with Oropharyngeal Cancer. N Engl J Med [Internet]. 2010 Jul;363(1):24–35.
4. Paner GP, Stadler WM, Hansel DE, Montironi R, Lin DW, Amin MB. Updates in the Eighth Edition of the Tumor-Node-Metastasis Staging Classification for Urologic Cancers. Eur Urol [Internet]. 2018;73(4):560–9.
5. Suk R, Mahale P, Sonawane K, Sikora AG, Chhatwal J, Schmeler KM, et al. Trends in Risks for Second Primary Cancers Associated With Index Human Papillomavirus–Associated Cancers. JAMA Netw Open [Internet]. 2018 Sep 7;1(5):e181999.
Written by Dr. Vikram M. Narayan (@VikramNarayan), Urologic Oncology Fellow and Ashish M. Kamat, MD (@UroDocAsh), Professor, Department of Urology, Division of Surgery, The University of Texas MD Anderson Cancer Center, Houston, TX at the 13th Update on the Management of Genitourinary Malignancies, The University of Texas (MDACC - MD Anderson Cancer Center) November 9-10, 2018, Dan L. Duncan Building, Houston, TX