[738] The Value of P16NK4a as a Histomarker for HPV in Subtypes of Penile Squamous Cell Carcinoma (SCC). A Study of 158 Tumors

AL Cubilla, M Alejo, B Lloveras, O Clavero, E Kasamatsu, A Chaux, EF Velazquez, N Monfulleda, S Tous, L Alemany, J Klaustermeier, N Munoz, W Quint, S de San Jose, FX Bosch. Instituto de Patologia e Investigacion, Asuncion, Paraguay; Catalan Institute of Oncology, Barcelona, Spain; Brigham Hospital, Harvard Medical School, Boston, MA; Delft Diagnostic Laboratories, Ad Delft, Netherlands

Background: The histomarker p16NK4a has been postulated as a valid surrogate for HPV in vulvar carcinomas. Penile and vulvar carcinomas are morphologically similar. At both sites, about a third of the tumors showing a warty (condylomatous) or basaloid pathological features are considered to be HPV related.
Design: To explore the value of P16NK4a as a simpler and less expensive marker for HPV in major subtypes of penile carcinomas we compared results of HPV testing and P16 staining of 158 penile tumors from Paraguay. HPV-DNA was amplified at the ICO (Barcelona) by SPF-10 broad spectrum primers PCR followed by DEIA and genotyping by LiPa 25 (version 1). P16ink4A was carried out using standard procedures (CIN TECH provided by MTM, Heidelberg), and tested blinded to HPV status. P16 positivity was a diffuse and continuous strong staining throughout the tumor or at basal layer. Patchy staining or discontinuous staining were considered negative. Tumors were grouped as follow: basaloid, warty and warty basaloid SCCs (B/W/WB), 57 cases, and usual, verrucous and papillary SCCs (non B/W/WB), 101 cases.
Results:

SCC type	No of Cases	HPV+ (%)	p16+ (%)	Sensitivity	Specificity	PPV	NPV
B/W/WB	57	34 (59.6)	37 (64.9)	88.2	69.6	81.1	80.0
Non B/W/WB	101	20 (19.8)	10 (9.9)	30.0	95.1	60.0	84.6
Total	158	54	47	66.7	90.4	76.6	83.8

There was no difference between the number of HPV and p16 positive B/W/WB SCCs (p=0.7). The difference was also no significant in the non B/W/WB group (p=0.07). Using HPV as a reference, sensitivity of p16 was 88.2% in B/W/WB and 30% in non B/W/B carcinomas. Conversely, the specificity of p16 was low in the B/W/WB group, but over 95% in the non B/W/WB cases.
Conclusions: These data indicate that in B/W/WB group the positivity of p16 correlates well with the presence of HPV but the sensitivity and specificity are not sufficient to substitute HPV testing for p16 staining. P16 may be used as a complement in the HPV related histological diagnosis.
Category: Genitourinary (including renal tumors)

Tuesday, March 10, 2009 1:00 PM

Poster Session IV # 120, Tuesday Afternoon