Immunostaining for placental alkaline phosphatase on fine-needle aspiration specimens to detect noninvasive testicular cancer: a prospective evaluation in cryptorchid men

OBJECTIVE: To assess, in a 12-year prospective study, the potential for early detection of testicular carcinoma in situ (CIS) by immunocytochemistry, using anti-placental alkaline phosphatase (PLAP) monoclonal antibodies on testicular fine-needle aspiration cytology (FNAC) specimens taken from a group of formerly cryptorchid patients, as such men are at greater risk of developing testicular cancer. PATIENTS AND METHODS: Sixty-eight men who had had orchidopexy at the Urological Department of the University of Padova between 1975 and 1983 were evaluated first in 1993, by a protocol including a history, physical examination, testicular ultrasonography and serum tumour markers, to eliminate the presence of testicular cancer. In 57 of the 68 men, specimens taken from bilateral testicular FNAC were stained immunocytochemically using anti-PLAP monoclonal antibodies. After 8 years, the same protocol was repeated on the 57 men, and the follow-up was prolonged until March 2005 for men with previous positive PLAP immunostaining. RESULTS: In 1993, six of the 57 men, (10.5%) had unilateral positive immunostaining for PLAP. By 2001, none of these men had developed testicular cancer, while of the other 51 men, only one developed a nonseminomatous tumour. The uninterrupted surveillance of PLAP-positive men showed no overt cancer until March 2005. CONCLUSION: The present findings do not seem to confirm the reliability of PLAP immunostaining of testicular specimens from FNAC for detecting CIS. These findings might depend on the geographical variability of both CIS and testicular cancer incidence, as well as on the variable relationship between CIS and successive occurrence of invasive testis cancer.