Human Placental Alkaline Phosphatase (hPLAP) is the Most Frequently Elevated Serum Marker in Testicular Cancer

Background: Testicular cancer is the most frequent cancer in patients between 20 and 40 years of age. Cure rates are very high due to standardised operative treatment as well as additional chemotherapy and radiotherapy according to histological subtype and tumour stage. Histological subtypes are seminoma, non-seminoma and mixed tumours (partly seminoma and partly non-seminoma). The aim of this study was to determine the value of different tumour markers in the primary diagnosis of testicular cancer. Material and Methods: In a retrospective study we investigated 152 consecutive patients with testicular cancer as well as 75 patients with benign scrotal conditions. In all patients the tumour markers human alkaline phosphatase (hPLAP), alpha-fetoprotein (AFP), human chorionic gonadotropin (hCG) and the enzyme lactate dehydrogenase (LDH) were measured. Statistical analyses included descriptive analysis, boxplots, fourfold table, receiver operating characteristic (ROC), calculation of confidence intervals and analysis of variance (ANOVA). Results: 145 patients with a mean age of 34.3 years were eligible. There were 72 seminomas, 33 non-seminomas and 40 mixed tumours with 69% of patients being in Lugano stage I, 19% in stage II and 11% in stage III. hPLAP, AFP and hCG were statistically significantly higher in patients with testicular cancer compared to patients with benign scrotal conditions (p<0.005). hPLAP showed the best sensitivity/specificity (51.1%/84.0%) followed by AFP (35.7%/97.1%), hCG (32.6%/98.6%) and LDH (31.4%/97,8%). ROC analysis demonstrated no difference between hPLAP, AFP and hCG in the specificity range of 80-100%. However, a combination of hPLAP, AFP and hCG provided statistically significantly better results than single markers (p<0.001). Conclusion: hPLAP is the most often elevated marker in the serum of patients with testicular cancer and potentially demonstrates a significant benefit for therapy monitoring. In our opinion there is a need to debate the consideration of hPLAP in the usual guidelines of the cancer societies. The unspecific elevation in smokers must be considered. In this regard, reference values of hPLAP depending on smoking habits could be a solution, but valid data are not yet available.