Growing incidence of testicular cancer around the world stimulates research attempting to explain the trends. This study quantified the contribution of different types of potential risk factors for testicular germ-cell cancer (TGCC) with differentiation between seminoma and non-seminoma. A standardized questionnaire containing demographic data, pre- and perinatal factors, social, lifestyle and occupational parameters was prepared. The data file consists of n = 356 TGCCs (seminoma: n = 195; non-seminoma: n = 161) and n = 317 controls, frequency matched on age to cases. The following factors were significantly associated with the risk of TGCCs in univariate analyses (ORs): atrophic testis (5.3), smoking over 12 pack-yr (4.9), cryptorchidism (2.9), testicular trauma (2.0), birth weight under 3,000 g (1.6), low degree of education (3.0) in correlation with manual occupation (2.3) and finally, overall familial cancer history (1.5) and familial history of breast (1.8) and prostate cancer (3.9). On the other hand, maternal age over 20 yr (OR < 0.4) and moderate recreational sport activity (OR = 0.5) significantly reduced the risk of TGCCs. A significant risk was associated with cryptorchidism (OR = 2.9; 95% CI = 1.5 - 5.9) where orchidopexy was delayed after 5 yr of age (OR = 5.2; 95% CI = 1.5-18.1). Delayed orchidopexy was associated namely with the risk of seminomas (OR = 7.5; 95% CI = 2.1-26.7). Only some of the variables were retained in multivariate model for TGCCs as well as for histological subtypes (multivariate adjusted OR for all TGCCs): atrophic testis (5.9), family history of prostate cancer (4.8), cryptorchidism (3.8) and interaction term 'low degree of education & manual occupation' (3.0). Familial history of breast cancer elevated risk of TGCCs and of seminomas (OR: 2.01 - 2.18). Birth weight under 3,000 g was retained in a multivariate model for TGCCs with a borderline significance (OR = 1.67). We could not rule out any type of risk factors, as each one was significantly represented in the final multivariate models. Familial cancer history remained to be an influential risk factor, altogether with some lifestyle and occupational parameters. This suggests that both environmental exposures and genetic inheritance can play role in the moderation of the risk of TGCC.

Institute of Biostatistics and Analyses Masaryk University Brno Czech Republic