All of the following are true about cryptorchidism,except:
Predisposing factors for testicular GCTs are

Cryptorchidism
Testicular feminization syndrome
GCT of one testis is a risk factor for the other testis
Testicular Ca in a sibling
Klienfelter syndrome - is associated with mediastinal GCT
Administration of estrogens (eg DES) to the mother during pregnancy is associated with increased incidence of testicular Ca in male offspring.

Some points are worth mentioning about cryptorchidism

Of the predisposing factors, cryptorchidism has the strongest association with testicular Ca.
Increased risk is seen for both the testis i.e. the cryptorchid testes as well as the normally descended testes
Abdominal cryptorchid testes are at a higher risk than inguinal cryptorchid testes.
Seminoma is the most common type of testicular cancer seen in a cryptorchid testes

Remember this : Placement of the cryptorchid testis into the scrotum (orchipexy) does not alter its malignant potential, however it facilitates examination and tumor detection 
(Note that Harrison (17/e, p601) contradicts the above statement but we should follow what Campbell & Smith say)
Cryptorchidism is a risk factor for testicular tumor
Seminoma is the most common tumor
Contalateral testis is also at risk
Orchidopexy reduces the risk of malignancy