How long does it take for testicular cancer to spred to the abdomen and brain? is spreading to the brain common?

Depends on the type: Testicular cancer is usually confined to the testicle, but spread to other organs, metastases, do occur. The type of primary testicular tumor and it's pathologic features determine both the chances of metastasis and if so, where. In particular, choriocarcinoma, a very rare type of testicular cancer, has been associated with brain metastases. Thankfully, brain mets are very rare.