פיזור משני is spreading of the cancer cells to another type of tissue. For example prostatic cancer spreading to bone tissue.
See here: http://www.sns.sheba.co.il/h/779/&mod=download&me_id=816

The term "secondary metastasis" usually means the same thing, but it sometimes means the spread of cancer cells from one metastatic site to another (a "secondary" spread; X -> Y -> Z).

At any case, I think you could simply use "secondary metastasis" vs. "metastasis" (for גרורה).