Blood test levels

Specifically for this post, CEA (general tumour marker)

My CEA has been going up, lately more quickly and from a normal of 4 has crept up to 6.5 - does anybody have any input on this?

Is there some level of vigorous cancer activity?

Since my breast cancer markers are normal, does this indicate the metastatic activity or could it be another cancer altogether?

Cheers
Letty