Cast Iron Pipes and Slab Foundations: What to do?

[Alfred Litton]

We have a SFH that has been having a number of minor plumbing problems, and now we have uncovered that one of the major drain lines (cast iron) has deteriorated and will need to be repaired. It's a slab foundation. Currently tenant occupied. Looking for advice. Would you try to replace all the cast iron while replacing this section? Anyone have any advice/experience with replacing cast iron in slab? Thanks.