-My wife is having weekly chemo at about $1000 a pop. No idea whether this would vary a lot with the drug; she's currently on Herceptin.

-It's not usual to have chemo for DCIS, as the cancer was in-situ there should be no risk of it having spread within the breast, to lymph nodes or beyond, so nothing for the chemo to do. Post surgery treatment is usually limited to radiotherapy and hormone therapy.

Are you talking about taking chemo electively simply as a prophylactic against recurrence after DCIS? I'm not sure that would work. I agree there is an increased risk of recurrence after DCIS but I don't think it is due to local metastasis. I think it is more along the lines of your simply being at higher risk of breast cancer generally, any recurrences being completely new tumours. This is important because the chemo will only attack growing tissues, so if there are cells elsewhere which have undergone some pre-cancerous changes but have not yet started to divide uncontrolledly, then chemo will not touch them. Of course if there are other undetectable tumours already there then it would work against them, but it would only give a very limited risk benefit.

Hormone therapy, being long term, would still be effective against cancers which developed later, and might help to prevent them developing.