Stage 2b idc breast cancer-neoadjuvant ... had taxol/herceptin (trastuzumab) for 16wks. now a/c chemo.. is it risky to be without herceptin (trastuzumab) until surgery in jan?

You must: Discuss this with your oncologist. No one should comment on this without knowing your whole case history and follow up exams.

Should be okay: You are receiving ac now and i think (and i hope) it should take care you cancer well --to shrink it down further- so you can have surgery in january. It is not safe to combine adriamyicn and Herceptin (trastuzumab) as it could give you significant problem with your heart. Once you are done with surgery- you will need Herceptin (trastuzumab) to be continued for 1 year.

Ok: If you started ac this month then your last ac will be sometime in the latter part of november that means your next cycle of something would have been the middle of december and then in the first part of january. Therefore you would only be missing one cycle of a therapy before your surgery. There is no reason to suspect that you would relapse quickly. You will be fine with the wait.