I have a 7 inch mass in my breast. biopsy showed no cancer but the surgeon want to go back in and put a wire in to double check. is it really necessar?

Need more info: Is your surgeon recommending removal of this mass? Needle-localization breast biopsy involves placement of a wire in the breast followed by surgical excision of non-palpable lumps. What did your pathology report state? If this is a fibroadenoma, we usually recommend removal of giant ones (bigger than 2-3 inches), since they often continue to grow & could be "cancer-like" phyllodes tumors.

Yes : A fine needle biopsy or core biopsy may have a false negative- in other words- missed a cancer even if the biopsy is negative. This is especially true if the mass is large and there is no way to sample the whole thing without its removal.

Probably yes!: Typically a 7 inch (18 cm.) mass in the breast would require surgical removal. Although a benign biopsy result is very comforting, when a mass is so large, it is impossible to evaluate the entire lesion for cancer without removal. Cancer may occupy part of a large mass and not involve other parts.