Best definitive investigation for carcinoma breast is ?

.* Corecut/Trucut biopsy is done under local anaesthesia. It gives clear histological evidence and also confirms DCIS (FNAC can not confirm DCIS). This allows proper neoadjuvant/primary chemotherapy, receptor status of the tumour. Wide bore needle biopsy with vacuum is also used. * Excision biopsy is done only when FNAC is inconclusive and a facility for frozen section is not available. Incision should be planned in such a way that it will be included in eventual mastectomy. ref:SRB&;s manual of surgery,ed 3,pg no 478