At what size is recommended to biopsy a breast cyst ? more than 1 cm (0, 39 inch )? thanks

There's no size: Size cannot tell a doctor whether a cyst needs to be biopsied. A 1 cm breast cyst could be totally benign, or it could be suspicious for cancer. The same is true for a 5cm cyst. Features of the cyst on imaging, the history of the cyst (does it get bigger and smaller), your symptoms, and family history all play a role in deciding whether a biopsy is needed.

Cyst: There is no recommended size. The decision to biopsy is based not on size, but on the specific features of the cyst.