Dear Heidyrenz25, Scar tissue can develop after a biopsy and is a possible explanation for the hardness felt after a biopsy, although without examination it is impossible to know. A biopsy does not cause breast cancer to occur. A biopsy is done to obtain a specimen so the cells from the area of concern can be examined under a microscope to see whether there is cancer or not. If you have continuing concerns about your biopsy area, you should return to your doctor for further evaluation.