In theory, biopsy is a very good means and method to determine cancer and should identify cancer, but not 100% certainty. A biopsy is a piece of tissue taken from a lump for pathological testing, and if the test result is cancer, it is not necessarily cancer. Because there are surgical excisional biopsy and puncture biopsy in biopsy, surgical excisional biopsy can basically determine whether it is cancer or not. While puncture biopsy may have false negative due to different puncture sites, i.e. it is cancer but not confirmed to be cancer. If it is clinically considered to be cancer, but the puncture does not have cancer, it is recommended to determine whether it is cancer after further multiple punctures, multiple tests, and pathology to confirm whether it is cancer or not. Therefore, puncture biopsy can determine to some extent that it is cancer, but if it appears negative and clinically considered to be cancer, it must be biopsied again to be sure.