Why is biopsy necessary? Surgery for breast cancer, especially radical surgery, is a heavy blow to the patient’s physiology and psychology, so a definitive preoperative diagnosis is an important principle in breast cancer surgery. There are many diagnostic methods for breast cancer, including physical examination, mammography, B-ultrasound, breast duct endoscopy, etc., but the final diagnosis still relies on pathological diagnosis. Biopsy is the most common means to obtain a preoperative pathological diagnosis, which includes both puncture needle biopsy and surgical biopsy. What are the advantages of a puncture needle biopsy of the breast? Compared to surgical biopsy, needle biopsy causes less damage to normal tissue, no scarring, requires only local anesthesia, and is relatively inexpensive. Most importantly, puncture biopsy can save some patients with benign breast lesions from unnecessary surgery. For patients with breast lumps found on physical examination, surgical biopsy can also be used in conjunction with surgical treatment. However, this approach is not conducive to the development of a detailed treatment plan prior to surgery and prolongs the duration of surgery. Preoperative puncture needle biopsy, if malignant, not only provides a basis for further treatment (including surgery and preoperative adjuvant chemotherapy), but also facilitates discussion between the physician and the patient about the modalities of surgical treatment, such as whether to adopt breast-preserving surgery. Can puncture needle biopsy cause metastasis of breast cancer? The fact is that various stimuli to the tumor, including general mechanical compression, surgery, etc. can cause tumor cells to be shed and enter the circulation, but this does not necessarily lead to metastasis, as the body’s immune system will quickly kill them off. It is found that the metastasis of breast cancer is still mainly related to factors in the tumor and the body’s internal environment itself. As for the problem of cancer implantation on the puncture tract, it is not necessary to worry much because the tumor cannot grow in the short term and the surgery will remove the puncture tract and the skin tissue at the puncture site together. There have been numerous follow-up studies abroad of breast cancer patients who have undergone puncture needle biopsy for up to 15 years, and it was found that surgical treatment within 2 weeks after puncture needle biopsy did not decrease the survival rate of the patients. There is also no evidence to confirm that a 1-month delay in surgery after puncture needle biopsy is detrimental to patients. Therefore, puncture needle biopsy of the breast is a safe and reliable diagnostic method, and patients do not need to worry about it causing metastasis of the cancer. Once a puncture needle biopsy is confirmed to be cancer, patients should actively cooperate with doctors to carry out regular treatment in a timely manner, and should not delay the treatment by refraining from treating the disease or believing in the so-called “secret recipes” of charlatans.