While considered a very safe practice, there is a small chance that a needle biopsy can cause cancer to spread in certain situations, according to Mayo Clinic. This small risk means that oncologists are careful to avoid performing the procedure in these situations.
In the past, a biopsy performed with a large needle was much more likely to disturb cancerous cells within the tumor. It could cause the cancer to spread to surrounding areas within the body. Doctors are now able to use much smaller needles, decreasing the risks associated with the procedure, reports the American Cancer Society. This risk does increase in situations such as testicular cancer, however, so doctors instead choose to remove the tissue completely rather than risk spreading the cells, explains Mayo Clinic.