A new technique for detecting breast cancer, sentinel node bioposy, is being fine-tuned by surgeons around the country. The technique, developed several years ago by Dr. Armando E. Giuliano of the John Wayne Cancer Institute in Santa Monica, California, involves a simple procedure that takes less than an hour and can be done on an outpatient basis. Unlike the standard technique, an auxiliary dissection, which involves removing a cluster of lymph nodes from the armpit, sentinel node biopsy removes one lymph node and examines that node for cancer. For women with small tumors, this procedure is 99% accurate; however, it is less accurate for women with larger tumors. Guiliano cautions that a sentinel node biopsy can only be done by an experienced surgeon.