A lumpectomy is a surgery to remove a breast tumor along with a resection margin of normal breast tissue. The margin is the healthy, noncancerous tissue that is next to the tumor. A pathologist analyzes the margin excised by the lumpectomy to detect any possible cancer cells. A cancerous margin is "positive", while a healthy margin is "clean" or "negative". A re-excision lumpectomy is performed if the margin is detected to be positive or cancerous cells are very close to the margin. Sentinel lymph node biopsy (SLNB) or axillary lymph node dissection (ALND) may be used to determine if the cancer has progressed away from the breast and into other parts of the body. Sentinel lymph node biopsy is the analysis of a few removed sentinel nodes for the presence of cancerous cells. A radioactive substance is used to dye the sentinel nodes for easy identification and removal. If cancer is detected in the sentinel node then further treatment is needed. Axillary node dissection involves the excision of lymph nodes connected to the tumor by the armpit (axilla). Radiation is usually used in conjunction with the lumpectomy to prevent recurrence. The radiation treatment can last five to seven weeks following the lumpectomy. Although the lumpectomy with radiation helps to decrease the risk of the cancer returning (local recurrence); it does not prolong survival; it is not a cure, and cancer may still come back. However, local recurrences (confined to the breast area) after lumpectomy can be treated effectively with mastectomy, and these women were still disease-free 20 years after their original lumpectomies and recurrence treatments.