Question: What are the methods used to investigate whether breast cancer has spread to the lymph nodes?
Answer: To test whether cancer has spread to lymph nodes in breast cancer, it is necessary to remove some of the lymph nodes under the armpit. Non-invasive tests such as ultrasounds, MRIs, or PET scans have not proven sufficiently accurate to give women the information they need to plan their subsequent chemotherapy or hormonal therapy.
Traditionally we've had to remove all the lymph nodes under the armpits -- about 15 to 20 lymph nodes; and over the last ten years, it's been proven that we can target the same lymph nodes that may have cancer in them, by doing what's called a 'sentinel lymph node biopsy,' and only remove an average of about three lymph nodes. Removing these fewer number of lymph nodes markedly reduces the pain, discomfort, and potential for long-term side effects for lymph node surgery, and it's been a major advance in the treatment of breast cancer.