“The practice of rebiopsy at relapse and metastasis is becoming increasingly common in the United States,” said Hope Rugo, MD, Professor at the University of California, San Francisco.

“More than 20% of patients have differing results from the primary tumor to rebiopsy at disease progression. It could be that diagnostic tests are faulty, but we believe there is some shift in the tumor characteristics as the disease progresses,” she noted.

A good reason to rebiopsy would be disease progression with different characteristics than those from the presentation at primary diagnosis, she continued. Biopsy is not needed in a patient who has a primary tumor and then 15 years later develops bone metastasis, she said. ■

Disclosure: Dr. Rugo reported no potential conflicts of interest.