Biopsy

It is not possible to treat DIPG by removing tumors surgically, but surgical biopsies to remove small amounts of tumor tissue for diagnostic testing are sometimes performed. Most diagnoses of DIPG are made from MRI. Because of the risks of the procedure, surgical biopsy has typically only been performed when it has not been possible to confirm a diagnosis based on imaging. In the United States and Canada, most doctors do not generally recommend biopsy, and few patients undergo the procedure.

However, recent research has shown that advanced stereotactic surgical techniques greatly reduce the risks of surgical biopsy, which can sometimes yield useful diagnostic information and influence treatment decisions. At some primarily European centers, stereotactic needle biopsy is now more widely used to confirm diagnosis when either neurological findings or imaging studies are atypical or inconclusive. Occasionally when biopsy for presumed DIPG is performed, an alternative histology is discovered, which can impact treatment and prognosis significantly.

Most recently, in the USA, Kieran et al are conducting a biopsy-driven DIPG study in which children undergo biopsy to determine their treatment. The study is ongoing, and over 20 centers in the US are participating. Based on these data, stereotactic biopsy for patients with DIPG appears feasible, safe, and diagnostic for molecular analysis. As targeted therapies become available, it will be imperative to obtain the molecular profile of the tumor in order to avoid exposing children to therapy that may not be effective given their tumor’s particular molecular signature.

Tumor tissue left over from surgical biopsy, as well as tumor tissue donated by families after children with DIPG have died, is very helpful to researchers studying DIPG.