Proton therapy offered the optimal combination of target coverage and organ-sparing in a recent study involving children with high-risk neuroblastoma.
Neuroblastoma is the most common solid tumor of early childhood, usually appearing in the chest or abdomen. Although several treatment options are available, high-risk forms of this cancer often don’t respond to conventional therapy, as noted in a statement from the Children’s Hospital of Philadelphia (CHOP) in Philadelphia, Pennsylvania.
Proton therapy, an advanced radiation treatment, employs the positively charged particles in an atom’s nucleus to destroy tumor DNA and prevent cancer cells from multiplying. In children, proton therapy is often used against spinal tumors.
CHOP radiation oncologist Christine Hill-Kayser, MD, led an analysis of the use of proton therapy or intensity-modulated x-ray therapy (IMXT) in 13 consecutive children (median age 3 years) with high-risk neuroblastoma, all of whom had undergone previous treatment. In IMXT, radiation emitted from seven different angles is sculpted to modify radiation dosages in and around the targeted area.
The investigators determined that 11 patients should receive proton therapy. The remaining two children were deemed to be better suited to IMXT based on their specific anatomy and the locations of their tumors.
The team reported in Pediatric Blood & Cancer (2013;60:1606-1611) that following proton therapy or IMXT, none of the children had experienced local recurrence or clinical organ toxicity. Both proton therapy and IMXT provided excellent target coverage. In addition, because protons are heavier than the particles in x-rays, they can stop at the target more easily, minimizing damage to surrounding tissue.
“[Protons] deposit 90% of their energy precisely at the tumor site, with nearly zero radiation away from the tumor,” explained Hill-Kayser in the CHOP statement. “That protects healthy organs, which, as growing tissues, are especially vulnerable to radiation damage in young children.”
The findings demonstrated that overall, proton therapy should be considered for children with high-risk neuroblastoma, concluded Hill-Kayser and colleagues, who acknowledged that larger studies are needed. The authors also pointed out that individual characteristics made IMXT preferable to proton therapy in two cases, underscoring the need to customize radiation treatment to the particular patient.