Proton beam therapy combined with surgical bioabsorbable spacer placement for pediatric malignancies

Abstract

Many pediatric tumors arising in the abdominopelvic region are radiosensitive, and radiotherapy plays an important role in multidisciplinary treatment. Proton beam therapy, which demonstrates better dose distribution compared with photon radiotherapy, is expected to reduce radiation toxicities. However, irradiating the entire tumor sufficiently when organs are at risk, such as those in the gastrointestinal tract and the kidneys, adjacent to the tumor is difficult even for proton beam therapy. In that case, surgical spacer placement, which provides a space between the tumor and the organ at risk, is useful to increase the radiation dose to the tumor. Moreover, as organs in children are developing and radiosensitive, tolerance doses are lower than those of adults, and a possibility of growth disorder exists in children even if the irradiated is lower than the tolerance dose. Therefore, we should consider the as low as reasonably achievable (ALARA) principle when treating pediatric patients.

A bioabsorbable spacer has been developed, and after a successful clinical trial, the product was released as Neskeep^® in June 2019. Moreover, the product was covered by public health insurance together with surgical spacer placement in December 2019. As childhood cancer survivors have a longer life expectancy than adult survivors, the bioabsorbable spacer is more useful. The non-absorbable spacer remains in the patient’s body for a lifetime and can cause functional and/or growth disorders of the organs along with infection. Removal of the non-absorbable spacer is occasionally performed; however, the burden on the patient increases.