It can be difficult to treat malignant tumours using radical particle therapy if the tumour is too close to healthy organs.

A team led by Professor Takumi Fukumoto and Professor Ryohei Sasaki (Kobe University Graduate School of Medicine) has collaborated with Alfresa Pharma Corporation to develop a new medical device "Neskeep" to separate tumours from adjacent normal organs during particle therapy. 

The details of this study have been published in the journal Advances in Radiation Oncology. 

The Neskeep is designed to be placed by surgical procedure.

Neskeep received pharmaceutical approval in December 2018. 

Radiation therapy, which is one of the less invasive and less stressful treatments, has been recognised as an important cancer treatment. 

In some cases, it can be difficult to apply particle therapy when malignant tumours are located near digestive tract organs sensitive to radiation (the small and large intestine).

Doctors currently use non-absorbent materials such as silicone balloons and Gore-Tex sheets to act as spacers in the abdomen and intestines, or they place the intestine or other organs outside the radiation field using an absorbent mesh.

Based on several observations, some patients may then undergo a second surgery to remove the spacer or it may cause serious complications in their bodies for the rest of their lives.

The team succeeded in developing a non-woven fabric bio-absorbable spacer that can create a space between healthy and cancerous tissues during particle therapy.

After that the spacer is safely absorbed by the body.

The Neskeep is available in 5, 10 and 15mm non-woven fabrics using polyglycolic acid, the same material as polyglycolic acid suture thread.

In their preclinical evaluation, the team conducted physical experiments to check that the spacer fulfilled the requirements for isolating cancer from organs and providing a barrier against radiation. 

After safety studies in animal models, a clinical trial was carried out in Kobe University Hospital and Hyogo Ion Beam Medical Center (HIBMC).

The human trial involved five patients with malignant tumours in the abdominal or pelvic region, for whom particle therapy was difficult because of the proximity of normal organs to the cancer.

In all treatments the spacer preserved enough distance between the tumour and healthy tissue during the particle therapy.

Having successfully reduced the radiation exposure to the intestines, they were able to use a full dose of radiation therapy.

There were no serious complications observed with this treatment, and they confirmed that the spacers safely disintegrated afterwards.

Particle therapy to treat malignant tumours is a promising new radiation treatment, and it is available in a growing number of clinics.

Initially this spacer will be used mainly to treat bone tumours that are covered by insurance for particle therapy treatment.

The team hopes to expand the use of this spacer alongside the expansion of insurance coverage for particle therapy, ultimately using it to treat conditions such as pancreatic and liver cancers.

Currently two kinds of treatment are used in clinical settings: proton therapy (using protons) and heavy-ion radiotherapy (using carbon ions).

Particle beams display a physical trait called the Bragg Peak, which can be used to focus the dose of radiation to target the tumour.

This also enables us to reduce the impact on healthy tissue.

Compared to X-rays, proton beams and carbon ion beams are very effective.

If we take the relative biological effect on organisms as 1, the effects of proton and heavy ion beams are 1.1 and 3, and there are high expectations for effective treatment against radiation-resistant tumours.

Source: Kobe University