Proton therapy for cancer treatment has arrived in Israel and the Middle East with a clinical trial underway that sees Hadassah Medical Center partnering with P-Cure, an Israeli company that has developed a unique system designed to fit into existing hospital settings.
Begun a month ago, the trial’s first stage is for patients with brain, head and neck cancers that have been previously irradiated but have now recurred. Patients with other types of cancer are to be included later on.
In addition, Tel Aviv Sourasky Medical Center – Ichilov Hospital was set to sign on Thursday an agreement with Medtechnica, the Israeli partner of IBA, a Belgian company that is building the largest and most advanced medical proton accelerator machine in the world.
“The Health Ministry has granted us the only license to operate a national proton therapy center. We were deemed to be the best fit and we have begun building a designated building,” said Dr. Natan Shtraus, chief of medical physics at Ichilov.
The building will house two treatment rooms, each with a machine, and should be completed in three to four years.
As its name suggests, proton therapy uses a proton beam rather than conventional X-rays (photons) in radiation therapy. The advantage of the proton beam is that it is more precise and less toxic to surrounding healthy tissues.
Reducing or eliminating the debilitating side effects of radiation is a key issue. Some 50 percent of cancer patients undergo radiation therapy at some point, often in combination with surgery, chemotherapy and/or immunotherapy.
“Photon X-ray radiation most damages the tissues right as it enters the body, and then the beam continues hitting the tissue all the way through. The maximum damage occurs initially, and then the beam gets to the tumor. Then it continues damaging the tissues behind,” said P-Cure founder and CEO Dr. Michael Marash.
He explained that a workaround helps deliver more of a therapeutic effect, “but at the end of the day, the whole body gets the radiation and that’s not safe,” he added.
In contrast, proton therapy delivers a beam of particles that stops at the tumor and doesn’t affect nearby healthy tissues.
A study published in the Journal of the American Medical Association (JAMA) in 2020 showed that patients treated with proton therapy were much less likely to suffer severe side effects. However, there was no difference in how long the patients lived.
Some in the medical community have argued that the jury is still out on whether proton therapy is truly the superior option and worth the expense until phase 3 randomized clinical trials are conducted.
Proton radiation therapy for cancer treatment has existed since the mid-1950s but was rarely employed. It came more into use beginning a couple of decades ago, but despite its perceived advantages over traditional X-ray radiation treatment, only about one percent of hospitals and cancer centers worldwide adopted it due to the costs involved.
Not only are the systems themselves expensive — in the range of $200 million — but their sizes usually require the construction of specially dedicated buildings with shielding walls three to five meters thick. The rooms being built at Ichilov Hospital will be 12 meters high and designed to accommodate the 70-ton systems, which include the proton beam accelerator along with imaging and monitoring equipment.
Individual cancer patients have also borne tremendous costs. Israelis opting for proton therapy have until now had to fly abroad for treatment and pay an average of $100,000 themselves.
The machines that Ichilov will acquire will have a full gantry, meaning that the proton beam will be rotated around the patient, who is lying down.
“We prefer to do proton therapy with the patient lying down because this is a much more stable position. It also is the only way you can treat patients under anesthesia — mainly children,” Shtraus said.
“Also, tumors move. There is no midline in a tumor. Therefore, it is better to keep the patient stable and move the gantry around them,” he said.
Shtraus gave the example of medulloblastoma, a cancer of the central nervous system and the most common cancerous brain tumor in children, requiring irradiation of the spine. He said that with proton therapy, children’s and pregnant women’s spines can undergo treatment leaving their “bellies clean.”
P-Cure’s approach is different. It has developed a less expensive system that is more compact and can fit into existing medical facility radiation vaults. This machine has the patient sitting up and repositioned around the beam. The idea is to achieve better angles for the proton beam to hit the tumors.
“Our approach is called adaptive therapy. Based on the knowledge or understanding of where the tumor is thanks to the imaging and navigation system, we can re-plan the treatment to the actual status of the tumor and the patient at every session,” Marash said.
The P-Cure system integrates the proton beam with an oncology CT machine and low-dose X-rays that always track the location and morphology of the tumor so that a patient’s treatment plan can be recomputed.
“Proton therapy requires knowledge on where to shoot. If we don’t know and end up shooting nearby, it will create very few side effects, but the efficacy won’t be the greatest. So what our company did by introducing the adaptive therapy is to take a ‘seeing is believing’ approach. This enables us to treat not only the tumors that do not move but also tumors that are constantly in a dynamic mode,” Marash explained.
P-Cure built a special vault just outside Modiin for the proton machine being used in the clinical trial with Hadassah. Prof. Aron Popovtzer, head of the oncology department and the Sharett Institute of Oncology at Hadassah, told The Times of Israel that there are a lot of firsts associated with the study.
“This is the first time we are treating with protons in Israel, and we are also studying irradiation where the patients pivot around the beam,” Popovtzer said.
“In addition, the study is unique in that it is not only looking at toxicity and patient survival rates, but that it is also comparing standard X-ray treatment to proton therapy head-to-head,” he said.
The patients are not undergoing two types of radiation. Rather, it’s a matter of planning and decision-making. The medical staff checks the capability to treat each patient with the standard treatment and compares that with how it looks in terms of the proton treatment.
“And then we treat according to what’s better for the patient,” Popovtzer said.
According to Popovtzer, the cases involved in the trial are “devastating and aggressive.”
“The ultimate goal here is to work to find new ways to improve our outcomes for patients with advanced cancer for whom we think that regular radiation is not good enough,” he said.