Friday, July 12, 2019

Proton Therapy

There are more than 200 different types of cancers. According to the US National Cancer Institute, nearly 40% of Americans will be diagnosed with cancer during their lives. The World Health Organization names cancer as the second leading cause of death globally, causing nearly one in six deaths. In case anyone needs reminding, cancer is a big deal. Lung cancer is the leading cause of cancer deaths around the world, causing more deaths than prostate, breast and colon cancers combined. Only 18.5% of patients will survive five or more years after being diagnosed with lung cancer. So smokers, take note! Alongside chemotherapy and surgery to remove tumors, about 40% of cancer patients are treated with radiotherapy, which fires ionizing radiation into the body, killing malignant cells with X-ray photons. Roughly 17,000 clinics worldwide deliver X-ray radiotherapy treatment today.

The rise in popularity of proton therapy (vs X-ray) is continuing across the globe. It is estimated that more than 165,000 patients suffering from a variety of cancers, such as prostate cancer, brain tumors, etc. have already been successfully treated using this method. In fact, the proton therapy market is on track to become a multibillion-dollar industry by 2024. The number of proton therapy centers is increasing globally. Still, industry experts believe that players will miss out on a majority of cancer patients who can benefit with proton therapy, overlooking a huge multi-Billion-dollar potential market.

The proton therapy market is likely to almost double by 2024 from its current market value.  Globally, the numbers of patients treated with proton therapy is very low whereas the potential candidates for it are in the Millions.

Shortly before 1975, I had started promoting Varian’s Clinacs throughout the Middle East (back then it was not yet proton beams but x-ray and electron beams) and Linacs (for inspecting fully loaded shipping containers). Unfortunately, the effort died in its track because of the Lebanese civil war and by October 4, 1976 I reported to work in Zug, Switzerland, not for the Medical group but for the Industrial Product Operation which was mainly semiconductor equipment and instruments based around high or ultra-high vacuum technology.

While I never got to sell any Clinacs or Linacs, at least I was for a very short period exposed to the technology (including a visit to Palo Alto where they were manufactured). The technology had been pioneered years earlier at the then 2-mile long SLAC (now 3-mile accelerator) of Stanford University, by Dr. Edward Ginzton, a Ukrainian-American engineer and Bill Hansen. As a student at Stanford, Ginzton worked with William (Bill) Hansen and brothers Russell + Sigurd Varian. In 1941 he became a member of the Varian-Hansen group at the Sperry Gyroscope Company and some years later joined the Varian brothers on their board of directors at Varian Inc. in Palo Alto, California. 

Actually, the first clinical Van de Graaff generator treatment was done at Harvard’s Medical School in 1937. 

In 1972, a Dr. Peter Fessenden joined Stanford and began developing a linear accelerator that combats tumor cells using two types of radiation. Working with Varian Medical group, Fessenden’s team creates the first linear accelerator that combined both X-ray and electron treatment.  So, Varian holds the claim to fame for developing the first medical linear accelerator in cooperation with Fessenden and his team. Since then, the company has developed a portfolio of technologies to treat and manage cancer, including equipment for radiotherapy, radiosurgery, brachytherapy, and proton therapy. Seems their Linac line for shipping containers either didn’t fly or got sold off; I lost track of that line long ago though I’m partly back in that fold with gamma ray detectors mainly as a tool to counter potential radiation terrorism (homeland security type equipment).

But post-WW2, cobalt therapy was the medical use of gamma rays from the radioisotope cobalt-60 to treat cancer. It was then widely used in external beam radiotherapy machines, which produced a beam of gamma rays which was directed into the patient's body to kill tumor tissue. Radiotherapy doctors were not yet hot on clinical linac technology; it was not yet the tool of choice. Indeed, when I started peddling Clinacs to any medical center with a semblance of serious oncology department, my main technology competitor was Cobalt-60 systems which back then were fairly well established in most Western nations.     

Philips introduced their SL25 in 1985, it was the “first fully digitally controlled” medical linear accelerator. They continue to be in many other medical equipment but no longer in proton therapy systems.

In proton therapy, the proton beam is generated through use of a particle accelerator, which uses electromagnetic fields to accelerate protons to very high energies. The use of protons to deliver radiation therapy allows physicians to maximize the radiation dose to the treatment target, while minimizing the adverse effects of radiation on the surrounding healthy tissue. (For those of you who no longer remember kindergarten physics, protons and neutrons makeup the nucleus of atoms.

Similar to traditional X-ray therapy, proton therapy is an external beam radiation therapy technique. High-energy protons deposit radiation dose in a more targeted manner than X-rays. When protons enter the body, they only leave a small amount of radiation along their path as they pass through the tissue. Upon reaching a specific depth, protons deposit a large focused amount of radiation and then stop, leaving virtually no radiation beyond that depth.

Today, while clinical linear accelerators are available in approximately 65 facilities worldwide. A few very poor nations in Africa and Latin America also have such capabilities, though probably far too few for the size of some of their populations. Not only do they need the therapy machine but also the imaging techniques as well as the sophisticated software programs dedicated to that type of intervention. It amounts to millions and millions in investments. The dominant players in proton therapy are IBA, Mitsubishi, Optivus, Hitachi, Mevion, Varian, ProNova, Sumitomo.

One shortcoming of stand-alone proton machines as seen below is they suffer from the same inherent issues that all cyclotrons and synchrotrons do, such as slow beam-energy modulation that’s problematic for accurate targeting. It can be overcome by adding a therapy station on a beamline, but this can mean systems with the footprint of a sports field, impossible for most hospitals. So, many accelerator labs worldwide have extended their beamline capabilities to include a “home-made” radiation therapy ward. It’s the case for South Africa, near the Stellenbosch wine country, iThemba have a therapy ward. In Switzerland, at the Paul Scherrer Institute, they rank among the most advanced for ophthalmology cancer therapy. In Geneva, Proton Beam Therapy and CERN hadron technology are fighting cancer with LIGHT; this accelerator produces a proton beam of 230 megaelectron volts traveling at 60 percent of the speed of light, almost 181 million m/s !


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