At home, I have trouble working the audio-visual system. A few years ago, my husband bought a television set for our family room with a huge screen, for better sports and movie viewing. Gradually components were added on—a surround sound system, the keyboard to stream video from Netflix, the standard DVD player, and, a gift from a movie loving friend who knows how much I like foreign language films, a DVD player that plays movies released only in Europe. The composite system required, at one point, five or six different remote controls to run and I was hopeless until Mick at the meat counter informed me that you could buy a single remote controller by Logitech that could run EVERYTHING. I invested in one at Best Buy, but I confess–I still have no clue how to work it.
It is a mystery to me why I cannot figure out how to work the television or the coffee maker, but the inner workings of linear accelerators and cyclotrons, and the generation of high energy X-ray, electron, and proton beams pose no problem. Thirty two years ago, when I started in radiation oncology, our tool box was very limited—treatment planning systems were rudimentary and “two dimensional”—in other words we could only visualize and calculate the trajectory of a beam from each direction separately, and sum the total, in one cross sectional plane of a patient’s body. Two developments in the last generation changed all of that: three dimensional treatment planning, where the body is reconstructed from a series of CAT scan images, along with intensity modulated radiation therapy, where the beams can enter the body from 360 degrees of rotation where tungsten rods not only shield the normal structures from every direction but also enter the path of the beam to block the “overshoot” of tissues beyond the tumor. “Star Wars” technology met radiation therapy at the turn of the millennium.
The last ten years have brought a new revolution in radiation oncology—the advent of the proton center. In November I had the opportunity to spend a full day at an orientation for the new Scripps Proton Therapy Center here in San Diego. Six years ago, I traveled to the existing proton facilities at Loma Linda, University of Florida, Massachusetts General Hospital and MD Anderson as part of a task force to determine the feasibility of my own institution building such a center. I was surprised at that point in time to discover that the technology of proton beam radiation therapy had not advanced since my old days at the Harvard Cyclotron in the early 1980’s. The opening of the new Scripps Center will change all that—for the first time a scanning “pencil beam” of high energy protons will be able to “dose paint” the radiation directly onto the exact shape of the tumor, delivering the fastest, most accurate and potentially the least toxic radiation therapy ever.
So what does this mean for patients in an era of cost reduction and intensive scrutiny of new technology? Of the utmost importance, it means that more and more children with cancer will be treated with a method which will not only save their lives, but will significantly reduce the risk of secondary complications from the radiation. In 2010, 465 children with cancer were treated with protons. In 2012 this number rose to 695. For the children who receive cranio-spinal radiation for brain and spinal cord tumors, this means a 7 to 12 fold reduction in secondary malignancies and a significant reduction in loss of IQ compared to standard radiation therapy. For patients previously thought to have incurable cancers such as hepatocellular carcinoma, local control rates of up to 80% are being achieved. For patients with brain or spinal cord or bone tumors in critical areas which abut sensitive normal tissues, it may mean the difference between sight and blindness, or ambulation versus paralysis.
The critics of proton beam therapy cite the fact that the majority of patients currently being treated with protons are prostate cancer patients, where as yet no real benefit has been shown in terms of survival or complications over intensity modulated radiation therapy. This may change as we select younger patients with more aggressive cancers for the treatment. In the meantime, I remain as excited by this technology as I was when I first followed the physicist into the cluttered old cyclotron building on the Harvard campus in 1982. Next month the techno-freak in me will be privileged to participate in the most advanced radiation therapy the world has ever seen.
Thank you to Dr. Carl Rossi for the statistics provided in this entry.