When I was a radiation oncology resident in Boston in the early 80’s, a few brilliant minds in physics and medicine came up with the notion that it would be a good idea to treat certain cancers with a beam of protons. Protons are the positively charged particles which are created with a hydrogen atom is split into its component parts, a proton and an electron. When accelerated towards a human being by means of a cyclotron, the proton has a unique characteristic compared to the regular x-ray beams we radiation oncologists use—it rolls into the body creating very little disturbance at the surface, comes to a stop at the tumor to do its damage, and unlike an x-ray, or photon as we say in the business, it does not exit the body leaving injured cells in its wake. It just stops.
This makes proton radiation therapy ideal to treat children, where the entrance and exit doses of radiation can cause growth defects and trigger secondary malignancies years and years down the line. But the first patients treated back at the old Harvard Cyclotron were not children—they were old men with advanced prostate cancer, where conventional therapy with the doses needed to control the disease had a high likelihood of rectal damage. My job, as the resident, was to insert a balloon into the rectum of said patients, to separate the posterior rectal wall from the prostate gland. Each day I would hitch a ride with our physicist over to the huge brick building which housed the cyclotron, insert and inflate the balloon, and wait while the patient was treated. I didn’t mind a bit—the technology was new and exciting, and the physicist was very handsome.
Thirty years later, I toured the new proton facility in San Diego, where my university, along with other institutions will soon be allowed to treat patients. The building itself is massive, over 100,000 square feet. There are five gantries and treatment rooms, and once the facility is up to peak capacity, the cyclotron will run sixteen hours a day, treating over 2,000 new patients a year. At 8pm this evening, a team of six engineers was still hard at work in the control room, honing the precision of a beam which will be responsible for curing cancer, for saving lives.
Patients with every kind of cancer will be treated here, but in the end, the population which has lived the longest and has the economic wherewithal to seek out the best and the latest treatments—our prostate cancer patients—will be the bread and butter volume income supporting the treatment of the youngest and most vulnerable of our patients, the pediatric cancer patients. As one of my old colleagues who treats the kids at Massachusetts General Hospital said to me a few years back, “Finally we have protons in the clinic, and I can sleep again at night, not worrying about the horrible late effects of radiation on my pediatric patients.”
Many things have changed about the way protons are produced and utilized in radiation therapy over the thirty years since I was a resident, but some things remain the same—as we were touring, one of the physicians mentioned that rectal balloons are still used to stabilize the prostate away from the rectum during prostate cancer treatment. I smiled inwardly and thought to myself, “Yes, but this time it won’t be me putting the balloons in.”
San Diego is about to join a small cadre of cities that boast the best, most advanced and safest radiation technology available to cancer patients. And I say, “Long live the Brotherhood of the Balloon!”
Miranda Fielding is a radiation oncologist who blogs at The Crab Diaries.
