Christopher Crane, MD
Novel radiation technologies, such as MRI-guided radiation treatment and proton radiation therapy, are the way of the future for image-guided radiotherapy in gastrointestinal (GI) malignancies, according to Christopher Crane, MD.
“Both of these modalities enable us to overcome limitations that we have had in the past to deliver definitive curative doses of radiation,” he said.
During the 2017 OncLive®
State of the Science SummitTM
on Gastrointestinal Cancers, Crane, vice chair of the Department of Radiation Oncology at Memorial Sloan Kettering Cancer Center, discussed modern innovative techniques in GI cancers. In an interview during the meeting, Crane shed light on the progress of these technologies in pancreatic cancer and hepatocellular carcinoma.
OncLive: Please provide an overview of your presentation.
My talk focused on some of the newer technologies and the applications of those technologies in GI malignancies, and how that is producing better outcomes as definitive treatment. Specifically, there is proton therapy for liver tumors, and the image-guided therapies, specifically magnetic resonance linear (MR-Linac) accelerator that enables us to deliver more precise treatment to tumors that are near the GI tract.
Many tumors can be controlled and cured with high enough doses of radiation, but the problem is that the GI tract is very sensitive to radiation. If we are indiscriminate about where the radiation goes, we can only give a palliative dose. That is the way things have been for the past 40 years.
These new technologies have helped up overcomes those limitations, with pancreatic cancer as an example. We are giving 2 to 3 times the normal dose of radiation to these malignancies, and we have now—for the first time ever—a tail to the survival curve. This is something that is very difficult to do, and the limitations are that you have internal organ motion to deal with. Either it is respiratory motion or you have day-to-day organ motion, so you must have solutions for those challenges. These tools, specifically the image guidance, help us overcome those challenges. These are things that I have innovated over the past 10 years—using tools that are not as good as this.
The MR-Linac accelerator will make it possible for people who are practicing at smaller institutions, including community practices, to perform this treatment. For instance, I have worked at large institutions, such as The University of Texas MD Anderson Cancer Center and Memorial Sloan Kettering Cancer Center, where we have a huge physics team and sub-specialized physicists who can come together as a team to overcome these challenges. This machine makes it easier for people in smaller practices to replicate that. That makes this treatment scalable, whereas before it was something that only academic places could do.
In the near future, 5 years or so, you'll see other institutions reproducing what we have done, and some people have already started to do that with this tool and have results that are very similar. By that, I mean unprecedented results that have appeared to be better than surgery—all without an operation. The results from Washington University in St. Louis indicate that 80% of patients are alive at 20 months with locally advanced unresectable pancreatic cancer. Normally, you have about 20% alive, so it’s not even close. This isn't [based on] selection because there is no way to select patients like that. We have similar outcomes, but with a 9-year follow-up. The bottom line is that it gives people hope, it’s not a solution for all pancreatic cancer but it does give people hope to experience a similar outcome to what an operation would be—as this is for inoperable patients.
A similar thing is possible with liver tumors. We are able to ablate very large liver tumors, but proton therapy would be what we would select in that situation because it is able to spare the liver better. The liver is very sensitive to radiation, but small amounts of the liver can take very high doses. We want to protect a certain fraction of the liver, about one-third to one-half, similar to how a surgeon would. We want to protect that portion from radiation and that is what proton therapy does, it enters the body and stops at whatever point we want it to.