Imaging Prostate Cancer
Posted: Nov 01, 2018
POSTED: July 05, 2017
Dr. Anthony D’Amico is Professor of Radiation Oncology at Harvard Medical School and Chief of the Division of Genitourinary Radiation Oncology at Brigham and Women’s Hospital and Dana-Farber Cancer Institute in Boston, Massachusetts.
Prostatepedia spoke with him about advances in radiation oncology for prostate cancer.
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Dr. Anothony D’Amico: I was studying physics at Massachusetts Institute of Technology (MIT) when I was assigned jury duty. Believe it or not, one of the other jurors was a woman who later became my wife and whose mom happened to be the head of infectious disease nursing at a Boston hospital. I got exposed to medicine from her perspective. Then, when I was in graduate school, I lost a woman who was a second mom to me during my childhood to breast cancer. After that, I decided to cross-register at Harvard Medical School, which I could do as an MIT student. I took introductory medical school classes—anatomy and physiology. I had an amazing experience and discovered that the medical students sitting next to me in the classroom were much more like me in terms of their desire and ability to want to help others than the graduate students sitting next to me at MIT in my physics courses.
I completed my PhD at MIT in radiological physics and decided to go to medical school. It was an eight-year commitment. At that point, it meant starting all over again, but it definitely was the right decision. I have never regretted that decision nor looked back. I’m extremely grateful. The lesson I learned is that just because you’re good at something doesn’t necessarily mean it’s what you should do. I was really amazing at physics and I’m great at medicine now, but I wasn’t great at medicine when I started.
It’s funny the path life takes you on.
Dr. D’Amico: There are no accidents. Everything happens for a reason.
What are the current points of controversy and/or trends in the field of radiation therapy for prostate cancer?
Dr. D’Amico: First of all, one of the most significant advances in our technical approach to radiation is image-guided radiation therapy (IGRT), which builds on intensity-modulated radiation therapy (IMRT).
Two decades ago, we had nothing to guide radiation treatment other than a regular x-ray, which only showed the bone. X-rays couldn’t see anything else: not the organs, not organ motion, not respiratory motion, nor any other factor that might go into making radiation therapy more precise.
From x-ray, we went to CT-based planning that allowed us to see some structure, but still didn’t fully account for motion.
Today, we have image-guided radiation therapy. We put markers in the organ—three gold seeds into the prostate or liver—and then take a picture each day, which shows us exactly where the target is. Using IMRT, we can create a radiation treatment that can treat a cancer the size of a dime with millimeter precision.
And we can account for motion. We can take pictures sequentially over seconds so that we can see how far the treatment area moves in one direction or the other when the patient is breathing. We can then sculpt the volume to account for respiratory and/or organ motion so we don’t miss the target.
Right now, we’re on the cusp of going from CT-based IMRT to MRI-based IMRT. MRI is a more sophisticated way of imaging structures that CT scans can’t see. For example, the very bottom of the prostate, where the nerve bundles that control erectile function reside, is not very well visualized on CT scan, but it is very well visualized on MRI.
We’re just now building machines that incorporate PET/CT that use functional imaging into radiation treatment planning and delivery. This means that we will be able to actually monitor the progress of a treatment as it is being delivered over the course of several weeks. We can see whether the cancer is now dead in a certain area or not, which means we can, in turn, modify treatment volume to make it smaller as we go along and only treat areas with still-viable cancer.
This is where we are right now in 2017. During the next five years, I expect that we’ll be able to use functional imaging to guide and sculpt your treatment while it is actually happening in real time.