Radiotherapy’s Radical Evolution: Q+A with Lisa A. Kachnic, MD

Reflections is a series featuring Columbia cancer experts, looking back at how far we’ve come in advancing and impacting change in research, treatment, care, and survivorship, and their perspectives on what lies ahead.

March 24, 2022

Lisa A. Kachnic, MD, a pioneer in radiation oncology, discusses the advancements made in the field and the innovation to come.

Your career in radiation oncology spans more than 20 years. What was the field like when you stepped into it as a trainee?

When I trained over two decades ago, we treated cancers with radiation in a very rudimentary two-dimensional fashion. For example, I took an x-ray of a patient’s abdomen and with a protractor and some colored crayons (often channeling my inner Picasso), reconstructed a pancreas cancer and the normal organs around the cancer (the kidneys, the small bowel, the liver, the stomach). Heavy lead blocks were then made to block out some of the normal organs from the radiation beam. Despite my best efforts, parts of the normal adjacent organs received the same radiation dose as the cancer and this significantly contributed to a patient’s side effects.

How has the field changed? Have your crayons been replaced with a newer technology?

Currently, we treat pancreas (and many other cancers) with a four-dimensional technique using CT and other advanced imaging technologies in which we consider both tumor and organ motion. Instead of drawing the tumor and normal organs on an x-ray with my crayon, I contour the tumor and normal organs on each 2 mm computer slice of the patient’s planning CT and now paint the dose of radiation to the tumor while sparing the normal surrounding organs through the aid of small metal leaves that are connected to the head of the radiation machine. Moreover, with increasing precision and built-in CT images, which all of our state-of-the-art new radiation machines here at Columbia allow for, we can also treat pancreas and other cancer in much shorter courses (5 treatments instead of 30) and much higher doses. This has allowed for safely increasing the radiation dose to the cancer, and in turn, improving cure rates. And it is also more convenient for our patients.

So you’ve seen a lot of change in radiation oncology treatments in the past two decades. Looking back, was there a defining moment that had the greatest impact on you and your career?

I credit several mentors for meaningfully impacting my career. An early, and continuing, role model was Anthony Zietman, MD, interim chief of the Department of Radiation Oncology at Massachusetts General Hospital-Harvard University. He stressed the radiation oncologist’s role was so much more than pushing a button to destroy cancer cells. Instead, he counseled, the most effective way to contribute to care is to address the whole patient and learn what is most valued by that patient and their family. I’ve embraced this important lesson throughout my career and strive to share these skills with our future generations of radiation oncologists.

Let’s talk more about how the future of cancer radiotherapy is shaping up.

We are always assessing novel, more effective methods to deliver radiation in the interest of optimizing cure, reducing side effects and providing the patient with the best quality of survivorship. While we have made significant improvements over the last two decades in all three of these goals for both adults and children, we can always strive for more.

While we may not find the ‘magic cure’ for all cancer types in my career despite all the advances, including combining radiation with immune-oncology, I am certain that we will make great strides in further improving radiation driven cancer outcomes and quality of survivorship.

Clinicians discuss in front of new ETHOS AI-driven radiation machine.

Drs. Lisa Kachnic (right) and Michael Price in front of ETHOS, new AI-based adaptive radiation accelerator machine. (Credit: Noel Casiano)

What are the biggest problems that you are focusing on today?

We still need to understand why some cancers don’t respond to radiation. For example, when we treat esophagus cancers with radiation and chemotherapy followed by surgery, only about 1/3 have no tumor cells remaining at the time of resection. The issue is that we just don’t understand the underlying biologic mechanisms that drive this radiation response. We believe that it is a combination of variables including factors within the cancer (such as genetic alterations) and influences from the environment around the cancer (such as the surrounding immune cells). Our radiation team in collaboration with leading investigators from the Center of Radiological Research and HICCC are working together to answer this important question. It is this community citizenship that will ultimately advance our scientific knowledge base driving improvements in cancer outcomes though the development of personalized radiation-based strategies.

Personalized cancer treatment is the ultimate goal. How is the field getting there?

Our radiation treatments are becoming “smarter.” Currently, radiation therapy planning is a complex process that can take up to two weeks to prepare and test before the patient receives the first dose. Once treatment begins, the patient is positioned the same way during each session to ensure that the radiation is delivered to the intended location. Imaging attached to the treatment machine may be used to help align the patient before each treatment, but these scans cannot be used to quickly alter a patient’s treatment plan. If a tumor shrinks after several weeks of treatment, the patient still receives radiation designed for the full-sized tumor from the original plan. We can create a new plan based on these changes, but it frequently leads to a pause in a patient’s course of treatment since it requires an additional CT scan and several days to create a new plan from scratch.

Instead of reconfiguring from scratch, what’s the next big idea?

We now have a new radiation delivery system, called the Ethos (Varian, A Siemens Healthineers Company), the only such machine in New York City, which leverages artificial intelligence to create a new personalized plan in minutes instead of days or weeks. The plan is automatically recalculated based on the shape and size of the tumor and the location of a patient’s internal anatomy during each treatment, allowing us to offer a highly personalized treatment experience. That means potentially better cancer control while simultaneously further reducing radiation side effects.

So much exciting change has happened in this field and it’s ever-evolving. What part of being in this field continues to  drive you?

While I love making a difference in the lives of patients, and discovering improved cancer treatments, it is my role as mentor that is most gratifying. It’s great to see the residents and young faculty who circle back, years later, and give me a big hug of thanks for making a positive impact on their lives and careers. Many of my earlier mentees are now department chairs or national leaders in the field. It’s really all about achieving the best cancer outcomes. With mentoring, you get to pay it forward for the good of all the patients and their families.


Lisa A. Kachnic, MD, is a nationally recognized pioneer in radiation oncology. Her contributions to the field are fueling advancements in radiation oncology research, including investigating novel techniques to deliver tailored, highly customized radiation therapy to cancer patients. Dr. Kachnic is associate director of Cancer Network Strategy and member of the Cancer Population Science program at the Herbert Irving Comprehensive Cancer Center; the Chang Professor of Radiation Oncology and chair of the Department of Radiation Oncology at Columbia University Vagelos College of Physicians and Surgeons; and chief of the Radiation Oncology Service at NewYork-Presbyterian/Columbia University Irving Medical Center.