Oncologists should look upon imaging as another biomarker, not just an anatomic picture

Annick Van den Abbeele, MD, couldn’t believe her eyes. Dr. Van den Abbeele, the chief of radiology at Boston’s Dana-Farber Cancer Institute, had seen the patient just a month earlier. At that time, the 35-year-old woman had a gastrointestinal stromal tumor in her abdomen that was so large, she looked six months’ pregnant. But at the patient’s follow up FDG-PET study, the tumor was completely gone.

“I had never seen that dramatic response before. At first, I thought it was the wrong patient,” Dr. Van den Abbeele said. “So we started checking the patient’s earlier imaging studies. I could see intense [radiotracer] uptake in the beginning, and then a month later, I could see the ghost of the mass in the liver, but I couldn’t see the mass. That’s when I realized we were on to something.”

What Dr. Van den Abbeele was looking at was the first GIST patient in the U.S. who was successfully treated with imatinib (Gleevec). She immediately put in a call to the referring physician, George Demetri, MD, the director of the center for sarcoma and bone oncology at Dana-Farber, and the principal investigator for an imatinib clinical trial. “It’s one of those moments where he told me that he still remembers what he was doing that day when I called him,” she said.

Dr. Van den Abbeele told this story at ASCO 2009 in Orlando to illustrate a key message of her talk on how oncologists and radiologists must work together to optimize patient care. The education session was jointly sponsored by ASCO and RSNA.

“Imaging has become an in vivo assay that provides unique information regarding tumor mechanism and how it responds to treatment,” she said. Modern modalities, such as MRI and PET, go way beyond anatomy, allowing clinicians to take a peek inside the tumor and its environment, she added. Imaging can assess how cancer grows; how drugs act on the cancer cells and the vessels that feed them; and how tumors respond to conventional and novel therapies, she explained.

“This use of imaging as a biomarker is very critical to the decision-making process and the management of patients with cancer,” said Dr. Van den Abbeele, who is also the founding director of the Center for Biomedical Imaging in Oncology at Dana-Farber Cancer Institute. Good communication between radiologists and oncologists is the cornerstone of excellent cancer care, Dr. Van den Abbeele said, offering some ways to foster the cancer care-imaging connection.

Defining personalized medicine
The traditional way of assessing tumors is to use linear measurements based on cross-sectional images. This method is valid when traditional cytotoxic chemotherapy is used because the tumor is expected to shrink. But linear measurements may be inadequate to assess response to molecular-targeted drugs. “These novel drugs stop tumor growth by blocking a molecular mechanism specific to the tumor cell,” she said. “Metabolic changes within the tumor may actually precede changes in tumor size by weeks and months.”

“It’s important to remember that tumor response assessment using RECIST does not take into account the changes in metabolism or density in tumor masses, so you can sometimes misread patients as having progressive disease when they are actually responding to treatment,” she said.

Maintaining communication between the oncologist and radiologist is important so that images are read within the right context, Dr. Van den Abbeele emphasized.

“A lot of effort is being applied to reevaluate tumor response criteria and to go beyond unidimensional or bidimensional measurements,” she said. “However, prospective clinical trials are needed to validate imaging measurements and have them be accepted by oncologists.”

Added value
Consider imaging as an add-on value to the clinical and research mission of your institute or practice, Dr. Van den Abbeele advised.

“Radiologists should not be thought of as push button providers. There is so much more to add to the interpretation if we communicate with the oncologist,” she said. “This is why I advocate an open-door policy in my department. We as radiologists need to remain open to being educated by oncologists, and also to educate oncologists about the possibilities that imaging can offer.”

She suggested that strategic planning between radiologists and oncologists needs to keep in line with what services are actually needed. For example, when the Dana-Farber radiologists quantified how much time they were spending giving second-opinion readings on studies that had been done elsewhere, they persuaded the institute to fund a designated radiologist who would be available each day for second readings.

“The Dana-Farber is a large second-opinion center, and the clinicians use us to re-read scans for them. It’s not uncommon for us to change a reading. Although this requires a lot of time, it’s important for us to deliver this service to the clinicians,” she said.

This consultation system has been so successful that when the new Yawkey Center for Cancer Care was designed (it’s slated to open in 2011), the oncologists wanted a second-read radiologist placed on all seven floors.

“That’s a lot of radiologists and it was just not feasible,” Dr. Van den Abbeele said. “We compromised and settled for one second-read radiologist for every three floors. But this just illustrates how valuable that service has been.”

Providing access
It’s important that imaging be perceived as a facilitator and not a gatekeeper, Dr. Van den Abbeele said. The idea is to balance imaging research with the development of imaging strategies that can be translated quickly into clinical use.

The Center for Biomedical Imaging in Oncology has been established at Dana-Farber with two main missions. First, it’s designed to support interdisciplinary collaboration between clinical imaging and pre-clinical imaging. Second, it supports translational research, allowing access to data by disease-focused investigators, basic scientists, and others who are interested.

Dana-Farber, along with the Harvard Cancer Center, also has created the Tumor Imaging Metrics Core (www.tumormetrics.org), which offers standardized, longitudinal, radiological measurements for clinical trials at all the institutions affiliated with Harvard.

Participation counts
Oncologists and radiologists have worked closely since both specialties were established. But medical institutions and departments are often organized in a vertical fashion, Dr. Van den Abbeele said, so that each entity becomes self-contained and self-sustaining.

“Patients, on the other hand, are confronted with problems that require a horizontal approach, that is, a strategy that takes into consideration all the aspects involved in problem-solving,” she said. “Radiologists need to become less image-centric and more disease-centric.”

Joining administrative, executive, and scientific committees within an institution is one way for both specialties to move toward a more horizontal approach. She also suggested involvement in educational activities such as residency and fellowship programs.

Finally, Dr. Van den Abbeele encouraged both specialties to keep up with each other’s national organizations, such as ASCO and RSNA. “If you work in a vacuum, you are not going to address relevant clinical questions, and in the end, are not going to help,” she said.