Experts Debate Controversies Surrounding Hodgkin's Lymphoma
Monday, Nov. 30, 2015
When should radiation therapy be used to treat patients with Hodgkin's lymphoma?
That question is becoming somewhat controversial according to Karen Winkfield, M.D., Ph.D., director, Hematologic Radiation Oncology, Massachusetts General Hospital, during the Sunday session, "Oncodiagnosis Panel: Hodgkin's Lymphoma: Current Controversies."
One problem facing radiation oncologists is that their medical oncology colleagues are often hesitant to send patients for a radiation therapy consultation because of concerns about associated toxicities.
"Back in the day there were many side effects accompanying radiation therapy," Dr. Winkfield said. "But remember, Hodgkin's lymphoma is often curable. We have cure rates for patients in stages 1 and 2 that are well above 90 percent, so we always have to be thoughtful about the actual volume of tissue that we are irradiating. With modern radiotherapy, radiation oncologists have dramatically changed the way we both deliver and the tools we use in order to determine how we deliver radiation therapy."
For example, 3-D conformal radiation therapy provides better shaping of the beam, improved visualization of the tumor and surrounding normal tissue and better dosimetry, she said.
These newer technologies and techniques help reduce the amount of radiation patients are exposed to, and by extension, the acute and later toxicities they experience.
"For much of that we depend heavily on our radiology colleagues in terms of not only what they are imaging, but how they report that imaging and where they see sites of the disease," she said. "And unlike when we just treated all the node areas, now we are honing in on involved node and involved site radiation therapy."
Assessment Criteria Revised
In another presentation, Steve Y. Cho, M.D., of the University of Wisconsin-Madison, discussed the latest developments surrounding the role of imaging for response assessment in Hodgkin's lymphoma, including recent revisions to response assessment criteria.
These revisions—the Lugano Classification published in 2014—update guidelines issued in 2007. According to Dr. Cho, one of the differences between the two is that the Lugano Classification involves CT-based response criteria.
The 2007 criteria examined whether or not a patient was a complete responder based on metabolic PET information, regardless of how much the tumor shrank. The Lugano Classification reaffirms that a patient is in complete remission—even with a residual mass—as long as the mass is not FDG-avid.
However, "it actually reintroduced some CT-based response criteria," Dr. Cho said. Now, a partial response to treatment requires a decrease by more than 50 percent in the sum of the product perpendicular diameters of up to six targeted lesions, while a progressive disease assessment requires only an increase of a single lesion by 50 percent.
Oncologists and Radiologists Forming Closer Partnerships
In a third presentation, Satish Shanbhag, M.B.B.S, M.P.H., pointed out that evolving changes in therapeutics are forging closer partnerships between oncologists and radiologists.
For example, immunotherapy for Hodgkin's lymphoma is one area that "we really need more collaboration between oncologists and radiologists," he said.
In one issue involved with immunotherapy—pseudoprogression—treatment sees a delayed clinical response in which an increase in tumor burden is later followed by tumor regression.
"So it's important for us to assess responses not just with a knee-jerk reaction to the first scan," Dr. Shanbhag said. "We have to wait for the second scan. It's really important that oncologists and radiologists talk to each other before we read scans in patients with immunotherapeutics."