Nasal natural killer (NK) T cell lymphoma is a rare, locally aggressive disease that responds poorly to the anthracycline-based chemotherapy regimens used to treat other non-Hodgkin lymphomas. Although high doses of radiation can provide effective local control of early-stage nasal NK T cell lymphoma, many oncologists are hesitant to use such therapy for fear of damaging nearby sensitive structures. However, physicians at The University of Texas MD Anderson Cancer Center use carefully targeted radiation therapy as the primary modality for the disease and give an intensive chemotherapy regimen as an adjunct. A clinical trial of this treatment combination is now enrolling patients with early-stage nasal NK T cell lymphoma.
“For most lymphomas, chemotherapy is the main treatment and radiation is given as an adjunct at minimal doses. This approach has been adopted in many institutions to treat nasal NK T cell lymphoma as well,” said Bouthaina Dabaja, M.D., a professor in the Department of Radiation Oncology. “But at MD Anderson, we’ve shifted from a chemotherapy paradigm to a radiation paradigm for nasal NK T cell lymphoma. Our approach is based on solid data showing that radiation is the main modality that can achieve cure in patients with localized disease. We hope the results of our trial will lead to a standardized treatment for this disease.”
Radiation as the main treatment
In past decades, high-dose radiation therapy could not be used for nasal NK T cell lymphoma without severely damaging the normal tissues and organs surrounding the tumor. But advances in radiation therapy techniques have enabled treatment of these tumors with high doses of radiation while minimizing toxicity to local structures. In Japan, where nasal NK T cell lymphoma is more common than in the United States, modern radiation therapy techniques have been used effectively against the disease. And at MD Anderson, physicians are improving these techniques by employing state-of-the-art technology in innovative ways.
Radiation oncologists at MD Anderson combine magnetic resonance imaging, positron emission tomography, and computed tomography to define the extent of the disease so that radiation can be directed to the tumor and not to uninvolved normal structures. Additionally, intensity-modulated radiation therapy (IMRT) is used to tailor the dose to the desired area. Before each treatment session, repeat imaging is performed to check the tumor’s response to previous treatments and to refine the target area if necessary.
In the current clinical trial (No. 2013-0367), patients with stage I or II nasal NK T cell lymphoma and no significant comorbidities receive a total radiation dose of 50.4–54.0 Gy in 28–30 fractions. Along with radiation, all patients in the trial receive three cycles of concurrent chemotherapy with dexamethasone, etoposide, ifosfamide, and carboplatin (DeVIC). DeVIC, which was developed as a salvage regimen for non-Hodgkin lymphomas, has previously shown activity against nasal NK T cell lymphoma.
The trial’s primary outcome measure is 5-year progression-free survival. The researchers will also evaluate overall survival and assess the safety of IMRT and concurrent DeVIC.
Although nasal NK T cell lymphoma is most commonly diagnosed in stage I or II, this trial is one of the few available for early-stage disease; nevertheless, the rarity of the disease has limited trial enrollment. So far, only eight patients have enrolled since the trial opened more than 2 years ago. Preliminary data are not yet available, but Dr. Dabaja said that thus far, the regimen of high-dose IMRT with concurrent DeVIC has provided excellent local tumor control for most patients in the trial.
“Through this trial, we want to show that high-dose radiation with concurrent chemotherapy can effectively treat nasal NK T cell lymphoma,” Dr. Dabaja said. “And we want to demonstrate that it’s possible to deliver a high dose of radiation to all possible disease sites without high toxicity.”
For more information, contact Dr. Bouthaina Dabaja at 713-563-2406 or firstname.lastname@example.org. For more information about the clinical trial of radiation and chemotherapy for nasal NK T cell lymphoma, visit www.clinicaltrials.org and search for study No. 2013-0367.
OncoLog, January 2018, Volume 63, Issue 1