Radiotherapy after chemotherapy is controversial, as evidenced by the fact that doctors for some patients in the study did not follow the protocol for those assigned to radiotherapy and may have affected the results.
Patients who have large tumors when diagnosed with advanced Hodgkin lymphoma may benefit from radiotherapy following chemotherapy, even if the first treatment seems to have wiped out all their cancer.
The potential survival benefit from this approach was reported in a study presented Monday at ESTRO 38, the meeting of the European Society for Radiotherapy and Oncology taking place in Milan, Italy.
Data have shown that 65% to 70% of patients with advanced Hodgkin lymphoma survive after receiving 6 cycles of ABVD chemotherapy, a combination of doxorubicin, bleomycin, vinblastine, and dacarbazine. Researchers for the new study sought to answer the controversial question of whether adding radiotherapy adds any benefit—but the apparent controversy over radiotherapy led some patients’ doctors to not follow the protocol in the study and may have affected the results.
Patients who are successfully treated with chemotherapy “can often have 4 to 5 decades of life expectancy ahead of them,” said study coauthor Mario Levis, MD, an oncologist at the University of Turin in a statement. “But given the cure rate, the cancer treatment can result in a high risk of complications for many long-term survivors. For this reason it’s important that we give patients the most effective treatment for curing their cancer, while at the same time, trying to keep the toxic side effects to a minimum.”
Researchers recruited 512 patients between 2008 and 2013 to take part in a randomized trial. Participants had been successfully treated in a phase 2 portion of the study, when positron emission tomography scans showed no trace of cancer during and at the end of chemotherapy. These patients proceeded to the phase 3 portion to either receive radiotherapy or no more treatment.
A total of 354 patients had scans showing they had no more cancer after chemotherapy. Of these, 116 had lesions at least 5 cm in diameter when diagnosed and were randomized to receive radiotherapy or no treatment. The study showed that more patients had progression-free survival (PFS) at the 3-year and 5-year marks if they had radiotherapy.
"We found that 3 years later 92% of patients who received radiotherapy were still alive without disease progression compared to 82% of patients who did not receive it. After 5 years, these figures were 89% and 82% respectively,” said Umberto Ricardi, MD, head of the Department of Oncology at the University of Turin and the president of ESTRO, in presenting the results.
The study authors say the results suggest that with large tumors who have responded to 6 cycles of ABVD chemotherapy may still benefit from radiotherapy, with a survival benefit ranging from 7% to 10% at 3 and 5 years. Notably, 9 patients who had been enrolled in the radiotherapy arm of the trial did not actually receive radiation treatment due to decisions made by their doctors, and the disease returned in 5 of them.
According to the researchers, at first look there was little difference between the 2 groups in PFS at 3 and 5 years. It was only when the researchers looked at whether patients actually received the radiotherapy that it was possible to see the benefit on survival for those treated with radiotherapy, although this was not statistically significant. This was mainly because of the small number of patients in whom the disease returned: 5 in the radiotherapy arm and 13 in the “no further treatment” arm of the trial.
“The results of this trial do not provide definitive evidence on the role of radiotherapy after chemotherapy for patients with advanced Hodgkin's lymphoma and large tumors. However, the improvement in survival among those who did receive radiotherapy is not negligible,” Ricardi said. “We think that the next step is for a meta-analysis of this and similar randomized trials in order to increase the robustness of the information we have on the best way to treat this disease.”
Ricardi U, Levis M, Evangelista A, et al. Role of consolidation RT to bulky lesions of advanced Hodgkin lymphoma: results of FIL HD0801 trial. Presented at: ESTRO 38 (European Society for Radiotherapy and Oncology); Milan, Italy; April 28, 2019; OC-0502.