PET-scans and treatment options in early-stage Hodgkin lymphoma

This trial examined the need for radiotherapy among early-stage Hodgkin lymphoma patients who responded well to chemotherapy. The authors concluded that in these patients, progression-free survival rates were high overall, but were slightly higher with additional radiation.

Hodgkin lymphoma is a cancer of the lymph system. It is highly curable, especially if detected in the early stages. Typical treatment for early-stage disease is ABVD (doxorubicin, bleomycin, vinblastine, and dacarbazine) chemotherapy. This is followed by targeted radiation therapy. These treatments can cause many short- and late-term negative side effects. It would be useful to know whether patients can avoid radiation.

Positron emission tomography (PET) scans are useful tools for diagnosing Hodgkin lymphoma. A PET scan uses a radioactive substance (a tracer) to image the location of cancer cells. PET scans can also help measure the response to treatment. It is not clear whether they can predict which patients can avoid radiation treatment. 

This study examined the need for radiation among patients who showed a response to chemotherapy on a PET scan. 571 Hodgkin lymphoma patients had PET scans after three cycles of ABVD chemotherapy. All had early-stage disease (Stage IA or Stage IIA). Of the 420 patients with favorable scans (no cancer activity), 209 were treated with radiation. 211 received no further treatment. Patients with unfavorable scans received a fourth cycle of chemotherapy. This was also followed by radiation. Patients were followed for an average of 5 years.  

Overall, there were only minimal differences in outcomes between groups. Among those with favorable scans treated with radiation, 94.6% were progression free after 3 years. 90.8% in the no-further-treatment group were progression free. Radiation reduced the absolute risk difference of negative outcomes by 3.8% compared to chemotherapy alone. In the patients who had unfavorable PET scans, 87.6% were alive without disease progression after 4 years.

The authors concluded that in patients who responded to three cycles of chemotherapy, radiation was associated with a small improvement in progression-free survival. However, the authors noted that survival rates were very high in all treatment groups.

This study followed patients for an average of 4 years. Longer studies are needed to determine rates of long-term complications and survival in these patients.