Some children with early-stage Hodgkin's lymphoma who respond to initial chemotherapy may not need subsequent radiotherapy, according to US research.
If confirmed in larger trials, this could allow such children to be spared from the potential side effects of radiotherapy. These include long-term effects such as a slightly increased risk of a second cancer in later life.
Professor Hamish Wallace, a Cancer Research UK supported clinician based at the Royal Hospital for Sick Children in Edinburgh, said the study was "interesting" because although treatments for Hodgkin's lymphoma have steadily improved, a big question remains about how to reduce longer-term side effects.
He added: "This study is small and doesn't use exactly the same chemotherapy regimen as in the UK, but indicates that using imaging to assess early response to chemotherapy could be used as a marker of whether a child can avoid radiotherapy."
Treatment for children with the Hodgkin's lymphoma is determined by how advanced their disease is, and whether or not they have symptoms such as night sweats and weight loss.
Doctors have suspected that some children with the best outlook could receive just chemotherapy, and avoid radiotherapy.
The study looked at a chemotherapy regime called VAMP used with radiotherapy.
VAMP, which involves the drugs adriamycin, methotrexate, vinblastine and prednisone, is considered a milder regime than that given to children with more advanced disease.
The researchers from St. Jude Children's Research Hospital led a small clinical trial involving 88 children with early-stage Hodgkin's lymphoma.
After two cycles of chemotherapy, the 47 children who had a 'complete response'- meaning that imaging showed their tumour had shrunk by at least 75% - only had additional chemotherapy, not radiotherapy.
The 41 patients whose tumours had not shrunk as much were given radiotherapy and two further rounds of chemotherapy.
After an average of nearly seven years, there was no significant difference in survival between the two groups
Dr Monika Metzger, from St. Jude Children's Research Hospital, said: "This study adds to evidence that it is possible to omit radiation even in patients treated with a less intense chemotherapy regimen and still achieve excellent long-term survival."
But Professor Wallace cautioned: "This US trial only looked at children with early-stage disease. Our own pan-European study, part supported by Cancer Research UK, involves nearly 2,000 patients with all stages of disease and uses PET scanning after two cycles of chemotherapy to identify which children have a very good response to chemotherapy and can safely avoid radiotherapy."
The study is published in the journal JAMA.
Source: Cancer Research UK