World-first clinical studies by researchers from King’s College London have changed treatment pathways for patients with Hodgkin lymphoma using PET scans as an early read-out of how treatment is working. Hodgkin lymphoma is a cancer of the lymph glands and is the commonest cancer occurring in teenagers and young adults.

Two studies using PET scanning led by Professor Sally Barrington from the School of Biomedical Engineering & Imaging Sciences and colleagues in Manchester and Southampton were conducted over ten years.

The studies called RAPID and RATHL were published in 2015 and 2016 in the New England Journal of Medicine. These studies found that patients with Hodgkin Lymphoma who have a PET scan early during chemotherapy showing a good response can have their treatment reduced safely.

The researchers found that patients with early-stage lymphoma in the RAPID trial had a greater than 90 percent chance of being alive without lymphoma three years after finishing treatment, whether or not they had radiotherapy, if the PET scan was ‘clear’. This means that many patients with early-stage disease now have the option to choose whether to have radiotherapy or not to try and reduce adverse side-effects later in life. These include an increased chance of getting a second cancer and developing heart disease.

Patients with advanced stage lymphoma in the RATHL trial were found to be just as likely to be cured when given less intensive chemotherapy than the usual chemotherapy if the early PET scan was ‘clear’. Importantly the patients who received the gentler chemotherapy had fewer side-effects than the patients who received the standard type.

For patients in the RATHL trial where the PET scan showed instead that chemotherapy was not working, a more intensive type of chemotherapy was prescribed.

Two out of three patients were alive and free of their lymphoma three years afterwards. This was much better than studies done in the past where the original chemotherapy was carried on in patients where the PET scan suggested it wasn’t working, when only one in five patients would be expected to be alive and free of their lymphoma three years later.

These trials aiming to prevent side-effects from treatment of Hodgkin lymphoma involved 1800 patients, mostly from the UK.

As part of the studies, the researchers had to ensure that all PET Centres around the country scanned patients in the same way and that PET scans were read in a similar way.

Patient impact

“What we found in the RAPID trial was that patients who had a clear PET scan three months into treatment had over 90 percent chance of being alive and free of their disease three years later,” Professor Barrington said.

Professor Barrington said while more patients were free of disease if they had radiotherapy instead of no radiotherapy, the difference affected just six percent of patients, and that the findings mean that patients can now discuss with doctors treating them about whether they wish to have radiotherapy or not.

Commenting on the results of the RATHL study Professor Barrington said:

“The approach we tested in the RATHL trial is now used in many countries. There are other options as well but this one is used commonly in the UK, the US, some parts of Europe and in Australia.”

Professor Barrington’s studies have changed patient treatment with fewer side effects and improved survival for some patients with this disease.

“Lymphoma patients in the UK will now pick-up a patient booklet and see these approaches described as ways in which their disease can be managed. This is a big impact for patients.”

The approaches are now also in international guidelines for clinicians.

The network of centres developed to make these studies happen was run from St Thomas’ Hospital. This has since grown and become the UK PET research network with the core lab based at St Thomas’ which has now coordinated 26 cancer trials involving PET.

The ways developed during these lymphoma research trials of reading PET scans have become the standard way in which scans are read worldwide for patients with lymphoma.