In one of the first long term clinical trials of older breast cancer patients globally, University of Edinburgh research reveals that the use of radiotherapy as treatment for older patients with breast cancer does not improve survival rates.

A 10-year study has found that radiotherapy can be safely excluded from treatment for patients who are over 65 years old with early stage, low risk breast cancer.

Radiotherapy involves using ionising radiation to control or kill cancerous cells and is part of current standard treatment for patients with early-stage breast cancer, alongside breast-conserving surgery and hormone therapy.

Radiotherapy can place a heavy burden on patients, particularly older ones, and can lead to side effects like heart problems and secondary cancers.

However, the new PRIME II study suggests the addition of radiotherapy makes no difference to death rates of patients aged 65 years or older. The researchers report that radiotherapy also had no impact on the risk of secondary tumours, known as metastases.

A total of 1,326 participants were involved in the University of Edinburgh and Western General Hospital study, with patients evaluated at annual clinic visits to review the difference between those selected to receive radiotherapy for three to five weeks following surgery, and those who were not.

Just over half were randomly assigned to receive no irradiation in their treatment plan, though all participants were prescribed breast-conserving surgery and at least five years of hormone therapy.

Overall 10-year survival was ‘almost identical in the two groups’, at 80.7% for those receiving radiotherapy and 80.8% for those not receiving radiotherapy.

Researchers emphasised that breast cancer-specific survival was not substantially different between the two groups. One more patient in the no-radiotherapy group died from breast cancer than those receiving radiotherapy, a 0.5% difference in breast cancer specific survival.

Professor Ian Kunkler, Professor of Clinical Oncology at the University of Edinburgh, said these findings will support treatment discussions between patients and clinicians:

“Radiotherapy can place a heavy burden on patients, particularly older ones. Our findings will help clinicians guide older patients on whether this particular aspect of early breast cancer treatment can be omitted in a shared decision-making process, which weighs up all the risks and benefits.”

All patients involved in the study were 65 or older with ‘low risk’ breast cancer – meaning a tumour which is likely to respond to hormone therapy, no more than 3cm in size which does not involve the underarm lymph nodes.

At least 50% of patients with this condition are 65 years or older but this is one of the first long term clinical trials for the age group.

The findings revealed that radiotherapy did slightly lower the likelihood of recurrence of breast cancer among participants.

The research team found that for patients treated without radiotherapy the risk of breast cancer recurrence at 10 years was 9.5%, while giving radiotherapy reduced the risk to 0.9%. Professor Kunkler explained that despite the difference, both recurrence risks at 10 years remain within the clinically acceptable range, which stands at 1% per year.

Funded by the Chief Scientist Office of the Scottish government and the Breast Cancer Institute Endowment Fund from Edinburgh’s Western General Hospital, the study presents options for patients concerned about the side effects of radiotherapy.

Disease-free survival at 10 years was 68.9% for those not receiving radiotherapy and 76.3% for those in the radiotherapy group and other causes of death were more likely than breast cancer for either group.

The researchers note that future work should collect information on patients’ co-existing conditions and monitor their adherence to hormone therapy, to give greater insight into the impact of radiography on patient outcomes.

While quality of life was not investigated in this study, a similar trial, PRIME I, reviewed quality of life – finding no significant difference at 5 years in patients who did or did not receive radiation. By omitting radiotherapy, patients can avoid some of its side effects including breast pain, dermatitis and potential heart and lung complications.

Professor Kunkler adds that there are ongoing studies reviewing quality of life with shorter courses of radiotherapy.

For now, he told healthandcare.scot these findings show omission of radiation is a reasonable option to discuss with patients:

“Clinicians and patients must balance the reduction in risk from radiation against its side effects in older patients.

“Where the risk of recurrence is low and the omission of radiation does not increase the risk of metastases and overall survival is not compromised, omission of radiation is a reasonable option to discuss with patients.”

Read more: Pandemic cancer care extended; Cervical cancer unit to treat patients in 30 minutes;  High cancer diagnoses rate via emergency care; Pandemic impact on cancer incidence in Scotland; New £10m fund for cancer treatment

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