Traditional management of many seminoma testicular cancers involves surgery followed by radiotherapy to target any residual tumour cells, also called adjuvant radiotherapy. However, there has been concern over the effects of such radiation, including over the risk of secondary cancers, and a need to assess its safety in comparison with alternative post-surgery strategies.
To determine accurate risk estimates of the long-term hazards of adjuvant radiotherapy, researchers from The Institute of Cancer Research (ICR), the Norwegian Radium Hospital in Oslo and the Medical Research Council Clinical Trials Unit, London, analysed records from 12 cancer centres (11 in the UK, and one in Norway) to identify secondary cancer risks in men with stage I seminoma.
The study, published in the British Journal of Cancer, used data collected from 2,629 seminoma patients who were treated with radiotherapy between 1960 and 1992, detailing the location of any secondary cancers.
Many patients with testicular seminoma are treated in young adult life and their risk of the cancer recurring is low, so they represent a unique group where the long-term risks associated with radiotherapy are fully measurable and can be accurately defined.
The researchers identified 468 secondary cancers reported in 403 men, and showed elevated risks for secondary bladder, pancreatic and stomach cancers. The increased risk was about one and a half times the background risk, and was confined to the pelvic-abdominal sites present in the radiation field; organs outside that area showed no significant elevated risk for cancers.
The authors concluded that the overall cure rate in patients with stage I seminoma was very high regardless of whether post-operation management involved adjuvant radiotherapy, adjuvant chemotherapy or surveillance, where further treatment is only used following a relapse. It was therefore important to avoid an increased risk of secondary cancers from adjuvant radiotherapy.
Study leader Professor Alan Horwich, Professor of Radiotherapy in the ICR’s Division of Radiotherapy and Imaging and honorary consultant at The Royal Marsden, said: "By studying men treated at a young age, with a good prognosis, we have been able to obtain reliable data on the long-term risks of radiotherapy in testicular cancer. Adjuvant radiotherapy is still widely used, so these findings have a direct bearing on current management strategies for treating stage I seminoma. As there are other ways of preventing recurrence, radiotherapy should be avoided because of the risks of cancer, especially as the patient population is relatively young.”