Patients with 2a testicular seminoma show improved outcomes with radiation.
A study published in Clinical Oncology revealed that radiation therapy was more effective in patients with stage 2a testicular seminoma than chemotherapy.
The findings, presented at the ESTRO 35 conference, are significant because of the lack of prior evidence on which treatment is more effective. The study is the largest performed thus far, containing 2437 patients with stage 2 testicular seminoma diagnosed between 1998 and 2012.
Participants were treated with either radiation therapy or a multi-agent chemotherapy after the cancerous testicle was removed. There were 960 stage 2a testicular cancer patients, with 78% who received radiation therapy and 22% who received chemotherapy.
There were 812 patients with 2b disease, of which 54% received radiation and 46% received chemotherapy. Lastly, 665 participants had 2c disease, with 4% given radiation and 96% chemotherapy.
The results of the study revealed that 99% of patients treated with radiotherapy were alive after 5 years compared with 93% of patients treated with chemotherapy. Stage 2b testicular cancer patients had a 5-year overall survival rate of 95% for those treated with radiation and 92% with chemotherapy.
“For patients with 2a testicular seminoma, this improvement in outcome with radiation over chemotherapy persisted after adjustments for all available factors that could introduce a bias,” said researcher Scott Glaser. “For patients with stage 2b disease, similar rates of overall survival were seen regardless of treatment with multi-agent chemotherapy or radiation therapy. This suggests that an individualized approach is necessary for such patients.
“For stage 2c patients, there is clear consensus that multi-agent chemotherapy is the preferred treatment as the risk of distant progression is high, whereas for stage 2a-b there is no such consensus as to the optimal treatment and practice patterns vary significantly,” Glaser continued. “In our series, 96% of stage 2c patients received multi-agent chemotherapy, which also severely limits meaningful comparison to other treatments.”
The data suggests that radiation therapy should be the preferred option for patients with stage 2a cancer.
“We view stage 2b disease as a spectrum where smaller volume disease patients (i.e. those with a 2-3 cm tumor in a single lymph node) may act more like 2a disease and attain the greatest benefit from radiation therapy, whereas patients with a larger volume of disease (i.e. 4-5 cm tumor or that has spread to multiple lymph nodes) may act more like 2c disease and attain the greatest benefit from chemotherapy,” Glaser said.
The results showed that a collaborative group effort is needed to open a randomized trial for stage 2a-b testicular seminoma that examines the role radiation and chemotherapy plays, researchers stated.
Some limitations to the study included its retrospective nature that used the national data registry the US National Cancer Data Base; a relatively short (average of 65 months) follow-up period, as some toxic treatment effects might only appear after a longer follow-up; and the inability to describe how well the disease was controlled and the cases of mortality specifically from cancer.
“In cases where there is an absence of prospective randomized trials, such as in rare tumors like stage 2 testicular seminoma, the analysis of 'real-life' data can help us to verify whether assumptions that are used to guide our treatment recommendations are valid or not,” said ESTRO President, Philip Poortmans, who was not involved in the research. “The movement away from radiation therapy in favor of chemotherapy, induced by the fear of a higher rate of late toxicity, is now suggested to be probably not the right one for patients with stage 2a testicular seminoma, with an overall survival benefit in favor of radiation therapy up to at least 10 years after treatment. Ideally, these results should be confirmed in a prospective trial with a very long-term follow-up, including a thorough analysis of side effects. However, this might be difficult to achieve."