ESTRO 2016: Radiotherapy vs Chemotherapy in a Study of Patients With Early Stage II Testicular Cancer
A large study of testicular cancer patients showed that radiation therapy was more effective than chemotherapy for patients with stage IIa disease (where one or more regional lymph nodes contain cancer cells, but they are less than 2 cm in diameter).
These findings, presented at the ESTRO 35 Conference on May 2, and published simultaneously by Glaser et al in Clinical Oncology, provide evidence about which treatment for testicular seminoma is more effective, as there has been a tendency to move away from radiation therapy towards chemotherapy for treating stage IIa/b patients.
Guidelines from the National Cancer Comprehensive Network (NCCN) recommend radiotherapy for stage IIa, while those from the European Association of Urology allow for either radiation therapy or chemotherapy; both sets of guidelines are equivocal for stage IIb.
Study Background
The study of 2,437 patients presented today is the largest group of patients with stage II testicular seminoma evaluated so far, and researchers found that 99% of patients with IIa disease were alive after 5 years if they had been treated with radiation therapy, vs 93% of patients treated with chemotherapy. For patients with IIb disease, the 5-year overall survival was 95% for those treated with radiation therapy and 92% for those treated with chemotherapy.
Scott Glaser, MD, Resident Physician at the University of Pittsburgh Cancer Institute, said, “Testicular seminoma is a rare disease, there is a lack of randomized data to guide treatment and many prior studies have been limited by small sample sizes. It has, therefore, been difficult to tease out small differences in efficacy of radiation therapy vs chemotherapy. The trend away from radiation therapy may be due to a misperception that it is more toxic than three or four cycles of multiagent chemotherapy.”
Study Findings
Dr. Glaser continued, “Across this large, national dataset, radiation therapy was associated with a better outcome for stage IIa patients and equivalent outcomes for stage IIb patients. However, potential explanations for these improved outcomes are less clear. For patients with IIa testicular seminoma, this improvement in outcome with radiation over chemotherapy persisted after adjustments for all available factors that could introduce a bias. For patients with stage IIb disease, similar rates of overall survival were seen regardless of treatment with multiagent chemotherapy or radiation therapy. This suggests that an individualized approach is necessary for such patients.”
The study, led by Sushil Beriwal, MD, an Associate Professor of Radiation Oncology at the University of Pittsburgh, analyzed data from 2,437 patients with stage II testicular seminoma diagnosed between 1998–2012 and treated with radiation therapy or multiagent chemotherapy after removal of the cancerous testicle. Of the total number, 960 patients had IIa disease, of whom 78% received radiation therapy and 22% received chemotherapy; 812 had IIb disease, with 54% and 46% receiving radiation therapy and chemotherapy, respectively; and 665 had IIc disease, with 4% and 96% receiving radiation therapy and chemotherapy, respectively.
“For stage IIc patients, there is clear consensus that multiagent chemotherapy is the preferred treatment as the risk of distant progression is high, whereas for stage IIa/b there is no such consensus as to the optimal treatment and practice patterns vary significantly. In our series, 96% of stage IIc patients received multiagent chemotherapy, which also severely limits meaningful comparison to other treatments,” explained Dr. Glaser.
He said the results support the recommendation that radiation therapy should be the preferred option for treating patients with stage IIa. “We view stage IIb disease as a spectrum where smaller volume disease patients (ie, those with a 2–3 cm tumor in a single lymph node) may act more like IIa disease and attain the greatest benefit from radiation therapy, whereas patients with a larger volume of disease (ie, 4–5 cm tumor or that has spread to multiple lymph nodes) may act more like IIc disease and attain the greatest benefit from chemotherapy.”
Dr. Glaser concluded, “Our results demonstrate the need for a collaborative group effort to open a randomized trial for stage IIa/b testicular seminoma patients examining the role of radiation therapy and chemotherapy.”
Limitations of the study include its retrospective nature as it used a national data registry (the US National Cancer Data Base); a relatively short follow-up period (an average of 65 months), as certain toxic effects of treatment may only become apparent after longer follow-up; and the fact that the researchers were unable to describe how well the disease was controlled and deaths that were specifically from the cancer.
The content in this post has not been reviewed by the American Society of Clinical Oncology, Inc. (ASCO®) and does not necessarily reflect the ideas and opinions of ASCO®.
