Does clinical trial participation improve overall survival of Hodgkin Lymphoma patients?

There has been a general observation that long-term survival among Hodgkin Lymphoma (HL) patients who participated in trials seems to be significantly higher than for other HL patients. In order to verify this trend, EORTC performed a review, published in British Journal of Haematology, that compared overall survival rate in HL patients who had participated in a clinical trial between 1989 and 2004 to those who had not. Though an initial comparison showed a superior survival rate in the first group, further analysis established that this result could be attributed to baseline characteristics for patient inclusion in trials, such as age and other health-related criteria.

“EORTC trials between 1964 and 2004 have greatly contributed to the improvement of HL patients over the years, while minimizing the negative impact of treatment,” said Dr Martin Hutchings, Chair of the Lymphoma Group at EORTC. “In fact, these trials have helped improve 10-year survival of early-stage HL patients by over 20% and advanced-stage HL patients by 15%. Analyzing the potential difference between clinical trial participants vs non-participants could be useful to inform possible future studies aiming at improving outcomes for all patients.”

The analysis was performed comparing overall survival of patients registered in EORTC clinical trials in the Netherlands to those not registered in trials figuring in the Netherlands Cancer Registry (NCR), which covers the entire Dutch population. Between 1986 and 2004, about 25% of HL patients in the Netherlands participated in an EORTC trial. The initial comparison showed an 8% higher overall survival rate amongst trial participants after 10 years and 20 years. However, recruited patients are often younger, and more often in earlier stages of the disease than the rest of the HL population. When the comparison of survival rates between the two groups is adjusted to take into account such baseline clinical trial inclusion criteria, the difference is no longer significant.

When looking at how treatment evolved over time, the trial shows that survival rate in non-clinical trial patients increases over time, coinciding with a take-up of best-practice treatment demonstrated in clinical trial settings. Interestingly, among patients with early stage HL, survival curves diverge after 5 years, suggesting that trial patients benefit from the long-term follow-up and surveillance included in clinical trial protocols. Further studies should examine this hypothesis, which could inform long-term follow-up guidance.

“There is a wealth of data available in cancer registries,” said Dr Otto Visser, Director of the Netherlands Cancer Registry. “Such real-world information, paired with clinical trial data, can help ensure research benefits a maximum number of patients.”

The results of the study demonstrate that improved survival rate in HL clinical trial participants can be attributed to better health and lower risk factors. However, the broad dissemination of trial findings have clearly contributed to better overall survival rate among that patient population.

“With this type of epidemiological research , EORTC is looking to bridge the gap between clinical research and real-world cancer care,” said Lifang Liu, Epidemiologist at EORTC. “By combining clinical research data to population-based cancer registry data, we are evaluating the real-world effectiveness of treatments tested in a clinical research setting. We also aim to examine whether trial populations are representative of the real-world patient population, and how trial findings are implemented.”