Differences in Survival Rates for Patients with Hodgkin Lymphoma, Who Were Treated Inside vs. Outside Therapy Optimisation Protocols in Germany.

Abstract

Introduction: Despite the improvements and knowledge brought by clinical trials to cancer treatment, it remained unclear how beneficial participation in a clinical trial with Therapy Optimisation Protocol (TOP) is for patients (pts) with Hodgkin Lymphoma (HL) in relation to pts treated outside of trials. In the TOPiCS project, trial participants (TOP) were compared with non-trial pts (non-TOP).Methods: In the population-based survey NLL, which aimed to register all incident HL-cases 356 pts were recorded in six counties of northern Germany with a first diagnosis of HL in 1988–1998. Data on staging, therapy, adverse events and survival were collected. The dataset was additionally screened for patients fulfilling inclusion and exclusion criteria for clinical trials of the German Hodgkin Study Group (GHSG). A total of 328 pts were documented of whom 198 pts (60%) met the inclusion criteria of the GHSG. Of these, 125 pts (63%) have not been recruited into GHSG trials (non-TOP pts). They were compared retrospectively with 4963 TOP pts randomised nation-wide between 1988–1998 in the GHSG trials HD4-HD9. Endpoints were Overall Survival (OS) and Progression Free Survival (PFS) which considered progression, relapse and death of any cause as events. Survival analysis was performed using Kaplan-Meier method and log-rank tests. Cox regression analysis was used for multivariable modelling of risk of death or progression and included 118 non-TOP pts and 4958 TOP pts.Results: The demographic parameters were not well balanced between the two groups: TOP pts were younger, had more often advanced stage and diagnosis in the later study generation than the non-TOP pts. The median observation time for OS was 7 yrs for the TOP group and 10 yrs for the non-TOP group. The 5-yrs OS for TOP pts is 89% (95%–CI [88–90]) and for non-TOP 89% (95%-CI [82–94])(p=0.63). The 5-year PFS for TOP pts is 79% (95%–CI [78–80]) and for non-TOP pts 68% (95%–CI [59–76])(p<0.001). According to Cox-regression analysis, 5 parameters were significantly (p<0.01) associated with poor OS and PFS: male sex, older age, advanced stage (according to DHSG classification considering Ann Arbor stage, B-symptoms and risk factors) and earlier study generation. Participation in a TOP-trial did not contribute independently for OS (Hazard Ratio (HR)=1.12, 95%–CI [0.71–1.79]) but contributed independently and positively for PFS (HR=0.66, 95%–CI [0.49–0.89]). The difference is mainly due to a higher number of relapses.Conclusion: For German patients fulfilling inclusion and exclusion criteria for TOP, a participation in therapy optimisation protocols results in a higher PFS, allowing for the influence of other factors, than for patients who were treated outside of TOP-trials. However, no difference was observed in OS.