Study Design Solutions for Adjuvant and Maintenance Therapy in Cancer: Ovarian Cancer as an Example

High-quality randomized controlled trials (RCTs) are the best evidence for clinical practice guideline developers to make recommendations to improve patients’ outcomes. However, after we conducted two guidelines regarding maintenance therapy and neoadjuvant/adjuvant therapy in patients with newly diagnosed ovarian cancer, respectively, we realized that despite being statistically sound, some of the eligible RCTs in the current literature have methodological limitations, which resulted in challenges for making strong recommendations. During patients’ treatment processes, the timepoint when they should be randomized into experimental and controlled groups is a key issue and should be dependent on different study objectives. In this article, we provide some study design options in accordance with three different study objectives in front-line settings: Objective 1. To study a novel agent as an addition to standard adjuvant chemotherapy; Objective 2. To study a novel agent as maintenance therapy; and Objective 3. To study a novel agent as an addition to adjuvant chemotherapy AND continue as maintenance therapy in one trial. These study design options are not only suitable for ovarian cancer research, but also for other types of cancer research. Overall, it is crucial to consider methodological soundness in addition to the conventional statistical soundness when conducting a high-quality RCT.