Is there a "low-risk" patient population in advanced epithelial ovarian cancer?: a critical analysis

Ovarian cancer is the leading cause of gynecologic cancer-related death in the United States. Historically, studies have demonstrated that ovarian cancer is a heterogeneous disease with several patient and oncologic characteristics, including BRCA status and residual disease at surgery, known to be predictive of clinical outcomes. However, during the last decade, the discovery and approval of bevacizumab and poly(adenosine diphosphate-ribose) polymerase inhibitors have moved the frontline treatment paradigm beyond platinum-doublet therapy for women with advanced ovarian cancer. Subsequently, investigators have sought to assess the therapeutic efficacy of these agents in women who are considered "high" risk and "low" risk to determine which patients may benefit the most from aggressive therapy and in whom additional treatment may be avoided. We reviewed historic and contemporary definitions of "high-risk" and "low-risk" ovarian cancer and how this has been incorporated into the subset analyses of randomized, clinical trials of therapeutic agents, including bevacizumab and poly(adenosine diphosphate-ribose) polymerase inhibitors. Next, we provided an in-depth discussion of landmark trials for frontline maintenance therapy with bevacizumab and/or poly(adenosine diphosphate-ribose) polymerase inhibitors, focusing on the impact of treatment efficacy according to a "high-risk" and "low-risk" paradigm. Furthermore, we highlighted that recent data have challenged this dichotomous classification, notably from the Gynecologic Oncology Group-0218, ICON7, SOLO-1, and PAOLA-1 trials. Although some studies have suggested that certain populations of women with advanced ovarian cancer may have a more favorable prognosis and be considered "low risk," the risk of progression and death remains unacceptably high in all women. Furthermore, in many cases, those considered the lowest risk have the most treatment benefit from maintenance therapy with poly(adenosine diphosphate-ribose) polymerase inhibitors and/or bevacizumab. From these data, we have advocated that virtually all women with advanced ovarian cancer are high risk and that the use of our most effective therapies in the frontline setting holds promise for potentially curing more patients. Lastly, we critically discuss the practice of using subanalyses in clinical trials, with emphasis that although this practice is important for hypothesis generation, caution must be taken before accepting findings from subanalyses as actual treatment effects.