An evaluation of factors impacting the survival of Manitoba women with ovarian cancer treated with neoadjuvant chemotherapy

Abstract

Prior analyses by the Manitoba Ovarian Cancer Outcomes study group identified that late-stage ovarian cancer patients receiving neoadjuvant chemotherapy had poorer survival than patients receiving adjuvant chemotherapy. This is consistent with other observational studies identifying neoadjuvant survival being worse compared to adjuvant survival. Additional investigations into potential causes behind poorer neoadjuvant survival in Manitoba between the years 2004-2010 were conducted. In this thesis project, possible predictors of neoadjuvant treatment were examined. Furthermore, a series of clinical questions were generated to investigate the effects of treatment-related factors on neoadjuvant patient survival, such as residual tumour post-surgery, chemotherapy-induced toxicities, chemotherapy dose reduction, delay in chemotherapy treatment, and the number of cycles of chemotherapy. It was determined that predictors of neoadjuvant treatment included older age, unclassified epithelial tumour histotype, and a short time period (0-50 days) from suspicion to diagnosis of malignancy. Variables that did not substantially affect neoadjuvant patient survival included chemotherapy dose reduction, chemotherapy dose interruption, chemotherapy toxicities, and absence of residual tumour post surgery. However, neoadjuvant patients were more likely to require more than one line of chemotherapy, which might contribute to their increased risk of death. It appears that neoadjuvant patients likely present with greater disease severity compared to adjuvant patients. This may lead to clinical selection bias, whereby sicker patients are appropriately treated with neoadjuvant chemotherapy. This study demonstrated that poor survival in the neoadjuvant patient population is due to greater disease severity upon presentation, unfavourable tumour histotype, and later disease stage resulting in treatment with neoadjuvant chemotherapy.