The outcome of patients with serous papillary peritoneal cancer, fallopian tube cancer, and epithelial ovarian cancer by treatment eras: 27 years data from the SEER registry

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Introduction

Serous papillary peritoneal cancer (SPPC) is a clinically well-recognized but biologically enigmatic entity that was considered historically a cancer of unknown primary subset 123 . It shares common molecular, histological, and clinical features with epithelial ovarian cancer (EOC), mainly high-grade serous ovarian cancer (HGSOC), which made it reasonable to manage the two entities similarly 456 . The 2014 International Federation of Gynecology and Obstetrics (FIGO) classification combined SPPC and EOC in the same staging depending on the disease extent and localization [7] . However, it did not address the biological behavior of these entities although they present different molecular patterns, which allude to different carcinogenic pathways [89] . The molecular differences between SPPC and EOC were reported in studies with relatively small numbers of cases and the differences in immunohistochemistry patterns were relatively minor compared to the substantial similarities. Thus a debate has emerged between experts as to whether these tumors should be managed similarly to EOC because the clinical experience shows that patients with SPPC had a poorer prognosis at similar stages [5] .

Patients with SPPC are commonly treated in line with the EOC guidelines and have achieved considerable survival benefit [51011] . The molecular advances during the last decade yielded two targeted therapies, bevacizumab and poly(ADP-ribose) polymerase (PARP) inhibitors, that were approved by the Food and Drug Administration and the European Medicines Agency based on pivotal trials mainly including EOC [1011] . Bevacizumab is a recombinant humanized monoclonal IgG1 antibody that targets vascular endothelial growth factor (VEGF)-A, a validated target that promotes tumor angiogenesis [12] . PARP inhibitors are mainly effective in tumors with defective repair of double-stranded DNA damage by homologous recombination [13] . The corresponding pivotal clinical trials of both bevacizumab and PARP inhibitors have also included patients with SPPC; however, the outcomes in these patients have never been reported specifically. The current study aimed to determine the differential effect of the treatment periods on the survival of patients with stage IV SPPC, fallopian tube cancers, and EOC according to patient information from the National Cancer Institute’s Surveillance, Epidemiology and End Results (SEER) Program data collected between 1990 and 2017.