Predictive and prognostic factors of epithelial ovarian cancer and pseudomyxoma peritonei

• The overall aim of my thesis was to investigate potential prognostic and predictive factors associated with the tumor cells of epithelial ovarian cancer (EOC) and the gastrointestinal tumor pseudomyxoma peritonei (PMP) to improve and individualize cancer therapy. Both PMP and EOC can develop into peritoneal carcinomatosis (PC), which is characterized by widespread metastasis of cancer tumors in the peritoneal cavity. Major improvements in the management of PC, such as cytoreductive surgery in combination with chemotherapy, have dramatically changed the prognosis.To further optimize and tailor treatment, increased knowledge on tumor biology and pathogenesis is needed. Today’s choice of treatment is mainly based on clinical trials and standard protocols that have not taken individual differences in drug sensitivity into consideration. With ex vivo testing of tumor drug sensitivity, individuals at risk of side effects only (and no treatment benefit) could potentially be identified prior to treatment.Napsin A is an anti-apoptotic protein that promotes platinum resistance by degradation of the cell cycle regulator and tumor suppressor TP53. Immunohistochemical stainings of 131 early EOC tumors in study I showed that expression of Napsin A was associated with expression of the apoptosis regulators p21 and p53 and with histological subtype. Positivity of Napsin A in an epithelial ovarian tumor strengthens the morphological diagnosis of clear cell carcinoma and should be useful in diagnostics. In study II, the relevance of the proteins HRNPM and SLC1A5 as prognostic factors for recurrent disease, survival and impact on clinical or pathological features was evaluated in 123 patients with early EOC. Our results support concomitant positivity of HRMPM and PUMA/p21 in ovarian cancer and indicate that HRNPM may trigger activity in systems of cell cycle regulation and apoptosis. In subgroup analyses of tumors from patients with non-serous EOC histology, expression of SLC1A5 was shown to be a prognostic factor in terms of prolonged disease-free survival. In studies III and VI, we investigated the ex vivo drug sensitivity of tumor cells from EOC and PMP with the 72-h cell viability assay fluorometric microculture cytotoxicity assay (FMCA). The two studies confirm that drug sensitivity varies considerably between tumor samples from patients within the same diagnostic group. In ovarian cancer, ex vivo results show that type I tumors were generally less sensitive to cytotoxic agents than type II tumors. Samples from patients previously exposed to cytotoxic drugs generally tended to be more resistant to most drugs than samples from unexposed patients in both EOC and PMP. This observation is in line with clinical experience and findings supporting that exposure to cytotoxic treatments contribute to development of chemo-resistance mechanisms. In ovarian cancer, resistance to the kinase inhibitors after exposure varied but was less pronounced than that for standard cytotoxic drugs. In PMP patients, ex vivo drug sensitivity provided prognostic information for progression-free survival, and this is in line with earlier findings.

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