Molecular profiling for predicting tumor prognosis, treatment outcome and progression of squamous cell carcinoma

Abstract: Squamous cell carcinoma is the most common histological tumor type in the cervix uteri and oral tongue. Although both cancers are diagnosed at an early stage in the majority of cases, cervical cancer has a better prognosis despite similarities in treatment. The aim of this thesis is to increase our knowledge of tumor progression in squamous cell carcinoma at the molecular level, and to use this knowledge to explore the clinical implications of this knowledge in the development of therapeutic regimens. We collected archived tissues from squamous cell carcinoma of the cervix uteri and oral tongue (OTSCC) and applied immunohistochemistry (IHC), DNA cytometry and fluorescence in situ hybridization (FISH) to paraffin-embedded tissues. Proliferative activity and genomic instability are two important factors in tumor progression. To identify patients with a high risk for locoregional recurrences we investigated Ki-67 expression (by means of IHC) and DNA ploidy (using DNA image cytometry) in 76 pretreatment OTSCC biopsy specimens. We found Ki-67 expression to be associated with an increased risk for locoregional recurrence in surgically-treated Stage I cancer patients (P=0.028). Ninety-seven percent of OTSCC specimens were aneuploid. Overexpression of epidermal growth factor receptor (EGFR) is associated with poor prognosis in head and neck cancer, but information on EGFR status in OTSCC is limited. We analyzed EGFR protein expression (IHC) and gene copy number (FISH) in 78 pretreatment OTSCC samples. We found EGFR gene copy numbers to be significantly associated with EGFR protein expression (P=0.002). EGFR was overexpressed in all OTSCC, suggesting that patients with this cancer type may benefit from EGFR targeting treatment. Non-smokers showed higher EGFR gene copy numbers and protein overexpression than did smokers. The presence of lymph node metastases is a strong prognostic factor in early stage cervical cancer and OTSCC. LAMP3, PROX1, PRKAA1 and CCND1 are genes associated with carcinogenesis. We analyzed these gene copy numbers using FISH probes in pretreatment cervical biopsies from LN positive and LN negative Stage IB-IIA cervical cancer patients (N=31) to explore their role in predicting LN metastasis. A combined marker panel consisting of amplified probes for LAMP3, PROX1 and PRKAA1 provided a significant (P=0.001) predictor for LN metastasis and needs to be evaluated in larger studies. To further explore genetic alterations in OTSCC, and inspired by the association between smoking habits and EGFR gene copy numbers, we applied five FISH probe markers (TERC, CCND1, EGFR, P53, CEP®4) to 65 pretreatment OTSCC specimens. CCND1 displayed the highest copy number of all markers and highest levels of this gene correlated significantly with better prognosis in Stage II OTSCC (P=0.03). Non-smoking habits were significantly related to higher copy numbers in all five markers (P=0.002).