Abstract 4614: Mutation detection in urine from bladder cancer patients as non-invasive prognostic tool
Authors: Critelli Rossana , Fasanelli Francesca , Assumma Manuela B. , Zwarthoff Ellen C. , Oderda Marco , Polidoro Silvia , Sacerdote Carlotta , Vineis Paolo , Matullo Giuseppe , Naccarati Alessio 
Published: August 2015

In Europe, bladder cancer (BC) is the second most common cause of death among patients with genitourinary tract malignancies. Patients with non-muscle invasive bladder cancer (NMIBC) have excellent survival; however two-thirds develop recurrences. For the diagnosis of BC, we mainly rely on urine cytology and cystoscopy. Although cystoscopy is the mainstay of the diagnosis, it is an invasive and costly procedure. Cytology has high specificity but has low sensitivity especially in low-grade, low-stage tumors. Urine sediment cells are a source of tumor DNA, they are easily accessible, and their sampling is not invasive. The identification of a urine-based biomarker could partly replace cystoscopies, thereby reducing the frequency and associated costs, improving patient's quality of life and even leading to earlier detection of recurrences. Tumor-specific mutations can be used to detect recurrences in urine, presenting a non-invasive diagnostic procedure respect to cystoscopy.

The present study involves 252 male subjects diagnosed with BC recruited between 1994 and 2012 from the Turin Bladder Cancer Study. Urine samples have been collected for the first time at the time of diagnosis, and exfoliated cells have been extracted. A subgroup of 83 patients has been followed-up for three years, collecting a urine sample every six months. We have investigated the diagnostic and prognostic potentiality of a panel of 40 mutations in hTERT, FGFR3, PIK3CA, and Ras genes detected in DNA from exfoliated cells by SNApShot assay. For each gene we calculated crude and adjusted (by age, smoking status, chemotherapy, low/intermediate/high risk, grade) Hazard Ratios (HR) and the corresponding 95% Confidence Intervals (95% CI) using the Cox proportional-hazard regression model. The results were correlated with stage and tumor grade, with response to therapy and the occurrence of recurrences, in order to assess the validity of exfoliated cells as a source of DNA for the development of a non-invasive test for the follow-up of patients.

Mutations in hTERT gene promoter and FGFR3 gene are the most frequent somatic mutations in BC. In particular, hTERT mutations were significantly correlated with high risk, high grade and muscle invasive tumors (p&lt;0.0001). In contrast, for FGFR3 the prevalence of mutations was significantly higher in non-high grade (p&lt;0.0001) and in NMIBC (p = 0.01). Cox regression analysis shows an increased risk of recurrence and recurrence/progression in association with hTERT mutations (adjp&lt;0.007 and p&lt;0.008, respectively). At first follow-up, the significant association between high grade and hTERT mutations was confirmed (p = 0.004). Cox regression analysis confirms an increased risk of recurrence and recurrence/progression in association with hTERT mutations (adjp&lt;0.007 and adjp&lt;0.008, respectively). These findings could suggest novel approach to identify biomarkers of BC at diagnosis and for prognostic reasons.

Citation Format: Rossana Critelli, Francesca Fasanelli, Manuela B. Assumma, Ellen C. Zwarthoff, Marco Oderda, Silvia Polidoro, Carlotta Sacerdote, Paolo Vineis, Giuseppe Matullo, Alessio Naccarati. Mutation detection in urine from bladder cancer patients as non-invasive prognostic tool. [abstract]. In: Proceedings of the 106th Annual Meeting of the American Association for Cancer Research; 2015 Apr 18-22; Philadelphia, PA. Philadelphia (PA): AACR; Cancer Res 2015;75(15 Suppl):Abstract nr 4614. doi:10.1158/1538-7445.AM2015-4614