Mark T.W. Teo

MRE11 expression is predictive of cause-specific survival following radical radiotherapy for muscle-invasive bladder cancer.

Radical radiotherapy and surgery achieve similar cure rates in muscle-invasive bladder cancer, but the choice of which treatment would be most beneficial cannot currently be predicted for individual patients. The primary aim of this study was to assess whether expression of any of a panel of DNA damage signaling proteins in tumor samples taken before irradiation could be used as a predictive marker of radiotherapy response, or rather was prognostic. Protein expression of MRE11, RAD50, NBS1, ATM, and H2AX was studied by immunohistochemistry in pretreatment tumor specimens from two cohorts of bladder cancer patients (validation cohort prospectively acquired) treated with radical radiotherapy and one cohort of cystectomy patients. In the radiotherapy test cohort (n = 86), low tumor MRE11 expression was associated with worse cancer-specific survival compared with high expression [43.1% versus 68.7% 3-year cause-specific survival (CSS), P = 0.012] by Kaplan-Meier analysis. This was confirmed in the radiotherapy validation cohort (n = 93; 43.0% versus 71.2%, P = 0.020). However, in the cystectomy cohort (n = 88), MRE11 expression was not associated with cancer-specific survival, commensurate with MRE11 being a predictive marker. High MRE11 expression in the combined radiotherapy cohort had a significantly better cancer-specific survival compared with the high-expression cystectomy cohort (69.9% versus 53.8% 3-year CSS, P = 0.021). In this validated immunohistochemistry study, MRE11 protein expression was shown and confirmed as a predictive factor associated with survival following bladder cancer radiotherapy, justifying its inclusion in subsequent trial designs. MRE11 expression may ultimately allow patient selection for radiotherapy or cystectomy, thus improving overall cure rates.

The role of microRNA-binding site polymorphisms in DNA repair genes as risk factors for bladder cancer and breast cancer and their impact on radiotherapy outcomes

MicroRNAs (miRNAs) are involved in post-transcriptional regulation of gene expression through binding to messenger RNAs (mRNA) thereby promoting mRNA degradation or altered translation. A single-nucleotide polymorphism (SNP) located within a miRNA-binding site could thus alter mRNA translation and influence cancer risk and treatment response. The common SNPs located within the 3′-untranslated regions of 20 DNA repair genes were analysed for putative miRNA-binding sites using bioinformatics algorithms, calculating the difference in Gibbs free binding energy (ΔΔG) for each wild-type versus variant allele. Seven SNPs were selected to be genotyped in germ line DNAs both from a bladder cancer case–control series (752 cases and 704 controls) and 202 muscle-invasive bladder cancer radiotherapy cases. The PARP-1 SNP rs8679 was also genotyped in a breast cancer case–control series (257 cases and 512 controls). Without adjustment for multiple testing, multivariate analysis demonstrated an association with increased bladder cancer risk with PARP1 rs8679 (Ptrend = 0.05) while variant homozygotes of PARP1 rs8679 were also noted to have an increased breast cancer risk (P = 0.03). In the radiotherapy cases, carriers of the RAD51 rs7180135 minor allele had improved cancer-specific survival (hazard ratio 0.52, 95% confidence interval 0.31–0.87, P = 0.01). This is the first report of associations between DNA repair gene miRNA-binding site SNPs with bladder and breast cancer risk and radiotherapy outcomes. If validated, these findings may give further insight into the biology of bladder carcinogenesis, allow testing of the RAD51 SNP as a potential predictive biomarker and also reveal potential targets for new cancer treatments.

Enteral feeding outcomes after chemoradiotherapy for oropharynx cancer: A role for a prophylactic gastrostomy?

To determine the outcomes of patients managed with different routes of enteral feeding during chemoradiotherapy for oropharynx cancer. The hospital and dietetic records of consecutive patients with oropharynx squamous cell carcinoma treated between January 2007 and June 2009 with concurrent chemoradiotherapy were reviewed retrospectively. One hundred and four patients were analysed. Seventy-one received a prophylactic gastrostomy, 21 were managed with a strategy of NG tube as required and 12 received a therapeutic gastrostomy. Patients with a prophylactic gastrostomy commenced enteral feeding a median of 24 days after commencing radiotherapy, compared with a median of 41 days (p<0.001) for the NG as required group. Comparing prophylactic gastrostomy, NG as required and therapeutic gastrostomy, median number of unplanned inpatient days were 6, 14 and 7, respectively (p<0.01 for prophylactic gastrostomy vs. NG as required). Mean percentage weight loss at the end of treatment (6.1% vs. 7.1% vs. 5.2%, respectively) and at 6 months post-radiotherapy (11.7%, 14.3% and 8.9%) were similar in all groups (p=0.23). There was no significant difference in type of diet post-radiotherapy between prophylactic gastrostomy and NG as required groups (p=0.22). Median duration of enteral feeding was 181, 64 and 644 days, respectively (p<0.01 for prophylactic gastrostomy vs. NG as required). Use of a prophylactic gastrostomy (p<0.01) and higher T stage (p<0.01) were associated with increased duration of enteral feeding on a multivariate analysis. These data reinforce concerns regarding the detrimental impact of prophylactic gastrostomy placement upon long-term enteral feed dependence.

Genome-wide association study yields variants at 20p12.2 that associate with urinary bladder cancer.

Genome-wide association studies (GWAS) of urinary bladder cancer (UBC) have yielded common variants at 12 loci that associate with risk of the disease. We report here the results of a GWAS of UBC including 1670 UBC cases and 90 180 controls, followed by replication analysis in additional 5266 UBC cases and 10 456 controls. We tested a dataset containing 34.2 million variants, generated by imputation based on whole-genome sequencing of 2230 Icelanders. Several correlated variants at 20p12, represented by rs62185668, show genome-wide significant association with UBC after combining discovery and replication results (OR = 1.19, P = 1.5 × 10(-11) for rs62185668-A, minor allele frequency = 23.6%). The variants are located in a non-coding region approximately 300 kb upstream from the JAG1 gene, an important component of the Notch signaling pathways that may be oncogenic or tumor suppressive in several forms of cancer. Our results add to the growing number of UBC risk variants discovered through GWAS.

Imatinib Radiosensitizes Bladder Cancer by Targeting Homologous Recombination

Radiotherapy is a major treatment modality used to treat muscle-invasive bladder cancer, with patient outcomes similar to surgery. However, radioresistance is a significant factor in treatment failure. Cell-free extracts of muscle-invasive bladder tumors are defective in nonhomologous end-joining (NHEJ), and this phenotype may be used clinically by combining radiotherapy with a radiosensitizing drug that targets homologous recombination, thereby sparing normal tissues with intact NHEJ. The response of the homologous recombination protein RAD51 to radiation is inhibited by the small-molecule tyrosine kinase inhibitor imatinib. Stable RT112 bladder cancer Ku knockdown (Ku80KD) cells were generated using short hairpin RNA technology to mimic the invasive tumor phenotype and also RAD51 knockdown (RAD51KD) cells to show imatinibs pathway selectivity. Ku80KD, RAD51KD, nonsilencing vector control, and parental RT112 cells were treated with radiation in combination with either imatinib or lapatinib, which inhibits NHEJ and cell survival assessed by clonogenic assay. Drug doses were chosen at approximately IC40 and IC10 (nontoxic) levels. Imatinib radiosensitized Ku80KD cells to a greater extent than RAD51KD or RT112 cells. In contrast, lapatinib radiosensitized RAD51KD and RT112 cells but not Ku80KD cells. Taken together, our findings suggest a new application for imatinib in concurrent use with radiotherapy to treat muscle-invasive bladder cancer. Cancer Res; 73(5); 1611-20. ©2012 AACR.

Definitive hypofractionated radiotherapy for early glottic carcinoma: experience of 55Gy in 20 fractions

IntroductionA wide variety of fractionation schedules have been employed for the treatment of early glottic cancer. The aim is to report our 10-year experience of using hypofractionated radiotherapy with 55Gy in 20 fractions at 2.75Gy per fraction.MethodsPatients treated between 2004 and 2013 with definitive radiotherapy to a dose of 55Gy in 20 fractions over 4 weeks for T1/2 N0 squamous cell carcinoma of the glottis were retrospectively identified. Patients with prior therapeutic minor surgery (eg. laser stripping, cordotomy) were included. The probabilities of local control, ultimate local control (including salvage surgery), regional control, cause specific survival (CSS) and overall survival (OS) were calculated.ResultsOne hundred thirty-two patients were identified. Median age was 65 years (range 33–89). Median follow up was 72 months (range 7–124). 50 (38 %), 18 (14 %) and 64 (48 %) of patients had T1a, T1b and T2 disease respectively. Five year local control and ultimate local control rates were: overall - 85.6 % and 97.3 % respectively, T1a - 91.8 % and 100 %, T1b - 81.6 and 93.8 %, and T2 - 80.9 % and 95.8 %. Five year regional control, CSS and OS rates were 95.4 %, 95.7 % and 78.8 % respectively. There were no significant associations of covariates (e.g. T-stage, extent of laryngeal extension, histological grade) with local control on univariate analysis. Only increasing age and transglottic extension in T2 disease were significantly associated with overall survival (both p <0.01). Second primary cancers developed in 17 % of patients. 13 (9.8 %) of patients required enteral tube feeding support during radiotherapy; no patients required long term enteral nutrition. One patient required a tracheostomy due to a non-functioning larynx on long term follow up.ConclusionsHypofractionated radiation therapy with a dose of 55Gy in 20 fractions for early stage glottic cancer provides high rates of local control with acceptable toxicity.

Impact of prophylactic gastrostomy or reactive NG tube upon patient-reported long term swallow function following chemoradiotherapy for oropharyngeal carcinoma: A matched pair analysis

OBJECTIVES The purpose of this matched pair analysis is to assess patient-reported long term swallow function following chemoradiotherapy for locally advanced oropharyngeal cancer in relation to the use of a prophylactic gastrostomy or reactive nasogastric (NG) tube. MATERIALS AND METHODS The MD Anderson Dysphagia Inventory (MDADI) was posted to 68 consecutive patients with stage III/IV oropharyngeal squamous cell carcinoma who had completed parotid sparing intensity modulated radiotherapy with concurrent chemotherapy between 2010 and 2012, had not required therapeutic enteral feeding prior to treatment, minimum 2years follow up post treatment, and who were disease free. 59/68 replies were received, and a matched pair analysis (matching for T and N stage) was performed for 52 patients, 26 managed with a prophylactic gastrostomy and 26 with an approach of an NG tube as needed. RESULTS There were no significant differences in patient demographics, pre-treatment diet and treatment factors between the two groups. Patient-reported swallowing function measured using the MDADI was superior for patients managed with an NG tube as required compared with a prophylactic gastrostomy: overall composite score 68.1 versus 59.4 (p=0.04), global score 67.7 versus 60 (p=0.04), emotional subscale 73.5 versus 60.4 (p<0.01), functional subscale 75.4 versus 61.7 (p<0.01), and physical subscale 59.6 versus 57.1 (p=0.38). CONCLUSIONS Compared with an approach of an NG tube as required, the use of a prophylactic gastrostomy was associated with inferior long term patient-reported long term swallow outcomes.

The Efficacy of Induction Chemotherapy with Docetaxel, Cisplatin and 5-fluorouracil Combined with Cisplatin Concurrent Chemoradiotherapy for Locally Advanced Head and Neck Squamous Cell Carcinoma: A Matched Pair Analysis

AIMS The role of induction chemotherapy (ICT) for head and neck squamous cell carcinoma (HNSCC) is controversial. The aim of the study was to assess the benefit of ICT with docetaxel, cisplatin and 5-fluorouracil (5-FU) (TPF) when combined with concurrent cisplatin chemoradiotherapy (CRT) for HNSCC. MATERIALS AND METHODS Patients with HNSCC treated between January 2005 and December 2010 with radical intent with either TPF or cisplatin and 5-FU (PF) ICT and documented intention to proceed with concurrent cisplatin CRT were identified retrospectively. The use and choice of ICT regimen was at the clinicians discretion. In total, 68 patients treated with TPF were identified and were matched for T and N stage and tumour site to 68 patients treated with PF. A survival analysis was carried out using Kaplan-Meier and the Cox proportional hazards model. RESULTS The median follow-up was 29.9 versus 36.3 months for the TPF and PF groups, respectively. Three year locoregional relapse-free survival (RFS), distant RFS, RFS, cancer-specific survival and overall survival rates for the TPF and PF groups were 84.2, 91.6, 82.6, 81.3 and 74.9% versus 73.7, 84.9, 71.9, 72.1 and 62.9%, respectively. On multivariate analysis, treatment with TPF predicted for improved locoregional RFS (P = 0.03) and overall survival (P = 0.05). CONCLUSION The addition of docetaxel to a cisplatin doublet ICT regimen before concurrent CRT may improve disease control for locally advanced HNSCC.

In vitro functional effects of XPC gene rare variants from bladder cancer patients

The XPC gene is involved in repair of bulky DNA adducts formed by carcinogenic metabolites and oxidative DNA damage, both known bladder cancer risk factors. Single nucleotide polymorphisms (SNPs) in XPC have been associated with increased bladder cancer risk. Recently, rarer genetic variants have been identified but it is difficult to ascertain which are of functional importance. During a mutation screen of XPC in DNA from 33 bladder tumour samples and matched blood samples, we identified five novel variants in the patients’ germ line DNA. In a case–control study of 771 bladder cancer cases and 800 controls, c.905T>C (Phe302Ser), c.1177C>T (Arg393Trp), c.*156G>A [3′ untranslated region (UTR)] and c.2251-37C>A (in an intronic C>G SNP site) were found to be rare variants, with a combined odds ratio of 3.1 (95% confidence interval 1.0–9.8, P = 0.048) for carriage of one variant. The fifth variant was a 2% minor allele frequency SNP not associated with bladder cancer. The two non-synonymous coding variants were predicted to have functional effects using analytical algorithms; a reduced recruitment of GFP-tagged XPC plasmids containing either c.905T>C or c.1177C>T to sites of 408 nm wavelength laser-induced oxidative DNA damage was found in vitro. c.*156G>A appeared to be associated with reduced messenger RNA stability in an in vitro plasmid-based assay. Although the laser microbeam assay is relevant to a range of DNA repair genes, our 3′ UTR assay based on Green fluorescent protein(GFP) has widespread applicability and could be used to assess any gene. These assays may be useful in determining which rare variants are functional, prior to large genotyping efforts.