Polymorphisms of the XRCC1 DNA repair gene in head and neck cancer

Inherited polymorphisms in the genes controlling the cell cycle or functioning in the DNA repair mechanisms may impair their function and contribute to genetic susceptibility. Abnormalities in the DNA repair have been reported in head and neck cancer. The XRCC1 gene functions in singlestrand break and base excision repair processes. In this study, two polymorphisms of the XRCC1 gene, Arg194Trp and Arg399Gln were investigated in 95 patients with head and neck carcinoma. The polymorphic regions were amplified by PCR followed by digestion with methylation-specific restriction enzymes, and analyzed electrophoretically. Genotype and allele frequencies were calculated, and association with cancer risk or clinical parameters was investigated. No association was observed between the genotypes and head and neck cancer for either polymorphism. Distribution of the alleles did not significantly differ between the patients and the control group. A significant association was only found for the Trp194 allele among the smoking individuals. Our data indicate that the Arg194Trp and Arg399Gln polymorphisms do not confer a significant risk for head and neck carcinogenesis.     

Balancing Safety and Efficacy of Epidermal Growth Factor Receptor Inhibitors in Patients With Squamous Cell Carcinoma of the Head and Neck

The epidermal growth factor receptor (EGFR) is overexpressed in more than 80% of squamous cell cancers of the head and neck (SCCHN). An evolving understanding of the role of EGFR in tumorigenesis has made the receptor an important therapeutic target in SCCHN. Several EGFR inhibitors (EGFRIs) are active in SCCHN, and their use is associated with improvement in progression-free survival and overall survival in various treatment settings. Nevertheless, EGFR inhibition is associated with significant mucocutaneous toxicity that must be balanced against its anticipated efficacy. This review summarizes the relevant clinical trial experience with EGFRIs, with attention to efficacy, toxicity, and methods of selecting patients most likely to benefit from therapy.

Implications for Practice:

Cetuximab and other inhibitors of the epidermal growth factor receptor (EGFR) have entered the medical oncologist’s arsenal against squamous cell carcinoma of the head and neck (SCCHN). They are modestly active as single agents and in combination with chemotherapy and radiotherapy. Despite their efficacy across multiple treatment settings, cetuximab and other EGFR inhibitors (EGFRIs) have not supplanted platinum-based therapies, which remain a standard of care for SCCHN. The modest benefits of EGFRI therapy must take into consideration patient, disease, and treatment characteristics and must be balanced against potential treatment toxicity.     

Prognostic significance of microscopic and macroscopic extracapsular spread from metastatic tumor in the cervical lymph nodes

It has been established that the presence or absence of cervical node metastases in patients with head and neck squamous cell carcinoma (HNSCC) is a powerful prognostic indicator. This report reviews the evolution of thinking over the past 70 years with regard to the import and detection of cervical nodal metastases which exhibit spread of tumor beyond the confines of the original encompassing nodal capsule. In the process, this discussion touches upon clinical examination, gross and microscopic pathologic examination, and radiographic imaging studies. In particular, the distinction between gross nodal extracapsular spread of tumor and microscopic nodal extracapsular spread of tumor has been drawn in recent reports; this raises the possibility that identification of microscopic breaching of the node capsule by tumor might provide clinically significant information which is not provided by the gross observation of an intact lymph node capsule. While it remains to be seen whether microscopic extracapsular spread alone will prove to be an important prognostic factor, it is recommended that selective neck dissection continue to be offered even in those patients with clinically negative necks; further studies should aid in defining the import of microscopic extracapsular tumor spread in patients with positive cervical nodes.     

丙泊酚经HIF-1α信号通路对头颈鳞状细胞癌SCC-74细胞增殖、凋亡与侵袭的影响

目的 探讨丙泊酚经HIF-1α信号通路对头颈鳞状细胞癌SCC-74细胞增殖、凋亡与侵袭的影响。方法 体外培养SCC-74细胞,丙泊酚低剂量组、丙泊酚中剂量组和丙泊酚高剂量组分别给予终浓度为2.5、10、20 μg/mL的丙泊酚,对照组给予等量DMEM培养液,继续培养48 h后收获细胞,检测SCC-74细胞增殖、凋亡与侵袭情况,同时检测SCC-74细胞中Akt、p-Akt、HIF-1α、Fas、FasL、Bcl-2、Bax蛋白和mRNA水平。结果 与对照组比较,各丙泊酚剂量组SCC-74细胞增殖率和侵袭数降低,细胞凋亡率增加(P＜0.05);与对照组比较,各丙泊酚剂量组SCC-74细胞中p-Akt蛋白、Bcl-2蛋白和mRNA水平降低,HIF-1α、Fas、FasL和Bax蛋白和mRNA水平增高,呈剂量依赖性(P＜0.05)。各组SCC-74细胞中Akt蛋白和mRNA水平无统计学差异(P＞0.05)。结论 丙泊酚通过激活HIF-1α信号通路,抑制SCC-74细胞增殖和侵袭,促进SCC-74细胞凋亡。     

Crosstalk between Desmoglein 2 and Patched 1 accelerates chemical-induced skin tumorigenesis

Aberrant activation of Hedgehog (Hh) signaling is causative of BCCs and has been associated with a fraction of SCCs. Desmoglein 2 (Dsg2) is an adhesion protein that is upregulated in many cancers and overexpression of Dsg2 in the epidermis renders mice more susceptible to squamous-derived neoplasia. Here we examined a potential crosstalk between Dsg2 and Hh signaling in skin tumorigenesis. Our findings show that Dsg2 modulates Gli1 expression, in vitro and in vivo. Ectopic expression of Dsg2 on Ptc1^+/lacZ background enhanced epidermal proliferation and interfollicular activation of the Hh pathway. Furthermore, in response to DMBA/TPA, the Dsg2/Ptc1^+/lacZ mice developed squamous lessons earlier than the WT, Ptc1^+/lacZ, and Inv-Dsg2 littermates. Additionally, DMBA/TPA induced BCC formation in all mice harboring the Ptc1^+/lacZ gene and the presence of Dsg2 in Dsg2/Ptc1^+/lacZ mice doubled the BCC tumor burden. Reporter analysis revealed activation of the Hh pathway in the BCC tumors. However, in the SCCs we observed Hh activity only in the underlying dermis of the tumors. Furthermore, Dsg2/Ptc1^+/lacZ mice demonstrated enhanced MEK/Erk1/2 activation within the tumors and expression of Shh in the dermis. In summary, our results demonstrate that Dsg2 modulates Hh signaling, and this synergy may accelerate skin tumor development by different mechanisms.     

Synchronous chemoradiotherapy in patients with locally advanced squamous cell carcinoma of the head and neck using capecitabine: a single-centre, open-label, single-group phase II study

Aim

To evaluate the efficacy of concurrent oral capecitabine with accelerated hypofractionated radical radiotherapy in locally advanced squamous cell carcinoma of the head and neck (SCCHN).

Materials and methods

Between 2001 and 2004, 50 patients with stage III/IV SCCHN (0 to 2 performance status) were enrolled into this study. The capecitabine dose was between 450 and 550 mg/m² twice daily, continuously for 28 days. The radiotherapy dose was 5500 cGy in 20 fractions over 4 weeks. No intensity-modulated radiation was used. We evaluated the complete response rate, toxicity, locoregional control, overall survival, disease-free survival and cancer-specific survival.

Results

The median age was 55 (range 38-76) years; 72% had stage IV disease. The median follow-up was 6 years on the 30 surviving patients. Eighty-two per cent of patients completed the course of capecitabine and 94% completed prescribed radiotherapy. There were no treatment-related deaths, grade 3/4 haematological or renal toxicity. Five patients developed drug-related grade 3/4 acute toxicity (cardiac, skin, bowel); 47 developed grade 3/4 mucositis from chemoradiotherapy. Twenty-two (44%) patients required tube feeding and the tube dependency rate at 1 year was 6%. The complete response rate at 3 months was 90% (45/50 patients). Relapse occurred in 17/50 (34%) patients by 5 years. The locoregional control, overall survival, cancer-specific survival and disease-free survival rates at 3 years were 78, 72, 82 and 62%, respectively, and at 5 years were 72, 64, 75 and 56%, respectively.

Conclusion

This schedule of synchronous capecitabine for locally advanced SCCHN is well tolerated. The local control in this series compares favourably with other synchronous chemoradiotherapy reports. Chronic dysphagia and tube dependence is uncommon with this approach. Capecitabine as targeted therapy given with each fraction of radiotherapy and administered orally may have significant advantages over intravenous, 3 weekly cisplatin.