Expression of Cox-2 protein in radioresistant laryngeal cancer.
BACKGROUND
Radiotherapy is the principal modality used to treat early stage laryngeal cancer. Unfortunately treatment failures occur in 10-25% of patients. Subsequent salvage surgery is technically more difficult, with increased complication and failure rates. The ability to predict or prevent radioresistance would improve the poor survival associated with this disease. Cox-2 is an inducible enzyme involved with prostaglandin synthesis. We investigated a potential role for Cox-2 in predicting radioresistance in laryngeal cancer.


METHODS
Using immunohistochemical techniques we examined the expression of Cox-2 protein in 122 pre-treatment laryngeal biopsies. All tumours were treated with single modality radiotherapy (curative intent). The group comprised of 61 radioresistant and 61 radiosensitive tumours matched for T stage, laryngeal subsite, gender and smoking history.


RESULTS
Cox-2 expression was detected in 41 of 61 (67%) biopsy samples from patients with radioresistant tumours and 25 of 61 (41%) radiosensitive tumours. Overexpression was significantly associated with radioresistant tumours (P = 0.004). Cox-2 has a 67% accuracy in predicting radiotherapy failure.


CONCLUSIONS
Cox-2 may have prognostic value in predicting response to radiotherapy. Cox-2 inhibitors such as NS-398 have been shown to enhance the effects of radiotherapy. We suggest that their use may be beneficial in patients who are destined to fail radiotherapy.
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Postgraduate Medical Institute of the University of Hull and Hull York Medical School, University of Hull, Castle Hill Hospital, Hull HU16 5JQ, UK.
Lind
M
M
Greenman
J
J
Stafford
N
N
Cawkwell
L
L
D000368:Aged; D014408:Biomarkers, Tumor / Q000032:analysis*; D001706:Biopsy; D051546:Cyclooxygenase 2; D005260:Female; D006801:Humans; D007150:Immunohistochemistry; D007527:Isoenzymes / Q000032:analysis* / Q000096:biosynthesis*; D007822:Laryngeal Neoplasms / Q000201:enzymology* / Q000532:radiotherapy*; D008297:Male; D008565:Membrane Proteins; D008875:Middle Aged; D010544:Peroxidases; D011237:Predictive Value of Tests; D011379:Prognosis; D011451:Prostaglandin-Endoperoxide Synthases / Q000032:analysis* / Q000096:biosynthesis*; D011453:Prostaglandins / Q000096:biosynthesis; D011836:Radiation Tolerance / Q000502:physiology*; D012189:Retrospective Studies
D014408:Biomarkers, Tumor; D007527:Isoenzymes; D008565:Membrane Proteins; D011453:Prostaglandins; D010544:Peroxidases; D051546:Cyclooxygenase 2; C496540:PTGS2 protein, human; D011451:Prostaglandin-Endoperoxide Synthases