Evaluation of diagnostic values of photodynamic diagnosis in identifying the dermal and mucosal squamous cell carcinoma.

ABSTRACT

OBJECTIVES: We conducted a study to determine and compare the efficacy of pathology and photodynamic studies in establishing diagnosis of malignant dermal and mucosal lesions. METHODS AND PATIENTS This descriptive cross-sectional study was performed on 40 patients suspected of SCC (squamous cell carcinoma). First, in PDD (photodynamic diagnosis) photosensitizing agent was applied to the lesion, and after 4-5h the fluorescence spectrum was detected by laser radiation. Based on fluorescence intensity, normal area was differentiated from malignant area. Also, biopsy samples from these suspected areas were sent to pathology simultaneously. Data were analyzed with SPSS v.16. The distribution of nominal variables was compared using the Chi-square test. Diagnostic index for photodynamic diagnosis were calculated. A two-sided p-value<0.05 was considered to be statistically significant. RESULTS: In 27 cases (90%), results of pathology and photodynamic studies similarly showed malignancy. In 8 cases (80%), results of pathology and photodynamic studies similarly showed non-malignant lesion. But in five cases (12.5%) the results of pathology and photodynamic studies were not the same. This difference was not statistically significant showed by the Chi-square test analysis (p-value>0.05). A sensitivity of 90%, specificity of 80%, accuracy of 87.5%, positive predictive value (PPV) of 93%, negative predictive value (NPV) of 72%, positive likelihood ratio (PLR) of 4.5, negative likelihood ratio(NLR) of 0.125 were found in diagnosing SCC for photodynamic studies. CONCLUSION: Photodynamic diagnosis is a useful non-invasive initial step in the diagnostic work-up of patients with suspected malignant lesions (SCC). In this work we have studied 40 SCC suspicious patients using PDD method and successfully carried out 27 cases as malignant all of which were matching with pathologic results. This outcome can prove both accuracy and reliability of PDD method for detecting SCC lesions on head and neck regions. Also PDD can fully demarcate the lesion peripheries less invasively as well as preserving much more time and effort. Although PDD method is a bit more expensive that biopsy and pathology but great advantages can easily cover this issue. We recommend PDD as a useful easy technique to visualize and detect the extension of the tumor preoperatively.