Po Wing Yuen

Clinicopathological analysis of local spread of carcinoma of the tongue

BACKGROUND The aims of the study are three-dimensional analysis of mode and distance of local spread of oral tongue carcinoma. METHODS The glossectomy specimens were examined in the coronal plane in 3 mm thickness section. RESULTS There were 50 glossectomy specimens. The maximum spread was 1.8 cm. Ninety-six percent of specimens had local spread within 1.2 cm. The distance of spread was not correlated with tumor size, including the diameter, depth, and volume. The incidence of local recurrence was 27% with positive histological margin. Perineural infiltration was the most important prognostic factor for local recurrence and survival. CONCLUSIONS A minimum of 1.5-cm surgical resection margin is recommended. A smaller margin is not recommended as it has significant risk of local recurrence. A maximum of 2-cm surgical resection margin is recommended; larger margins will increase the surgical morbidity without a significant advantage of local control.

Current status of pharyngolaryngo-esophagectomy and pharyngogastric anastomosis

Pharyngolaryngo‐esophagectomy and pharyngogastric anastomosis (PLO & PGA) is one of the surgical options in the management of tumors arising from the hypopharynx and cervical esophagus. Indications of the operation and the outcome are changing over the years. To examine these, the experience of this operation in one Institute (the Head and Neck Division of the Department of Surgery, The University of Hong Kong at Queen Mary Hospital, Hong Kong) over the last 30 years was reviewed.

Comparative genomic hybridization analysis of nasopharygeal carcinoma:: consistent patterns of genetic aberrations and clinicopathological correlations

To define the patterns of genetic imbalances in nasopharyngeal carcinoma (NPC), we studied 30 primary NPC tumors with comparative genomic hybridization (CGH). The common sites of chromosomal gains were found in descending order of frequency in 12p11.2-p12 (36%), 12q14-q21 (33%), 2q24-q31 (23%), 1q31-qter (20%), 3q13 (20%), 1q13.3 (20%), 5q21 (17%), 6q14-q22 (13%), 7q21 (13%), 8q11.2-q23 (13%) and 18q12-qter (13%). The common sites of chromosomal loss were at 3p14-p21 (20%), 11q23-qter (20%), 16q21-qter (17%) and 14q24-qter (13%). Correlation with clinicopathologic features showed that 3p loss was associated with a significantly higher risk of death related to recurrence as compared with patients without 3p loss (50% vs. 9%, P=.029). The presence of 16q loss was associated with more advanced stage tumors (stages I & II: 6% vs. stages III & IV: 33%, P=.046). We conclude that consistent patterns of genetic imbalances can be observed in NPC. Deletion of 3p and 16q were associated with higher risk of tumor recurrence and advanced stage cancer.

Cervical lymph node metastatic patterns of squamous carcinomas in the upper aerodigestive tract

The radical neck dissection specimens of 384 ethnically Chinese patients with different primary squamous carcinomas in the head and neck region were studied. Over 50 per cent of the specimens showed metastatic disease at one level in the neck. For oral cavity carcinoma, the levels of metastasis frequently involved were I, II and III while for carcinoma of the oropharynx, hypopharynx and larynx the levels were II, III and IV. Extracapsular spread was present in 112/384 of patients (29 per cent) and this increased with advancing N-stages. Based on these findings, different selective neck dissections could be used for patients harbouring different primary head and neck carcinomas with limited neck disease.

Classification of in vivo autofluorescence spectra using support vector machines

An algorithm based on support vector machines (SVM), the most recent advance in pattern recognition, is presented for use in classifying light-induced autofluorescence collected from cancerous and normal tissues. The in vivo autofluorescence spectra used for development and evaluation of SVM diagnostic algorithms were measured from 85 nasopharyngeal carcinoma (NPC) lesions and 131 normal tissue sites from 59 subjects during routine nasal endoscopy. Leave-one-out cross-validation was used to evaluate the performance of the algorithms. An overall diagnostic accuracy of 96%, a sensitivity of 94%, and a specificity of 97% for discriminating nasopharyngeal carcinomas from normal tissues were achieved using a linear SVM algorithm. A diagnostic accuracy of 98%, a sensitivity of 95%, and a specificity of 99% for detecting NPC were achieved with a nonlinear SVM algorithm. In a comparison with previously developed algorithms using the same dataset and the principal component analysis (PCA) technique, the SVM algorithms produced better diagnostic accuracy in all instances. In addition, we investigated a method combining PCA and SVM techniques for reducing the complexity of the SVM algorithms.

Mucosal Changes of the Free Jejunal Graft in Response to Radiotherapy

BACKGROUND Microvascular free jejunal transfer was employed for reconstruction of pharyngeal defect resulting from circumferential resection of the hypopharynx. Postoperative radiotherapy to the neck might affect the graft, but this information was lacking. The mucosal changes of the jejunum in response to radiation were identified in this prospective study. METHODS Normal jejunal mucosa was obtained at operation, and endoscopic jejunal mucosal biopsies were taken during and at completion of radiotherapy. Endoscopic biopsies were repeated at 1, 3, 6, 12, and 24 months afterwards. All jejunal biopsies were subjected to histologic and scanning electron microscopic (SEM) examinations. Nine patients had a complete set of biopsy while 5 other patients who received no radiotherapy also went through a similar sequence of biopsies as controls. RESULTS Histologic examination showed mucosal edema and extensive blunting of jejunal villi at the completion of radiotherapy. Increased fibrosis with focal loss of glands was noticed at 3 months after radiotherapy, and this remained throughout the 2-year period. SEM revealed patchy loss of microvilli at completion and at 1 month after radiotherapy, but this feature was not apparent in biopsies taken at 3 months onwards, showing that it was only a transient event. CONCLUSIONS Transient responses and persistent changes of jejunal mucosa to radiotherapy were identified and characterized. The presence of these mucosal lesions was not associated with any clinically significant adverse effect in the graft up to 2 years postradiotherapy.

The clinicopathologic significance of p53 and p21 expression in the surgical management of lingual squamous cell carcinoma

The aim of the present study was to evaluate the clinicopathologic significance of p53 and p21 expression in lingual squamous cell carcinomas. Immunohistochemical staining was performed with p53 and p21 monoclonal antibodies on surgical specimens from 87 patients who underwent primary surgical treatment for lingual carcinoma between 1976 and 1996. We found positive expression of p53 in 45 (52%) of 87 cases and of p21 in 49 (56%) of 87 cases. There was no correlation of p53 and p21 expression with cancer stage, T stage, nodal metastasis, and tumor grade. Univariate analysis revealed that p21 expression, tumor stage, T stage, and nodal stage were significant prognostic factors for survival. However, only p21 expression and tumor stage were significant independent prognostic factors for survival in a multivariate Cox regression analysis. Overexpression of p21 but not p53 has prognostic value for survival in the surgical treatment of lingual carcinomas. The combination of stage with p21 expression is recommended for evaluation of prognosis and for management planning.

Light-induced autofluorescence spectroscopy for detection of nasopharyngeal carcinoma in vivo

Autofluorescence spectral signals were measured in vivo from 85 nasopharyngeal carcinoma lesions and 131 normal tissue sites of 59 subjects during routine nasal endoscopy. Diagnostic algorithms based on principal component analysis and the ratio of the spectral signals between multiple-wavelength bands were developed for classifying the autofluorescence spectra. Performances of the algorithms were evaluated using the cross-validation method. The principal component analysis based algorithms using information from the entire fluorescence spectrum can differentiate nasopharyngeal carcinoma lesions from normal tissue with 95% sensitivity and 93% specificity. With 94% sensitivity, the specificities of multiple-wavelength ratio algorithms are about 83%. The results demonstrate that light-induced autofluorescence endoscopy with principal component analysis algorithms can provide accurate diagnostic information for the detection of nasopharyngeal carcinoma in vivo and may be potentially used in clinical practice combined with the routine white-light endoscopy procedure.

Light induced autofluorescence for detection of nasopharyngeal carcinoma in vivo

To improve the accuracy of conventional white light endoscopy in detecting the small lesion and identifying the margin of observable tumors, in vivo, the potential of light-induced fluorescence (LIF) spectroscopic imaging, using a general multivariate spectral classification algorithm, was evaluated. A conventional endoscopic system with a multiple channel spectrometer was used to measure the autofluorescence of nasopharyngeal tissue in vivo. Classification was based on the spectral difference between the carcinoma and normal tissue. A sophisticated algorithm based on Principal Component Analysis (PCA) was developed to differentiate between the nasopharyngeal carcinoma (NPC) from the normal tissue. Firstly, preprocessing was done to reduce noise and to calibrate the different measurement distances and geometry. Secondly, processing by PCA was done to effectively reduce the variable dimensions while maintaining useful information for analysis. Thirdly, various post-processing techniques were investigated and the classification performance was compared. Algorithms based on ratio of autofluorescence at two-wavelength and three-wavelength bands were used for comparison. The PCA based method shows a significant improvement over the two-wavelength and three-wavelength algorithm. Based on the entire spectra, the sensitivity of 92% and specificity of 96% were achieved using the PCA based algorithm for the detection of nasopharyngeal carcinomas. In conclusion, the PCA based statistical algorithm is efficient to achieve high spectral classification performance of NPC.

In-vivo autofluorescence of nasopharyngeal carcinoma and normal tissue

An optical imaging and spectroscopy system has been developed for the study of in vivo fluorescence of nasopharyngeal tissue through an endoscope. The system records the fluorescence signal in the imaging plane of the endoscopic system. This allows analyze the characteristics of the light induced fluorescence (LIF) spectra recorded by each pixel of the 2D detector which may be used for fluorescence endoscopic imaging. If the endoscope for fluorescence endoscopy is the same as one employed for the in vivo fluorescence study, the algorithms developed to distinguish the diseased tissue from normal tissue based on the in vivo fluorescence study should be highly reliable for fluorescence imaging of lesions. In this work, fluorescence spectra were collected from 27 full term patients. Different algorithms were tested for separation of cancerous lesions from normal tissue. High sensitivity and specificity were achieved.