clinically negative necks has lead to wide spread use of elective neck dissection7.Currently apart from the physical palpation, several modalities are available for investigating the presence and extent of cervical nodal metastasis. Imaging has great impact on treatment of head and neck cancers8, 9.Imaging modalities that are used to evaluate the oral cavity includes plain radiography (panoramic and intraoral radiography), nuclear medicine scintigraphy, ultrasound, magnetic resonance imaging, computed tomography and positron emission tomography. However, there are apprehensions regarding the efficacy of these investigations.
OBJECTIVE
To evaluate the status of clinically not detectable lymph nodes using Computerized Tomography in patients with Oral squamous cell carcinoma which might help in determining prognosis, treatment and also to compare accuracy between the clinical examination and Computerized Tomography in the evaluation of cervical lymph node metastasis.
MATERIALS AND METHODS
This is observational study and was conducted in the wing of Oral Medicine and Radiology at A.V. Super specialty dental hospital. 40 who have been histopathologically diagnosed as Oral squamous cell carcinoma were included in the study. All patients were drawn from outpatient department of A.V. Super Specialty Dental Hospital and MNJ Institute of Oncology and Regional Cancer Centre, Hyderabad.
Before conducting the study ethical clearance has been obtained from ethical clearance committee of GSL Medical College and Hospital, Rajahmundry.
Information regarding the nature and purpose of the study was thoroughly explained to every patient and a written consent was obtained. A structured Questionnaire has been filled which includes a detailed case history, clinical examination (CE), histopathological, radiological, and haematological findings. CE was performed using a disposable latex rubber gloves and a mouth mirror. Measuring tape, ruler and a divider were used to assess the extent of lesion and size of lymph nodes.
CLINICAL EXAMINATION OF LYMPH NODES Palpation of lymph nodes were done commencing with most superior nodes and working down to the clavicle. Submandibular lymph nodes in the submandibular triangle were palpated from behind the patient’s chin tipped slightly toward the chest. With fingers cupped and tips pressed lightly against the Mylohyoid muscle, the tissue is rolled laterally across
inferior border of the mandible. The Submental lymph nodes are palpated in the Submental triangle under chin. The nodes along the anterior triangle (nodes located along the anterior aspect of Sternocleidomastoid muscle) are palpated with the patients head tipped slightly forward and area medial to the Sternocleidomastoid muscle is pressed with finger tips. The fingers are rotated along the entire length of the muscle. The nodes in the posterior triangle are palpated by placing the finger tips behind the muscle. Palpation is started at Trapezius muscle and moved to the Sternocleidomastoid muscle. The Suboccipital nodes have been in the posterior triangle at the base of the skull. The Supraclavicular lymph nodes are palpated in Subclavian triangle by tipping the patients head forward, to relax the muscles in the neck. The finger is placed in the triangle, and the area is palpated with a rotary motion. The primary tumor along with the lymph nodes were staged clinically using the TNM system developed by the American Joint Committee on Cancer. The palpable lymph nodes were documented according to the number, size, consistency and mobility. The site was recorded according to the levels of the lymph nodes in the neck.
Later each patient underwent a spiral CT with a Somatom Emotion (Siemens) scanner. Scanning was performed in an axial plane in 3-5mm thick contiguous sections at a table speed of 5mm per second after the administration of 50 ml of non ionic contrast medium (Omnipaque or Iohexol) at a rate of 1-1.5 ml/sec. The patients subjected to CT were positioned in a supine position with the chin elevated. Transverse scans were obtained from the supraclavicular fossa to the base of the skull parallel to the inferior border of the mandible.
Scanning began after a delay of 50-60 seconds.
Scanning parameters were 140 kv and 160 mA. The period of CT scan to the neck dissection was within 35 days.
All CT scans were evaluated retrospectively without the knowledge of the clinical staging. The neck nodes were classified into different anatomical levels based on the Imaging Based Nodal Classification developed by Peter M. Som, Hugh D.Curtin and Anthony A.Mancuso.
The lymph nodes were diagnosed as positive for metastasis if the following criteria were met.
1. Lymph nodes size greater than 1.5 cm for level I node and 1.0 cm for rest of the subsequent nodes along the short axis.
2. Three or more lymph nodes in the primary drainage area.
3. Lymph nodes with central nodal necrosis and peripheral rim enhancement after intravenous contrast.
27 Prasanth Vanela 110-114.pmd 111 8/27/2012, 6:39 PM
4. Round shape of lymph nodes.
5. Extracapsular spread of the disease.
After neck dissection was performed, the surgical specimen was subjected to the histopathological examination of pathology where the lymph nodes were dissected and classified the nodes into levels as indicated by the surgeon. The nodes were then fixed in formalin, embedded in paraffin, sectioned and stained with haematoxylin and eosin. All nodes were microscopically evaluated by a pathologist for the presence of malignancy at each level. A node was considered positive when there was evidence of tumour on histopathological examination. The clinical examination and CT findings were correlated with pathological findings from the neck dissection.
Sensitivity, Specificity, Negativity, Positive Predictive Value and Accuracy were calculated for the both the clinical examination and CT.
Statistical analysis was performed using the Chi Square Test and differences were considered significant when the P value is less than 0.05.
RESULTS
Out of these 40 patients included in the present study, 19(47.5%) were males and 21(52.5%) were female. The age group ranged from 25 years to 68 years with a mean of 46.5 years.
In the total 40 cases, 15 were involving buccal mucosa (37.5%), 11 were involving tongue (27.5%), 9 were involving the gingivoalveolar region (22.5%), 4 were involving palate (10%) and in 1(2.5%) patient there was retromolar trigone involvement. In present sample five patients were classified as T1, 26 patients as T2, 4 patients as T3 and 5 patients as T4.Of the 40 cases, 27 (67.5 %) patients were histologically graded as grade I (Well Differentiated), 11(27.5%) patients as grade II (Moderately Differentiated) and 3 (7.5%) patients as grade III (Poorly Differentiated).
CLINICAL EXAMINATION
Of the 40 patients examined, 12 were clinically diagnosed as positive nodes. Among those 12 patients seven had pathological evidence of metastasis. Hence these cases were considered as true positive (58.33%).5 patients with clinically positive showed no histopathological evidence of metastasis. These were grouped as false positive (41.66%).In 28 of clinically negative cases, pathologic confirmation of absence of metastatic disease was reported in 18 cases. These were grouped as true negative (64.28%) and 10 cases which
have shown to be clinically positive showed negative nodes histopathologically (35.71%).
CT SCANNING
Of the 40 patients evaluated by CT, 18 patients showed positive neck nodes. Out of these 18 patients, 13 were histopathologically proved to be positive (true positive – 72.22%).In other 5 patients although CT showed positive nodes, pathological examination showed no evidence of neck metastasis (false positive – 27.78%).22 patients showed negative nodes on CT, out of which 18 patients were histopathologically negative (true negative – 81.81%) and 4 patients showed metastatic nodes histopathologically (false negative –18.19%)
HISTOPATHOLOGY
Out of 40 patients, 17 (42.5%) were found to be positive on histopathologic analysis and 23 were negative (57.5%). Out of 17 pathologically positive nodes, 7 patients were correctly diagnosed clinically where as CT was able to diagnose 13 patients.
OCCULT GROUP
10 out of 40 patients have evidence of neck metastatic involvement with no clinical evidence of neck disease. Of these clinically negative necks, 4 patients were identified by CT as negative and 6 patients showed positive in CT. this is to say that CT was able to upstage the neck in 6 patients.
STATISTICAL ANALYSIS
Table 1. Number of true positives detected by clinical examination versus CT
Diagnostic Aid True Positive chi-value p-value
Clinical Examination 7 1.8 0.17
CT 13
Table 2. Number of true negatives detected by clinical examination versus CT
Diagnostic Aid True Negative chi-value p-value
Clinical Examination 18 0 1
CT 18
Table 3. Number of false positives detected by clinical examination versus CT
Diagnostic Aid False Positive chi-value p-value
Clinical Examination 05 0 1
CT 05
Table 4. Number of false negatives detected by clinical examination versus CT
Diagnostic Aid False Negative chi-value p-value
Clinical Examination 10 2.57 0.1
CT 04
Table-5: Sensitivity for clinical examination versus CT Diagnostic Aid Sensitivity chi-value p-value
Clinical Examination 41.17% 6.77 0.00
CT 68.42%
Table 6. Specificity of clinical examination versus CT Diagnostic Aid Specificity chi-value p-value
Clinical Examination 78.26% 0.00 1.00
CT 78.26%
Table 7. Positive Predictive Value of clinical examination versus CT
Diagnostic Aid Positive chi-value p-value Predictive
Value
Clinical Examination 58.33% 1.47 0.001
CT 72.22%
Table 8. Negative Predictive Value of clinical examination versus CT
Diagnostic Aid Negative chi-value p-value Predictive
Value
Clinical Examination 64.28% 0.67 0.001
CT 75%
Table 9. Accuracy of clinical examination versus CT Diagnostic Aid Accuracy chi-value p-value
Clinical Examination 62.50% 1.6 0.001
CT 77.50%
DISCUSSSION
Pre-treatment assessment of lymph node metastases is important for therapy and prognosis of patients with carcinoma of the oral cavity. Any modality that detects metastatic nodes accurately would have a great impact on the management of such patients.9 Sensitivity of clinical examination was found to be 41.17%, whereas in previous studies it is reported between 48.7% to 86%.10-15. Specificity of clinical examination was found out to be 78.42% whereas in previous studies it is reported between 70% to 96.7%.13-16 The positive predictive value (PPV) of clinical examination was found out to be 58.33% which was lower when compared to the previous studies values i.e. 74-79.2%.14-16 The negative predictive value for clinical examination was found out to be 64.28%
whereas in previous studies it ranged between 63.63%
to 84.1%.14-16. The accuracy of the clinical palpation was found out to be 62.5% which was low when compared to the previous studies values ranged between 68 to
85%.14-16 The sensitivity of CT was found out to be 68.42
% whereas in previous studies it is reported between 52.5 to 93%.10-16 The specificity of CT was found out to be 78.26% whereas previous studies reported values ranging from 81 to 100%.12-18 The present study revealed PPV of CT as 72.2% whereas previous studies reported 53.1 to 92.3%.10-18 The present study revealed PPV of CT as 75% compared to previous studies that showed values from 75 to 94 %.14-18 The present study showed an overall accuracy for CT as 77.5%,whereas previous studies reported 75.3 to 90 %.12-19 Among 18 true positives detected by CT, 8 cases were based on size criteria (>1.5cm), 5 were based on grouping of lymph nodes in one drainage area, 3 were having central nodal necrosis and 2 with peripheral rim enhancing node. Central nodal necrosis and peripheral rim enhancement seems to be most accurate as it gave a specificity of 100%. CT was able to correctly evaluate 6 cases (21.42%) which were clinically not detectable.
ACKNOWLEDGEMENTS
We at A.V. Super specialty dental Hospital express our sincere gratitude to management, and administrative staff for rendering their support. We are grateful to our colleagues involved in this program for planning, discussing the details and generalities in developing strategies for smooth implementation of the study.
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