Neck Dissections Based on Sentinel Lymph Node Navigation Versus Elective Neck Dissections in Early Oral Cancers: A Randomized, Multicenter, and Noninferiority Trial.

PURPOSE: This study aimed to compare patients with early oral cavity squamous cell carcinoma (OCSCC) (tumor category [T] 1-2, node-negative, and no distant metastasis) treated with traditional elective neck dissection (ND) with those managed by sentinel lymph node biopsy (SLNB) using survival and neck function and complications as end points. METHODS: Sixteen institutions in Japan participated in the study (trial registration number: UMIN000006510). Patients of age ≥ 18 years with histologically confirmed, previously untreated OCSCC (Union for International Cancer Control TNM Classification of Malignant Tumors 7th edition T1-2, node-negative no distant metastasis), with ≥ 4 mm (T1) depth of invasion, were randomly assigned to undergo standard selective ND (ND group; n = 137) or SLNB-navigated ND (SLNB group; n = 134). The primary end point was the 3-year overall survival rate, with a 12% noninferiority margin; secondary end points included postoperative neck functionality and complications and 3-year disease-free survival. Sentinel lymph nodes underwent intraoperative multislice frozen section analyses for the diagnosis. Patients with positive sentinel lymph nodes underwent either one-stage or second-look ND. RESULTS: Pathologic metastasis-positive nodes were observed in 24.8% (34 of 137) and 33.6% (46 of 134) of patients in the ND and SLNB groups, respectively (P = .190). The 3-year overall survival in the SLNB group (87.9%; lower limit of one-sided 95% CI, 82.4) was noninferior to that in the ND group (86.6%; lower limit 95% CI, 80.9; P for noninferiority < .001). The 3-year disease-free survival rate was 78.7% (lower limit 95% CI, 72.1) and 81.3% (75.0) in the SLNB and ND groups, respectively (P for noninferiority < .001). The scores of neck functionality in the SLNB group were significantly better than those in the ND group. CONCLUSION: SLNB-navigated ND may replace elective ND without a survival disadvantage and reduce postoperative neck disability in patients with early-stage OCSCC.

Attempting to define sentinel node micrometastasis in oral squamous cell carcinoma.

OBJECTIVE: The aim of this supplemental study of a sentinel node (SN) biopsy (SNB) trial for oral squamous cell carcinoma (OSCC) was to assess the effectiveness in identifying micrometastasis and determining whether elective neck dissection (END) is necessary. MATERIALS AND METHODS: Twenty-three patients with pathologically positive SNs were included. The sizes of the metastatic lesions in positive SNs (SMSNs) were classified and the rates of occult metastasis of non-SNs were compared. RESULTS: The patients were divided according to the SMSN:<0.2 mm (group A, n=3);0.2 mm to <2.0 mm (group B, n=7);and ≥2.0 mm (group C, n=13). The rates of occult metastasis in groups A, B, and C were 0% (0/3), 14% (1/7) and 23% (3/13), respectively. CONCLUSION: Rare cancer cell distribution to nodes other than SNs was observed in the patients with SN metastatic lesions of at least smaller than 0.2 mm in size, suggesting the possibility of defining SN micrometastasis in N0 OSCC.

Sentinel node biopsy for oral cancer: A prospective multicenter Phase II trial.

OBJECTIVE: A recent study identified a survival benefit with prophylactic neck dissection (ND) at the time of primary surgery as compared with watchful waiting followed by therapeutic neck dissection for nodal relapse, in patients with cN0 oral squamous cell carcinoma (OSCC). Alternative management of cN0 neck cancer is recommended to minimize the adverse effects of ND, indicating the need for sentinel node biopsy (SNB) and limited neck dissection. We conducted a multicenter Phase II study to examine the feasibility of SNB for clinically N0 OSCC. METHODS: Previously untreated N0 OSCC patients (n=57) with clinical late-T2 or T3 tumors were enrolled across 10 institutions. SNB navigated with multislice frozen section analysis of sentinel nodes (SNs) and SNB supported sentinel node lymphatic basin dissection (SN basin dissection) were performed in a one-stage procedure. The endpoint was to investigate the rate of false-negative metastases after SN basin dissection and SNB alone. RESULTS: Most tumors were late-T2 lesions (n=50; 87.7%). SNs were identified in all patients. A total of 196 SNs were detected. Among these SNs, 35 (17.8%) were positive for metastasis (9 in level I, 12 in level II, 12 in level III, 1 in level V and 2 in the contralateral region of the neck). The false-negative rate of SNB supported by SN basin dissection and SNB alone was 4.5% and 9.1%, respectively. The concordance of the SN status in intraoperative frozen sections with the permanent histopathology was 97.4% (191/196). The sensitivity and specificity of intraoperative pathological evaluation were 85.7% (30/35) and 100% (30/30), respectively. The 3-year overall survival (OS) and disease-free survival was 89.5% and 82.5%, respectively. The OS of SN-negative patients was significantly longer than that of SN-positive patients (P=0.047). CONCLUSION: The current study verified that SN basin dissection was a useful back-up procedure for SNB performed as a one-stage procedure, showing a low false-negative rate. SNB alone is an appropriate staging method for patients with clinical N0 staging, and a reliable procedure to determine the appropriate levels for neck dissection.

Diffusion kurtosis imaging study of prostate cancer: preliminary findings.

PURPOSE: To evaluate the differences in parameters of diffusion kurtosis imaging (DKI) between prostate cancer, benign prostatic hyperplasia (BPH), and benign peripheral zone (PZ). MATERIALS AND METHODS: Twenty-four foci of prostate cancer, 41 BPH nodules (14 stromal and 27 nonstromal hyperplasia), and 20 benign PZ from 20 patients who underwent radical prostatectomy were investigated. Diffusion-weighted imaging (DWI) was performed using 11 b-values (0-1500 s/mm(2) ). DKI model relates DWI signal decay to parameters that reflect non-Gaussian diffusion coefficient (D) and deviations from normal distribution (K). A mixed model analysis of variance and receiver operating characteristic (ROC) analyses were performed to assess the statistical significance of the metrics of DKI and apparent diffusion coefficient (ADC). RESULTS: K was significantly higher in prostate cancer and stromal BPH than in benign PZ (1.19 ± 0.24 and 0.99 ± 0.28 versus 0.63 ± 0.23, P < 0.001 and P < 0.001, respectively). K showed a trend toward higher levels in prostate cancer than in stromal BPH (1.19 ± 0.24 versus 0.99 ± 0.28, P = 0.051). On the ROC analyses, a significant difference in area under the curve was not observed between K and ADC, however, K showed the highest sensitivity among three parameters. CONCLUSION: DKI may contribute to the imaging diagnosis of prostate cancer, especially in the differential diagnosis of prostate cancer and BPH.

[Impact of 131I SPECT/CT on the management of differentiated thyroid carcinoma outpatients with radioablation].

OBJECTIVE: The purpose of this study was to comparatively assess the diagnostic accuracy between 131I SPECT/CT and 131I whole-body scintigraphy (WBS) in differentiated thyroid carcinoma outpatients following radioablation. METHODS: a retrospective cohort study was performed in eleven patients with differentiated thyroid carcinoma (fourteen studies), who underwent both 131I WBS and 131I SPECT/CT, 7-10 days after administration of 1,110 MBq of 131I for radioablation, following a total thyroidectomy. A head and neck surgeon and two nuclear medicine specialists first interpreted the WBS images, followed by SPECT/CT images. RESULTS: SPECT/CT led to accurate revisions of the first diagnoses in 13 of 24 cervical foci of 131I uptake on WBS. Out of the 5 distant lesions, which were diagnosed as metastases by WBS alone, 5 (100%) were found out to be benign lesions by SPECT/CT. Thus, WBS was prone to be false-positive both in detecting cervical node metastases (13/28, 46.4%) and distant metastases (5/17, 29.4%). Eventually, SPECT/CT after 131I radioablation altered postoperative patients' management in 42.8% of patients with thyroid carcinoma by upstaging or down-staging their disease. CONCLUSION: SPECT/CT after 131I radioablation for differentiated thyroid cancer patients determines more accurately cervical lymph node metastasis, thyroid remnants and distant metastasis than does WBS alone. Both WBS and SPECT/CT after 131I radioablation are highly recommended for appropriate management of differentiated thyroid cancer patients who have undergone a total thyroidectomy.

Novel Indocyanine Green-Phytate Colloid Technique for Sentinel Node Detection in Head and Neck: Mouse Study.

OBJECTIVE: Sentinel node navigation surgery using real-time, near-infrared imaging with indocyanine green is becoming popular by allowing head and neck surgeons to avoid unnecessary neck dissection. The major drawback of this method is its quick migration through the lymphatics, limiting the diagnostic time window and undesirable detection of downstream nodes. We resolved this problem by mixing indocyanine green (ICG) with phytate colloid to retard its migration and demonstrated its feasibility in a nude mouse study. STUDY DESIGN: Experimental prospective animal study. SETTINGS: Animal laboratory. SUBJECTS AND METHODS: Indocyanine green at 3 concentrations was tested to determine the optimal concentration for sentinel lymph node detection in a mouse model. Effect of indocyanine green with phytate colloid mixture solutions was also analyzed. Indocyanine green or mixture solution at different mixing ratios were injected into the tongue of nude mice and near-infrared fluorescence images were captured sequentially for up to 48 hours. The brightness of fluorescence in the sentinel lymph node and lymph nodes further downstream were assessed. RESULTS: Indocyanine green concentration >50 µg/mL did not improve sentinel lymph node detection. The addition of phytate colloid to indocyanine green extended the period when sentinel lymph node was detectable. Second echelon lymph nodes were not imaged in mice injected with the mixture, while these were visualized in mice injected with indocyanine green alone. CONCLUSION: This novel technique of ICG-phytate colloid mixture allows prolonged diagnostic time window, prevention of downstream subsequent nodes detection, and improved accuracy for the detection of true sentinel lymph nodes.

Pseudomesotheliomatous lung cancer mimicking mesothelioma on ¹8F-FDG PET/CT images: report of 2 cases.

The authors report two cases of pseudomesotheliomatous lung cancer (PLC) detected by (18)F-FDG PET/CT scan. (18)F-FDG PET/CT clearly revealed the extent of the disease in both cases, a case of adenocarcinoma of the lung and a case of squamous cell carcinoma of the lung. Intense (18)F-FDG uptake by the diffusely thickened pleurae and primary lesion was observed in both cases, and increased (18)F-FDG uptake by a pelvic bone metastasis was observed in the case of squamous cell carcinoma. Although PLC is indistinguishable from malignant pleural mesothelioma on (18)F-FDG PET/CT scans, (18)F-FDG PET/CT was helpful in identifying the primary focus of the PLCs and in staging the disease. Diagnostic image interpreters should be familiar with the (18)F-FDG PET/CT findings in PLC.

Superparamagnetic iron oxide-enhanced interstitial magnetic resonance lymphography to detect a sentinel lymph node in tongue cancer patients.

CONCLUSION: This is the first report on human sentinel node (SN) detection by interstitial magnetic resonance (MR) lymphography with superparamagnetic iron oxide (SPIO) in tongue cancer patients who also underwent lymphoscintigraphy. Our results indicate that further studies are warranted, as this novel method may replace current scintigraphic techniques. OBJECTIVES: To examine the feasibility of interstitial MR lymphography using SPIO for SN detection in the head and neck region. METHODS: MR images were acquired sequentially at 10 min, 30 min, and 24 h after submucosally injecting 0.1 ml SPIO (ferucarbotran) around the tumor in three patients with tongue cancer without cervical lymph node metastasis (clinical T2N0M0). RESULTS: The SNs were clearly visualized in the 10 min interstitial MR lymphography images and were completely concordant with those visualized by (99m)Tc-radiocolloid lymphoscintigraphy and a gamma probe in all cases. Iron incorporation into the SNs was confirmed by pathological examination.

Radiation-induced myositis mimicking chest wall tumor invasion in two patients with lung cancer: a PET/CT study.

Two patients with lung cancer who had undergone stereotactic body radiation therapy (SBRT) exhibited increased F-18 FDG uptake in the chest wall after 6 months and 18 months, respectively, after SBRT. The prescribed dose of 50 Gy to the planning target volume was delivered on 4 consecutive days in each patient. It is important for nuclear medicine physicians to be familiar with F-18 FDG PET/CT findings ascribed to radiation-induced myositis in lung cancer patients treated with SBRT so that an appropriate differential diagnosis can be established.

Comparison of animal studies between interstitial magnetic resonance lymphography and radiocolloid SPECT/CT lymphoscintigraphy in the head and neck region.

OBJECTIVE: To comparatively assess two techniques, radiocolloid SPECT/CT lymphoscintigraphy and interstitial MR lymphography using SPIO and gadoxetate disodium, in animal models. MATERIALS AND METHODS: We used twenty one 8-week-old male nude mice of strain BALB/c Slc-nu/nu, weighing 23-27 g. The 4.7-T MRI equipment was used to detect the SNs. T2*WI of gradient-echo sequences was acquired sequentially up to 24 h after administering SPIO, ferucarbotran. T1WI was acquired sequentially up to 80 min after administering gadoxetate disodium. (99m)Tc-phytate SPECT/CT lymphoscintigraphy was taken at 30 min after the injection to detect the SNs using animal-dedicated whole-body SPECT/CT hybrid scanner. The injection was submucosally performed in the right tongue margin of each mouse. Reading performances concerning SN visualization and its quality on interstitial MR lymphogram and SPECT/CT lymphoscintigram were performed by 3 radiologists. RESULTS: The SN intensities were 0.43 for the right, 0.61 for the left at 30 min after ferucarbotran injection, with gradual decrease in intensity, and 1.43 for the right, 1.33 for the left at 10 min after gadoxetate disodium injection with a fast decrease in intensity. The base value of 1.0 was at pre-examination. The mean numbers of lymph nodes visualized were 4.00 nodes for on SPECT/CT lymphoscintigram and 2.0 for interstitial MR lymphogram. There was a statistically significant difference in the mean scores between SPECT/CT lymphoscintigraphy and interstitial MR lymphography (two factor mixed design with repeated measures on one factor: p < 0.0002). CONCLUSIONS: In our comparative study using mice, the results of radiocolloid SPECT/CT lymphoscintigraphy were superior to those of interstitial MR lymphography, while both SPIO and gadoxetate disodium have a potential of being employed for sentinel node navigation surgery by interstitial MR lymphography in the head and neck region.

Questionnaire survey of hospitals in Saitama Prefecture regarding the shortage of 99mTc-labeled radiopharmaceuticals and 99Mo/99mTc generators.

OBJECTIVE AND METHODS: A questionnaire survey was conducted at all 32 hospitals in Saitama Prefecture to investigate the current difficult situation in terms of nuclear medicine management in the face of the (99m)Tc shortage due to insufficient supply, and 29 hospitals (90.6%) replied. RESULTS: Of the 29, 15 (51.7%) reported a reduction in the number of nuclear medicine studies performed due to the shortage of supply, although the reduction was small. The decrease per month was less than 20 studies in 73% of the institutions. Of the nuclear medicine studies that involve the use of (99m)Tc, the studies whose reduction in number most seriously affected patient management were, in decreasing order: (99m)Tc-MAA lung perfusion scans, (99m)Tc-MAG(3), (99m)Tc-DTPA, or (99m)Tc-DMSA renoscans, (99m)Tc-MDP bone scans, (99m)Tc-HMPAO or ECD brain SPECT studies, (99m)Tc-MIBI or tetrofosmin myocardial SPECT studies, (99m)Tc-radiocolloid sentinel lymphoscintigraphy, (99m)Tc-HSA-D or pyrophosphate bleeding scans, (99m)Tc-GSA hepatic function reserve scans, and (99m)Tc-MIBI parathyroid scans. The reduction is probably ascribable to factors such as cancellations of emergency studies, absence of substitute studies, sequential studies using the same radiopharmaceutical, and higher cost of the syringe-type products than the vial-type products. Substitutes for (99m)Tc studies were performed at 52% (15/29) of the institutions. Myocardial perfusion imaging with (201)Tl chloride was the most common substitute study. CONCLUSIONS: The results of this survey suggested the several procedures to resolve the issues related to the shortage. The staffs at all institutions except one gave the impression that their nuclear medicine ordering systems had been greatly affected by the shortage of supply. This adverse circumstance, however, may provide a good opportunity to educate the public about nuclear medicine studies that use (99m)Tc and SPECT, with which citizen are now unfamiliar.

Intense accumulation of Tc-99m MDP in pericardial metastasis from breast cancer.

Extraosseous uptake often seen on Tc-99m methylene diphosphonate bone scintigraphy has clinical significance. In a routine follow-up study on a 54-year-old female patient with breast cancer, we encountered a rare finding of pericardial metastasis clearly demonstrated by Tc-99m methylene diphosphonate bone scintigraphy. This incidental finding of increased uptake in the periphery of the cardiac contour on a bone scan reflects radionuclide accumulation in pericardium, myocardium, or pericardial effusion itself. In our case, an additional computed tomography examination of the chest was useful for making the definitive diagnosis of dystrophic calcification of the pericardium.

How should tracers be injected to detect for sentinel nodes in gastric cancer--submucosally from inside or subserosally from outside of the stomach?

BACKGROUND: In sentinel node (SN) detection for cases of early gastric cancer, the submucosal dye injection method appears to be more reasonable than the subserosal injection. To compare the two injection methods, we have focused on the rate of concordance between hot nodes (HNs) obtained from the radioisotope (RI) method and green nodes (GNs) obtained from the dye-guided method in addition to the number and distribution of GNs detected, and the sensitivity of metastatic detection. METHODS: The subjects of this study were 63 consecutive patients with gastric cancer (sT1-T2, sN0, tumor diameter <== 4 cm) in whom we attempted SN detection using a combination of RI and dye methods. 99mTc-tin colloid was injected a day before the surgery, and indocyanine green was injected either submucosally (n = 43) with endoscopes or subserosally (n = 20) by direct vision. RESULTS: An average of hot and green nodes (H&G: 4 +/- 3 vs. 4 +/- 3), hot and non-green nodes (H&NG: 2 +/- 3 vs. 1 +/- 2), cold and green nodes (C&G: 2 +/- 2 vs. 3 +/- 4), and the rate of concordance (H&G/H&G + H&NG + C&G: 45 + 27% vs. 48 +/- 30%) were not significantly different between the submucosal and subserosal injection methods. The spread of GNs to tier 2 stations (24% vs. 30%) and metastatic detection sensitivity (86% vs. 100%) were also not different between the submucosal and subserosal injection methods. CONCLUSION: The tracer injection sites do not have to be limited to the submucosa.

18F-FDG-PET/CT as an indicator for resection of pulmonary epithelioid hemangioendothelioma.

A 60-year-old man with a 7-year history of multiple pulmonary nodules presented to our hospital because the nodules were seen to have increased in size on review of films on a regular medical checkup 1 week earlier. Computed tomography (CT) revealed multiple pulmonary nodules with calcification in the lungs. The largest nodule measuring 2.5 cm in the maximum dimension was lobulated and ill-defined. The patient underwent 18F-fluorodeoxyglucose positron emission tomography/CT (18F-FDG-PET/CT) to evaluate the multiple nodules and to search for a primary lesion. 18F-FDG-PET/CT revealed increased uptake in only two nodules with a standardized uptake value of 4.61 and 2.10, respectively. The two foci with increased 18F-FDG uptake were resected and pathologically proven to be pulmonary epithelioid hemangioendothelioma (PEH). PEH can transform into malignancy with metastasis. An 18F-FDG-PET/CT finding may be an indicator to decide on PEH resection.

Histiocytic sarcoma of the spleen: case report of asymptomatic onset of thrombocytopenia and complex imaging features.

Histiocytic sarcoma of the spleen, in which the malignant cells display morphologic and immunophenotypic features similar to those of mature tissue histiocytes, is a rare but potentially lethal condition that can remain asymptomatic or only mildly symptomatic for a long period of time. We studied a case of histiocytic sarcoma of the spleen in an 82-year-old woman with prolonged chronic thrombocytopenia that was non-responsive to steroid therapy. Ultrasonography, computed tomography, and magnetic resonance imaging showed a characteristically enlarged spleen and liver. Palliative irradiation therapy was clinically effective; however, disease progression proved lethal. Autopsy revealed the proliferation of tumor cells within the splenic sinus and the liver sinusoids, which displayed extreme hemophagocytosis and strong expression of the histiocytic markers CD68 (KP1 and PG-M1) and CD163. The postmortem diagnosis showed histiocytic sarcoma of the spleen with liver infiltration. This and previous reports indicate that early detection (facilitated by imaging and clinical features) and management may improve patient prognosis and survival. Histiocytic sarcoma of the spleen should be considered as a differential diagnosis in therapeutically unresponsive patients with chronic thrombocytopenia.

[Chronological change in the national health insurance reimbursement based on the DPC package payment system regarding 131I internal therapy].

The national health reimbursement in 131I internal therapy for thyroid cancer and Graves' disease has increased by introducing the DPC package payment system. The thyroid cancer administration fee for shield room should be increased because of the strict regulation for 131I internal therapy, expensive equipments, confinement of radiopharmaceutical supply, and low efficiency in admission to shield rooms. In addition, the Graves' disease administration fee for shield room should be introduced since the inpatients undergo the same administration and care as the thyroid cancer inpatients.

[Statistical study on the self-selection bias in FDG-PET cancer screening by a questionnaire survey].

A questionnaire survey was performed to investigate the possible presence of self-selection bias in 18F-FDG PET cancer screening (PET cancer screening). Responders to the questionnaires survey consisted of 80 healthy persons, who answered whether they undergo PET cancer screening, health consciousness, age, sex, and smoking history. The univariate and multivariate analyses on the four parameters were performed between the responders who were to undergo PET cancer screening and the responders who were not. Statistically significant difference was found in health consciousness between the above-mentioned two groups by both univariate and multivariate analysis with the odds ratio of 2.088. The study indicated that self-selection bias should exist in PET cancer screening.

Clinical significance of the serum IL-2R level and Ga-67 scan findings in making a differential diagnosis between sarcoidosis and non-Hodgkin's lymphoma.

OBJECTIVE: To compare the serum-soluble interleukin-2 receptor (sIL-2R) levels of non-Hodgkin's lymphoma patients and active sarcoidosis patients in relation to the (67)Ga scan findings. METHODS: A total of 29 adenopathy patients suspected of having non-Hodgkin's lymphoma or sarcoidosis were enrolled in the study. All patients underwent a whole-body (67)Ga scan and single-photon emission computed tomography studies 48 h after intravenous injection of (67)Ga citrate. The sIL-2R levels were compared between the sarcoidosis patients and non-Hodgkin's lymphoma patients, the patients with and without the panda and/or lambda sign, the lymphoma patients with stage I/II disease and with stage III/IV disease, and the sarcoidosis patients and non-Hodgkin's lymphoma patients with stage III/IV disease. RESULTS: The range of the sIL-2R levels was 195-3750 U/ml in sarcoidosis and 240-62 300 U/ml in non-Hodgkin's lymphoma. The sIL-2R levels of the six non-Hodgkin's lymphoma patients with stage III/IV disease were significantly higher than those of the 15 sarcoidosis patients (P < 0.001). The sIL-2R levels of the sarcoidosis patients with the panda and/or lambda sign were significantly higher than those with neither sign (P < 0.005). The sIL-2R levels of the non-Hodgkin's lymphoma patients with stage III/IV disease were significantly higher than those of the patients with stage I/II disease (P < 0.005). CONCLUSIONS: Measurement of sIL-2R levels was sometimes useful in differentiating between sarcoidosis and stage III/IV non-Hodgkin's lymphoma, staging non-Hodgkin's lymphoma, and predicting the presence of the panda and/or lambda sign in sarcoidosis patients.

Analysis of sentinel node involvement in gastric cancer.

BACKGROUND & AIMS: Sentinel node navigation surgery (SNNS) is performed for patients with early gastric cancer. Because sentinel nodes (SNs) to gastric cancer exist but they have not been well-described, we attempted to validate the SN concept at the micrometastasis level. METHODS: For 53 patients who underwent curative gastrectomy for T1/T2 (<4 cm) N0 gastric cancer, SNNS was performed with radioactive tin colloid and/or indocyanine green, and subsequent modified D1 lymphadenectomies were added. Whole formalin-fixed paraffin-embedded tissues of all resected lymph nodes from these patients were cut into 5-mum thick serial step sections at 85-mum intervals, and occult metastases were examined immunohistochemically. RESULTS: Metastases were detected in 3 (1.5%) of 204 SNs and 3 (0.33%) of 901 non-SNs in pN0 cases and in 18 (46%) of 39 SNs and 3 (1.9%) of 158 non-SNs in pN1 cases. On a patient basis, metastases were detected in 4 (9%) of 46 pN0 patients, 2 (4%) each in SNs and non-SNs, and in 7 pN1 patients, of whom 7 and 4 had SN and non-SN metastases, respectively. The sensitivity, false-negative rate, and accuracy of SN identification by SNNS were 82%, 18%, and 96%, respectively, at the occult metastasis level. However, on the basis of the concept of the sentinel lymphatic station (SLS), which represents all lymphatic stations to which SNs belong, metastases were always limited to the lymph nodes in SLS in the 11 cases with metastases. Non-SN metastases occurred in 3 (60%) of 5 patients with SN metastases >2.0 mm in diameter but not in 4 patients with SN metastases