This study was conducted to identify factors associated with lymph node (LN) metastasis in nasopharyngeal carcinoma (NPC) patients, analyze node distribution patterns, and explore the prognostic value of the LN metastasis level for survival. We included 2994 patients with primary NPC diagnosed between 2006 and 2015 with information in the Surveillance, Epidemiology, and End Results (SEER) database. Patients' demographic and clinicopathologic features were compared according to LN status using chi-squared tests. The 5-year overall survival (OS) and cancer-specific survival (CSS) rates were calculated by the Kaplan–Meier method, and the differences were estimated by log-rank tests. Multivariate Cox proportional hazard models were used to evaluate independent risk factors for OS and CSS. Logistic regression was used to evaluate the risk of each LN metastasis category for distant metastasis. There were 695 patients in the N0 stage and 2299 with LN metastasis (classified as stage N1, N2, or N3). The overall incidence of LN metastasis was 76.8%. Sex and T stage were not associated with LN metastasis. Older patients had a significantly worse 5-year OS and CSS than younger patients. In terms of histologic type, keratinizing squamous cell carcinoma had the lowest 5-year OS and CSS at 48.2% and 53.8%, respectively. The most common nodal involvement level was II (65.9%), followed by III (29.1%), V (25.6%), I (17.6%), IV (15.7%), and retropharynx (13.5%). The skip metastasis rate was 5.7% (130/2299). Patients with only level II metastasis (classified as level 2) was the most common category, accounting for 30%. Compared to level 2, patients with only level I (classified as level 1) had an OR of 2.101 (95% CI: 1.090–4.047, P=0.027) for distant metastasis, patients with simultaneous levels II, III, IV, and V (classified as levels 2345) had the highest OR of 4.064 (95% CI: 2.155–7.666, P < 0.001) for distant metastasis, and level 24 had an OR of 3.003 (95% CI: 1.074–8.395, P=0.036) for distant metastasis. In survival analysis, levels 235 had a significant HR of 1.708 (95% CI: 1.089–2.678, P=0.020) for CSS compared to level 2 after adjustment for age, sex, race, histology, TNM (tumor, node, and metastasis) stage, and treatment.

#1015 Background: China multicenter study of sentinel lymph node biopsy (SLNB) substituting axillary lymph node dissection (ALND) in breast cancer– CBCSG-001 trial was conducted from Jan. 2002 to Jun. 2007, with 1,970 SLNB pts recruitment. One of the second objectives of the CBCSG–001 trial was to evaluate the optimal methods and intervals for the detection of SLN macrometastases, MMs and isolated tumor cells (ITCs) and their prognostic significance in patients received SLNB without ALND or axillary radiotherapy.&#x2028; Material and Methods: Two hundred and forty-five continuous breast cancer patients with 569 SLNs identified “negative” with routine standard HE stain carried on initial 4 levels were retrospectively analyzed. All the patients received SLNB only, without ALND or axillary radiotherapy after the diagnoses of metastases in their SLNs later. All SLNs were step sectioned (SS) at 100µm interval, and for each level both HE and IHC with AE1/AE3 were performed. Forty-nine patients were identified to have metastases, with macrometastases of 12.2%, micrometastases of 61.2%, and isolated tumor cells of 26.5%. All patients had received SLNB only, with no ALND and axillary radiotherapy.&#x2028; Results: Of the 245 patients, breast conserved surgery and SLNB were performed on 106 patients (43.3%), and mastectomy and SLNB in 139 patients. With a median follow up of 50 months, there were 20 breast related events occurred. The disease free survival (DFS) of patients with routine negative SLNs was 91.6%, and 93.9% for patients with positive SLNs after SS with HE+IHC (p&gt;0.05). The overall survival (OS) were 97.4% and 98.0 for each group, respectively (p&gt;0.05). The results were the same for patients with macrometastases, micrometastases, and isolated tumor cells. Due to the relatively less events occurred, the DFS and OS had not been calculated for macrometastases, micrometastases, and isolated tumor cells, separately.&#x2028; Discussion and Conclusions: Without ALND and axillary radiotherapy, there were no significant differences of DFS and OS between patients with routine negative SLNs and patients with positive SLNs after SS with HE+IHC. It might be safe for these patients to receive SLNB only. The possible reasons might include: SLNs were the only positive lymph nodes in more than 60% patients, effective adjuvant systemic therapy for regional lymph nodes just as neoadjuvant chemotherapy, axillary coverage of radiotherapy in patients with breast conserved therapy, and the relatively less events occurred during the 50 months follow up period. Citation Information: Cancer Res 2009;69(2 Suppl):Abstract nr 1015.