[Lymph node metastasis patterns and influencing factors in patients with limited esophageal small cell carcinoma]

To explore the patterns and influencing factors of lymph node metastasis in limited esophageal small cell carcinoma (PESCC).

A total of 98 limited stage PESCC patients who underwent surgery were selected for this study. The lymph node metastasis ratio at different sites, depth of invasion, tumor length and other factors were analyzed to assess their influence on lymph node metastasis.

Among the 98 PESCC cases, 46 cases had lymph node metastasis (46.9%). 100 out of 833 lymph nodes had metastasis, with a metastasis ratio of 12.0%. For upper thoracic esophageal small cell carcinomas, lymph node metastasis ratios were 42.9%, 12.5%, 0 and 0 in the superior mediastinum, middle mediastinum, inferior mediastinum and abdominal cavity, respectively. In the middle thoracic PESCCs, the lymph node metastasis ratios were 18.8%, 7.7%, 15.7%, and 15.3%, respectively. In the lower thoracic PESCCs, the lymph node metastasis ratios were 0, 0, 27.3% and 23.5%, respectively. Lymph node metastasis rates in PESCCs at stages T1, T2, T3, T4 were 15.4%, 42.3%, 63.9%, and 80.0%, respectively. The lymph node metastasis ratios in PESCCs at stages T1, T2, T3, T4 were 2.0%, 8.3%, 17.8% and 25.0%, respectively. Lymph node metastasis rate and lymph node metastasis ratio at different T stages were of significant difference (P<0.05 for all). Lymph node metastasis rates in patients with tumor <3 cm, 3-5 cm, and >5 cm were 30.6%, 46.9% and 66.7%, respectively, and lymph node metastasis ratios were 5.4%, 11.0% and 21.1%, respectively. Lymph node metastasis rate and lymph node metastasis ratio in patients with different tumor length had significant differences (P<0.05 for all). Lymph node metastasis ratio was 11.6% in the Chr-A negative and weak positive group, much higher than 4.3% in the Chr-A positive group (P=0.013). There was a tendency that lymph node metastasis ratio of NSE-positive group was higher than that of NSE-negative and weak positive group (P=0.069). The logistic univariate analysis did not find high risk factors of distant lymph node metastasis (all P>0.05). Logistic multivariate analysis found that only depth of invasion was a risk factor of lymph node metastasis in limited PESCC (P=0.002).

Esophagus small cell carcinomas sometimes have early lymph node metastases in many sites and distant range. The middle thoracic PESCCs tend to have extensive metastasis quite common in the upper mediastinal lymph nodes. Lower mediastinal and abdominal lymph node metastases are often seen in lower thoracic PESCCs. The depth of invasion and tumor length are main factors influencing mediastinal lymph node metastasis. The depth of invasion is an independent risk factor for lymph node metastasis.