Oncologic significance of lymphovascular invasion in patients with superficial esophageal squamous cell carcinoma reaching the muscularis mucosae or with slight invasion of the submucosa.

Background: The clinicopathological features and the distribution of lymph node metastasis in patients with T1a-MM and T1b-SM1 superficial esophageal squamous cell carcinoma remain unclear; therefore, the optimal treatment strategy is still controversial.

Methods: One hundred and ninety-one patients who had undergone a thoracic esophagectomy with 3-field lymphadenectomy and who were pathologically confirmed to have thoracic superficial esophageal squamous cell carcinoma that had reached the T1a-MM or T1b-SM1 stage were retrospectively reviewed. Risk factors of lymph node metastasis, the distribution of lymph node metastasis, and long-term outcomes were evaluated.

Results: A multivariate analysis revealed that lymphovascular invasion was the only independent risk factor of lymph node metastasis (odds ratio: 6.410, P < .001). Patients with primary tumors in the middle thoracic region had lymph node metastasis in all 3 fields, whereas patients with primary tumors in the upper or lower thoracic region did not have distant lymph node metastasis. The frequencies of neck (P = .045) and abdominal (P < .001) lymph node metastasis were significantly higher in lymphovascular invasion-positive patients than those in lymphovascular invasion-negative patients in all cohort. MM/lymphovascular invasion-positive patients with middle thoracic tumors had lymph node metastasis spread from the neck to the abdomen. SM1/lymphovascular invasion-negative patients with middle thoracic tumors did not have lymph node metastasis in the abdominal region. The SM1/pN+ group had a significantly poorer overall survival and relapse-free survival than the other groups.

Conclusion: The present study revealed that lymphovascular invasion was associated with not only the frequency of lymph node metastasis, but also the distribution of lymph node metastasis. It also suggested that superficial esophageal squamous cell carcinoma patients with T1b-SM1 and lymph node metastasis had a significantly poorer outcome than those with T1a-MM and lymph node metastasis.