Esophageal cancer associated with multiple cancerous lesions: clinicopathologic comparisons between multiple primary and intramural metastatic lesions.

Detailed histopathological examination of serial blocks and subserial sections of the entire resected esophagus in 111 patients who underwent esophagectomy for esophageal squamous cell carcinoma revealed 38 associated cancerous lesions apart from the main tumors, in 33 patients (29.7%). These associated lesions were divided into multiple primary lesions (MPLs; 27 lesions in 23 patients) and intramural metastatic lesions (IMLs; 11 lesions in 10 patients). Thirteen and fourteen MPLs were distributed on the proximal and distal sides, respectively, of the main tumor with the same mean distance of 2.6 cm. Three and 8 IMLs were located on the proximal and distal sides, respectively, with mean distances of 3.4 cm and 4.6 cm. With respect to the histological depth of cancer invasion, MPLs were all confined within the submucosal layer (superficial cancer) while IMLs varied from the submucosa to the adventitia. Histological findings indicate that MPLs may be associated with a possible increased multicentric carcinogenic potential in the non-cancerous epithelium of the esophagus of patients who have had an antecedent esophageal cancer, and that IMLs are developed by intramural lymphatic spread from the primary esophageal cancer. These results emphasize the need for careful attention to the choice of margins during the surgical resection of the esophagus.