Does preoperative radiation for thoracic esophageal cancer promote intramural lymphatic invasion?

Between 1976 and 1983, 43 patients with carcinoma of the thoracic esophagus underwent esophagectomy in the Department of Surgery, Tottori University. Of these 43, 22 received a total dose of 30 to 40 Gy of Co60 (2 Gy/day) preoperatively: 21 were not given preoperative irradiation treatments. The spread of intramural lymphatic cancer invasion into the esophageal wall was compared in these two groups. The preoperatively irradiated patients manifested a significantly lower rate of lymphatic cancer invasion and the depth of invasion tended to be less than in the non-irradiated patients. However, in preoperatively irradiated subjects, the horizontal cancer spread into the extra-radiation field anal to the cancer site was greater than in the other group. In addition, a significantly higher intra-abdominal lymph node metastasis rate was found in the irradiated group than in the non-irradiated group. Our findings suggest that patients with thoracic esophageal cancer who are treated with preoperative radiotherapy must be carefully monitored for the occurrence of intramural lymphatic cancer invasion and distant lymph node metastasis.