10 Background: Recently, a limited operation to avoid needless lymph node (LN) dissection in clinical T1bN0 esophageal cancer (EC) is considered. However, how LN dissection or radiation field should be decided for such cases has not yet been clarified. The information about prevalence of LN metastases (LNMs) would be valuable when the radiation field and extent of LN dissection are considered in the treatment of T1bN0 EC. Methods: JCOG0502 is a randomized controlled trial including a patient preference arm comparing surgery alone to definitive chemoradiotherapy in clinical T1bN0 EC. By using baseline clinical and pathological data of JCOG0502, diagnosis accuracy of LNM was evaluated by comparing clinical and pathologic findings. Then, the sites of pathologic LNMs were determined and the initial sites and the prevalence of LNM were estimated. Results: Between Dec 2006 and Feb 2013, 213 patients (pts) enrolled to the surgery arm in JCOG0502. Pts with multiple lesions or without esophagectomy were excluded and remaining 186 pts were analyzed. Of the 186 pts of clinical T1bN0, 137 pts were diagnosed as LNM negative (73.7%: accuracy of diagnosis), however, 49 pts (26.3%) had pathologic LNMs. Pathologic LNMs were seen at 106recR, 106recL (all in mediastinal region) in upper thoracic (Ut) EC, 101R, 101L, 104R, 104L (in the neck region), 106recR, 106recL, 106tbL, 105, 107, 108, 109L, 110 (in the mediastinal region), 1,2,3,7, 11 (in the abdominal region) in middle thoracic (Mt) EC, and 105, 106recL, 110 (in the mediastinal region), 1, 2, 3, 7 (in the abdominal region) in lower thoracic (Lt) EC, respectively. Of the 49 pts who had pathologic LNMs, 32 pts (65%) were of pathologically N2 or more. Furthermore, 18 pts (37%) had skip LNM (LNM of N2, N3 or N4 without N1). The solitary pathologic LNM was observed in 25 pts: N1 (106recR, 106recL) in Ut, N1 (106recR, 106recL, 108), N2 (101R, 105, 110, 1, 3, 7), in Mt, N1(110, 1), N2 (106recL, 3, 7) in Lt, respectively. Conclusions: In the current status of clinical diagnosis, limited LN dissection or limited field of radiation are not recommended. In surgery, D2 LN dissection is necessary and three-field LN dissection is recommended especially in middle thoracic EC even for clinical T1bN0. Clinical trial information: UMIN000000551.
Comparison of the effects of radiotherapy doses of 50.4 Gy and 60 Gy on outcomes of chemoradiotherapy for thoracic esophageal cancer: subgroup analysis based on the Comprehensive Registry of Esophageal Cancer in Japan from 2009 to 2011 by the Japan Esophageal Society
