136 Background: The main objective of this study was to develop and validate a method to reconstruct the gross and clinical tumor volume (GTV and CTV) on the esophageal specimen in order to facilitate a good pathologic examination of the original tumor area after neo-adjuvant chemoradiation (CRT).
METHODS: The GTV and CTV borders of 25 patients were defined by a radiation oncologist on the planning CT in relation to 5 anatomical reference points. After CRT, the GTV and CTV borders were marked in vivo on the esophagus during surgical resection. Finally, the pathologist evaluated the presence of macroscopic and microscopic tumor in- and outside the GTV and CTV. The radiation tumor response was scored according to the standardized 5-tier Mandard classification. Radiation induced side effects were scored as well.
RESULTS: The Mandard classification could be scored on basis of the GTV alone in 68% of the cases (N=17). For the other patients (N=8), the GTV and the CTV should both be incorporated for correct evaluation of the tumor response. Five patients (20%) showed complete tumor response (Mandard 1), 68% (N=17) showed partial response (Mandard 2-3) and 12% (N=3) showed hardly any response (Mandard 4-5). In the partial responders, macroscopic tumor was found within the delineated GTV and microscopic tumor remained within the CTV both in 100% of the cases. In two patients (40%) with hardly any response, microscopic tumor was also found outside the CTV. This might be caused by tumor growth during the neo-adjuvant treatment or by geographical miss. Nine patients turned out to have positive lymph nodes. On average 18 (range 8-30) lymph nodes were evaluated per patients. Giant cell reactions, lymphocyte infiltration, and fibrosis, which indicate tumor regression were seen in the CTV and GTV, and were most pronounced in the GTV.
CONCLUSIONS: This study suggested that demarcation of the GTV and CTV on the esophagus in vivo is important for standardized pathologic evaluation of the esophagus after neo-adjuvant chemoradiation. Furthermore using this method we determined microscopic tumor outside the CTV in 40% of the cases (N=2) of the bad responders (Mandard 4-5), illustrating the importance of our method in this patient category.