PURPOSE To analyze the effect of radiation dose escalation to the primary tumor on local tumor control in definitive chemoradiation (dCRT) for patients with esophageal cancer. PATIENTS AND METHODS Patients with medically inoperable and/or irresectable esophageal carcinoma, referred for dCRT, were randomly assigned between a standard dose (SD) of 50.4 Gy/1.8 Gy for 5.5 weeks to the tumor and regional lymph nodes and a high dose (HD) up to a total dose of 61.6 Gy to the primary tumor. Chemotherapy consisted of courses of concurrent carboplatin (area under the curve 2) and paclitaxel (50 mg/m2) in both arms once a week for 6 weeks. The primary end point was local progression-free survival. RESULTS Between September 2012 and June 2018, 260 patients were included. Squamous cell carcinoma (SCC) was present in 61% of patients, and 39% had adenocarcinoma (AC). Radiation treatment was completed by 94%, and 85% had at least five courses of chemotherapy. The median follow-up time for all patients was 50 months. The 3-year local progression-free survival (LPFS) was 70% in the SD arm versus 73% in the HD arm (not significant). The LPFS for SCC and AC was 75% versus 79% and 61% versus 61% for SD and HD, respectively (not significant). The 3-year locoregional progression-free survival was 52% and 59% for the SD and HD arms, respectively ( P = .08). Overall, grade 4 and 5 common toxicity criteria were 12% and 5% in the SD arm versus 14% and 10% in the HD arm, respectively ( P = .15). CONCLUSION In dCRT for esophageal cancer, radiation dose escalation up to 61.6 Gy to the primary tumor did not result in a significant increase in local control over 50.4 Gy. The absence of a dose effect was observed in both AC and SCC.

281 Background: To analyze the effect of radiation dose escalation to the primary tumor on local control, locoregional control, survival and toxicity in definitive chemoradiation for esophageal cancer. Methods: Patients with clinical stage T2-4, N0-3, M0 carcinoma of the esophagus were randomized between a standard dose of 50.4 Gy/1.8 Gy/5,5 weeks to the tumor and regional lymph nodes (SD) versus the same dose combined with an integrated boost of 0,4 Gy per fraction (total 61,6 Gy) to the primary tumor (HD). Chemotherapy consisted of 6 weekly concurrent carboplatin (AUC 2) and paclitaxel (50 mg/m2) in both arms. The primary endpoint was local progression free survival (LPFS) and 260 patients were needed to detect a difference of 15% (power: 80%). Secondary endpoints were locoregional progression free survival (LRPFS), overall survival (OS) and toxicity. Patients were stratified for histological subtype. Results: Between September 2012 and June 2018, 260 patients were included. Reasons for inoperability were proximal localization and patient preference (44%), comorbidity (30%), unresectable lymph nodes (11%), T4 (5%), local recurrence 2% and combinations (7%). 61% of the patients had a squamous cell carcinoma (SCC) and 39% had an adenocarcinoma (AC). 94% completed radiation treatment and 85% had at least 5 courses chemotherapy. Median follow up time was 45 months. 3-year LPFS was 70% in the SD arm versus 76% in the HD arm (ns). LPFS for SCC and AC was 74% versus 81% and 62% versus 65% for SD and HD, resp. (ns). 3-year LRPFS was 53% and 63% for the SD and HD arm resp. (p = 0.08). 1 year any progression free survival was 60% for SCC and 50% for AC, without a significant difference between SD and HD (p = 0,5). 3-year OS was 41% versus 40% for SD and HD resp. Overall grade 4 and 5 CTC toxicity was 12% and 4% in the SD arm versus 14% and 10% in the HD arm, resp. Conclusions: In definitive chemoradiation for esophageal cancer, radiation dose escalation up to 61,6 Gy to the primary tumor did not result in a significant increase in local control over 50,4 Gy. Numerical improvement of locoregional control after HD was observed with an increase in toxicity and without improving OS. Clinical trial information: NL38343.018.11.

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In esophageal cancer treated with dCRT, the number of affected lymph nodes is an important independent prognostic factor, whereas involvement of a SCN is not. Supraclavicular lymph nodes should be considered as regional lymph nodes and treated with curative intent if the total number of involved lymph nodes is limited.

Objective: Delineation variation of esophageal tumors remains a large source of geometric uncertainty. In the present study, we investigated the inter-and intra-observer variation in esophageal gross tumor volume (GTV) delineation and the impact of endoscopically implanted fiducial markers on these variations. Material/Methods: Ten esophageal cancer patients with at least two markers endoscopically implanted at the cranial and caudal tumor borders and visible on the planning computed tomography (pCT) were included in this study. Five dedicated gastrointestinal radiation oncologists independently delineated GTVs on the pCT without markers and with markers. The GTV was first delineated on pCTs where markers were digitally removed and next on the original pCT with markers. Both delineation series were executed twice to determine intra-observer variation. For both the inter-and intra-observer analyses, the generalized conformity index (CI gen ), and the standard deviation (SD) of the distances between delineated surfaces (i.e., overall, longitudinal, and radial SDs) were calculated. Linear mixedeffect models were used to compare the without and with markers series (a ¼ 0.05). Results: Both the inter-and intra-observer CI gen were significantly larger in the series with markers than in the series without markers (p < .001). For the series without markers vs. with markers, the inter-observer overall SD, longitudinal SD, and radial SD was 0.63 cm vs. 0.22 cm, 1.44 cm vs. 0.42 cm, and 0.26 cm vs. 0.18 cm, respectively (p < .05); moreover, the intra-observer overall SD, longitudinal SD, and radial SD was 0.45 cm vs. 0.26 cm, 1.10 cm vs. 0.41 cm, and 0.22 cm vs. 0.15 cm, respectively (p < .05). Conclusion:The presence of markers at the cranial and caudal tumor borders significantly reduced both inter-and intra-observer GTV delineation variation, especially in the longitudinal direction. Our results endorse the use of markers in GTV delineation for esophageal cancer patients.