The association between adherence to elective nodal volume guidelines and reduced distant metastasis in esophageal and gastroesophageal junction cancer: a retrospective analysis of elective nodal irradiation.

BACKGROUND

In 2015, expert guidelines on esophageal/gastroesophageal junction (GEJ) cancer contouring for intensity-modulated radiation therapy (IMRT) were published in International Journal of Radiation Oncology, Biology and Physics (IJROBP) delineating recommended elective nodal basins (celiac, para-aortic, gastrohepatic ligament, supraclavicular) to be irradiated depending on the primary tumor location. The aim of this study seeks to determine if chemoradiotherapy (CRT) that is compliant with the recommendations from these guidelines affects disease free survival and distant failure rates. We hypothesize that incomplete coverage of these areas increases the risk of developing distant failures.

METHODS

Patients treated for non-metastatic esophageal or GEJ cancer with CRT pre-operatively or definitively from 2012 to 2021 were retrospectively identified from a single institution database. Radiation plans of eligible patients were then analyzed by tumor location. Plans were deemed guideline-compliant if radiation dose coverage, greater than 41.4 Gy, encompassed nodal basins recommended by the 2015 guidelines. The primary endpoint of this study was the overall rate of distant metastatic disease. Summary and descriptive statistics were used to characterize key cohort features.

RESULTS

With a median follow-up of 22.3 months, 38 patients, with a median age at diagnosis of 66 years, were included in the study. Most patients were male (94.7%) with cT3 (52.6%), cN0 (44.7%), moderately differentiated (44.7%) and poorly differentiated (44.7%) adenocarcinoma (73.7%) located at the GEJ (57.9%). The median radiation dose used was 50.4 Gy, with most patients receiving concurrent carboplatin and paclitaxel (86.8%). Four patients received induction chemotherapy and 20 (52.6%) underwent esophagectomy. When examining guideline compliance, 17 (44.7%) radiation plans demonstrated adequate elective nodal irradiation (ENI). The most common improperly covered nodal basin was para-aortic (66.7%), followed by gastrohepatic (23.8%). One patient with sufficient ENI coverage (1/17) developed distant failure compared to 38.1% (8/21) with insufficient coverage (P=0.02). There were inappreciable differences in locoregional or local failure rates between those with and without complete ENI.

CONCLUSIONS

These results suggest that proper coverage of nodal basins could improve distant metastasis. ENI analysis of previous prospective CRT studies for esophageal cancer could validate these findings.