O122 INTERVAL DISTANT METASTASES DURING OR AFTER NEOADJUVANT CHEMORADIOTHERAPY FOR ESOPHAGEAL OR GASTROESOPHAGEAL JUNCTION CANCER: A NATION-WIDE POPULATION-BASED COHORT STUDY

A certain proportion of esophageal or gastro-esophageal junction cancer patients develop interval distant metastases during neoadjuvant chemoradiotherapy (nCRT) or in the time interval after nCRT to planned surgery. The aims of this study were to assess the post-detection survival rates and prognostic factors affecting post-detection survival in patients with interval distant metastases.

Esophageal and gastro-esophageal junction cancer patients who underwent nCRT and in whom distant metastases were detected during nCRT, after nCRT in the time interval to surgery or at the time of planned surgery, between 2010 and 2016, were included in this nation-wide population-based cohort study. The primary outcome measure was post-detection overall survival. Prognostic factors (including management) affecting the post-detection overall survival were studied using multivariable Cox proportional hazard models.

A total of 150 patients were included in this study. The median post-detection overall survival was 6.1 months (95% confidence interval [CI] 5.1–7.7). Multivariable analysis identified signet ring cell carcinoma morphology (hazard ratio [HR] 2.88, 95%CI 1.35-6.13; p=0.021), poor tumor differentiation (HR 2.70, 95%CI 1.60-4.57; p<0.001), and palliative anti-tumor treatment as opposed to best supportive care (HR 0.38, 95%CI 0.23-0.61; p<0.001) as independent prognostic factors associated with post-detection survival. An observed survival advantage in a small selected group of 11 patients who received localized treatment with curative intent (metastasectomy and/or stereotactic body radiotherapy) did not reach statistical significance as compared to best supportive care (HR 0.62, 95% CI 0.26-1.43; p=0.263). Patient characteristics including WHO performance score, age, number of comorbidities, and characteristics of interval distant metastases including the location or number of affected locations were not significantly related to overall survival.

In this study the largest series of patients with esophageal or gastroesophageal junction cancer with interval distant metastases are reported. These patients have a poor prognosis with a median post-detection overall survival of 6.1 months. Prognostic factors independently associated with detrimental survival include poor tumor differentiation and signet ring cell carcinoma morphology. Anti-tumor treatment with palliative intent is associated with improved survival as compared to best supportive care.