Combined assessment of clinical and pathological prognostic factors for deciding treatment strategies for esophageal squamous cell carcinoma invading into the muscularis mucosa or submucosa after endoscopic submucosal dissection

<jats:sec><jats:title>Objectives</jats:title><jats:p>We aimed to clarify the prognostic factors for patients with esophageal squamous cell carcinoma (ESCC) invading into the muscularis mucosa (pT1a‐MM) or submucosa (pT1b‐SM) after endoscopic submucosal dissection (ESD).</jats:p></jats:sec><jats:sec><jats:title>Methods</jats:title><jats:p>This retrospective study enrolled such patients at 21 institutions in Japan between 2006 and 2017. We evaluated 15 factors, including pathological risk categories for ESCC‐specific mortality, six non‐cancer‐related indices, and treatment strategies.</jats:p></jats:sec><jats:sec><jats:title>Results</jats:title><jats:p>In the analysis of 593 patients, the 5‐year overall and disease‐specific survival rates were 83.0% and 97.6%, respectively. In a multivariate <jats:ext-link xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="https://sphweb.bumc.bu.edu/otlt/MPH-Modules/BS/BS704_Survival/BS704_Survival6.html">Cox analysis</jats:ext-link>, male sex (hazard ratio [HR] 3.56), Charlson comorbidity index (CCI) ≥3 (HR 2.53), ages of 75–79 (HR 1.61) and ≥80 years (HR 2.04), prognostic nutrition index (PNI) <45 (HR 1.69), and pathological intermediate‐risk (HR 1.63) and high‐risk (HR 1.89) were prognostic factors. Subsequently, we developed a clinical risk classification for non‐ESCC‐related mortality based on the number of prognostic factors (age ≥75 years, male sex, CCI ≥3, PNI <45): low‐risk, 0; intermediate‐risk, 1–2; and high‐risk, 3–4. The 5‐year non‐ESCC‐related mortality rates for patients without additional treatment were 0.0%, 10.2%, and 45.8% in the low‐, intermediate‐, and high‐risk groups, respectively. Meanwhile, the 5‐year ESCC‐specific mortality rates for the pathological low‐, intermediate‐, and high‐risk groups were 0.3%, 5.3%, and 18.2%, respectively.</jats:p></jats:sec><jats:sec><jats:title>Conclusions</jats:title><jats:p>We clarified prognostic factors for patients with pT1a‐MM/pT1b‐SM ESCC after ESD. The combined assessment of non‐ESCC‐ and ESCC‐related mortalities by the two risk classifications might help clinicians in deciding treatment strategies for such patients.</jats:p></jats:sec>