Background The role of surgery and chemotherapy for stage IV small bowel adenocarcinoma (SBA) is still confused. The results from previous analyses have been limited by small sample sizes and different treatment regimens. Methods Patients with stage IV SBA were identified in the Surveillance, Epidemiology, and End Result Program (SEER) database. Cause‐specific survival (CSS) and overall survival (OS) were calculated with Kaplan‐Meier methods and log‐rank test. Multiple logistic and Cox regression identified covariates associated with treatment options and survival. Results 1219 eligible patients were involved in this study. The median age was 67 (range, 20‐95) with 655 (53.7%) males and 564 (46.3%) females. Age and primary tumor site were significantly associated with surgery performance, age was also significantly associated with chemotherapy (P < .01). To reduce bias, further six subgroups were divided by age (≤65 and >65) and primary tumor site (duodenum, jejunum and ileum). Chemotherapy and surgery conferred a benefit on survival of the whole cohort (the median CSS of different treatment groups were 17, 9, 4, and 1 month respectively, P < .001) and most subgroups (83.3%, 5/6). In multivariate analysis, surgery (P = .006), and chemotherapy (P = .038) are still independent factors of favorable CSS and OS. For patients with surgery (n = 362), radical surgery was not associated with better survival. Conclusion For stage IV SBA patients, the present study showed that age and primary tumor site were significantly associated with treatment preference. Surgery and chemotherapy were consistently correlated with favorable survival for the whole cohort or most specific subgroups. However, compared with palliative surgery, significant association was not found in patients with radical surgery with better outcome. More prospective well‐defined cohorts would add knowledge for this rare disease.

Colon cancers with mismatch repair deficiency (dMMR) have specific clinicopathologic characteristics compared with mismatch repair proficiency (pMMR); however, the effect of MMR status on the efficiency of neoadjuvant chemotherapy (NCT) remains unclear. In our study, 439 dMMR and 26 pMMR colon cancer patients with or without NCT from 2010 to 2017 were retrospectively collected. Clinicopathological features, treatment response, and survival were compared between different groups. In the dMMR group, patients with NCT were likely to have higher CEA (abnormal CEA: 51.6% vs. 17.4%, p < 0.001), more multiorgan resection (38.7% vs. 16.8%, p = 0.006), and larger postoperative tumor diameter (7.26 vs. 6.21, p = 0.033) than those without NCT, but nearly half of cT4b patients who had NCT (42.9%, 9/21) avoid multiorgan resection. pT4 stage (HR, 14.97; 95% CI, 1.88–118.92; p = 0.010), number of positive lymph nodes (HR, 1.17; 95% CI, 1.09–1.26; p < 0.001), and tumor deposit (HR, 6.73; 95% CI, 2.08–21.74; p = 0.001) were independent prognosis factors of disease‐free survival (DFS). For the advanced tumor subset, there is no significant difference between patients with or without NCT for OS ( p = 0.13) and DFS ( p = 0.11), although the survival rate of NCT was higher than non‐NCT patients. Moreover, tumor regression grade was similar between dMMR and pMMR patients who had NCT. This study showed that NCT was more likely to be employed in dMMR patients with advanced tumors and may reduce the rate of multiorgan resection for cT4b dMMR patients. More large‐scaled researches are needed to further explore if MMR status could predict the efficacy of neoadjuvant chemotherapy in patients with colon cancer.