Assessment of the external validity of the AJCC 8th staging system for small intestinal adenocarcinoma: a time to reconsider the role of tumor location?

Routine contrast-enhanced CT is insufficient for TNM-staging of duodenal adenocarcinoma

PURPOSE

Adequate TNM-staging is important to determine prognosis and treatment planning of duodenal adenocarcinoma. Although current guidelines advise contrast-enhanced CT (CECT) for staging of duodenal adenocarcinoma, literature about diagnostic tests is sparse.

METHODS

In this retrospective single-center cohort study, we analyzed the real life performance of routine CECT for TNM-staging and the assessment of resectability of duodenal adenocarcinoma. Intraoperative findings and pathological staging served as reference standard for resectability, T-, and N-staging. Biopsies, ¹⁸FDG-PET-CT, and follow-up were used as the reference standard for M-staging.

RESULTS

Fifty-two consecutive patients with duodenal adenocarcinoma were included, 26 patients underwent resection. Half of the tumors were isodense to normal duodenum on CECT. The tumor was initially missed in 7/52 patients (13%) on CECT. The correct T-stage was assigned with CECT in 14/26 patients (54%), N-stage in 11/26 (42%), and the M-stage in 42/52 (81%). T-stage was underestimated in (27%). The sensitivity for detecting lymph node metastases was only 24%, specificity was 78%. Seventeen percent of patients had indeterminate liver or lung lesions on CECT. Surgery with curative intent was started in 32 patients, but six patients (19%) could not be resected due to unexpected local invasion or metastases.

CONCLUSION

Radiologists and clinicians have to be aware that routine CECT is insufficient for staging and determining resectability in patients with duodenal adenocarcinoma. CECT underestimates T-stage and N-stage, and M-stage is often unclear, resulting in futile surgery in 19% of patients. Alternative strategies are required to improve staging of duodenal adenocarcinoma. We propose to combine multiphase hypotonic duodenography CT with MRI.

Tumor Microenvironmental Prognostic Risk in Primary Operable Small Intestinal Adenocarcinoma

The tumor microenvironment (TME) has become an important area of investigation with respect to improving prognosis in malignancies. Here we evaluated TME prognostic risk in small intestinal adenocarcinomas based on histologic assessment of tumor budding at the peritumoral-invasive front (pTB) and stromal tumor-infiltrating lymphocytes (sTILs). pTB and sTILs were analyzed in 230 surgically resected small intestinal adenocarcinomas, as recommended by the International Tumor Budding Consensus Conference (ITBCC) and the International TILs Working Group (ITWG). On the basis of high levels of pTB count (≥10) and sTIL density (≥20%), we combined pTB and sTIL to produce a collective TME-based prognostic risk index: low-risk (pTBLow/sTILHigh; n=39, 17.0%), intermediate-risk (pTBLow/sTILLow or pTBHigh/sTILHigh; n=99, 43.0%), and high-risk groups (pTBHigh/sTILLow; n=92, 40.0%). TME risk index provided better prognostic stratification than the individual pTB and sTIL (14.9 vs. 6.7 vs. 10.3). Tumors with higher TME prognostic risk were associated with an infiltrative growth pattern and nonintestinal immunophenotype (both P=0.001), pancreatic invasion (P=0.010), lymphovascular (P<0.001) or perineural invasion (P=0.006), higher T-category (P<0.001), N-category (P=0.004), and stage grouping (P=0.002), and KRAS mutation (P=0.008). In multivariate analysis, higher TME prognostic risk index (P<0.001), distal tumor location and nonintestinal immunophenotype (both P=0.001), higher N-category (P<0.001), and microsatellite stable (P=0.015) were worse-independent prognosticators. TME prognostic risk index consistently stratified patient survival regardless of tumor location (P<0.001 in proximal; P=0.002 in distal), stages (P<0.001 in lower stages I to II; P=0.028 in stage III), and DNA mismatch repair gene status (P<0.001 in microsatellite stable; P=0.001 in microsatellite instability). TME risk index is a powerful prognostic predictor for risk stratification of patients with small intestinal adenocarcinoma.