Lymphatic invasion: An important prognostic factor for stages T1b-T3 gallbladder cancer and an indication for additional radical resection of incidental gallbladder cancer

Background: Laparoscopic cholecystectomy is being performed with increasing frequency worldwide. This has led to more frequent discovery of incidental gallbladder cancer (IGBC) and in turn to the need for an independent prognostic factor for stages T1b-T3 gallbladder cancer so that is can be determined clinically which cases of IGBC are indicated for additional radical resection (ARR). Methods: A retrospective study was conducted that included 72 patients who underwent macroscopically curative surgical resection (R0, R1) at our center for stages T1b-T3 GBC. Survival analysis was performed, and the usefulness of ARR was analyzed in 15 patients with IGBC. Results: Univariate analysis of disease-specific survival showed stage T3, histologic grade II-IV, lymphatic invasion, vessel invasion, perineural invasion, lymph node metastasis, and a positive resection margin to be factors indicative of poor prognosis. Independent predictors of poor disease-specific survival were stage T3 (hazard ratio, 2.33 [95% CI, 1.10-4.95]), lymphatic invasion (5.97 [1.29-27.6]), and a positive resection margin (3.17 [1.51-6.63]). Among the 15 IGBC patients, 4 of 5 patients without lymphatic invasion were cured, 2 of whom underwent cholecystectomy alone; 4 of 10 patients with lymphatic invasion did not undergo ARR, and the cancer recurred in all 4 patients; the other 6 patients underwent ARR, and 4 of them were cured by reoperation. Conclusions: Lymphatic invasion well reflects the malignant phenotype of stages T1b-T3 GBC. We advocate ARR for IGBC patients with lymphatic invasion.