Prognostic Significance of Synchronous Colorectal Adenocarcinoma: A Matched-Pair Analysis.

Objective: To determine the prognostic significance of the synchronous colorectal cancer (S-CRC) on survival and recurrence rate.

Methods: Authors conducted an analysis of 90 colorectal adenocarcinoma patients who received a curative (R0) resection with a full course of standard adjuvant treatment. A total of 45 patients diagnosed with S-CRC at the time of initial presentation were individually matched to a group of 45 solitary CRC patients in pair at a ratio of 1:1. The case-matched criteria included age (± 5 years), gender, tumor location, and tumor stage. For S-CRC, the most advanced pathologic lesion was defined as the index lesion, and the matching cancer stage was categorized according to the index lesion. The N-stage was determined based on all lymph nodes.

Result: There were a higher number of retrieved nodes in patients with S-CRC than those with solitary CRC. The median (min, max) of the total number of retrieved nodes for S-CRC was 18 (3, 53) nodes, compared to 14 (4, 45) nodes for solitary CRC (p < 0.01). All patients were without distant metastasis (stage I to III). The total accumulative number of patients experiencing tumor recurrence was 9 (20%) amongst the solitary CRC patients and 18 (40%) amongst the S-CRC patients at the 15-year surveillance period (p<0.05). The disease-free survival (DFS) (mean + SD) was 147.6 + 9.3 months in the solitary CRC group, compared to 110.5 + 11.7 months in the S-CRC group (p<0.05). Amongst S-CRC patients, those having primary and synchronous tumors located across anatomical segments had poorer DFS (70.5 months) and higher 15-year tumor recurrence rate (17.8%) than those with all tumors in the same or contiguous anatomical segments. In addition, the S-CRC patients with all tumors located in contiguous segment had a longer DFS (123.7 months) than the other types of anatomical correlation.

Conclusion: Patients with S-CRC had worse prognosis than those with solitary CRC. For S-CRC, the anatomical correlation between the primary and the synchronous tumors may influence DFS and recurrence rate.