Treatment and Outcome of Synchronous Colorectal Carcinomas: A Nationwide Study

Background Synchronous colorectal carcinomas (CRC) occur in 1–8% of patients diagnosed with CRC. This study evaluated treatment patterns and patient outcomes in synchronous CRCs compared with solitary CRC patients. Methods All patients diagnosed with primary CRC between 2008 and 2013, who underwent elective surgery, were selected from the Netherlands Cancer Registry. Using multivariable regressions, the effects of synchronous CRC were assessed for both short-term outcomes (prolonged postoperative hospital admission, anastomotic leakage, postoperative 30-day mortality, administration of neoadjuvant or adjuvant treatment), and 5-year relative survival (RS). Results Of 41,060 CRC patients, 1969 patients (5%) had synchronous CRC. Patients with synchronous CRC were older (mean age 71 ± 10.6 vs. 69 ± 11.4 years), more often male (61 vs. 54%), and diagnosed with more advanced tumour stage (stage III–IV 54 vs. 49%) compared with solitary CRC (all p