Natural history and outcomes in a population-based cohort of synchronous and metachronous colorectal cancers (CRC).

Abstract

485 Background: Early data suggest that synchronous and metachronous CRC may portend a worse prognosis when compared to solitary CRC. Our study objectives were to 1) characterize the clinical features and treatment patterns of synchronous and metachronous CRC and 2) compare their survival outcomes with those of solitary CRC. Methods: All patients diagnosed with either synchronous or metachronous CRC between 1999 and 2008 and referred to 1 of 5 regional cancer centers in British Columbia were reviewed. Synchronous and metachronous CRC were defined as multiple (2 or more) distinct tumors that were diagnosed within and beyond 6 months of the date of index CRC diagnosis, respectively. Patients with liver metastases at initial diagnosis were excluded. Kaplan-Meier and multivariate Cox regression analyses were used to estimate survival for synchronous and metachronous CRC, and to compare outcomes with solitary CRC. Results: A total of 213 patients with 388 synchronous and 69 metachronous cases of CRC were included: median age was 70 (range 26-94), 55% were men, and 30% were ECOG 0 to 1 at index diagnosis. At initial presentaiton, 35% and 51% of patients who manifested with synchronous and metachronous tumors, respectively, were TNM stage III. Concurrent colorectal adenomas were found in 45% of synchronous and 33% of metachronous cases. The most prevalent symptoms experienced by patients included changes in bowel movements and abdominal pain. The majority of patients underwent a curative resection (99% of synchronous and 97% of metachronous). Adjuvant chemotherapy was used to treat 44% of both synchronous and metachronous tumors. Compared to solitary CRC, patients with synchronous and metachronous CRC had similar 3-year relapse-free survival (66 vs. 66 vs. 56%, p=0.20), 5-year cancer-specific survival (69 vs. 67 vs. 53%, p=0.34), and 5-year overall survival (62 vs. 59 vs. 49%), p=0.74. Similar observations persisted in the multivariate Cox regression model. Conclusions: There appears to be no differences in survival outcomes in patients with solitary, synchronous, or metachronous CRC. Patients who present with multiple CRC tumors should be managed similarly to those who only present with an isolated tumor.