Sequencing of treatment matters in synchronous liver or lung only metastatic colon cancer.

Abstract

4049 Background: Per SEER database, approximately 21% of patients have synchronous metastatic disease at presentation with a median 5 year survival of 14%. Liver is by far the most common site of metastatic disease followed by lung. Metastatectomy of appropriate lesions have achieved a 5 year survival ranged between 40%-70% depending on the extent of the metastasis. For liver or lung only metastatic disease, practice varies from surgery followed by adjuvant chemotherapy to perioperative chemotherapy. Benefit of one approach versus the other has not been demonstrated. We decided to study this using the National Cancer Database (NCDB) database available from the 2010-2015 period. Methods: Adults > 20 years with primary colon cancer (excluding rectal and recto sigmoid junction) with single organ metastatic disease to liver and/or lung at diagnosis were identified. All patients had received surgery to the primary site, resection of the distant site and chemotherapy in the neoadjuvant setting (NAC) or adjuvant setting (AC) within 1 year of diagnosis. Histology except for adenocarcinoma and variants were excluded. Patients who died within 90 days of surgery were excluded. Descriptive analysis, Kaplan-Meier plots, Log-Rank tests for univariate and proportional hazards models for multivariate survival analyses were performed. To reduce biases, a sensitive analysis was also performed based on the intention to treat principle by including additional surgery only and chemotherapy only cases. Results: A total of 3175 colon cancer patients with liver or lung only metastatic disease were identified. 2487 (78%) had AC and 688 (22%) had NAC. Approximately 54% were males with 90% less than 75 years of age. More patients had private insurance and were treated in academic centers in the NC group (62 Vs 51%) and (58 Vs 42%) respectively. Both groups had similar Charlson comorbidity index. NC approach had better OS with HR of 0.75 (CI 0.65-0.85; p < 0.0001) on univariate analysis and 0.86 (0.74-0.98; P < 0.0281) on multivariate analysis. On multivariate analysis, age group > 75 years, black race, treatment outside academic research program had worse survival (p < 0.0001, 0.0139, 0.0001) respectively. The sensitive analysis showed the similar effects. Conclusions: Within the limitations of database review, our analysis suggests survival advantage of neoadjuvant chemotherapy approach over surgery first.