Palliative primary tumor resection in minimally symptomatic (asymptomatic) patients with colorectal cancer and synchronous unresectable metastases versus chemotherapy alone: a metaanalysis

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AIM: to evaluate outcomes (overall survival, rate of surgical intervention due to complications of first treatment, 30-day mortality rate) of palliative primary tumor resection (PTR) followed by chemotherapy and chemotherapy/ radiotherapy (chemo/RT) alone in patients with asymptomatic or minimally symptomatic colorectal cancer (CRC) and synchronous unresectable metastases.MATERIALS AND METHODS: a meta-analysis based on Preferred Reporting Items for Systematic Reviews and Metaanalyses (PRISMA) guidelines was conducted on PubMed and Cochrane database. Odds ratio (OR) and 95% confidence interval (95% CI) were used as the treatment effect measure for comparing results. Combined overall effect measures were calculated for a random effect model. All analyses were performed using the Review Manager 5.3 software.RESULTS: eighteen non-randomized studies, including a total of 2,999 patients (1,737 PTR and 1,262 chemo/RT) were identified. Gender, age, site of primary tumor and distant metastasis of patients were comparable between groups in all analyzed studies. Two-year (38.2% vs. 21.1%; OR 0.42; 95% CI 0.28–0.64; p < 0.0001) and 5-year (12.7% vs. 5.3%; OR 0.45; 95% CI 0.21–0.97; p = 0.04) overall survival rates were significantly higher in the PTR group than in the chemo/RT group. No significant differences in 30-day mortality rate between the two groups (1.7% vs. 1%; OR 1.92; 95% CI 0.79–4.68; p = 0.15). However, the rate of surgical intervention due to complications of first treatment was significantly lower in the PTR group comparing to the chemo/RT group (2.3% vs. 14.53%; OR 0.18; 95% CI 0.08–0.40; p < 0.0001). At the same time, one hundred and fourteen patients (13.8%; OR 0.19; 95% CI 0.09–0.40; p < 0.0001) in the chemo/RT group required surgery for symptoms associated with a primary tumor.CONCLUSIONS: PTR in patients with asymptomatic or minimally symptomatic CRC and synchronous unresectable metastases significantly improves overall survival, allows to prevent surgical intervention due to complications related to primary tumor and is not associated with increased postoperative mortality rate comparing to systemic chemotherapy/radiotherapy as a treatment of first line. The current data are based on non-randomized comparative studies and data from early terminated randomized controlled trials (RCTs) and further well-designed RCTs are required.