Background : The pathophysiology of colon and rectal cancer is very intricate. Despite their common site of origin, these tumors vary greatly in their virulence and behavior. Patients with oligometastases were shown to have a 0% to 43% 5-year overall survival (OS) rate. it’s really challenging to understand on how patients with oligometastases differ widely in their prognosis.

Methods : Our review had focused on 30 studies(1-30) published from 2003 to 2017. We have compared the survival outcome of patients with metastases to single sites against those with oligometastases (from liver, pulmonary, and peritoneum) and subsequently analyzed the factors that could have influenced the survival of the latter group. 25 studies have compared the outcome of patients with liver metastases (LM) alone against those with simultaneously occurring LM and extra hepatic diseases (EHD), whereas 4 studies have compared those with peritoneal metastases (PC) alone against those with (PC) and (LM) and 1 study has compared those with pulmonary/lung metastases (PM) alone against those (PM) and LM. All extra-peritoneal and extra-pulmonary metastases(27) were found in the liver.

Results : Patients with single site metastases had a 6% to 54% higher chance of reaching 5-years compared to their counterpart. In 15 studies, the difference was considered statistically significant. In 7 studies, the difference in survival is small and non-significant, nonetheless 2of these 7 studies showed that patients with single metastatic site had a 19.1% to 26% higher chance of reaching 5-years despite the lack of significance. Data were lacking in 6 studies. The OS was significantly lower in patients with oligometastases in 15 studies; no significant difference was found in 9. No statistical analysis was shown in the remaining 6 studies. The 3-year, 5-year, 10-year and median OS were 9% to 67.1%, 0% to 45%, 0 to 19% and 13 months to 53 months respectively. In Chua et al, the 2-year OS was 65%. Our analysis revealed that the survival outcome in these studies is strongly influenced by 3 main factors: patients’ selection (with less tumor burden, favorable neoadjuvant response and those who did not exhibit progression during staged surgical interventions), efficiency of treatment and tumor biology.

Conclusions : Surgery is not an absolute contraindication in oligometastases in particular to those with less tumor burdens, significant chemotherapy response and when R0 margin is possible. Treatment combinations have contributed significantly to the survival of patients with oligometastases.