Meta‐analysis of the association between primary tumour location and prognosis after surgical resection of colorectal liver metastases

Background Primary tumour location is emerging as an important prognostic factor in localized and metastatic colorectal cancers. However, its prognostic role in colorectal liver metastasis (CRLM) after hepatectomy remains controversial. A systematic review and meta-analysis was undertaken to evaluate its prognostic value. Methods References were identified through searches of PubMed, Embase, Web of Science and the Cochrane Library comparing overall or disease-free survival after hepatic resection between patients with CRLM originating from right- or left-sided colorectal cancers. Data were pooled using hazard ratios (HRs) and 95 per cent confidence intervals according to a random-effects model. Meta-regression and subgroup analyses were conducted to assess the effect of underlying confounding factors on HR estimates and to adjust for this. Results The final analysis included 21 953 patients from 45 study cohorts. Compared with left-sided primary tumour location, right-sided location was associated with worse overall survival (HR 1 center dot 39, 95 per cent c.i. 1 center dot 28 to 1 center dot 51; P < 0 center dot 001; prediction interval 1 center dot 00 to 1 center dot 93), and also tended to have a negative impact on disease-free survival (HR 1 center dot 18, 1 center dot 06 to 1 center dot 32; P = 0 center dot 004; prediction interval 0 center dot 79 to 1 center dot 75). Subgroup analysis showed that the negative effect of right-sided primary tumour location on overall survival was more prominent in the non-Asian population (HR 1 center dot 47, 1 center dot 33 to 1 center dot 62) than the Asian population (HR 1 center dot 18, 1 center dot 05 to 1 center dot 32) (P for interaction <0 center dot 01). Conclusion This study demonstrated a prognostic role for primary tumour location in patients with CRLM receiving hepatectomy, especially regarding overall survival. Adding primary tumour location may provide important optimization of prognosis prediction models for CRLM in current use.