Objective  To investigate the effect of age on distant metastasis and prognosis in patients with stage IV rectal cancer.

Methods  The 4 269 patients with stage IV rectal cancer from SEER database were divided into younger group (<50 years old) and elderly group (≥50 years old). Kaplan-Meier method was used to generate survival curves. Cox regression was applied to predict prognostic factors for OS. Fur-thermore, logistic regression was performed to analyze the effect of age on metastasis site in patients with stage IV rectal cancer.

Results  Compared with the younger group, the elderly group was more likely to appear liver metastasis (P=0.016), but had fewer lung metastasis(P=0.011). And there was no significant difference in other metastatic sites (bone, brain, and multiple sites) among two age groups. Survival analysis showed that younger patients had better survival rate than the elderly group (P<0.001) with the median survival time being 28 months and 18 months, respectively. Among pa-tients with liver metastasis only, lung metastasis only and multiple sites metastases, younger group showed better survival than elderly group (all P<0.05). Multivariate analysis revealed that age was an important independent prognostic factor for patients with IV rectal cancer, and race, T-stage, N-stage, chemotherapy, radiation and sur-gery are also independent prognostic factors.

Conclusion  Age was an important factor affecting the metastasis site and prognosis of patients with IV rectal cancer.

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