Background: The recognition of oligometastatic disease as a distinct cancer state has resulted in advances in treatment paradigms, whereby patients with limited metastatic disease are potentially curable with metastasis-directed therapies. We performed a systematic review to identify clinical features consistently associated with prognosis across multiple cancer types, with the goal of identifying risk factors which may be considered in the stratification of such patients.

Methods: We searched 3 databases – PubMed, Embase and the Cochrane Library from inception till 5 May 2021 using both free text and controlled vocabulary terms. Additional articles were identified via a “snowball” search by screening the list of references of articles eligible for full-text review to identify and screen studies citing these articles.

Findings: We identified the following factors which conferred for poorer prognosis in patients with oligometastatic disease: multiple organ involvement (HR 2.06; 95% CI 1.43-2.99), multiple metastatic lesion (HR 1.57; 95% CI 1.21-2.04), and the presence of bone metastases (HR 3.32; 95% CI 1.47-7.49). Notably, we also found female gender (HR 1.43; 95% CI 1.14-1.92) was associated with better survival in patients with oligometastatic disease. Additionally, the absence of bone metastases appears to confer survival advantage in patients (HR 3.32; 95% CI 1.48-7.49).

Interpretation: Disease burden, site of involvement and gender appears to influence survival in the setting of oligometastatic disease. These above prognostic factors should be considered to guide patient selection for future clinical trials and metastasis-directed therapies.