Management of pulmonary metastases: a narrative review on the oncologist’s perspective

Abstract

Background and Objective: In a large proportion of patients affected by solid tumors, metastatic disease is identified at diagnosis; alternatively, cancer patients might develop metastases during their follow up after treatment of the primary tumor. Among distant metastases, pulmonary lesions are particularly relevant, as they are frequent in many solid malignancies. While the management of disseminated tumors relies mainly on systemic treatments with palliative intent, the interest in local treatments of single or limited pulmonary metastases (oligometastatic disease) has developed throughout years, either with curative intent or with the intent of prolonging survival. In spite of this growing interest, published scientific data on the oligometastatic setting are relatively limited, and randomized trials are particularly scarce; hence, the available evidence mostly relies on retrospective patient series. The aim of this review is to summarize the currently available data on the management of pulmonary metastases, with specific reference to oligometastases from the oncologist’s point of view. Methods: We evaluated the evidence supporting local approaches to pulmonary metastases, including surgery and radiation therapy, either alone or in combination to systemic treatments. In this context, we included a specific focus on colo-rectal cancer, as this was the first tumor in which regional approaches for pulmonary oligometastases were developed; furthermore, colo-rectal cancer provides an optimal model for describing the physiopathology leading to the development of pulmonary metastases and the local approaches to pulmonary metastases. In order to evaluate the most up-to-date information, we evaluated the available literature in English language published on PubMed between 2000 and 2021, identified during an informal search, and we assessed the most relevant international oncology meetings in the same time span to support our expert opinion. Key Content and Findings: The content of this narrative review includes data on epidemiology and physiopathology of pulmonary metastases, as well as the most solid available evidence on loco-regional and integrated approaches to pulmonary oligometastases. Conclusions: Based on the available evidence, the local management of pulmonary metastases, when feasible depending on limited size and number, controlled primary tumor, and absence of other metastatic lesions, appears to have a positive impact on patients’ prognosis, although the robustness of these data is limited by the general lack of prospective trials. Results from studies designed to assess the effectiveness of combined local and systemic treatments, especially in the era of biological agents and cancer immunotherapy, albeit difficult to conduct, are warranted.