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Stereotactic body radiation therapy (SBRT) for lung metastases from colorectal cancer: A single-institution experience
Background
Colorectal cancer (CRC) is the third most common cancer diagnosed worldwide (1). The lung is one of the most commonly involved sites of distant metastasis, with 5-25% of patients presenting lung metastases at diagnosis (2). In selected patients with a limited burden of disease, considered as oligometastatic patients (3), local treatment is a valid therapeutic option. Surgical resection is the mainstay of treatment for patients with lung oligometastatic cancer with long-term survival (4). In recent years, some studies with stereotactic body radiotherapy (SBRT) have been conducted in these group of patients and proved to be a safe and effective option for the treatment of lung metastases (5-7). This study aims to evaluate the efficacy of SBRT, patterns of recurrence and identify prognostic factors influencing survival and local control in CRC cancer with pulmonary oligometastases treated with SBRT.
Methods
We performed a retrospective review of 109 patients with CRC lung oligometastases treated with SBRT between 2013 and 2020. Patients lost to follow-up were excluded. Primary and metastatic tumor characteristics, treatment and follow-up data including survival, local control and distant metastases were evaluated. Overall survival (OS) and Progression Free Survival (PFS) were estimated by the Kaplan-Meier method. Cox proportional hazard models were used to analyze factors associated with OS and PFS.
Results
A total of 109 patients with 173 metastatic lesions met the inclusion criteria. Two-thirds of patients were male and the median age was 66 years. Sixty-eight patients (62%) presented rectal cancer and 41 patients (38%) with colon cancer as primary cancer, respectively. Sixty percent of patients were treated for a single metastasis, 35% for 2-3 and 4.6% ≥3 with a median metastatic volume of 1.99cc [0.113-99.2]. Of the 173 treated lesions 75% had a diameter < 20mm. A single fraction was performed in 56% of lesions with a dose of 30Gy (2 lesions 34Gy); 4 fractions in 11.6% with 50Gy (1 lesion with 45Gy); 5 fractions in 31.2% with 40-50Gy. After a median follow-up of 29 months, 3-year OS and PFS were 71.5% and 24.4%, respectively. Median OS was 51 months, median PFS was 11.7 months and median local-PFS was 23.8 months, respectively. Eighty-one patients had progression of the disease, with the following pattern: 48.1% with new lung metastasis; 24.7% metastasis in other organs; 27.1% progression of the treated lesion. A metastatic volume ≥5cc and a diameter ≥25mm were associated with poor OS in univariate analysis, non-significant in multivariate analysis. The metastatic volume (≥10cc) was also associated with poor regional-PFS in multivariate analysis and in PFS in univariate analysis. Patients who went through more than 3 chemotherapy lines before SBRT had smaller PFS in multivariate analysis.
Conclusions
SBRT is an effective local treatment option for lung metastases providing a chance for long term survival. Nearly half of the patients with progression of disease presented regional progression; the remaining patients showed progression at distance (25%) and progression of the treated lesion (27%), respectively. The lesion size and the number of previous chemotherapy lines were important prognostic factors.
Legal entity responsible for the study
The authors.
Funding
Has not received any funding.
Disclosures
All authors have declared no conflicts of interest.
