Abstract 107P
Background
Standard treatment of oligometastatic colorectal cancer is systemic therapy +/- local therapy +/- metastatic directed therapy. The best strategy to treat patients with repeat oligopersistance is unknown. We report outcomes of patients after liver brachytherapy precisely in that clinical setting.
Methods
Patients with at base oligometastatic colorectal cancer, during active systemic therapy and with persistent non-progressive oligometastases localized in liver only were selected. Up to 5 liver metastases were allowed. Changing of systemic treatment line were not allowed. Single fraction of 15-25 Gy was used. Patients were followed with serial imaging, starting at 6 months after brachytherapy, for local response analysis, PFS, OS and toxicity. PFS and OS were counted from the day of brachytherapy.
Results
68 patients were included, with 47% of women, a median age of 66 years and an ECOG-PS ≤ 2. The number of systemic therapy lines used before brachytherapy was 1,2,3,4,5 in 2,5%, 40%, 37%, 19% and 1,5%, respectively. 1,2,3 and 4 liver metastases were diagnosed in 44%, 35%, 9% and 12%, respectively. Dose of 15 Gy, 20 Gy, 25 Gy was prescribed in 8%, 29% and 63% of patients, respectively. Objective response rate (ORR) and disease control rate (DCR) were, 51,5 % and 94%, respectively. Median PFS and OS was 9 (7-10) and 16 (14-17) months. Median 1y- and 2yPFS were 50% and 4.4%, and 1y- and 2yOS were 78% and 18%, respectively. In multivariate analysis, the factors associated with longer PFS were, DCR (1yPFS:52% vs.25%; 2yPFS:4.7% vs.0%) and ORR (1yPFS:60% vs.39%; 2yPFS:8.6% vs.0%). ORR was the only factor associated with better OS (1yOS: 83% vs.73%; 2yOS: 29% vs.6,1%). Higher DCR and ORR were achieved with the 25 Gy dose. There were no > G2 adverse events observed.
Conclusions
Liver brachytherapy is associated with high DCR and ORR and is well tolerated. Selected patients with repeat oligopersistent liver metastases from colorectal cancer, may achieve long OS and PFS. In that case decision of switching to next systemic therapy line may be potentially postponed. Prescription of 25 Gy should be applied.
Legal entity responsible for the study
Brachytherapy Department, St. John's Cancer Center, Lublin, Poland.
Funding
Has not received any funding.
Disclosure
All authors have declared no conflicts of interest.