Background and purpose: Clinical challenges arise in the oligoprogressive (OP) state with little evidence to support the use of ablative strategies. Our aim is to report on outcomes and prognostic variables following stereotactic body radiotherapy (SBRT) for OP and oligometastases (OM).
Material and methods: Overall (OS) and progression-free survivals (PFS) were calculated for 163 patients for 209 lesions (106 OM and 57 OP) treated with SBRT over 9 years. OS and PFS comparisons were calculated using the Kaplan-Meier actuarial survival and log rank methods. Uni, multi-variate analyses and cumulative incidences of local failure were performed using the Cox modelling and Gray's test respectively.
Results: The median OS and PFS was 37 and 15 months versus 21.7 and 6.4 months in the OM and OP groups respectively (P = 0.02 and P = 0.01). Performance status (⩾2 HR 2.95) and number of metastases (1/2 vs ⩾3 HR 1.88) were independent prognosticators for survival. The 1/2-year PFS were 55%/25% versus 22%/6% in the OM and OP cohorts. Patterns of first relapse were four times higher outside the irradiated field and OP status (p = 0.03), ⩾3 metastasis (p = 0.002) and concurrent systemic therapy (p = 0.001) conferred a greater risk. Time to second-line treatment was 20 vs 11 months in the OM and OP groups (P = 0.001).
Conclusion: Survival and distant relapse following SBRT to OM/OP is determined by the extent of metastatic disease and performance status. Future research should address the benefit of integrating SBRT with systemic therapies to allow deferral or continuation of therapeutic agents.
Keywords: Oligometastases; Oligoprogression; SBRT; Stereotactic radiotherapy.
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