85P - Oligometastatic solid tumors: Disease characteristics and role of local therapies

Background

Treatment recommendations and benefit of local therapy in oligometastatic disease (OMD) are an era of interest and debate; however, it’s quite difficult to plan RCTs including patients with metastases due to ethical considerations as patients may lose an effective treatment if they are assigned to a control arm, furthermore, most of the clinical literature on OMD is cancer site specific, this study included OMD of different solid tumors.

Methods

In this observational prospective cohort study Patients with stage IV solid tumors who met the criteria of OMD (≤5 metastatic lesions, and or ≤2 organs) with performance status 0-2 were eligible; we studied disease characteristics and outcomes regarding local therapies of OMD.

Results

Two hundred and thirty-four patients with solid tumors met the criteria of OMD, 126 (53.8%) Patients received local therapies; surgery, Radiotherapy (RT), local ablative therapy (group I) and 108 (46.2%) Patients didn’t receive local therapy (group II). Comparing both groups, Group I: patients had significantly younger age, earlier initial TNM stage, higher rates of metachronous onset, symptomatic disease, soft tissue disease, single lesion and or single organ involvement and complete response, but lower rates of managed pulmonary OMD compared to group II. However, no significant association with specific primary cancer site, histological grade, molecular subtype, SUV activity level in PET/CT, type and number of systemic therapy lines, type of OMD (genuine vs. induced and repeated vs. de novo), cut of point of serum tumor markers or any subsequent delay of systemic treatment were noticed with local therapy (p value >0.05) and unexpectedly metastatic size of ≥ 3 cm was more amenable for local therapy (p value ≤0.05). Regarding survival, local therapy of OMD was associated with better PFS and OS: The mean OS in local therapy group was 64 months vs. 38 months in non local therapy patients and the median PFS was not reached in local therapy patients vs. 30 months in no local therapy patients. By multivariate regression analysis; local therapy for OMD is an independent prognostic factor for both PFS and OS.

Conclusions

For selected oligometastatic solid tumor patients, local therapy for OMD could improve PFS and OS.

Clinical trial identification

Editorial acknowledgement

Legal entity responsible for the study

Menoufia University.

Funding

Has not received any funding.

Disclosure

All authors have declared no conflicts of interest.