(P 461) OUTCOMES FOR OLIGOMETASTATIC PULMONARY DISEASE RECURRENCE TREATED WITH SURGERY ALONE FOR PATIENTS WITH SOFT TISSUE SARCOMAS A CASE SERIES

Objective: Oligometastatic disease refers to patients with metastases limited in number and organ sites, who may have a more indolent biology. Systemic therapy is generally used as a palliative measure for patients with STS initially presenting with metastatic disease or after distant relapse . The benefit of treating patients with systemic therapy for STS with oligometastatic recurrence amenable to resection or ablative therapies needs to be better understood. Identifying the patients most likely to benefit from local management alone is of the utmost importance in deciding whether or not to offer metastasis-directed therapy vs. systemic therapy vs. combined modality. We aimed to retrospectively look at patients in our institution with STS and oligometastatic pulmonary recurrence treated with surgical management only, and here we describe our findings.

Methods: Under an IRB-approved protocol, we retrospectively reviewed patients diagnosed at our institution with STS who underwent the first treatment for their localized disease, followed by the development of metastatic disease to the lung, characterized as an oligometastatic disease recurrence managed with metastasectomy only. The European consensus definition used in this study was up to five metastases from up to three different sites. All data were retrieved from electronic medical records. The primary endpoint was investigator-assessed progression-free survival, and all analysis was done with “R” software.

Results: A total of 11 patients were identified to have been diagnosed with localized STS with subsequent oligometastatic pulmonary recurrence from January 2004 to December 2021, histology included: leiomyosarcoma (N=2), myofibroblastic sarcoma (N=1), pleomorphic myxofibrosarcoma (N=1), alveolar soft part sarcoma (N=1), synovial sarcoma (N=1), epithelioid hemangioepithelioma (N=1), rhabdomyosarcoma (N=1), extrskeletal osteosarcoma (N=1) and high grade sarcoma (N=2). All these patients underwent standard-of-care treatment for their localized disease that involved surgery with (N=9) or without (N=2) chemotherapy and radiation therapy. Median follow-up was 88 months (range 5.9 to 340). The median time to development of oligometastatic recurrence was 23.2 months. After the detection of the pulmonary metastasis, the mean time to surgical management (TSM) was 33.3 days, median TSM was 28 days (range 8- 88 days). Modalities of surgery were Video-Assisted Thoracic Surgery (VATS) (2/11, 18%) and thoracotomies (9/11, 82%). Four of the 11 patients developed another recurrence (36.4%) until data was collected on June 2023, and 7/11 (63.6%) had no recurrence. The median PFS was 30.7 months after the surgical management.

Conclusion: Oligometastatic pulmonary recurrence in patients with STS is an increasingly recognized tumor presentation with an opportunity for long-term tumor control with minimal side effects. A multidisciplinary approach is usually employed, combining surgery, radiation therapy, and systemic treatment. Lung metastasectomy through either thoracotomy or VATS yields excellent results in patients with oligometastatic pulmonary disease recurrence. In our small series, median PFS was over 2.5 years which is more impressive than studies evaluating chemotherapy (single agent doxorubicin with mPFS of 2.52 months) and FDA-approved pazopanib (4.6 months). This data warrant the possibility for prospective studies evaluating the best management for this group of patients.