Ho, Thanh P.

Background: Localized soft tissue sarcoma (STS) is primarily treated with surgical resection with or without radiotherapy (RT), while the role of chemotherapy (CT) as a radiosensitizer remains unclear. We report our single-institution experience with combined chemoradiotherapy (CCRT) in treating localized STS. Methods: We conducted a retrospective analysis of patients with localized STS treated at Mayo Clinic with mitomycin, cisplatin, and doxorubicin (MitoAP) concurrently with RT between 1/1/85 and 12/12/19. Results: We identified 179 patients (median age 58 years; median tumor size 9.5 cm), with 83.8% of tumors located in the extremities or trunk. Among them, 77.1% received perioperative CT in addition to CCRT, with 95% of those treated in the neoadjuvant setting. Median RT dose was 50 Gray. The 5-year disease-specific survival (DSS) was 77.9% (95% confidence interval, CI: 70.8–83.4%). The addition of perioperative CT to CCRT was associated with improved DSS compared with CCRT alone (p = 0.01, Hazard Ratio, HR: 0.48, 95% CI: 0.27–0.85). Median post-CCRT tumor viability was 30% and did not differ by CT use (p = 0.39), but varied significantly by histology (p < 0.001). Conclusions: Our institutional protocol utilizing two cycles of MitoAP with RT was well tolerated. DSS in our cohort was similar to historical data using perioperative RT alone, suggesting no clear benefit from CCRT. However, the majority of patients in our cohort were classified as high risk, which may have attenuated a potential survival benefit in the absence of appropriate comparative controls. Furthermore, additional perioperative CT to CCRT was associated with improved DSS and differential histology-specific responses in tumor viability, suggesting that a more aggressive neoadjuvant and perioperative approach may be beneficial in selected patients.

Background: Myxofibrosarcomas are notoriously highly infiltrative soft-tissue sarcomas, making negative surgical margins difficult to obtain. Recently, vacuum-assisted closure (VAC) is used to delay wound closure until a negative margin has been achieved; however, this can delay care and increase costs. Our institution has historically performed single-stage resections with intraoperative frozen margin analysis and reconstruction in these patients. The purpose of this study is to report the outcomes of this technique. Methods: We reviewed 112 patients (62 males, mean age 70 ± 14 years) with superficial myxofibrosarcoma. Eighty-eight patients received preoperative radiation. All patients underwent surgical resection with intraoperative frozen margin analysis, and the planned reconstruction was performed in a single anesthetic. Results: The 10-year local recurrence-free survival was 90%; positive intraoperative frozen section (HR 7.44, p = 0.004) and final permanent margins (HR 8.53, p = 0.007) were associated with local recurrence. Intraoperative margins were negative in 103 (92%) of patients, 1 of which was positive on final permanent section. There were nine cases of microscopically positive margins, of which seven underwent immediate re-excision to a negative margin. The accuracy of frozen margin assessment for myxofibrosarcoma was between 92.92 and 98.23%. All patients underwent reconstruction at the time of resection, with 19% needing an additional procedure, most commonly due to a wound complication (12%). Conclusions: Multidisciplinary single-stage excision with intraoperative frozen margin assessment and soft-tissue reconstruction yields low rates of local recurrence in patients with superficial myxofibrosarcoma.

Abstract Purpose: Soft-tissue sarcomas are rare malignancies with poor prognosis and limited systemic treatment options. We conducted a phase II study to assess the efficacy and safety of trabectedin and olaparib in patients with advanced disease. Patients and Methods: Patients with soft-tissue sarcoma who received ≥1 prior therapy were recruited into two cohorts. Cohort 1 included leiomyosarcoma and liposarcoma; cohort 2 included other histologies. All patients received trabectedin (1.1 mg/m2 24-hour infusion every 21 days) and olaparib (150 mg twice daily continuously). The study was conducted using a Simon minimax two-stage design with a primary endpoint of objective response (OR) rate per RECIST 1.1. Results: Twenty-nine (cohort 1, 16; cohort 2, 13) patients enrolled; one patient in cohort 2 was not evaluable. There were no confirmed ORs in cohort 1; the best response was stable disease in 12 (75%) patients and progressive disease in four (25%). Two partial responses were observed in cohort 2 (n = 12). The most common adverse events were fatigue (75%), neutropenia (75%), anemia (68%), and thrombocytopenia (68%). The median progression-free survival and overall survival for all patients were 3.5 (95% confidence interval, 3.3–8.2) and 13.2 months (95% confidence interval, 10.3–20.9), respectively. Next-generation sequencing of 17 tumors revealed multiple abnormalities, most commonly in TP53, RB1, and ATRX. Conclusions: Trabectedin plus olaparib conferred high rates of toxicity and failed to demonstrate ORs in leiomyosarcoma and liposarcoma. Preliminary evidence of clinical benefit in two patients in cohort 2 suggests potential value of either or both drugs in other sarcomas.

ABSTRACT Background and Objectives Hepatic epithelioid hemangioendothelioma (HEHE) is an uncommon vascular neoplasm characterized by variable clinical behavior. Our aim was to describe the therapeutic approach for HEHE at diagnosis and define clinicopathological characteristics associated with tumor progression and long‐term survival. Methods This is a retrospective study that includes patients with HEHE who received treatment at Mayo Clinic Rochester between 1984 and 2023. Results Eighty patients were included in the study (median age: 44 years; 62.5% female), 24 underwent liver transplantation, 26 underwent liver resection, and 30 were managed medically. The 3‐year overall survival rates were 86.7%, 80.9%, and 51.1%, respectively. Notably, 26 patients had extrahepatic metastases at the time of diagnosis, four (16.7%) in the transplantation group, four (15.4%) in the resection group, and 18 (69.2%) in the nonsurgical group. On multivariable modeling, bone metastasis was independently associated with long‐term mortality (HR 6.3, p < 0.001) while lung metastasis and surgical intervention were not associated with long‐term mortality (HR 0.8, p = 0.8; HR 1.1, p = 0.9, respectively). Conclusion Bone metastasis emerged as a strong predictor of poor survival. Hence, aggressive surgical intervention may not be advantageous in patients with skeletal metastases but can still be offered for those with other extrahepatic metastases.

Background: Myxoid liposarcoma predominantly affects young and middle-aged individuals, and little is known regarding treatment tolerability and outcomes in older patients. This study aims to better understand this older patient population. Methods: This single institution retrospective study included patients aged 70 years and older with localized (non-metastatic) myxoid liposarcoma. Results: Sixteen patients were included. The median age was 75 years, and 9 (56%) were female. Fourteen (88%) were extremity tumors and two (12%) were trunk. The median tumor size was 10.4 cm (range, 3.6 to 28 cm). Five (31%) tumors had a round cell component. All patients had surgery. Fourteen (88%) had perioperative radiation, and three (19%) had perioperative chemotherapy. One patient had postoperative infection, and one patient had neutropenic fever from preoperative chemotherapy. The median follow up from surgery was 6.3 years. Eight (50%) patients died from MLPS. The median relapse-free survival and overall survival were 34 months and 75 months, respectively. Conclusions: Most older patients with localized MLPS received perioperative radiation therapy with surgery, and few serious toxicities were reported. Even with treatment, half of the patients relapsed.

Background: Synovial sarcoma is rare and may present as a small, slow-growing mass. These tumors are often mistaken as benign and are therefore prone to unplanned and/or non-oncologic excision. We sought to identify the rate of unplanned excision of synovial sarcoma and risk factors for recurrence and survival among this cohort. Methods: The medical records of 246 patients evaluated at a single institution for synovial sarcoma between 1997 and 2022 were retrospectively reviewed. Of these, 87 (35%) underwent unplanned, non-oncologic excision. The mean age of the cohort was 49 years. Primary tumors were located in the extremity (n = 63), abdomen (n = 6), thorax (n = 7), head/neck (n = 8), and paraspinal region (n = 3). The median maximum pre-treatment dimension of the primary tumor was 4.8 cm (IQR 7–2.4). Seventy-seven (86%) patients underwent re-excision of the tumor bed, 39 (45%) received chemotherapy, and 63 (72%) received radiation therapy. Results: Among patients who underwent unplanned excision, local recurrence-free survival (LRFS) was 98% at 1 year and 82% at 5 years. Metastasis-free survival (MFS) was 91% at 1 year and 72% at 5 years. Disease-specific survival (DSS) was 98% at 1 year and 72% at 5 years. When adjusting for tumor size, tumors which underwent unplanned excision did not have worse recurrence or survival compared to those which had planned excision (p > 0.10). Size > 5 cm, monophasic subtype, and axial location were associated with increased risk of disease recurrence. Forty-six patients had residual tumor following re-excision, which was associated with worse MFS (HR 8.17, 95% CI [1.89, 35.2], p < 0.01) and DSS (HR 7.66, 95% CI [1.76, 33.4], p < 0.01). Patients who received radiotherapy had improved MFS (HR 6.4, 95% CI [1.42, 29.0], p = 0.02) and DSS (HR 5.86, 95% CI [1.27, 26.9], p = 0.02). Conclusions: One-third of patients presenting with synovial sarcoma were diagnosed after unplanned, non-oncologic excision. Patients with large, axial tumors had worse survival. Approximately half of patients who underwent unplanned excision had no residual tumor after pre-operative radiation. The use of radiation was associated with decreased rates of recurrence and improved disease-specific survival. Our results suggest that margin-negative re-resection and radiotherapy should be considered when feasible following unplanned excision of synovial sarcoma.

Background: Liposarcoma, one of the most prevalent sarcoma histologies, is recognized for its tendency for extra-pulmonary metastases. While oligometastatic cardiac disease is rarely reported, it poses a unique challenge as oligometastatic sarcomas are often managed with surgical resection. Case Report: We present a case of a 62-year-old man diagnosed with an oligometastatic myxoid liposarcoma (MLPS) to the heart 19 years after the primary tumor resection from the lower limb. The metastatic mass, situated in the pericardium adjacent and infiltrating the left ventricle, was not managed surgically but with a combination of chemotherapy and radiotherapy. The patient’s disease remains stable to date, for more than 10 years. Literature Review: We conducted a review of the literature to determine the preferred management approach for solitary cardiac metastases of sarcomas. We also conducted an in-depth analysis focusing on reported cases of MLPS metastasizing to the heart, aiming to extract pertinent data regarding the patient characteristics and the corresponding management strategies. Conclusions: Although clinical diagnoses of solitary or oligometastatic cardiac metastases from sarcomas are infrequent, this case underscores the significance of aggressive management employing chemotherapy and radiotherapy for chemosensitive and radiosensitive sarcomas, especially when surgical removal is high-risk. Furthermore, it challenges the notion that surgery is the exclusive therapeutic option leading to long-term clinical benefit in patients with recurrent sarcomas.

11521 Background: Osteosarcomas (OS) comprise the majority of new primary bone tumors in the US and affect a bimodal distribution of young adults (2nd-3rd decades) and older adults >65 yrs. Most large collaborative studies demonstrating the efficacy of HDMTX-containing chemotherapy regimens in OS limited enrollment to patients <40 yrs. Our study aims to fill the gap of reported clinical outcomes in adult OS patients ≥ 40 yrs by describing the feasibility and tolerability of HDMTX in these patients at Mayo Clinic. Methods: We conducted a retrospective chart review of patients ≥18 yrs with OS seen at our institution between 1/1/1980-9/30/2019 and who received ≥1 dose of HDMTX (12 g/m2, max 20 g). Extraosseous OS were excluded. Survival analyses were run for both the entire study population and the subset of patients age ≥40. Patient demographics, disease characteristics, and clinical outcomes were collected. The primary outcome evaluated was 5-year overall survival (5-yr OS). Results: We identified 94 patients whose demographic data are summarized (Table). Twenty-three of 94 (24%) were ≥40 yrs. Both the median number of HDMTX doses received and number of patients who received ≥50% recommended doses were significantly less among patients ≥40 yrs. However, HDMTX-related AKI and median number of hospital days did not differ significantly between the age groups. Among all patients, 5-yr OS was significantly improved (p=0.0025) at 45% (95% CI 35%-58%) for those who received ≥50% doses HDMTX compared to 5-yr OS of 25% (95% CI 12%-53%) for those who did not. Among patients ≥40 yrs, 5-yr OS was significantly improved (p=0.017) at 86% (95% CI 63%-100%) for those who received ≥50% doses HDMTX compared to 5-yr OS of 31% (95% CI 14%-68%) for those who did not. Conclusions: In our cohort, 5-yr OS was superior in those patients who received at least 50% of the planned doses of HDMTX. Older adults were significantly less likely to receive the majority of planned doses, which may be due to clinician bias regarding anticipated toxicity. However, we show that common HDMTX-associated toxicities did not vary significantly by age. If feasible, we recommend referring older patients with osteosarcoma to centers equipped to handle the staffing and supportive care needs of HDMTX administration. [Table: see text]

OBJECTIVE The objective of this study was to clarify the detailed clinical course of recurrent clival chordoma and the outcomes of each treatment modality. METHODS A single-center retrospective analysis was conducted on patients seen for recurrent clival chordoma. The cohort was identified from those who underwent surgery, stereotactic radiosurgery, or proton therapy at the authors’ institution between 1990 and 2022. RESULTS A total of 95 recurrences in 40 patients with a median (interquartile range [IQR]) follow-up of 43 (18–79) months were identified. The median (IQR) age at the time of diagnosis was 48 (36–62) years, and 55% of patients were male. Twenty-three patients were treated with surgery followed by adjuvant radiation before the first recurrence. The median (range) number of recurrences per patient was 2 (1–8), and the median (IQR) time to the first recurrence was 29 (9–51) months. The recurrences were treated with one or more of the following therapies: surgery, radiation, systemic therapy, and laser interstitial thermal therapy (LITT). Surgery was performed for 44 recurrences in 25 patients. Radiation was used to treat 42 recurrences in 28 patients. Patients with recurrences treated with surgery plus radiation had the longest progression-free survival (PFS) (median [95% CI] overall survival [OS] 120 [0–245] months, p < 0.01, log-rank test). Patients with recurrences but without prior radiation had longer PFS than those patients with prior radiation. The median (95% CI) OS after the first recurrence was 68 (54–82) months, 5-year OS after the first recurrence was 48%, and 10-year OS was 27%. Multivariate Cox regression analysis showed that mortality after the first recurrence was significantly associated with no adjuvant radiation (HR 0.149, 95% CI 0.038–0.59, p = 0.0067), older age at the time of the first recurrence (HR 1.04, 95% CI 1.01–1.08, p = 0.021), and total number of recurrences (p = 0.032). Seven patients received systemic therapy, and the median (95% CI) OS of these patients since initiation of systemic therapy was 31 (11–51) months. Imatinib and/or nivolumab were used in 6 patients (15%). One patient (3%) was treated with LITT for his fourth recurrence. CONCLUSIONS Despite the aggressive nature of recurrent chordoma, 14 of 29 patients (48%) survived for more than 5 years after the initial recurrence using combined therapies. Multiple treatment options may contribute to the long-term survival of patients with this intractable tumor.

e24016 Background: Recent studies of patients (pts) with gastrointestinal stromal tumor (GIST) have included an older patient population. The majority of these have focused on treatment, but little is known regarding the optimal duration of surveillance following surgery for localized disease. Methods: We conducted a retrospective study of pts age 70 years (yrs) and above (≥) at diagnosis (dx), who underwent surgery for their localized GIST. Charts were reviewed of GIST diagnosed between 1992 to 2016, to allow at least 5 yrs for surveillance, if performed. Demographics were analyzed and pts were risk stratified using modified NIH criteria. Results: We identified 42 pts with a median age of 74 yrs (70 to 89 yrs) at dx. The majority of pts were male (31, 74%) and non-Hispanic White (37, 88%). Most pts had gastric GIST (25, 60%). The median resected tumor was 47 mm (range 6 to 190). Thirty-nine of 42 pts had margin status documented R0 resection. The median overall survival for all pts was 7.9 yrs (1.1 to 17.7), with median recurrence free survival 5.6 yrs (1.1 to 13.7). Only 4 of 16 (25%) pts died from GIST recurrence, and all were detected under 5 yrs from surgery. Fourteen of 34 pts (41%) who survived over 5 yrs from resection had extended surveillance imaging. Demographics and risk stratification are shown in Table. None of the 16 low risk pts developed recurrence, including 6 (38%) whose surveillance imaging continued beyond 5 yrs. Among 7 intermediate risk pts, only 1 pt (14%) extended surveillance imaging beyond 5 yrs. Two intermediate risk pts (29%) developed recurrence and were symptomatic at dx. One intermediate risk pt died from GIST metastasis within 1 yr from surgery. Seven of 19 (37%) high risk pts had surveillance imaging beyond 5 yrs following surgical resection. Seven high risk pts (37%) developed recurrence within median 5.6 yrs (1.6 to 13.7) from surgery; five of these were detected on imaging. In the high risk pts with recurrence, 5 had received adjuvant imatinib and 2 declined any systemic therapy. Three pts (16%) in the high risk cohort died from GIST. Conclusions: In this cohort of pts age ≥ 70 yrs with resected GIST, the majority of pts were symptomatic at relapse. Older pts who undergo surgery for low risk GIST may not require extended surveillance. Fit, older pts with high risk GIST may benefit from extended surveillance imaging, even if they received adjuvant imatinib.[Table: see text]