Reexamining Time From Breast Cancer Diagnosis to Primary Breast Surgery.

Importance: Although longer times from breast cancer diagnosis to primary surgery have been associated with worse survival outcomes, the specific time point after which it is disadvantageous to have surgery is unknown. Identifying an acceptable time to surgery would help inform patients, clinicians, and the health care system. Objective: To examine the association between time from breast cancer diagnosis to surgery (in weeks) and overall survival and to describe factors associated with surgical delay. The hypothesis that there is an association between time to surgery and overall survival was tested. Design, Setting, and Participants: This was a case series study that used National Cancer Database (NCDB) data from female individuals diagnosed with breast cancer from 2010 to 2014 (with 5-year follow-up to 2019). The NCDB uses hospital registry data from greater than 1500 Commission on Cancer-accredited facilities, accounting for 70% of all cancers diagnosed in the US. Included participants were females 18 years or older with stage I to III ductal or lobular breast cancer who underwent surgery as the first course of treatment. Patients with prior breast cancer, missing receptor information, neoadjuvant or experimental therapy, or who were diagnosed with breast cancer on the date of their primary surgery were excluded. Multivariable Cox regression was used to evaluate factors associated with overall survival. Patients were censored at death or last follow-up. Covariates included age and tumor characteristics. Multinomial regression was performed to identify factors associated with longer time to surgery, using surgery 30 days or less from diagnosis as the reference group. Data were analyzed from March 15 to July 7, 2022. Exposures: Time to receipt of primary breast surgery. Measures: The primary outcome measure was overall survival. Results: The final cohort included 373 334 patients (median [IQR] age, 61 [51-70] years). On multivariable Cox regression analysis, time to surgery 9 weeks (57-63 days) or later after diagnosis was associated with worse overall survival (hazard ratio, 1.15; 95% CI, 1.08-1.23; P < .001) compared with surgery between 0 to 4 weeks (1-28 days). By multinomial regression, factors associated with longer times to surgery (using surgery 1-30 days from diagnosis as a reference) included the following: (1) younger age, eg, the adjusted odds ratio (OR) for patients 45 years or younger undergoing surgery 31 to 60 days from diagnosis was 1.32 (95% CI, 1.28-1.38); 61 to 74 days, 1.64 (95% CI, 1.52-1.78); and greater than 74 days, 1.58 (95% CI, 1.46-1.71); (2) uninsured or Medicaid status, eg, the adjusted OR for patients with Medicaid undergoing surgery 31 to 60 days from diagnosis was 1.35 (95% CI, 1.30-1.39); 61 to 74 days, 2.13 (95% CI, 2.01-2.26); and greater than 74 days, 3.42 (95% CI, 3.25-3.61); and (3) lower neighborhood household income, eg, the adjusted OR for patients with household income less than $38,000 undergoing surgery 31 to 60 days from diagnosis was 1.35 (95% CI, 1.02-1.07); 61 to 74 days, 1.21 (95% CI, 1.15-1.27); and greater than 74 days, 1.53 (95% CI, 1.46-1.61). Conclusions and Relevance: Findings of this case series study suggest the use of 8 weeks or less as a quality metric for time to surgery. Time to surgery of greater than 8 weeks may partly be associated with disadvantageous social determinants of health.

Development and Validation of an Explainable Machine Learning Model for Major Complications After Cytoreductive Surgery.

Importance: Cytoreductive surgery (CRS) is one of the most complex operations in surgical oncology with significant morbidity, and improved risk prediction tools are critically needed. Machine learning models can potentially overcome the limitations of traditional multiple logistic regression (MLR) models and provide accurate risk estimates. Objective: To develop and validate an explainable machine learning model for predicting major postoperative complications in patients undergoing CRS. Design, Setting, and Participants: This prognostic study used patient data from tertiary care hospitals with expertise in CRS included in the US Hyperthermic Intraperitoneal Chemotherapy Collaborative Database between 1998 and 2018. Information from 147 variables was extracted to predict the risk of a major complication. An ensemble-based machine learning (gradient-boosting) model was optimized on 80% of the sample with subsequent validation on a 20% holdout data set. The machine learning model was compared with traditional MLR models. The artificial intelligence SHAP (Shapley additive explanations) method was used for interpretation of patient- and cohort-level risk estimates and interactions to define novel surgical risk phenotypes. Data were analyzed between November 2019 and August 2021. Exposures: Cytoreductive surgery. Main Outcomes and Measures: Area under the receiver operating characteristics (AUROC); area under the precision recall curve (AUPRC). Results: Data from a total 2372 patients were included in model development (mean age, 55 years [range, 11-95 years]; 1366 [57.6%] women). The optimized machine learning model achieved high discrimination (AUROC: mean cross-validation, 0.75 [range, 0.73-0.81]; test, 0.74) and precision (AUPRC: mean cross-validation, 0.50 [range, 0.46-0.58]; test, 0.42). Compared with the optimized machine learning model, the published MLR model performed worse (test AUROC and AUPRC: 0.54 and 0.18, respectively). Higher volume of estimated blood loss, having pelvic peritonectomy, and longer operative time were the top 3 contributors to the high likelihood of major complications. SHAP dependence plots demonstrated insightful nonlinear interactive associations between predictors and major complications. For instance, high estimated blood loss (ie, above 500 mL) was only detrimental when operative time exceeded 9 hours. Unsupervised clustering of patients based on similarity of sources of risk allowed identification of 6 distinct surgical risk phenotypes. Conclusions and Relevance: In this prognostic study using data from patients undergoing CRS, an optimized machine learning model demonstrated a superior ability to predict individual- and cohort-level risk of major complications vs traditional methods. Using the SHAP method, 6 distinct surgical phenotypes were identified based on sources of risk of major complications.

Prognostic Significance of Preoperative Tumor Markers in Pseudomyxoma Peritonei from Low-Grade Appendiceal Mucinous Neoplasm: a Study from the US HIPEC Collaborative.

BACKGROUND: Tumor markers are commonly utilized in the diagnostic evaluation, treatment decision making, and surveillance of appendiceal tumors. In this study, we aimed to determine the prognostic significance of elevated preoperative tumor markers in patients with pseudomyxoma peritonei secondary to low-grade appendiceal mucinous neoplasm who underwent cytoreductive surgery and hyperthermic intraperitoneal chemotherapy. METHODS: Using a multi-institutional database, eligible patients with measured preoperative tumor markers [carcinoembryonic antigen (CEA), carbohydrate antigen 19-9 (CA 19-9), or cancer antigen 125 (CA-125)] were identified. Univariate and multivariate Cox-proportional hazards regression analysis assessed relationships between normal and elevated serum tumor markers with progression-free and overall survival in the context of multiple clinicopathologic variables. RESULTS: zTwo hundred and sixty-four patients met criteria. CEA was the most commonly measured tumor marker (97%). Patients who had any elevated tumor marker had a higher peritoneal carcinomatosis index (PCI) as compared to those with normal range markers. Elevated CEA and CA 19-9 levels were individually associated with longer inpatient length of stay, requirement for intraoperative transfusion, and incomplete cytoreduction. Utilization of neoadjuvant chemotherapy, increased PCI score, elevated CA 19-9 (p = 0.007), and CA-125 levels (p = 0.01) were predictive of decreased progression-free survival on univariate analysis. However, in a multivariate model, only elevated PCI was a statistically significant predictor of progression-free survival. CONCLUSION: Elevated preoperative tumor markers indicate a higher burden of disease but are not independently associated with survival in this retrospective multi-institutional cohort. Further prospective studies are needed to clarify the utility of these markers in this patient population.

Impact of Perioperative Blood Transfusions on Outcomes After Hyperthermic Intraperitoneal Chemotherapy: A Propensity-Matched Analysis.

BACKGROUND: Cytoreductive surgery (CRS) with hyperthermic intraperitoneal chemotherapy (HIPEC) is a major operation frequently necessitating red blood cell transfusion. Using multi-institutional data from the U.S. HIPEC Collaborative, this study sought to determine the association of perioperative allogenic blood transfusion (PABT) with perioperative outcomes after CRS/HIPEC. METHODS: This retrospective cohort study analyzed patients who underwent CRS/HIPEC for peritoneal surface malignancy between 2000 and 2017. Propensity score-matching was performed to mitigate bias. Univariate analysis was used to compare demographic, preoperative, intraoperative, and postoperative variables. Factors independently associated with PABT were identified using multivariate analysis. RESULTS: The inclusion criteria were met by 1717 patients, 510 (29.7%) of whom required PABT. The mean Peritoneal Cancer Index (PCI) of our cohort was 14.8 ± 9.3. Propensity score-matching showed an independent association between PABT and postoperative risk of pleural effusion, hemorrhage, pulmonary embolism, enteric fistula formation, Clavien-Dindo grades 3 and 4 morbidity, longer hospital stay, and reoperation (all P < 0.05 in the multivariate analysis). Compared with the patients who received 1 to 5 red blood cell (RBC) units, the patients who received more than 5 units had a greater risk of renal impairment, a longer intensive care unit (ICU) stay, and more postoperative infections. Finally, PABT was an independent predictor of worse survival for patients with appendiceal and colorectal primaries. CONCLUSION: Even low levels of PABT for patients undergoing CRS/HIPEC are independently associated with a greater risk of infectious and non-infectious postoperative complications, and this risk is increased for patients receiving more than 5 RBC units. Worse survival was independently predicted by PABT for patients with peritoneal carcinomatosis of an appendiceal or colorectal origin.

What Drives High Costs of Cytoreductive Surgery and HIPEC: Patient, Provider or Tumor?

INTRODUCTION: Cytoreductive surgery with hyperthermic intraperitoneal chemotherapy (CRS/HIPEC) is utilized for peritoneal malignancies and is associated with significant resource use. To address potentially modifiable factors contributing to excessive cost, we sought to determine predictors of high cost of care for patients undergoing CRS/HIPEC. METHODS: An institutional CRS/HIPEC database was queried for adult patients from 2014 to 2018. Cost was defined as cost for the index hospitalization, and high-cost cases were defined as > 75th percentile for cost. Bivariate analyses for cost were performed, and all significant tumor, patient, and surgeon-specific variables were entered in a linear regression for cost. A separate linear regression was performed for length of stay (LOS). RESULTS: In total, 59 patients underwent 61 CRS/HIPEC procedures. The median direct variable cost was $20,509 (16,395-25,240). Median length of stay (LOS) was 8 (7-11.5) days and ICU stay was 1 (1-1.5) day. LOS, length of ICU stay and operative time were predictive of cost. Factors associated with increased LOS were Clavien-Dindo grade II complications and ostomy creation. Patient-related factors, including age and BMI, tumor-related factors, such as PCI and CCR, and surgeon were not predictive of cost nor LOS. DISCUSSION: Our results, the first to identify predictors of high cost of CRS/HIPEC-related care in the US, reveal cost was largely related to length and intensity of care. In turn, these drivers were influenced by complications and operative factors. Future work will focus on identifying an appropriate ERAS protocol following CRS/HIPEC and selection of those patients that may avoid routine ICU admission.

Development and Assessment of the Wisconsin Surgical Coaching Rubric.

Importance: Surgical coaching continues to gain momentum as an innovative method for continuous professional development. A tool to measure the performance of a surgical coach is needed to provide formative feedback to coaches for continued skill development and to assess the fidelity of a coaching intervention for future research and dissemination. Objective: To evaluate the validity of the Wisconsin Surgical Coaching Rubric (WiSCoR), a novel tool to assess the performance of a peer surgical coach. Design, Setting, and Participants: Surgical coaching sessions from November 2014 through February 2018 conducted by 2 statewide peer surgical coaching programs were audio recorded and transcribed. Twelve raters used WiSCoR to rate the performance of the surgical coach for each session. The study included peer surgical coaches in the Wisconsin Surgical Coaching Program (n = 8) and the Michigan Bariatric Surgery Collaborative coaching program (n = 15). The data were analyzed in 2019. Interventions or Exposures: Use of WiSCoR to rate peer surgical coaching sessions. Main Outcomes and Measures: There were 282 WiSCoR ratings from the 106 coaching sessions included in the study. WiSCoR was evaluated using a framework, including inter-rater reliability assessed with Gwet weighted agreement coefficent. Descriptive statistics of WiSCoR were calculated. Results: Eight coaches (35%) and 11 coachees (29%) were from the Wisconsin Surgical Program and 15 coaches (65%) and 27 coachees (71%) were from the Michigan Bariatric Surgery Collaborative. The validity of WiSCoR is supported by high interrater reliability (Gwet weighted agreement coefficient, 0.87) as well as a weakly positive correlation of WiSCoR to coachee ratings of coaches (r = 0.22; P = .04), rigorous content development, consistent rater training, and the association of WiSCoR with coach and coaching program development. The mean (SD) overall coach performance rating using WiSCoR was 3.23 (0.82; range, 1-5). Conclusions and Relevance: WiSCoR is a reliable measure that can assess the performance of a surgical coach, inform fidelity to coaching principles, and provide formative feedback to surgical coaches. While coachee ratings may reflect coachee satisfaction, they are not able to determine the quality of a coach.

Association of Personality and Thinking Style With Effective Surgical Coaching.

Importance: While interest in surgical coaching programs is rising, there is no objective method for selecting effective surgical coaches. Objective: To identify a quantitative measure to determine who will be an effective surgical coach. Design, Setting, and Participants: This prospective cohort study included coaches and coachees from 2 statewide peer surgical coaching programs: the Wisconsin Surgical Coaching Program and the Michigan Bariatric Surgical Collaborative coaching program. Data were collected from April 2014 to February 2018, and analysis began August 2018. Interventions: The Myers-Briggs Type Indicator was administered to coaches and coachees, and the Life Styles Inventory was administered to surgical coaches before their first coaching session. Main Outcomes and Measures: Coach performance in the first coaching session and all coaching sessions using the Wisconsin Surgical Coaching Rubric. Results: Twenty-three surgical coaches and 38 coachees combined for a total of 65 unique pairs and 106 coaching sessions. Overall, 22 of 23 coaches (96%) and 32 of 38 coachees (84%) were men. An increase in a coach's Life Styles Inventory constructive style score correlated with an increase in overall coach performance for the first coaching session (r = 0.70; P = .002). Similarity in the coaching pair's Myers-Briggs Type Indicator judging/perceiving dichotomy was also associated with an increase in overall coach performance for their first coaching session (ß = 0.38; P = .02). When all sessions were included in the analysis, these objective measures were no longer associated with coach performance. Conclusions and Relevance: Surgeons of all personalities and thinking styles can become an effective coach with appropriate training and experience. Coach training can be tailored to support diverse behavioral styles and preferences to maximize coach effectiveness.

What is the Optimal Preoperative Imaging Modality for Assessing Peritoneal Cancer Index? An Analysis From the United States HIPEC Collaborative.

BACKGROUND: Radiographic prediction of peritoneal carcinomatosis index (PCI) can improve patient selection for cytoreductive surgery. We aimed to determine the correlation of computed tomography (CT)-predicted PCI (CT-PCI) and magnetic resonance imaging (MRI)-predicted PCI (MRI-PCI) with intraoperative-PCI, and if a preoperative-PCI cutoff is associated with incomplete cytoreduction. PATIENTS AND METHODS: Patients from the US HIPEC Collaborative (2000-2017) with appendiceal, colorectal, or peritoneal mesothelioma (PM) histology who underwent cytoreductive surgery were included. Pearson correlation coefficients were used to determine correlation between preoperative and intraoperative-PCI values. Fisher r-to-z transformation was used to compare correlations. RESULTS: A total of 488 patients were included. Of these, 34% had noninvasive appendiceal, 30% invasive appendiceal, 28% colorectal, and 8% PM histology. CT-PCI was correlated with intraoperative-PCI for patients with noninvasive and invasive appendiceal and colorectal histologies (r = 0.689, 0.554, and 0.571; all P < .001), but not PM (r = 0.188; P = .295). MRI-PCI was correlated with intraoperative-PCI for all histologies (non-invasive appendiceal: r = 0.591; P = .002; invasive appendiceal: r = 0.848; P < .001; colorectal: r = 0.729; P < .001; PM: r = 0.890; P = .007). Comparing CT and MRI, correlations were similar in noninvasive appendiceal and colorectal histologies; MRI was better for invasive appendiceal and PM (P = .005 and P = .021, respectively). Twenty-eight (6%) patients underwent an incomplete cytoreduction (cytoreduction score, 2-3). PCI greater than 15 was associated with cytoreduction score of 2 to 3 for both CT and MRI (CT-PCI: odds ratio, 3.0; P = .033; MRI-PCI: odds ratio, 7.6; P = .071). CONCLUSIONS: In this multi-institutional cohort, CT and MRI-PCI correlate well with intraoperative-PCI. MRI appears to be superior for invasive appendiceal and peritoneal mesothelioma. External validation in a larger population is needed.

Time to initiation of neo-adjuvant chemotherapy for breast cancer treatment does not influence patient survival: A study of US breast cancer patients.

Delays in the initiation of adjuvant chemotherapy or radiation therapy are associated with worse outcomes in patients undergoing treatment for breast cancer. However, the impact of the time to initiation of neo-adjuvant chemotherapy (NAC) on patient outcomes has not previously been studied. The purpose of this study was to determine whether delays in NAC initiation impact patient survival. The National Cancer Database was queried for women ≥ 18 years old who underwent NAC within 6 months of being diagnosed with stage I-III invasive breast cancer in 2010-2011. ER+ or PR+, Her2- cancers were excluded from analysis. Multivariable Cox proportional hazard modeling was used to evaluate the relationship between time to NAC, sociodemographic, diagnosis, and treatment factors with patient survival. The median age of the 12 806 women included in this study was 52 (range 21-90) with 62% presenting with cT2 disease and 62% with nodal involvement. Half of the women (50%) had triple negative, 30% ER/PR+Her2+ and 20% ER-PR-Her2+ cancers. The median time to starting NAC was 4 weeks (range 0-26) for all subtypes. Time to NAC initiation was not associated with a difference in survival for triple negative or Her2+ cancers. Delays from diagnosis to starting NAC are not associated with worse survival for patients with Her2+ or triple negative breast cancer. This study demonstrates that the majority of women in the modern era start NAC in a timely fashion and delays in starting NAC within 6 months of diagnosis do not impact long-term patient outcomes.

Optimal Surveillance Frequency After CRS/HIPEC for Appendiceal and Colorectal Neoplasms: A Multi-institutional Analysis of the US HIPEC Collaborative.

BACKGROUND: No guidelines exist for surveillance following cytoreductive surgery with hyperthermic intraperitoneal chemotherapy (CRS/HIPEC) for appendiceal and colorectal cancer. The primary objective was to define the optimal surveillance frequency after CRS/HIPEC. METHODS: The U.S. HIPEC Collaborative database (2000-2017) was reviewed for patients who underwent a CCR0/1 CRS/HIPEC for appendiceal or colorectal cancer. Radiologic surveillance frequency was divided into two categories: low-frequency surveillance (LFS) at q6-12mos or high-frequency surveillance (HFS) at q2-4mos. Primary outcome was overall survival (OS). RESULTS: Among 975 patients, the median age was 55 year, 41% were male: 31% had non-invasive appendiceal (n = 301), 45% invasive appendiceal (n = 435), and 24% colorectal cancer (CRC; n = 239). With a median follow-up time of 25 mos, the median time to recurrence was 12 mos. Despite less surveillance, LFS patients had no decrease in median OS (non-invasive appendiceal: 106 vs. 65 mos, p < 0.01; invasive appendiceal: 120 vs. 73 mos, p = 0.02; colorectal cancer [CRC]: 35 vs. 30 mos, p = 0.8). LFS patients had lower median PCI scores compared with HFS (non-invasive appendiceal: 10 vs. 19; invasive appendiceal: 10 vs. 14; CRC: 8 vs. 11; all p < 0.01). However, on multivariable analysis, accounting for PCI score, LFS was still not associated with decreased OS for any histologic type (non-invasive appendiceal: hazard ratio [HR]: 0.28, p = 0.1; invasive appendiceal: HR: 0.73, p = 0.42; CRC: HR: 1.14, p = 0.59). When estimating annual incident cases of CRS/HIPEC at 375 for non-invasive appendiceal, 375 invasive appendiceal and 4410 colorectal, LFS compared with HFS for the initial two post-operative years would potentially save $13-19 M/year to the U.S. healthcare system. CONCLUSIONS: Low-frequency surveillance after CRS/HIPEC for appendiceal or colorectal cancer is not associated with decreased survival, and when considering decreased costs, may optimize resource utilization.

Breast Cancer Found Incidentally After Reduction Mammaplasty in Young Insured Women.

BACKGROUND: Reduction mammaplasty is a common operation performed for healthy women. The estimated incidence of breast cancer diagnosed at the time of reduction mammaplasty varies from 0.06 to 4.5%, and information on the care of these patients is limited. This study aimed to determine the incidence of breast cancer identified incidentally during reduction mammaplasty and to characterize preoperative imaging. METHODS: Women 18 years of age or older who underwent reduction mammaplasty from 2013 to 2015 were identified from the Truven Health MarketScan® Research Databases. Patients with prior breast cancer were excluded. Descriptive statistics were calculated for patient characteristics, incidental breast cancer, preoperative breast imaging, and postoperative treatment. RESULTS: Reduction mammaplasty was performed for 18,969 women with a mean age of 42.5 years. Of these patients, 186 (0.98%) were incidentally found to have breast cancer, with 134 (0.71%) having invasive breast cancer and 52 (0.27%) having carcinoma in situ. The patients with incidentally found cancer were older than the patients without cancer (50.8 vs. 42.5 years; p < 0.001). Overall, 58.2% of the patients had undergone mammography before reduction mammoplasty. The rates were higher (> 80%) for the patients older than 40 years. Preoperative mammography was performed for 76.3% of those with a diagnosis of breast cancer at time of reduction mammoplasty. CONCLUSIONS: Breast cancer diagnosed incidentally at the time of reduction mammaplasty is uncommon and often radiographically occult. The majority of women older than 50 years appropriately received preoperative mammography. These data can be used to manage patient expectations about the potential for the incidental diagnosis of breast cancer at reduction mammaplasty, even with a negative preoperative mammography.

Does Tumor Size Predict Response to Neoadjuvant Chemotherapy in the Modern Era of Biologically Driven Treatment? A Nationwide Study of US Breast Cancer Patients.

BACKGROUND: Tumor size has historically been used to stage breast cancer and guide treatment recommendations. The importance of tumor biology in long-term outcomes is increasingly being acknowledged. No large studies have examined the relative roles of tumor size and receptor status on response to neoadjuvant chemotherapy (NAC) in breast cancer. PATIENTS AND METHODS: The National Cancer Database was queried for women who underwent NAC and surgery for unilateral clinical stage I to III (cT1-3) invasive breast cancer from 2010 to 2013. Multivariable logistic regression models were used to assess the relation between receptor status, tumor size, and pathologic complete response (pCR) while controlling for other biologic, sociodemographic, diagnosis, and treatment factors. RESULTS: We included 38,864 women in this study, most presented with cT2 disease (55%). Patients predominantly had estrogen receptor (ER)/progesterone receptor (PR)-positive (ER/PR+) HER2- (45%) or ER/PR- HER2- (28%) disease. Nineteen percent (7432 patients) had a pCR. cT3 (odds ratio [OR], 0.64; 95% confidence interval [CI], 0.59-0.70) but not cT2 cancers (OR, 0.95; 95% CI, 0.89-1.02) were associated with lower pCR rates compared with cT1 disease. HER2+ (ER/PR+ HER2+: OR, 2.94; 95% CI, 2.72-3.18; ER/PR- HER2+: OR, 6.45; 95% CI, 5.92-7.02) and ER/PR- HER2- cancers (OR, 3.94; 95% CI, 3.68-4.22) were more likely to experience pCR than those with ER/PR+ HER2- cancers. Receptor status was more strongly associated with pCR than tumor size. CONCLUSION: Tumor size is independently associated with pCR after NAC after controlling for receptor status, although the effect of receptor status is stronger. These data reinforce the importance of receptor status as well as tumor size, each of which might act as surrogates for tumor biology, in setting expectations for outcomes in patients who undergo NAC.

Predictors of Disease-Free and Overall Survival in Retroperitoneal Sarcomas: A Modern 16-Year Multi-Institutional Study from the United States Sarcoma Collaboration (USSC).

BACKGROUND: Retroperitoneal sarcomas (RPS) comprise approximately 15% of all soft-tissue sarcomas and frequently associated with significant morbidity and as little as 30% 5-year survival. Here, we provide a large, contemporary, and multi-institutional experience to determine which tumor, patient, and treatment characteristics are associated with long-term outcomes in RPS. METHODS: 571 patients with primary RPS were identified from the United States Sarcoma Collaboration (USSC). RPS patients who underwent resection from January 2000 to April 2016 were included with patient, tumor, and treatment-specific variables investigated as independent predictors of survival. Survival analyses for disease-free and overall survival were conducted using Kaplan-Meier and Cox proportional hazards model methods. RESULTS: The study cohort was 55% female, with a median age of 58.9 years (IQR: 48.6-70.0). The most common tumor histiotypes were liposarcoma (34%) and leiomyosarcoma (28%). Median follow-up was 30.6 months (IQR: 11.2-60.4). Median disease-free survival was 35.3 months (95% CI: 27.6-43.0), with multivariate predictors of poorer disease-free survival including higher grade tumors, nodal-positive disease, and multivisceral resection. Median overall survival was 81.6 months (95% CI: 66.3-96.8). Multivariate predictors of shorter overall survival included higher grade tumors, nodal-positive and multifocal disease, systemic chemotherapy, and grossly positive margins (R2) following resection. CONCLUSIONS: The strongest predictors of disease-free and overall survival are tumor-specific characteristics, while surgical factors are less impactful. Nonsurgical therapies are not associated with improved outcomes despite persistent interest and utilization. Complete macroscopic resection (R0/R1) remains a persistent potentially modifiable risk factor associated with improved overall survival in patients with retroperitoneal sarcomas.