Citations

12122 Background: Aromatase Inhibitors (AI) have become the standard of care to reduce breast cancer recurrence in hormone receptor-positive (HR+) breast cancer patients. AIs have been shown to be effective in reducing the risk of breast cancer recurrence by 47%. However, up to 52% of patients prematurely discontinue their use due to AI-associated musculoskeletal pain symptoms called Aromatase Inhibitor-associated musculoskeletal pain syndrome (AIMSS). No effective treatment exists to treat AIMSS. The present study examined the effectiveness of a multicomponent pain treatment program in reducing symptoms of AIMSS with the goal of improving adherence to AI medication. Methods: This trial enrolled breast cancer survivors with AIMSS in an intensive multicomponent pain treatment program. Pain, impact on functioning, fatigue, and mood were assessed with the Brief Pain Inventory, Center for Epidemiologic Studies of Depression- Revised Questionnaire, Pain Catastrophizing Scale, Symptom Impact Questionnaire Revised, and Fatigue Questionnaire at baseline, 3-month, 6-month, 9-month, and 12-month intervals. Adherence to AI medication was obtained from patients’ self-reports. The treatment program consisted of a two-day structured intervention focused on Cognitive-Behavioral skills to address strategies to improve pain control, fatigue, sleep disturbance, and stress while educating patients on the efficacy of Aromatase Inhibitors in prolonging cancer-free survival. Results: A total of 73 patients were enrolled, with a median age of 63 years (range 31-79). Participants were primarily white, married, and highly educated. The measures showed elevated levels of pain, fatigue, and psychological distress at baseline with decrements in self-reported levels of functioning. Significant improvements across all measures were observed at the 3-month follow-up after participation in the multicomponent pain treatment program. Significant improvements in painrelated outcomes were observed at 3 months (WPI Δ −1.6; SS Δ −4.0; both p < 0.001), with sustained reductions in symptom severity through 6-month, 9-month, and 12-month follow-up. Self-report of AI medication adherence at one year showed that 77.9% of patients were still taking their prescribed medication. Conclusions: Patients with AIMSS experienced substantial emotional distress, pain, fatigue, and functional impairment at baseline. Following the intervention, significant improvements were observed across pain, physical functioning, fatigue, and psychological distress, with benefits sustained at one year. Importantly, the intervention was associated with high long-term adherence at one-year follow-up, highlighting its potential to improve both quality of life and treatment persistence.

12010 Background: BWEL (Alliance A011401; NCT02750826) is a Phase III trial that randomizes patients (pts) with stage II-III breast cancer and body mass index (BMI) ≥27 kg/m 2 1:1 to a 24-month (mo) lifestyle-based WLI + health education (HE) or HE alone. Here we report prespecified secondary outcomes of the impact of the WLI on patient-reported QOL and symptoms. Methods: The first 540 BWEL pts (randomized between 9/2016 and 7/2017) were included in this substudy that collected PROMIS 29 Profile 2.0 and Global Health scores at enrollment, 6 and 24 mos. Adjusting for baseline scores, mean physical function (predefined substudy primary outcome), global physical and mental health, fatigue and other scores were compared at 6 and 24 mos using analysis of covariance (ANCOVA). P-values <0.05 were considered significant. Positive differences in positive attributes (e.g., physical function) and negative differences in negative attributes (e.g., anxiety) represented better outcomes in the WLI arm. Results: At baseline, median BMI was 32.9 kg/m 2 (26.5 – 69.1), median age was 53 (25 - 78) years; 83.9% of pts were non-Hispanic White, 10.7% were Black and 5.9% were Hispanic. At 6 mos, the WLI (vs HE) arm had significantly better physical function (ANCOVA-based mean difference between arms 1.9 [95% CI 0.8, 3.0]; p<0.001), global physical health (2.0 [95% CI 0.9, 3.0]; p<0.001), global mental health (1.30 [95% CI 0.2, 2.4], p=0.03), social roles and activities (2.3 [95% CI 1.1, 3.6]; p<0.001), and fatigue (-1.7 [95% CI -3.1, -0.4], p=0.01) (Table). Improvements were generally maintained at 24 mos. Similar findings were seen in analyses using longitudinal mixed modeling. Conclusions: The BWEL WLI demonstrated QOL benefits for patients with breast cancer, resulting in significantly better physical function, global physical and mental health, and symptoms. Future analyses will evaluate which populations experienced the most benefit, as well as the relationships among QOL, symptoms, and weight loss. Support: U10CA180821, U10CA180882, UG1CA189823; U10CA180820; U10CA180868; U10CA180863, CCS 707213; U10CA180888; UG1CA189858; https://acknowledgments.alliancefound.org. Clinical trial information: NCT02750826 . Analysis of covariance-adjusted least squares means values at 6-mos adjusted for baseline scores. QOL/Symptom Attributes HE WLI Between arm difference (95% CI)* P value Physical Function 47.1 49.0 1.9 (0.8, 3.0) <0.001 Global Physical Health 46.2 48.1 2.0 (0.9, 3.0) <0.001 Global Mental Health 48.6 49.9 1.3 (0.2, 2.4) 0.03 Social Roles and Activities 52.7 55.0 2.3 (1.1, 3.6) <0.001 Anxiety 50.2 50.0 -0.2 (-1.6, 1.2) 0.77 Depression 47.5 47.5 -0.0 (11.2, 1.2) 0.96 Fatigue 50.6 48.9 -1.7 (-3.1, -0.4) 0.01 Sleep Disturbance 51.0 51.1 0.1 (-0.6, 0.8) 0.80 Pain Interference 51.3 50.3 -1.0 (-2.4, 0.4) 0.15 *Positive differences in positive attributes and negative differences in negative attributes favor WLI arm.

12007 Background: YAs with cancer, defined as those diagnosed prior to the age of 40, may experience greater symptom burden compared to those diagnosed at older ages. We evaluated the impact of an ePROM-triggered, CC-based, supportive care intervention on symptom burden in YAs with cancer. Methods: The Enhanced, Electronic Health Record-facilitated Cancer Symptom Control (E2C2) trial was a cluster-randomized, pragmatic trial (NCT03892967) that enrolled oncology patients seen at Mayo Clinic Rochester and within the Mayo Clinic Health System (sites in Minnesota and Wisconsin) between March 2019 and January 2023. Patients routinely reported the severity of six SPPADE symptoms (Sleep deficit, Pain, Physical function impairment, Anxiety, Depression, and Energy deficit/fatigue) on 11-point numerical rating scales. Symptom severity was classified as none to mild (0-3), moderate (4-6), or severe (7-10). Those with moderate or severe symptoms were offered symptom management education, while those with severe symptoms were also offered the option to work virtually with a symptom care manager. In this post hoc analysis, we examined the effects of the intervention on change in symptom scores among YAs and time to improvement to a mild/moderate level in those with at least one severe symptom. Results: Among 40,659 patients who responded to at least one survey, 2,598 were YAs and 38,061 were adults ≥ 40 years. Among YAs, 10.7%, 24.3%, and 65.1% were 18-24 years, 25-31 years, and 32-39 years, respectively. A greater proportion of YA patients were female (61.5% vs 57.0%), of a non-white race (12.4% vs 5.3%), living in an urban setting (65.7% vs 55.1%), single (36.4% vs 9.6%), on non-government insurance (78.1% vs 36.6%), employed (72.6% vs 37.4%), and had a Bachelor’s degree or greater (37.8% vs 28.3%, p < 0.001 for all). Fewer YA patients had metastatic disease compared to older patients (24.2% vs 35.2%, p < 0.001). Compared to a pre-intervention baseline, the mean change in symptom score for YA patients following the intervention demonstrated improvements in anxiety (-0.195) and depression (-0.168, p < 0.0001 for both), while physical function impairment worsened over the intervention period (0.101, p = 0.014). Compared to adults ≥ 40 years, YAs experienced greater intervention effects for management of depression ( p < 0.001), fatigue ( p = 0.01), pain ( p < 0.0001), and physical function impairment ( p < 0.0001). Among YAs with a severe symptom during the intervention period, median time to improvement to a mild/moderate level was longer for anxiety compared to those ≥ 40 years (3.5 vs 2.7 months, p = 0.009). Conclusions: Routine ePROM surveillance, coupled with CC-based symptom management, led to improvements in anxiety and depression among YAs with cancer, although, time to improvement was longer for anxiety compared to adults ≥ 40 years.

11502 Background: To report results from the open-label alveolar soft part sarcoma (ASPS) cohort of the phase III APROMISS trial (NCT03016819) evaluating Catequentinib hydrochloride (AL3818), an oral multitargeted receptor tyrosine kinase inhibitor, in adults with advanced or metastatic ASPS. Methods: Adult patients with pathologic and molecularly confirmed advanced ASPS, either treatment-naive or previously treated (excluding cediranib), were enrolled in the open-label, non-randomized ASPS cohort of the phase III APROMISS trial conducted across the United States, Asia, and Europe. Catequentinib hydrochloride was administered orally at 12 mg once daily in 21-day cycles (14 days on/7 days off) until disease progression, toxicity, or death. The primary endpoint was objective response rate (ORR) assessed per RECIST by Blinded Independent Central Review (BICR) (predefined threshold: 31%). Secondary endpoints included duration of response (DOR) with a predefined target of =/>6 months, progression free survival (PFS) and overall survival (OS). Results: From July 2017 to August 2022, a total of 56 patients entered the trial; 56 patients were evaluable for the primary endpoint. Median (m-) age was 29.5 years (range: 18 – 66), with 24 female and 32 male. Best overall response included 1/56 complete response (1.8%), 14/56 partial responses (25.0%), 36/56 stable disease (64.3%), and 3/56 (5.4%) progressive disease. RECIST ORR by BICR was 26.8% (95% CI, 15.8–40.3); m-DOR was 22.57 months (95%CI: 10.38-NE). The study data was collected close to 8 years for all patients. mPFS was 18.33 months (95% CI, 14.19–23.13), with 6- and 12-month progression-free rates of 88.77% (95% CI, 76.68–94.79) and 65.54% (95% CI, 50.42–77.06), respectively. mOS was 59.27 months (95% CI, 44.09–NE), with 6- and 12-month overall survival rates of 94.64% (95% CI, 84.30–98.24) and 90.81% (95% CI, 79.30–96.08), respectively. Overall, 27/56 (48.2%) patients experienced grade ≥3 treatment-related adverse events, most commonly diarrhea (50.0%), hypertension (44.6%), fatigue (37.5%), nausea (35.7%), and palmar-plantar erythrodysesthesia syndrome (30.4%); one patient (1.8%) had a grade 5 event (respiratory failure). Conclusions: Catequentinib hydrochloride demonstrated meaningful antitumor activity and durable responses in adults with advanced ASPS. Despite the ORR of 26.8% slightly below the predefined 31% threshold, disease control was prolonged, with a m-DOR exceeding 22 months. Favorable PFS and OS outcomes, together with a manageable safety profile, support its clinical benefit in this ultra-rare sarcoma. Clinical trial information: NCT03016819 .

11186 Background: Cancer survival is shaped by tumor biology, treatment access, and socioeconomic context, yet population-level quantification of long-term survival disparities related to chemotherapy use and income is limited. We assessed five-year cancer-specific survival across demographic, treatment, and socioeconomic strata in a national registry. Methods: We performed a retrospective, population-based survival analysis using the Surveillance, Epidemiology, and End Results (SEER) database. Cancer-specific survival was evaluated at 12, 24, 36, 48, and 60 months after diagnosis. Outcomes were stratified by sex, race, chemotherapy receipt, and area-level median household income categories. Survival estimates were summarized descriptively and visualized using time-to-event curves. Results: Overall cancer-specific survival declined progressively over five years, from ~84% at 12 months to ~58% at 60 months. Sex differences were minimal, with similar five-year survival among males and females (~57–58%). Racial disparities were substantial: Asian/Pacific Islander patients demonstrated the highest survival across follow-up, while Black and American Indian/Alaska Native patients had lower early survival and persistent gaps at five years. Patients with recorded chemotherapy use had improved survival compared with those without or with unknown chemotherapy status; 12-month survival was ~88% versus ~80%, and five-year survival was ~65% versus ~57%, respectively. A pronounced socioeconomic gradient was observed: individuals in areas with median household income ≥$120,000 had higher five-year survival (~67%), whereas those in areas with income < $40,000 had markedly lower survival (~52%). Conclusions: In this national registry analysis, both chemotherapy utilization and higher socioeconomic status were strongly associated with improved long-term cancer survival, whereas persistent racial and income-related disparities remained evident. These findings highlight ongoing inequities in access to oncologic care and support the need for targeted policy interventions and equity-focused treatment delivery models. Interpretation should account for limitations inherent to observational registry data and potential residual confounding.

11177 Background: Early detection of recurrence after curative-intent treatment is a critical priority, traditional imaging often detects relapse when disease burden is high, potentially limiting treatment efficacy. ctDNA has emerged as an established prognostic biomarker for molecular residual disease (MRD) detection and early relapse. We performed a real-world meta-analysis on published datasets that utilized personalized, tumor-informed ctDNA testing to assess its performance across tumor types and clinical management approaches. Methods: Real-world studies published from December 2022 to December 2025 using the personalized, tumor-informed Signatera ctDNA assay (Natera, Inc.) were included. Eligibility required ctDNA assessment in the MRD (2–16 weeks post-surgery (histology dependent)/pre adjuvant therapy (ACT)) and/or surveillance (post-ACT/end of the MRD window if no ACT was given) settings, with outcomes stratified by ctDNA status and hazard ratios (HR) reported from univariable or time-dependent Cox regression analysis. Exclusions included: clinical trials, biobanks, metastatic disease treated with palliative intent, case reports, reviews, editorials, or commentaries. Clinical outcomes were harmonized into a composite event-free survival (EFS) endpoint (time to recurrence, progression, or death). Pooled HRs and 95% CIs were estimated using random and fixed effects models and heterogeneity between studies was assessed using the I 2 and Cochran’s Q test. Median lead time from ctDNA-positivity to radiographic or clinical recurrence was summarized when available. Results: We identified 18 eligible publications comprising 3,004 unique patients across 15 solid tumor types. During the MRD window, ctDNA positivity was associated with a significantly increased risk of an EFS event compared with ctDNA negativity (pooled HR: 8.15; 95% CI: 6.12–10.85, I 2 = 0.00%, P = 0.844, n = 13). During the surveillance window, inclusive of post-definitive treatment, ctDNA positivity conferred an even greater EFS risk (pooled HR: 18.30; 95% CI: 14.17–23.65, I 2 = 0%, P = 0.911 for heterogeneity, n = 16). Across studies, ctDNA detection during surveillance preceded radiographic or clinical recurrence by a median of 3.20 months (95% CI: 2.50-4.10, P < 0.0001, n = 10), although this varied substantially by study/tumor type (I 2 = 80.9%). Conclusions: In this pan-cancer real-world meta-analysis, ctDNA positivity assessed using a tumor-informed assay was highly prognostic following curative-intent therapy at all timepoints evaluated with low heterogeneity between studies. These findings support the broad clinical utility of tumor-informed ctDNA testing for post-treatment risk stratification and longitudinal disease monitoring across solid tumors.

11127 Background: Immune-related adverse events (irAEs) often require treatment discontinuation in patients with cancer receiving immune checkpoint inhibitors (ICIs). Given limited subsequent treatment options, ICI rechallenge is frequently considered. We aimed to estimate the incidence of recurrent irAEs and objective response rates (ORR) in patients receiving ICI rechallenge following prior irAEs. Methods: PubMed, Web of Science, and Embase were searched for studies evaluating ICI rechallenge in patients with advanced solid tumors who previously suspended treatment due to irAEs. Outcomes included the incidence of grade 1-5 (Gr1-5), Gr1-2, and Gr3-5 irAEs, recurrent irAEs, new irAEs, ORR, and disease control rate (DCR). Random-effects meta-analyses and subgroup analyses by cancer type were performed. Meta-regression analysis was conducted to evaluate the impact of the grade and type of initial irAEs on response outcomes. Heterogeneity was assessed using I 2 statistics (≥50% considered high). Results: Thirty-seven studies comprising 1,126 patients with initial irAEs (Gr1-2: 62.8%, Gr3-4: 37.2%) leading to suspension of ICIs were included. The most common initial irAEs in the pooled cohort were hepatitis/liver enzyme elevations (20.5%), pneumonitis (16.1%), and nephritis/acute kidney injury (14.8%). Pooled incidences of Gr1-5, Gr1-2, and Gr3-5 irAEs after ICI rechallenge were 42.2% (95% confidence interval [CI]: 35.3-49.3), 27.1% (95% CI: 22.9-31.7), and 18.8% (95% CI: 14.7-23.8), respectively. Subgroup analysis showed overall higher incidences of irAEs in melanoma (Gr1-5: 54.6%, Gr1-2: 23.2%, Gr3-5: 26.4%) than those in lung cancer (Gr1-5: 39.7%, Gr1-2: 27.4%, Gr3-5: 14.0%) and solid tumors (Gr1-5: 36.7%, Gr1-2: 22.8%, Gr3-5: 20.1%). The same type of irAEs recurred in 23.8% (95% CI: 20.1-28.0) of patients, while new types of irAEs developed in 29.3% (95% CI: 25.2-33.7) of patients undergoing ICI rechallenge. The overall ORR was 45.2% (95% CI: 34.5-56.4), with cancer type-specific ORRs of 60.5% (95% CI: 47.9-71.9) in melanoma, 39.1% (95% CI: 17.4-66.2) in lung cancer, and 39.5% (95% CI: 27.7-52.6) from studies investigating solid tumors. DCR was high across cancer types: 77.3% (95% CI: 67.7-84.7) overall, 68.2% (95% CI: 41.3-86.8) in melanoma, 91.2% (95% CI: 67.7-98.1) in lung cancer, and 72.5% (95% CI: 63.3-80.1) in solid tumors. Meta-regression analysis showed that commonly observed initial irAE types or grades of initial irAEs (Gr1-2 vs. Gr3-4) did not significantly impact ORR or DCR. Conclusions: ICI rechallenge after discontinuation due to irAEs demonstrates clinical activity but carries a substantial risk of both recurrent and new irAEs. These findings highlight the need for predictive biomarkers to optimize patient selection and maximize survival without compromising safety.

11059 Background: Payments from the drug industry to oncologists are common and influence physicians’ prescribing decisions. However, whether payments affect the likelihood that patients receive optimal cancer treatment has not been assessed. Methods: This was a population-based cohort study. We used fee-for-service Medicare claims to identify patients with incident cancer diagnosis (new cancer diagnosis code after >= 1 year with no cancer diagnosis codes) from 2014-2020. We used National Comprehensive Cancer Network (NCCN) Guidelines to identify treatment scenarios (e.g., metastatic melanoma, stage III colon adjuvant therapy) with variation in the clinical benefit among recommended treatment options. The patient cohort corresponding to each scenario was identified using claims. We used NCCN Guidelines to identify the “optimal” treatment for each scenario (defined as the designated “preferred” treatment, with NCCN Evidence Blocks scores used for tiebreaks) at each time point across the study period. The primary outcome was whether a patient received the treatment that was, as of their diagnosis date, the optimal treatment for their cancer (vs. any non-optimal treatment). The primary exposure[s] were whether a patient’s medical oncologist received personal (“general”) payments (source: linked Open Payments data) related to 1) optimal treatment or 2) any non-optimal treatment, during the year prior to the patient’s cancer diagnosis. We fit Poisson-family generalized estimating equations, with physician-level clustering and adjustment for scenario, year, and patient characteristics, to estimate the relative risk (RR) of optimal treatment. Results: There were 14 clinical scenarios comprising 15,835 patients. There were 3,429 (21.7%) patients whose oncologist received payment for the optimal treatment, 4,891 (30.9%) for non-optimal payments, and 1,993 (12.6%) to both payment types. Oncologist receipt of payment for optimal treatment was associated with a greater likelihood (RR=1.07, 95%CI:1.01-1.13), and payment for non-optimal treatment was associated with lower likelihood (RR= 0.94, 95%CI:0.89-0.98) of patients receiving optimal treatment. Associations became stronger as payment dollar value increased; for optimal payments ≥$10,000, RR=1.26 (95%CI:1.02-1.57), and for non-optimal payments ≥$10,000, RR=0.70 (95%CI: 0.49-1.00). An estimated 41.6% of unexposed patients received optimal treatment; versus 52.6%, 29.3%, and 33.8% among patients exposed to ≥$10,000 of payments for optimal treatment only, ≥$10,000 non-optimal payments only, and ≥$10,000 of both payment types, respectively. Conclusions: Industry payments related to the optimal cancer treatment were associated with increased use of the optimal treatment. However, payments related to non-optimal treatments were more common and were associated with decreased use of optimal treatment.

1107 Background: Bria-IMT is an allogeneic whole cell immunotherapy expressing tumor associated antigens and GM-CSF to stimulate adaptive and innate immunity. The phase 3 Bria-ABC trial (NCT06072612) evaluates Bria-IMT + retifanlimab vs physician’s choice in MBC w/ no meaningful therapeutic options. Characterization of on-trial pt experience, including quality of life (QOL) and tolerability, remains clinically relevant yet underreported. We evaluated QoL and toxicity to assess feasibility of home self administration. Methods: EORTC QLQ-C30 at baseline (BL) and subsequent visits. Raw item responses were aggregated into domain scores. Changes quantified as absolute point differences; domain scores defined as medians of constituent items. Lower functional/symptom and higher global scores indicate better outcomes. Wilcoxon matched pairs test assessed change from BL. Missing QoL data handled by observed cases approach. QoL evaluated at BL, V3, V6, and V9. TWiST and TOX summarized descriptively. TOX defined as cumulative time w/ grade ≥3 TEAEs w/o progression; TWiST as time w/o grade ≥3 toxicity or progression. TOX and TWiST constitute component health states for planned QTWiST analysis pending mature OS. Results: At submission, 251 pts screened, 173 randomized, 147 treated. 75% Caucasian, 20% other, 5% not reported; median 6 prior lines (2-15); ECOG 2 -6%; intracranial mets 9%; 42% HR+, 37% TNBC, 12% HER2+. Median 5 QoL assessments/pt completed. 127 pts completed ≥2 assessments. Paired data available at V3 52%, V6 17%, V9 6%. Global health medians BL 5.0, V3 5.0, V6 5.0, V9 4.5. Score maintenance/improvement: @V3 63% (p=0.7), V6 62%, V9 71%. Functional domains: role (BL 1.5, V3 2.0, V6 2.0, V9 2.0; maintenance 62.7% [p=0.02], 52.4%, 71.4%). Physical (BL 1.0, V3 2.0, V6 2.0, V9 2.0; maintenance 68.7% (p=0.002), 47.6% (p=0.03), 71.4%), cognitive (BL 1.5, V3 1.5, V6 1.5, V9 1.5; maintenance 63.6%, 61.9%, 85.7%). Emotional (BL 1.5, V3 1.5, V6 1.5, V9 1.5; maintenance 75.8% (p=0.9), 81.0%, 85.7%). Social (BL 1.5, V3 1.5, V6 2.0, V9 2.5; maintenance 58.5%, 75.0%, 57.1%). Symptoms: nausea/vomiting (1.0 throughout; maintenance V3 73%, V6 86%, V9 86%), fatigue median 2.0 all timepoints; maintenance 61%, 67%, 71%), pain (BL/V3 1.5, V6/V9 2.0; maintenance V3 57% [p=0.03], V6 62% [p=0.9], V9 86%). TWiST and TOX restricted mean 3.12 mo and 0.63 mo, respectively; 83.2% and 16.8% of observed follow-up. Pts w global health maintenance demonstrated longer median TWiST v deterioration (4.3 v 2.7 mo). ECOG stable in 78% (n=99). Conclusions: Heavily pretreated MBC pts in Bria-ABC demonstrated stable global health and key functional domains. Findings support sustained QoL in advanced disease. TWiST demonstrates meaningful benefit w/o significant toxicity. Ongoing follow up will further characterize durability of pt-reported outcomes and clinical correlation. Results support decentralized care and potential home self administration. Clinical trial information: NCT06072612 .

11064 Background: Local and state paid sick leave (PSL) mandates have been associated with increased use of preventive services, including cancer screening, and reduced emergency care utilization. Little research has examined PSL policies and cancer after diagnosis. This study evaluates associations of PSL policies and timely treatment initiation among women with early-stage breast cancer. Methods: We identified patients aged 18-64 years newly diagnosed with stages 0-II breast cancer from the National Cancer Database in 2004-2023 and linked then to area-level policy implementation, measured as the month and year the state, county, or city required PSL. Primary outcomes were receipt of definitive surgery or neoadjuvant therapy within 30, 60, and 90 days of diagnosis. We compared changes in treatment initiation between patients residing in areas with and without PSL policies during and after the month and year of diagnosis. We used a staggered difference-in-differences design to account for differential timing of implementation, adjusting for patient demographics, clinical, and area-level characteristics. Random errors were clustered at the state level. Supplemental analyses stratified by county-level unemployment rates and individual insurance coverage. Results: The study included 1,891,411 patients, of whom 249,313 (13.2%) resided in an area with PSL policies at diagnosis. Patients in areas with PSL policies were more likely to have Medicaid, reside in higher-income and metropolitan areas. PSL policy implementation was significantly associated with a 3.4 percentage point (PPT) increase in the probability of treatment ≤30 days (95% CI: 1.1-5.7), 3.0 PPT increase ≤60 days (95% CI: 1.6-4.3), 1.3 PPT increase ≤90 days (95% CI: 0.5-2.1) (Table). Improvements in timely treatment were concentrated in low-unemployment areas; no significant improvements were observed in high-unemployment areas. The magnitude of associations between PSL policies and treatment initiation was stronger among patients without private insurance than with private insurance. Conclusions: Local and state PSL mandates were associated with earlier treatment initiation among working-age patients with early-stage breast cancer, especially in areas with low female unemployment rate. Findings suggest that PSL policies play an important role in timely cancer treatment for employed women who may not have PSL through their jobs. Association of paid sick leave policies and breast cancer treatment initiation. Time from diagnosis to surgery/neoadjuvant therapy (days) DID PPT Lower 95% CI Upper 95% CI P-value Overall ≤30 3.4 1.1 5.7 0.004 ≤60 3.0 1.6 4.3 0.000 ≤90 1.3 0.5 2.1 0.001 Low female unemployment ≤30 2.2 -0.7 5.0 0.136 ≤60 3.8 1.8 5.8 0.000 ≤90 1.2 0.3 2.2 0.012 High female unemployment ≤30 1.8 -0.6 4.2 0.145 ≤60 -1.2 -4.5 2.0 0.459 ≤90 -1.4 -3.7 0.9 0.232