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TPS650 Background: The TAILORx and RxPONDER trials showed that recurrence score (RS) identifies many postmenopausal pts who do not benefit from addition of ACT to endocrine therapy (ET); however, RS also identifies subsets who do benefit (node-neg/high clinical risk/RS 16-20, node-neg/RS 21-25, and node-pos/RS ≤25). Most premenopausal pts in these trials did not receive ovarian function suppression (OFS) as part of their ET regimen. Given the observed benefit from OFS in high-risk premenopausal pts with HR+/HER2– BC in SOFT/TEXT, we question whether the ACT benefit in TAILORx/RxPONDER was due to chemotherapy-induced OFS. To address this, we developed OFSET, a phase III clinical trial comparing OFS+ET to ACT+OFS+ET. Methods: We hypothesize that addition of ACT to OFS+ET is superior to OFS+ET in improving invasive breast cancer-free survival (IBCFS) among premenopausal pts with early-stage HR+/HER2– tumors, and a 21-gene RS between 16-25 (for pN0 pts) and 0-25 (for pN1 pts). Secondary objectives include invasive disease-free survival, overall survival, distant recurrence-free interval, breast cancer-free interval, and health-related quality of life (HRQOL). Pts must be node-neg with RS 16-20 (plus high clinical risk), RS 21-25, or have 1-3 positive nodes with RS ≤25. Stratification is by nodal status/RS status (pN0 RS 16-25; pN1 RS 0-15; pN1 RS 16-25), intent to receive CDK4/6 inhibitor (yes; no), and age (18-39; ≥40). Pts are randomized after surgery to either OFS+ET or ACT+OFS+ET. ET is an aromatase inhibitor (AI) per physician discretion; or tamoxifen if AI is not tolerated or if OFS is incomplete. Radiotherapy will be administered per protocol guidelines. An HRQOL sub-study will assess severe menopausal symptoms (measured by FACT ESS-19) and pain severity (PROMIS) between arms. Blood and tumor specimens will be collected for future research. We anticipate accrual of 3,960 pts in 7 yrs, 7 mos. Per NSABP B-28/RxPONDER data, 5-yr IBCFS of pN1 pts on the ACT+OFS+ET arm is estimated at 92.3%. Per TAILORx data, 5-yr IBCFS of pN0 pts on the ACT arm is ~95%. Assuming 56% of pts to be pN0 and 44% pN1, and a 0.5% annual loss-to-follow-up rate, the definitive analyses to detect a hazard ratio: 0.75 with ACT+OFS+ET v OFS+ET, with 1-sided α of 0.025 and 80% power, will require 380 IBCFS events, expected to occur ~11 yrs after study initiation. Accrual is 496/3,960 (from 8/2023 to 1/2026). NCT #: NCT05879926. Clinical trial information: NCT05879926 .

e21607 Background: The association between timing of palliative care referral and survival outcomes in patients with melanoma brain metastases (MBM) treated with immune checkpoint inhibitors remains poorly characterized. Methods: We conducted a retrospective cohort study of patients with MBM treated with combination ipilimumab and nivolumab at Mayo 3 sites from 2016 to 2024. Palliative care referral timing relative to MBM diagnosis was categorized as early (≤56 days), late ( > 56 days), or none. Patients without referral documentation were excluded from referral-based analyses. Overall survival (OS) was estimated using Kaplan–Meier methods and compared with log-rank tests. Multivariable Cox proportional hazards models were used to identify factors independently associated with OS, with stepwise selection (entry p < 0.25; stay p < 0.15). Results: Among 147 patients, 139 had referral information: 33 (23.7%) early, 56 (40.3%) late, and 50 (36.0%) no referral. Median OS differed significantly by referral timing (log-rank p < 0.0001): 2.8 months (early), 7.9 months (late), and 47.8 months (no referral). Among patients with ECOG 2–3, a higher proportion had early or late referral (each 42.9%) compared with no referral (14.3%), whereas patients with ECOG 0–1 were more evenly distributed across referral groups (early 21.6%, late 40.0%, none 38.4%). In multivariable analysis of 88 patients with complete covariate data, both early (HR 4.54; p = 0.0016) and late referral (HR 2.86; p = 0.011) were independently associated with worse OS compared with no referral. Progressive disease versus objective response (HR 4.45; p = 0.0002), hemorrhagic metastases (HR 2.79; p = 0.0015), male sex (HR 2.07; p = 0.044), and increasing age (HR 1.02 per year; p = 0.032) were also associated with inferior OS. Treatment with ipilimumab 1 mg/kg plus nivolumab 3 mg/kg showed a trend toward improved OS compared with ipilimumab 3 mg/kg plus nivolumab 1 mg/kg (HR 0.48; p = 0.055). Conclusions: Timing of palliative care referral was strongly associated with overall survival in patients with MBM treated with ipilimumab and nivolumab. Although patients with ECOG 2–3 were more frequently referred early or late, ECOG category overall did not clearly differentiate referral timing groups, suggesting referral may reflect unmeasured clinical factors beyond baseline performance status. Prospective studies incorporating more granular functional and symptom measures are needed to better define the role of palliative care integration in this population. Multivariable cox model for overall survival. Variable Comparison HR P value Referral timing Early vs None 4.54 0.0016 Late vs None 2.86 0.011 Best overall response PD vs ORR 4.45 0.0002 SD vs ORR 2.16 0.098 Hemorrhagic metastases Yes vs No 2.79 0.0015 Sex Male vs Female 2.07 0.044 Age Per year increase 1.02 0.032 Regimen Ipi1+Nivo3 vs Ipi3+Nivo1 0.48 0.055

e15647 Background: Colorectal cancer (CRC) screening offers an opportunity to prevent invasive disease by detecting and removing precancerous lesions. Colonoscopy-based detection of adenomas and serrated polyps is strongly associated with reduced risk of interval CRC. While the performance of noninvasive CRC screening tests is well described, comparative evidence on adenoma detection across screening colonoscopy and stool-based strategies with follow-up colonoscopy remains limited. We conducted a systematic review to compare adenoma detection across CRC screening modalities. Methods: MEDLINE (PubMed) and Embase were searched from January 1, 2000, through July 10, 2025, for peer-reviewed, U.S.-based studies reporting colonoscopy among average-risk adults aged ≥45 years, who underwent screening colonoscopy or follow-up colonoscopy after a positive stool-based screening test [fecal immunochemical test (FIT) or multi-target stool DNA (mt-sDNA) test]. The primary outcome was the detection of one or more adenomas at colonoscopy. High-risk or surveillance cohorts, AI-assisted colonoscopy, diagnostic accuracy trials, and non-U.S. studies were excluded. Results: Among 7,710 de-duplicated records, 147 studies underwent full-text review, and 47 studies were included in quantitative synthesis, with reported adenoma detection for screening colonoscopy alone (n = 31), follow-up colonoscopy after a positive FIT alone (n = 4), follow-up colonoscopy after a positive mt-sDNA test alone (n = 4), and for more than one of the screening strategies of interest (n = 8). Across included studies, overall adenoma detection differed by screening pathway. Follow-up colonoscopy after a positive mt-sDNA test demonstrated the highest adenoma detection (66.3%; 95% CI, 61.2-71.1), with lower adenoma detection observed for colonoscopy after a positive FIT (50.6%; 95% CI, 43.4-57.8) and screening colonoscopy alone (33.8%; 95% CI, 30.9-36.8) (Table 1). Conclusions: Detection of adenomas was highest following colonoscopy performed after a positive mt-sDNA test compared with FIT-positive follow-up or screening colonoscopy alone. These findings highlight differences in downstream detection across CRC screening tests and suggest that, in settings where colonoscopy resources are constrained, initial mt-sDNA screening with timely follow-up colonoscopy may help prioritize patients most likely to benefit. CRC screening modality No. of Studies Adenoma detected Study population Proportion, % (95% CI) Heterogeneity, I² (%) Between-study variance (τ 2 ) P-value* mt-sDNA 8 17,436 29,098 66.3 (61.2-71.1) 94.6 0.0924 <0.0001 FIT 11 17,588 32,630 50.6 (43.4-57.8) 94.0 0.2187 <0.0001 Screening colonoscopy 38 2,351,801 6,378,891 33.8 (30.9-36.8) 99.8 0.1710 NA *P-value represents adenoma detection vs. screening colonoscopy adenoma detection.

e13730 Background: Financial toxicity, the burden of treatment cost, affects up to half of people with cancer and can affect survival. Financial toxicity is a health equity issue, disproportionately affecting Black patients. This cross-sectional study used baseline data from the Discussions of Cost (DISCO) Trial, an RCT to improve patient-provider treatment cost discussions and, in turn, mitigate financial toxicity, to examine whether Black and White patients differed in patient-provider communication perceptions and financial toxicity correlates. Methods: Data were collected from 2021-2025 at an NCI-designated comprehensive cancer center. Participants were Black or White patients diagnosed with solid tumor cancers. At baseline, patients completed demographic measures; communication measures of self-efficacy in patient-provider interactions (e.g., “I am confident I know what questions to ask a provider”); self-efficacy in managing cancer treatment costs (e.g., “I am confident I can understand treatment costs”); and whether they have a provider- or patient-centered approach (e.g., “the provider should decide what gets talked about”); and financial measures including economic burden (e.g., “it’s difficult to live on my income”); treatment cost distress (e.g., “worries about paying for my cancer treatment keep me up at night”); and anticipated material hardship (e.g., “I worry about the financial problems I will have in the future as a result of my treatment”). Comparisons were conducted by patient race. Results: A total of 202 patients participated (116 Black patients, 86 White patients). White patients were more likely to have advanced degrees, a higher annual income, and less likely to have Medicaid compared to Black patients. Black patients reported higher self-efficacy for managing treatment costs ( p = .002) and a higher provider-focused orientation to the patient-provider relationship ( p = .001), than White patients. Black patients reported greater levels of financial burden ( p < .001), cost distress ( p = .005), and anticipated material hardship ( p = .003). There was no difference in self-efficacy for interacting with providers. Conclusions: These results suggest that a communication intervention for patients may help mitigate the experience of financial toxicity, especially for Black patients. Clinical trial information: NCT04766190 . Patient characteristics. Black Patients White Patients p -value Race 116 86 Education < High School High School/GED Some College 2 or 4-year College Degree Graduate/Professional College Trade/Technical/Vocational School 10352626712 0141631187 < .001 Annual Household Income 0 - $19,999 $20,000 - 39,999 $40,000 - 59,999 $60,000 - 79,999 $80,000 - 99,999 $100,000 - 149,999 $150,000 + 53201611431 51215991716 <.001 Insurance Type* Medicaid Medicare Medicare supplement Private None 604911330 113726393 <.001>.99<.001.20.15 *Patients could select more than one

9558 Background: Ipilimumab 3 mg/kg plus nivolumab 1 mg/kg (Ipi3+Nivo1) is the standard immunotherapy regimen for metastatic melanoma with brain metastases (MBM) but is associated with significant immune-related toxicity, particularly neurologic toxicity. Ipilimumab 1 mg/kg plus nivolumab 3 mg/kg (Ipi1+Nivo3) has demonstrated improved tolerability in extracranial melanoma, though comparative data in MBM are limited. We compared efficacy and toxicity of these dosing strategies in a multisite real-world cohort. Methods: We retrospectively identified patients with MBM treated with ipilimumab plus nivolumab across three Mayo Clinic sites between 2016 and 2024. Patients were classified by induction dosing as Ipi1+Nivo3 or Ipi3+Nivo1. Overall survival (OS) and progression-free survival (PFS) were estimated using the Kaplan–Meier method and compared using log-rank tests. Best overall response (BOR) and toxicity outcomes were summarized descriptively. Results: Among 147 patients (Ipi1+Nivo3 n=32; Ipi3+Nivo1 n=115), 144 were evaluable for survival. Median age was higher in the Ipi1+Nivo3 group (69.5 vs 66.0 years); males predominated in both groups (71.9% vs 61.7%), and the cohort was predominantly White (>96%). Most patients had ECOG 0–1 in both groups (84.4% in Ipi1+ Nivo3 and 90.4% in Ipi3+Nivo1). BRAF mutation status was balanced between regimens, with approximately half of patients harboring BRAF-mutant disease (51.6% vs 53.2%). Median OS was 18.5 months (95% CI, 5.7–54.7) with Ipi1+Nivo3 versus 10.6 months (95% CI, 6.5–19.1) with Ipi3+Nivo1 (log-rank p=0.25). Two-year OS was 45.9% and 35.0%, and five-year OS was 24.5% and 19.2%, respectively. Median PFS was 7.3 months (95% CI, 1.8–10.9) versus 2.8 months (95% CI, 2.1–4.4) (log-rank p=0.16). BOR was available for 138 patients; objective response rates were 35.5% and 31.8%, respectively. 3–5 adverse events occurred in 24.1% of Ipi1+Nivo3 versus 30.5% of Ipi3+Nivo1 patients. Hospitalizations were less frequent (16.7% vs 36.1%), and neurologic adverse events occurred only with Ipi3+Nivo1 (11.9% vs 0%). Conclusions: In this multisite real-world MBM cohort, Ipi1+Nivo3 demonstrated comparable efficacy, numerically longer survival, and a more favorable toxicity profile compared with standard Ipi3+Nivo1. Notably, no neurologic toxicity was observed with the Ipi1+Nivo3 regimen. These findings support further prospective evaluation of lower dose ipilimumab strategies. Response and survival outcomes. Outcome Ipi1 + Nivo3 Ipi3 + Nivo1 Complete response (CR) 2 / 31 (6.5%) 8 / 107 (7.5%) Partial response (PR) 9 / 31 (29.0%) 26 / 107 (24.3%) Objective response rate (ORR = CR+PR) 11 / 31 (35.5%) 34 / 107 (31.8%) Disease control rate (DCR = CR+PR+SD) 18 / 31 (58.1%) 51 / 107 (47.7%) Median PFS, months (95% CI) 7.3 (1.8–10.9) 2.8 (2.1–4.4) 2-year PFS 27.6% 22.3% Median OS, months (95% CI) 18.5 (5.7–54.7) 10.6 (6.5–19.1) 2-year OS 45.9% 35.0% 5-year OS 24.5% 19.2%

9568 Background: Stage IIB/C cutaneous melanoma is associated with high recurrence risk, however stratification of risk in relation to time after surgery has not been comprehensively evaluated. We evaluated recurrence-free survival (RFS) at key time points, stratified by clinicopathologic factors, to identify patients (pts) at higher recurrence risk and personalize postoperative surveillance strategies. Methods: In this multi-institutional, international retrospective cohort study from the Sentinel Lymph Node Working Group database, we included pts with pathologic T3b/T4a/T4b and N0 disease who underwent surgical resection and sentinel node biopsy from 1994-2025. The type of first recurrence (local, regional, distant) was characterized based on time category (0-12, 12-24, 24-60, and 60+ months after surgery). Restricted mean survival time (RMST) analysis was used to measure the average survival time up to a specified time point (6-, 12-, 24-, and 60-months after surgery), and associations of clinicopathologic variables (age, sex, Breslow thickness, ulceration and lymphovascular invasion [LVI]) with RFS. Results: We included 2514 stage IIB/C pts from 19 sites in 4 countries, with a median follow-up of 53 (stage IIB) and 49 (stage IIC) months. 675 (27%) pts experienced a recurrence (92 [14%] local, 238 [35%] regional and 345 [51%] distant), and 400 (59%) recurrences occurred within 24 months. The proportion of distant recurrences as the first recurrence increased significantly with time, comprising 39%, 50%, 62%, and 59% of recurrences in the 0-12, 12-24, 24-60, and 60+ month time categories respectively (χ 2 p<0.001). No significant differences were observed for the included clinicopathologic variables for 6-month RMST estimates. At 12 months, RMST estimates for thickness ≥4 mm (11.2 vs 11.6 months for thickness 2-3.99 mm, p<0.001) and presence of LVI (10.7 vs 11.4 months, p=0.009) were significantly different. 24-month RMST estimates differed for male sex (20.7 vs 21.5 months vs females, p=0.002), thickness ≥4 mm (20.5 vs 21.9 months, p<0.001), and presence of LVI (19.0 vs 21.1 months, p<0.001). Lastly, 60-month RMST estimates differed for male sex (42.0 vs 45.2 months, p=0.001), thickness ≥4 mm (41.5 vs 46.2 months, p<0.001), LVI (36.0 vs 43.7 months, p<0.001), and age >65 years (41.5 vs 46.4 for age <42, p=0.022). Conclusions: In this real-world, multi-center analysis of pathologic stage IIB/C melanoma pts, recurrence patterns varied based on time after surgery. Breslow thickness, LVI, male sex, and age were significantly associated with earlier recurrence at different time intervals on RMST analysis. Additionally, given that >50% of first recurrences 12+ months after surgery were distant, active surveillance for distant relapses may be warranted.

7546 Background: MRD assessment informs relapse risk in MM but is typically bone marrow-based and invasive. We therefore compared two minimally invasive MRD assays: BM-informed cfDNA whole-genome sequencing (cfWGS) and plasma proteomic MRD (EasyM). Methods: 71 longitudinal plasma samples (22 diagnosis, 49 follow-up) from 22 newly diagnosed MM patients across 8 Canadian sites (TFRIM4) had paired cfWGS and EasyM (Rapid Novor Inc). cfWGS MRD used patient-specific mutation lists from diagnostic BM WGS (Abelman et al., medRxiv 2025). EasyM used mass spectrometry to quantify residual M-protein from baseline. The primary endpoint was progression-free survival (PFS). Results: Among 22 MM patients (8 male, 14 female; median age at diagnosis 62 years), 8 progressed at a median follow-up of 52.6 months (range: 10-79 months). At 1-year maintenance (n = 18 available), cfWGS MRD+ (6/18) predicted inferior PFS (HR 20.12, 95% CI 2.23-181.60, p = 0.007). EasyM any-detect positivity was frequent (16/18, reflecting delayed clearance) and not prognostic (p = 0.99), with poor agreement vs cfWGS (44.4%, κ = 0.118). An exploratory EasyM clearance threshold of 0.93% (hypothesis-generating) classified 5/18 patients as MRD+ and stratified PFS (HR 8.78, 95% CI 1.55-49.82, p = 0.004), improving agreement with cfWGS (17/18, 94.4%, κ = 0.870). Progression clustered in cfWGS+/EasyM-high patients (EasyM >0.93%; 4/5; median 11.9 months post-collection [1.9–22.8]) and occurred once in cfWGS−/EasyM-low patients (1/12, 27.6 months). The only discordant case (cfWGS+/EasyM−) progressed 8.7 months after collection. Higher quantitative MRD burden was associated with inferior PFS (cfWGS: HR 2.92 per 1 SD, 95% CI 1.29-6.59, p = 0.01; EasyM: HR 5.48 per 1 SD, 95% CI 0.79-37.90, p = 0.085). At ~100 days post-autologous stem cell transplantation (ASCT; n = 16 available), EasyM was uniformly MRD+ (16/16) while cfWGS was MRD+ in 7/16 patients. Applying an EasyM clearance threshold (2.13%; 9 cleared vs 7 residual) improved agreement with cfWGS (14/16; 87.5%; κ = 0.746). Of two discordant cases, one cfWGS+/EasyM-cleared patient relapsed 38.6 months post-collection and one cfWGS−/EasyM-residual patient remained progression-free at last follow-up. At post-ASCT, both assays showed consistent but underpowered associations with PFS (cfWGS HR 6.32, 95% CI 0.70–56.76, p = 0.100; EasyM-clearance HR 2.36, 95% CI 0.39–14.18, p = 0.335). Across all post-treatment samples (n = 49), continuous cfWGS burden correlated with EasyM residual M-protein (rho = 0.535, p < 0.001). Conclusions: BM-informed cfWGS MRD strongly stratified PFS, whereas EasyM required a clearance definition due to near-universal early positivity. Concordant plasma burdens support complementary MRD information. Future work will validate these findings in larger cohorts and quantify the incremental value of combined cfWGS and proteomic MRD for early relapse prediction.

3626 Background: For patients (pts) with dMMR stage III colon cancer, the addition of atezolizumab (atezo) to adjuvant 5-fluorouracil, leucovorin plus oxaliplatin (mFOLFOX6) significantly improved disease-free survival in ATOMIC (NCT02912559). Here we present HRQOL data. Methods: Pts with surgically resected stage III dMMR colon cancer were randomized (1:1) to receive mFOLFOX6 + atezo (840 mg IV q2 weeks) for 12 cycles (6 months [mo]) followed by atezo monotherapy for 13 cycles (12 mo total) versus mFOLFOX6 for 12 cycles. HRQOL was an exploratory endpoint measured using the FACT-C (includes FACT-G), FACT/GOG-NTX, EQ5D-5L, and PRO-CTCAE. Optional participation was by paper surveys at trial registration, prior to treatment cycles 4 and 7, and at 6, 12, and 36 mo after registration. Mean changes from baseline (BL) were compared between treatment arms using general linear mixed models (negative mean changes indicate worsening). At 6 mo, a two-sided 95% confidence interval excluding a difference of 1.9 points (FACT/GOG-NTX) and 6 points (FACT-C Trial Outcome Index [TOI]) favoring the mFOLFOX6 arm would indicate non-inferiority of the addition of atezo. Rates of side effect bother (FACT-G item GP5) and pt-reported adverse events (AEs) by PRO-CTCAE (composite scores, baseline adjusted) were compared using Fisher’s exact tests. Results: Of 712 randomized pts, 581 (285 atezo+mFOLFOX6; 296 mFOLFOX6) consented to participate in the survey. Pts completed 2398/3021 (79%) of expected surveys across all time points (1218/1489 [82%] atezo+mFOLFOX6; 1180/1532 [77%] mFOLFOX6). The difference in mean changes from BL between arms indicated non-inferiority of the addition of atezo at 6 mo (table); differences remained small at 12 and 36 mo. No significant differences in mean changes from BL between arms were found at 6, 12, or 36 mo for any scale. At 6 mo, 16% vs 20% of pts in each arm reported at least “quite a bit” of side effect bother (p=0.34), favoring atezo. Across cycles, atezo was associated with higher rates of pt-reported itchy skin (62% vs 48%), cough (53% vs 43%), and shortness of breath (51% vs 41%) [all p<0.05]. Conclusions: Addition of atezo to mFOLFOX6 slightly increases pt-reported AEs, but its effect on HRQOL is minimal and not clinically meaningful. Results support tolerability of atezo+mFOLFOX6 as standard of care adjuvant treatment for pts with dMMR stage III colon cancer. Support: UG1CA189823, U10CA180821, U10CA180882; Genentech, a member of the Roche group; https://acknowledgments.alliancefound.org. Clinical trial information: NCT02912559 . Scale Mo Mean change from BL – atezo+mFOLFOX6 Mean change from BL – mFOLFOX6 Diff (95% CI) FACT/GOG-NTX 6 -10.0 -10.6 0.6 (-0.8, 2.1) 12 -8.0 -9.4 1.4 (-0.2, 2.9) 36 -7.2 -6.9 -0.4 (-2.1, 1.4) FACT-C TOI 6 -4.1 -2.5 -1.6 (-3.7, 0.6) 12 2.1 1.8 0.3 (-1.9, 2.6) 36 0.7 1.8 -1.1 (-3.7, 1.5)

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.

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.