Ancestry-linked, stage-specific delay to tertiary care is associated with survival differences in colorectal cancer

Background: African-ancestry (AFR) patients with colorectal cancer (CRC) have worse overall survival (OS) than non-AFR patients. While biological and socioeconomic (SES) factors are known to play a role, delayed access to specialized care remains a critical, underexplored driver of this inequity. This study investigates how the time from diagnosis (Dx) to arrival at a tertiary cancer center interacts with ancestry, disease stage, SES, and genomics to affect OS. Methods: We analyzed data from 4,328 CRC patients (259 AFR, 4,069 non-AFR) treated at Memorial Sloan Kettering Cancer Center (MSK) since 2014. Tumors were sequenced with MSK-IMPACT, a targeted DNA sequencing assay that profiles genomic changes in 341-505 genes. Genetic ancestry was inferred from sequencing data with >80% African ancestry fraction grouped as AFR. OncoKB identified clinically actionable genomic alterations. Covariates included tumor location, stage at Dx, time from Dx to MSK arrival (Early ≤90 days vs Late >90 days), insurance type and metastatic burden. OS from Dx was compared using Kaplan-Meier curves and log-rank test, with left-truncation for genomic sequencing date. Results: AFR patients had worse OS from Dx than Non-AFR patients (median 39.3 vs 62.7 months, p<0.001). This difference remained when stratified by stage at Dx (Stage I-III: 65.3 vs 96 months, p<0.001; Stage IV: 31.6 vs 36.7 months, p=0.03). AFR patients also had significantly longer delays from Dx to arrival (median: 22 [IQR: 10, 173] vs 14 [IQR: 6, 38] days; p<0.001) and a higher proportion of late arrivals (28.7 vs 17.1%, p<0.001). This difference was more evident in Stage I-III (49.6 vs 25.9%, p<0.001) than in Stage IV (6.3 vs 5.6%, p=0.69). There was no significant difference in OS between AFR and Non-AFR for Stage I-III early (median: Not Reached (NR) vs NR, p=0.98), Stage I-III late (median: 36 vs 43.5 months, p=0.24), and Stage IV late (median:43.7 vs 33.9 months, p=0.48) arrival, but was significant in Stage IV early arrival (median: 31.6 vs 36.9 months, p=0.034). Patients diagnosed with Stage I-III disease who arrived late at MSK were often Stage IV at their time of arrival (AFR: 68.9%, Non-AFR 65.8%) but this was much less frequent among early arrivals (AFR: 6.1%, Non-AFR: 2.6%); and was linked to higher Medicaid use in both AFR (10.8% vs 1.5%; p=0.03) and Non-AFR (4.4% vs 2.4%; p=0.015) patients. AFR had higher KRAS mutation frequency compared to Non-AFR across all stages and arrival groups (Stage I-III Early: 51.5 vs 38.8%, p=0.04; Stage I-III Late: 58.2 vs 47.2%, p=0.10; Stage IV Early: 58.5 vs 44.5%, p=0.004; Stage IV Late: 75 vs 50.5%, p=0.28). Conclusion: Delayed specialized care appears to be linked to CRC survival gaps in AFR patients, especially in the non-metastatic setting where timely multidisciplinary care is crucial. Expediting referral of AFR patients to tertiary care centers could help to achieve CRC outcome equity.