2053 - Impact of Histology and Treatment Pathway in a 10-Year Radical-Intent Oesophageal Cancer Cohort

03:00pm - 04:00pm ET

Poster Hall - Exhibit Hall A

Screen: 21

POSTER

Presenter(s)

Caroline Dobeson, MB, ChB - The Newcastle upon Tyne NHS Foundation Trust, Newcastle upon Tyne, Tyne and Wear

M. AlHilali^1,2, A. Ellacott¹, M. Ahmed¹, A. Bakhtiar¹, T. Spencer¹, A. Burns¹, A. Waton¹, P. Atherton¹, C. Dobeson¹, and A. Bradshaw¹; ¹The Newcastle upon Tyne NHS Foundation Trust, Newcastle upon Tyne, United Kingdom, ²Newcastle University, Newcastle upon Tyne, United Kingdom

Purpose/Objective(s):

Histologic subtype is often used to guide definitive treatment in oesophageal cancer, especially when considering definitive chemoradiotherapy (dCRT). We tested whether overall survival (OS) is independently associated with histology after adjusting for treatment pathway and baseline factors, and whether histology modifies pathway specific survival benefit in a mature real world cohort.

Materials/Methods:

Ten year single centre retrospective audit of radical intent oesophageal cancer. OS measured from decision to treat. Pathways were definitive radiotherapy (dRT) n=201, dCRT n=181, neoadjuvant chemoradiotherapy (nCRT) n=75. Covariates were age, WHO performance status PS 0–1 vs =2, grouped T stage T0–2 vs T3–4, grouped nodal status N0 vs N+, histology adenocarcinoma (AC) vs squamous cell carcinoma (SCC), and pathway. Baseline distributions were compared across pathways. Multivariable Cox models included main effects and a pathway by histology interaction. A radical non surgical sensitivity analysis dRT vs dCRT was performed. Median follow up used reverse Kaplan–Meier.

Results:

457 patients were analysed with 272 deaths. Median follow-up was 52.2 months. Median OS was 18.3 months (dRT), 28.6 months (dCRT), 80.2 months (nCRT), and 26.4 months overall. Five-year OS was 19.7% (dRT), 29.8% (dCRT), and 56.2% (nCRT). Ten-year OS was 2.7% (dRT), 14.7% (dCRT), and 34.1% (nCRT).

PS differed across pathways (PS =2: dRT 32%, dCRT 4%, nCRT 1%; p<0.000001). T3–4 disease was more frequent in nCRT (92%) and dCRT (87%) than dRT (76%) (p=0.001). Nodal positivity was highest in dCRT (75%; p<0.001).

In multivariable analysis adjusting for age, PS, T and N group, pathway independently predicted OS: dCRT vs dRT HR 0.56 (95% CI 0.41–0.77), p=0.00032; nCRT vs dRT HR 0.29 (95% CI 0.19–0.46), p=8.0×10^-8. T3–4 predicted worse OS (HR 1.58, p=0.0088). N+ was borderline (HR 1.30, p=0.051). Histology was not independently associated with OS (HR 1.06, p=0.67).

Adding a pathway by histology interaction did not significantly improve model fit (LRT p=0.069).

In the radical non-surgical cohort (n=382), dCRT remained independently associated with improved OS (HR 0.52, 95% CI 0.38–0.71, p=5.97×10^-5), while histology remained non-significant.

Conclusion:

In this mature ten year cohort with long term follow up, survival separated primarily by treatment pathway rather than tumour subtype. Although PS differed across pathways consistent with clinical selection, the independent association with pathway persisted after adjustment for age, PS and stage. Histology was not independently prognostic and did not robustly modify pathway specific benefit. In contemporary practice, pathway selection and delivery appear to exert greater influence on long term survival than tumour histology alone, suggesting optimisation of access to and delivery of combined modality radical pathways may yield greater survival gains than histology led expectations when selecting definitive non surgical strategies.