Pre-operative radiotherapy for early-stage rectal cancer has risks and benefits that may impact treatment choice in young patients. We reviewed radiotherapy use and outcomes for rectal cancer by age. Patients with early-stage rectal cancer in the Canadian province of British Columbia from 2002-2016 were identified (n=6232). Baseline characteristics, treatment response, overall survival (OS), disease-free survival (DFS), disease-specific survival (DSS), and locoregional recurrence rate (LRR) were compared between patients <50 (early-onset) (n=532) and ≥50 years old (average-onset) (n=5700). Early-onset patients were more likely to receive pre-operative chemoradiotherapy than short-course radiotherapy (OR: 2.20, 95% CI: 1.67-2.89, P<0.0001), but also had higher nodal (P=0.00096) and overall clinical staging (P=0.033). Cancer downstaging and pCR rates were similar in those receiving neoadjuvant chemoradiotherapy by age. Early-onset and average-onset patients had similar DSS (P=0.91) and DFS (P=0.27) in multivariate analysis unless non-colorectal deaths, which were higher in older patients, were censored in the DFS model (HR: 1.30, 95% CI: 1.01-1.68, P=0.042). LRR also did not differ between age groups (P=0.88). Outcomes did not differ based on radiotherapy type. Young patients with rectal cancer are more likely to present with higher staging and receive long-course chemoradiotherapy. DSS did not differ by age group, however young patients had worse DFS when we censored competing risks of death in older patients.

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2023
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Supplementary data

Supplemental Table 1

Supplemental Table 1 – Characteristics and treatment response in rectal cancers treated with neoadjuvant therapy.

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Supplemental Figure 1

Supplemental Figure 1. Consort diagram showing patient inclusion at each stage of analysis. Patient groups used in each stage of analysis are adjacent to the indicated analyses. Patients excluded at each stage of analysis are also indicated.

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Supplemental Figure 2

Supplemental Figure 2. (A) Overall clinical stage and (B) overall pathological stage distribution stratified by age.

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Supplemental Figure 3

Supplemental Figure 3. Kaplan Meier curves for locoregional recurrence (LRR) in (A) early-onset and average-onset patients, (B) early-onset decile groups, and (C) early-onset and average-onset patients that received long-course chemoradiotherapy or (D) short-course radiotherapy.

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Supplemental Figure 4

Supplemental Figure 4. Disease-free survival (DFS) by age in early-stage rectal cancers. The Kaplan-Meier survival curves are shown for a period of 10 years. The survival curves begin to separate towards the end of the routine follow-up period of 5 years.

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Supplemental Figure 5

Supplemental Figure 5. Overall survival, disease-specific survival and disease-free survival by age group and treatment type in early-stage rectal cancers.

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Supplemental Figure 6

Supplemental Figure 6. Disease-specific disease-free survival (DSDFS) for early-stage rectal cancer receiving neoadjuvant short-course radiotherapy with non-colorectal deaths censored (DSDFS).

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