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Session: ePoster: Rectal Cancer 5 (Sun350)

EP589 - Young-Onset versus Late-Onset Locally Advanced Rectal Cancer: A Retrospective Study from Two Tertiary Hospitals in Thailand

Sunday, May 11, 2025
4:39 PM – 4:44 PM PT
Location: Monitor 6, Sails Pavilion, Upper Level

    ePoster Presenter(s)

  • Thanat Tantinam, MD (he/him/his)

    Colorectal fellow and PhD candidate of Medical science in Surgery
    Vajira Hospital and Maharaj Nakorn Chiang Mai Hospital
    Namom, Songkhla, Thailand

    All of the relevant financial relationships listed below have been mitigated.
    This individual has no financial relationships with ineligible companies.

    • Senior Author(s)

  • AT

    Apichat Tantraworasin, n/a

    Associate professor
    Department of Surgery, Faculty of Medicine, Chiang Mai University
    Chiang Mai, Chiang Mai, Thailand

    All of the relevant financial relationships listed below have been mitigated.
    This individual has no financial relationships with ineligible companies.

All of the relevant financial relationships listed below have been mitigated.
Thanat Tantinam, MD: This individual has no financial relationships with ineligible companies.
Apichat Tantraworasin, n/a: This individual has no financial relationships with ineligible companies.
Image or Table (Do Not add text here):

Purpose/Background: The increasing incidence of young-onset rectal cancer (YORC) has raised concerns about potential biological differences compared to late-onset rectal cancer (LORC). While colorectal cancer has been extensively studied, limited attention has been given to the clinical outcomes of locally advanced rectal cancer (LARC) in younger patients. This study aims to compare the characteristics and survival outcomes of YORC and LORC, using data from two tertiary medical centers in Thailand.

Methods/Interventions: This retrospective study included patients with LARC who were treated at two tertiary hospitals in Thailand between 2012 and 2020. Patients were categorized into two groups: YORC ( < 50 years) and LORC (≥50 years). Demographic, clinical, and pathological data were collected. Survival analysis was conducted using multilevel mixed-effects parametric survival models, and Kaplan-Meier survival curves were generated to present the results.

Results/Outcomes: A total of 159 patients were included, with 32 in the YORC group and 127 in the LORC group. The mean age was 42.1 years in the YORC group and 62.3 years in the LORC group. Fewer YORC patients had underlying comorbidities compared to LORC patients (18.8% vs. 55.1%). Median carcinoembryonic antigen (CEA) levels were lower in the YORC group (2.3 ng/mL vs. 4 ng/mL). No significant differences were observed in tumor differentiation or treatment response between the two groups, including in cases of mucinous or signet-ring cell carcinoma. Disease-specific survival (DSS) was comparable between the groups, while overall survival (OS) showed a trend toward better outcomes in the YORC group, though this was not statistically significant. The recurrence rate was similar between groups (11% in LORC vs. 9.4% in YORC), with most recurrences being local. Time to recurrence tended to be shorter in YORC patients compared to LORC patients (303 days [IQR 151.8–483.5] vs. 406 days [IQR 345–939], p = 0.072). The mean follow-up duration was 5.3 years.

Conclusion/Discussion: Contrary to prior studies suggesting more aggressive histopathological features in YORC, this study did not find such differences within the LARC subgroup. Additionally, no significant differences in OS or DSS were observed between YORC and LORC, consistent with previous studies reporting mixed outcomes. Further research is needed to determine whether distinct biological or clinical features exist between YORC and LORC in the LARC population, which may influence future therapeutic strategies.