Survival of Young Versus Late-Onset Post Neoadjuvant Treatment Pathologic Node Negative Rectal Cancer: A Retrospective Study from Two Tertiary Hospitals in Thailand
Thanat Tantinam¹,²,³, Pawit Sutharat¹, Suwan Sanmee¹, Ekkarin Supatrakul¹, Jiraporn Khorana¹, Sunhawit Junrungsee¹, Kullawat Bhatanaprabhabhan², Boonchai Ngamsirimas², Nataphon Santrakul², Rangsima Thiengthiantham², Punnawat Chandrachamnong², Apichat Tantraworasin¹
Affiliation : ¹ Clinical Surgical Research Center, Chiang Mai University, Chiang Mai, Thailand; ² Colorectal Surgery Unit, Faculty of Medicine Vajira Hospital, Navamindradhiraj University, Bangkok, Thailand; ³ Surgery Unit, Phatthalung Hospital, Phatthalung, Thailand
Background: Although pathological node-negative (ypN0) status is associated with favorable outcomes in rectal cancer patients, recurrence still occurs.
Objective: To compare the clinical stage, tumor biology, treatment response, and survival outcomes between ypN0 young-onset rectal cancer (YORC) and late-onset rectal cancer (LORC) patients and identified factors associated with recurrence.
Materials and Methods: The present study was a retrospective cohort study included 159 ypN0 rectal cancer patients treated between 2013 and 2019 at two tertiary centers in Thailand. Patients were categorized into YORC, younger 50 years, and LORC at 50 years or older groups. Clinical and pathological characteristics, treatment response, disease-free survival (DFS), and overall survival (OS) were analyzed. Prognostic factors for recurrence were identified via Cox proportional hazards regression.
Results: Among 159 patients, 32 (20.1%) had YORC and 127 (79.9%) had LORC. YORC patients presented a greater prevalence of poorly differentiated, mucinous, and signet-ring cell histology. No significant differences were observed in 5-year DFS (p=0.072) or 5-year OS (p=0.127), although YORC patients demonstrated a trend toward earlier recurrence at 303 versus 406 days. Independent risk factors for recurrence included lateral lymph node involvement (adjusted HR 3.341, p=0.011), positive resection margins (adjusted HR 6.519, p=0.004), and a lower number of harvested lymph nodes with less than 12 (adjusted HR 1.099, p=0.007).
Conclusion: There were no statistically significant differences in OS or DFS between ypN0 YORC and LORC patients. However, optimizing lymph node retrieval and positive resection margin remain essential, and closer follow-up may be beneficial for YORC patients given their trend toward earlier recurrence.
Received 22 September 2025 | Revised 2 November 2025 | Accepted 4 November 2025
DOI: 10.35755/jmedassocthai.2025.12.1006-1015-03634
Keywords : Young adult; Rectal cancer; Recurrence; Survival; Lymph nodes; ypN0; Retrospective
