Does the initial treatment of primary tumor impact prognosis after recurrence in locally advanced rectal cancer? Results from a retrospective cohort analysis.

Introduction: The role of neoadjuvant therapy (NAT) in the treatment of locally advanced rectal cancer (LARC) has been well proven, but its impact on patients who relapse remains unknown. This study aims to elucidate the influence of initial treatment and MRI-defined risk factors on postrecurrent survival in patients with LARC recurrence.

Patients and methods: LARC patients who underwent radical surgery and subsequently developed recurrence were retrospectively identified. Patients were stratified on the basis of MRI-defined local risk assessment and the initial treatment modality for the primary tumor (NAT or primary surgery). The patients were classified into four groups: high-risk LARC with NAT (HiN), high-risk LARC with primary surgery (HiS), low-risk LARC with NAT (LoN), and low-risk LARC with primary surgery (LoS). The primary endpoint was survival after recurrence.

Results: A total of 381 patients who experienced relapse were identified from among 2329 LARC patients. Salvage surgery was performed on 33.1% of these patients. Patients who experienced single-site recurrence or who underwent salvage surgery exhibited significantly prolonged survival times after recurrence (P < 0.001). Patients in the HiS group had poorer survival after recurrence than those in the other three groups (P = 0.034). This subset of patients, characterized by receiving less adjuvant treatment after primary surgery, had a shorter recurrence interval than those in the other groups (P = 0.001).

Conclusions: Our findings reaffirm the prognostic significance of salvage surgery in patients from a LARC cohort who experienced relapse. Moreover, MRI-defined high-risk LARC patients who received upfront surgery without NAT had shorter intervals of recurrence and poorer survival outcomes after recurrence. Our results highlight the critical role of NAT in improving patient survival after recurrence.

Trial registration: Supplementary registration was carried out at clinicaltrials.gov (Registration number: NCT06314737) on March 14, 2024. The study was retrospectively registered.