Pathological Complete Response in Rectal Cancer Patients: A Correlation Between Pathological and Clinical Stage and...

In rectal cancer, the choice of treatment strategy depends on the tumor stage and the response to neoadjuvant therapy. Accurate assessment of tumor regression through magnetic resonance imaging (MRI) may help to guide personalized approaches, including delayed or nonoperative management. This study aimed to assess the correlations between pathological complete response (pCR) and clinical staging before and after neoadjuvant treatment in rectal cancer patients.

We conducted a retrospective analysis of rectal cancer patients treated with neoadjuvant therapy followed by radical resection in our oncological surgery department between July 2012 and December 2024. Clinical staging and tumor response were assessed using MRI, focusing on T- and N-stage evaluation. Pathological complete response (pCR) was defined as the absence of tumor cells on histopathological examination. Associations between pCR and clinical variables were explored.

Out of a total of 1693 rectal cancer patients, 783 (46.25%) received neoadjuvant therapy, with 62 patients (7.92%) presenting pCR. The majority had tumor stage cT3 (n = 45, 72.6%) and lymph node stage cN2b (n = 25, 40.3%) before treatment. Post-treatment MRI showed complete tumor response (T0) in 20 patients (32.3%) and nodal downstaging to N0 in 34 patients (54.8%). MRI provided imaging findings that indicate a limited correlation between clinical assessment of tumor response and pathological outcome. Six patients (9.6%) developed distant metastases, and there were no local recurrences.

While MRI provides valuable preoperative information, its accuracy in predicting pCR remains limited. Achieving pCR is a favorable prognostic indicator, but it does not eliminate the risk of distant metastasis; therefore, continued surveillance and individualized management strategies remain essential to optimize outcomes in rectal cancer patients.