Colorectal cancer (CRC) is among the most prevalent malignancies worldwide, ranking third in incidence and second in cancer-related mortality [1]. Accurate staging at diagnosis is critical, as it determines prognosis, guides therapeutic decisions, and facilitates appropriate surgical planning. The tumor–node–metastasis (TNM) classification system remains the gold standard, requiring precise assessment of local tumor extent, nodal involvement, and metastatic spread to ensure optimal outcomes [2]. Radiological modalities, particularly computed tomography (CT) and magnetic resonance imaging (MRI), are widely employed for preoperative staging. MRI is especially valuable in rectal cancers, while CT continues to be the first-line modality for colonic lesions [1,3]. These techniques provide essential information on tumor morphology, depth of invasion, nodal status, and metastatic disease. Nevertheless, despite technological advances, radiology has inherent limitations. Both overstaging and understaging are common, especially in nodal assessment, where inflammatory changes may mimic malignancy, while micrometastases frequently remain undetected [2,4]. Intraoperative evaluation, in contrast, enables direct inspection and palpation of the tumor and regional structures, often providing more definitive real-time staging. Discrepancies between radiological and intraoperative findings have been shown to influence oncological decision-making, surgical margins, and postoperative management strategies [3,5]. Evaluating these variations is particularly important in settings where clinical management heavily relies on radiological assessment before surgery. The present retrospective observational study was undertaken to compare radiological and intraoperative staging in colorectal cancer patients. By analyzing concordance across T, N, and M components of the TNM system, the study aims to highlight the strengths and limitations of preoperative radiological assessment in accurately reflecting intraoperative findings.

Study Design and Setting This retrospective observational study was carried out in the Department of General Surgery and Surgical Oncology at Governament General Hospital and Kurnool Medical College, Kurnool, Andhra Pradesh, between 15 February and 31 May 2024. Study Population Patients with histologically confirmed colorectal carcinoma who underwent both preoperative radiological staging (CT or MRI) and surgical resection with intraoperative staging during the study period were included. Patients with incomplete imaging records, missing intraoperative documentation, or those who had received neoadjuvant therapy were excluded. Radiological Evaluation All patients underwent standardized imaging protocols. Contrast-enhanced computed tomography (CT) of the abdomen and pelvis was performed for colonic tumors, while magnetic resonance imaging (MRI) was employed for rectal lesions. Radiological staging was reported by qualified radiologists using the TNM classification system. Intraoperative Assessment Intraoperative staging was recorded by the operating surgeons based on direct inspection and palpation of the primary tumor, evaluation of regional lymph nodes, and identification of peritoneal or distant metastases. Findings were documented immediately after surgery. Data Collection and Variables Demographic details (age, sex), tumor location (colon or rectum), histological subtype, and staging details from both radiology and intraoperative findings were extracted from hospital records using a structured proforma. Data Analysis Radiological staging was compared with intraoperative findings for T, N, and M stages. Accuracy, understaging, and overstaging were calculated. The overall agreement between radiological and intraoperative staging was assessed, and concordance was expressed as percentages. Statistical analysis was performed using SPSS software, with p < 0.05 considered statistically significant.

A total of 100 patients with histologically confirmed colorectal cancer were included in the study. The mean age of the cohort was 58.4 ± 11.2 years, with a male-to-female ratio of 57:43. The majority of tumors were located in the colon (64%), while rectal cancers accounted for 36%. Adenocarcinoma was the predominant histological type (92%), followed by mucinous carcinoma (6%) and other rare subtypes (2%) (Table 1). Table 1. Baseline Characteristics of Patients (n = 100) Parameter Value Mean age (years) 58.4 ± 11.2 Gender (Male:Female) 57:43 Tumor location Colon – 64%, Rectum – 36% Histological type Adenocarcinoma – 92%, Mucinous – 6%, Others – 2% T-Staging Radiological assessment of the primary tumor correctly identified the T stage in 72% of cases. Understaging was observed in 14% and overstaging in another 14%. The highest concordance was noted for T3 lesions (80.4%), while early-stage tumors (T1–T2) were frequently underestimated, and advanced T4 lesions were often overstaged (Table 2). Table 2. Comparison of Radiological vs Intraoperative T-Staging T Stage Intraoperative (n) Radiological (Correctly Identified) Understaged Overstaged Accuracy (%) T1 8 5 3 0 62.5 T2 18 12 4 2 66.7 T3 46 37 4 5 80.4 T4 28 18 3 7 64.3 Total 100 72 14 14 72.0 N-Staging Radiological nodal staging demonstrated an overall accuracy of 68%. While N0 disease showed relatively high agreement (82.6%), discrepancies were more pronounced in node-positive cases. N1 tumors were correctly staged in 64.7% of cases, whereas N2 disease had the lowest accuracy (40%). Overstaging was more common than understaging, particularly in cases with pericolic fat stranding mimicking nodal involvement (Table 3). Table 3. Comparison of Radiological vs Intraoperative N-Staging N Stage Intraoperative (n) Radiological (Correctly Identified) Understaged Overstaged Accuracy (%) N0 46 38 4 4 82.6 N1 34 22 6 6 64.7 N2 20 8 4 8 40.0 Total 100 68 14 18 68.0 M-Staging Radiological assessment of distant metastasis achieved the highest concordance, with an overall accuracy of 94%. All non-metastatic cases (M0) were accurately identified, while two patients with peritoneal nodules were missed preoperatively. The sensitivity for detecting metastatic disease (M1) was 88.9% (Table 4). Table 4. Comparison of Radiological vs Intraoperative M-Staging M Stage Intraoperative (n) Radiological (Correctly Identified) Missed Accuracy (%) M0 82 82 0 100.0 M1 18 16 2 88.9 Total 100 98 2 94.0 Overall Concordance When compared across all parameters, the overall concordance between radiological and intraoperative staging was 78%. Agreement was substantial for tumor depth and distant metastasis but moderate for nodal staging, which remained the major source of discrepancy.

Accurate staging of colorectal cancer is fundamental to treatment planning, surgical strategy, and prognostication. In this study of 100 patients, radiological staging demonstrated substantial concordance with intraoperative findings, with an overall accuracy of 78%. While radiological imaging reliably identified tumor depth and metastatic disease, discrepancies were most pronounced in nodal staging. T-Staging In our cohort, radiology correctly identified the T stage in 72% of cases, with the highest accuracy for T3 lesions. Early-stage tumors (T1–T2) were often underestimated, while T4 lesions were occasionally overstaged. These findings align with earlier reports demonstrating the value of MRI and CT in assessing tumor invasion, while acknowledging their reduced sensitivity for differentiating early stages [6,7]. MRI has been particularly emphasized for rectal cancers, where depth of invasion and circumferential resection margin are critical [6]. N-Staging Nodal staging showed lower accuracy (68%), with concordance dropping to 40% in N2 disease. Overstaging was more common, likely due to inflammatory changes mimicking nodal metastasis. Such limitations are consistent with previous literature highlighting the variable sensitivity of imaging for nodal disease, often ranging from 55–75% [8]. Advanced techniques such as diffusion-weighted MRI and PET-CT may improve diagnostic performance, though access remains limited [7,10]. M-Staging Radiology achieved the highest reliability in metastatic staging, with 94% overall accuracy. However, two cases of peritoneal metastases were missed, reflecting the known difficulty of detecting small-volume peritoneal disease radiologically. The DISCO trial similarly highlighted discrepancies between MRI staging and surgical findings for peritoneal metastases, underlining the need for multimodal assessment [8]. Hepatic and pulmonary metastases are more reliably detected on cross-sectional imaging, whereas peritoneal involvement continues to pose a challenge [10]. Clinical Implications The observed discrepancies underscore the importance of cautious interpretation of radiological findings, particularly for nodal staging. Intraoperative evaluation remains indispensable in providing a definitive assessment that can influence surgical planning. Recent ESGAR guidelines recommend a multidisciplinary approach that integrates radiological, surgical, and pathological findings to improve staging precision [6]. Furthermore, evolving strategies such as radiomics and clinicopathological integration have shown promise in predicting survival and refining risk stratification beyond conventional staging [12]. Future Directions With emerging imaging technologies and the increasing role of precision oncology, individualized treatment planning based on integrated staging is becoming a priority [10,11]. Radiotherapy and systemic therapy decisions in locally advanced colorectal cancer also depend heavily on accurate staging, further reinforcing the importance of refining imaging protocols [9]. Limitations This study was limited by its retrospective design, relatively small sample size, and single-center setting. Histopathological correlation, considered the gold standard, was not included in this comparison, which may limit definitive conclusions. Larger multicenter studies with combined radiological, intraoperative, and histopathological staging are warranted.

This retrospective study demonstrated that radiological staging in colorectal cancer shows substantial concordance with intraoperative findings, particularly for tumor depth and metastatic disease. Radiological accuracy was highest for T3 lesions and M staging, while nodal assessment remained the major source of discrepancy due to frequent overstaging or understaging. Although imaging remains the cornerstone of preoperative evaluation, intraoperative findings continue to provide indispensable confirmation, especially in complex cases. Integrating radiological assessment with intraoperative staging enhances diagnostic precision, facilitates tailored surgical planning, and improves patient outcomes. Future multicenter studies incorporating histopathological correlation are essential to strengthen the evidence for optimal staging strategies.

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