A prospective comparison study for predicting circumferential resection margin between preoperative MRI and whole mount sections in mid-rectal cancer: significance of different scan planes

Evaluation of endorectal ultrasound (ERUS) and MRI for prediction of circumferential resection margin (CRM) for rectal cancer

ERUS and MRI are used for preoperative imaging of rectal cancer. Here, we compare ERUS and MRI for accuracy of CRM prediction at mid- and distal rectal locations. In retrospective review, 20 rectal cancer patients having TME surgery had both ERUS and MRI preoperatively: 8 mid rectum and 12 in distal rectum. Predicted CRM by ERUS and MRI were compared to TME pathology. Overall, predicted CRM was 6.5 ± 3.6 mm by ERUS, 7.7 ± 5.0 mm by MRI, and 6.0 ± 4.6 mm by pathology. Overall, correlation coefficients to pathology were 0.77 (p = 0.0004) for ERUS and 0.64 (p = 0.008) for MRI. In distal rectum, correlation coefficients were 0.71 (p = 0.02) for ERUS and -0.10 (p = 0.79) for MRI. In mid rectum, correlation coefficients were 0.92 (p = 0.01) for ERUS and 0.44 (p = 0.38) for MRI. While MRI is used routinely for preoperative rectal cancer imaging, ERUS can provide additional assessment of CRM for mid or distal rectal lesions. Further investigation is needed to support these preliminary ERUS CRM findings in mid and distal rectum.

Characteristics and Prognostic Significance of Preoperative Magnetic Resonance Imaging-Assessed Circumferential Margin in Rectal Cancer

Purpose. To study the characteristics and prognostic significance of preoperative magnetic resonance imaging- (MRI-) assessed circumferential margin (CRM) in rectal cancer. Methods. Patients underwent preoperative high resolution pelvic MRI, followed by resection of primary tumor. The relationship between MRI-assessed CRM and pathological CRM (pCRM) was studied, and survival analysis was used to determine the prognostic significance of MRI-assessed CRM. Results. Of all the 203 patients, the total accuracy of MRI-assessed CRM for predicting involvement of pCRM was 84.2%, sensitivity was 50%, and specificity was 86.8%. Anterior tumors were more possible to assess involvement of CRM by MRI, while the false positive rate was significantly higher than lateral or posterior tumor (87.5% versus 50%, p = 0.0002). The 3-year local recurrence, disease-free survival, and overall survival rates were 35.6%, 58.1%, and 85.2% in patients with involved mrCRM, compared with 8.9%, 78.9%, and 92.3% in patients with clear mrCRM. In multivariate analysis, MRI-assessed CRM found an independent risk factor for local recurrence, with a hazard ratio of 3.49 (p = 0.003). Conclusions. High resolution MRI was accurate to assess CRM preoperatively, while anterior tumor should be assessed more cautiously. Involvement of mrCRM was significantly associated with local recurrence regardless of pCRM status.

Factors affecting the restaging accuracy of magnetic resonance imaging after preoperative chemoradiation in patients with rectal cancer

PURPOSES

We evaluated patient or tumor factors associated with the preoperative restaging accuracy of magnetic resonance imaging (MRI) for determining T and N stages as well as circumferential resection margin (CRM) involvement after chemoradiation (CRT) in patients with locally advanced rectal cancer.

METHODS

Seventy-seven patients with rectal cancer that were treated with preoperative CRT (50.4 Gy) followed by radical resection were included. Post-CRT MRI was performed approximately 4 weeks after preoperative CRT.

RESULTS

The median tumor distance from the anal verge was 6 cm, 48 (62%) of which were anterior and 29 (38%) posterior. The median tumor diameter was 3 cm. A stage-by-stage comparison showed that correct staging occurred in 62%, 43%, and 86% of patients for T staging, N staging, and CRM prediction, respectively. Shorter distance to the anal verge (<5 cm), smaller tumor diameter (<1 cm), and anterior tumor location were associated with incorrect T staging. There were no significant variables in terms of N staging accuracy. Shorter tumor distance and anterior tumor location were associated with incorrect CRM prediction.

CONCLUSIONS

Our findings suggest that specific tumor factors such as small, distal, or anterior rectal tumors are closely associated with the accuracy of MRI after preoperative CRT.

Evaluation of mesorectal fascia in mid and low anterior rectal cancer using endorectal ultrasound is feasible and reliable: a comparison with MRI findings

BACKGROUND

Accuracy of MRI in assessing mesorectal fascia and predicting circumferential resection margin decreases in low anterior rectal tumors.

OBJECTIVE

The purpose of this work was to evaluate the accuracy of endorectal ultrasound in predicting the pathologic circumferential resection margin in low rectal anterior tumors and to compare it with MRI findings.

DESIGN

This was a prospective series comparing the preoperative circumferential resection margin assessed by endorectal ultrasound and MRI with pathologic examination.

SETTINGS

The study was conducted by a specialized colorectal multidisciplinary team at a tertiary teaching hospital.

PATIENTS

Between 2002 and 2008, 76 patients with mid to low rectal cancer were preoperatively evaluated by endorectal ultrasound and MRI and underwent total mesorectal excision without neoadjuvant radiochemotherapy. Twenty-seven patients with posterior or postero-lateral tumors were excluded, leaving 49 patients with anterior or antero-lateral tumors for the present subanalysis. We compared preoperative circumferential resection margin status using endorectal ultrasound and MRI with pathologic examination.

INTERVENTIONS

We conducted a comparison between preoperative circumferential resection margin status and pathologic examination after total mesorectal excision surgery.

MAIN OUTCOME MEASURES

Accuracy in predicting pathologic circumferential resection margin status was measured.

RESULTS

Overall accuracy of endorectal ultrasound and MRI in assessing circumferential resection margin status was 83.7% and 91.8%, with negative predictive values of 97.2% and 97.5%. When focusing on low rectal tumors, the overall accuracy of endorectal ultrasound increased to 87.5%, whereas the accuracy of MRI decreased to 87.5%, with a negative predictive value of 95.6% for both diagnostic tests.

LIMITATIONS

The sample size is small, and interobserver variability in radiologic assessment was not evaluated.

CONCLUSIONS

Endorectal ultrasound can help MRI in predicting circumferential resection margin involvement in mid to low anterior rectal cancer, especially at the low third of the rectum, with a high negative predictive value.

Tailored rectal cancer treatment--a time for implementing contemporary prognostic factors?

AIM

To report data supporting the development of tailored treatment strategies for rectal cancer.

METHOD

A comprehensive review of the literature on the impact of prognostic factors cur-rently not included in international guidelines in rectal cancer management.

RESULTS

There is considerable variation in treatment guidelines for rectal cancer worldwide, especially for Stage II and Stage III disease. Long-term side effects of chemoradiotherapy are not considered in any guideline. Detailed knowledge, and the prognostic impact, of the circumferential resection margin, tumour grade and venous invasion should be factored into the development of a treatment strategy.

CONCLUSION

Factors additional to the TNM system should improve decision making for contemporary rectal cancer treatment. Optimized radiological and pathological evaluations, and a focus on detailed clinical factors, should be the basis for treatment decisions. International guidelines should consider all known prognostic factors for long-term oncological and functional outcomes.

Accuracy of endorectal ultrasound for measurement of the closest predicted radial mesorectal margin for rectal cancer

BACKGROUND

At present, pelvic phased array-coil MR is used as the validated imaging modality for measurement of the closest predicted radial mesorectal margin for rectal cancer. Endorectal ultrasound is also used to assess the clinical stage of the cancer that will determine the recommendation for neoadjuvant chemoradiation, but it has not been used to assess the closest predicted radial margin.

OBJECTIVE

We propose to assess endorectal ultrasound identification of mesorectal margins and the measurement of the closest predicted radial tumor-mesorectal margin.

PATIENTS AND METHODS

Patients included were those having MRI and endorectal ultrasound for evaluation of primary rectal cancer in 2010 at a tertiary cancer referral colorectal clinic. Clinical data, MRI, and endorectal ultrasound images were assessed. Two independent retrospective measurements of mesorectal dimensions were correlated to evaluate the reproducibility of identifying mesorectal margins. MRI and endorectal ultrasound images were compared for independent measurements of mesorectal dimensions and of the closest predicted radial mesorectal margin. MRI and endorectal ultrasound determination of margin involvement were assessed for agreement.

RESULTS

Fifty-two patients were studied with an average rectal cancer distance to the anal verge of 6.8 cm. Interobserver correlation coefficients of endorectal ultrasound mesorectal dimensions ranged from 0.47 to 0.53 (p < 0.01). MR and endorectal ultrasound measurements of the closest predicted radial mesorectal margin were correlated r = 0.56 (p < 0.0001). MR and endorectal ultrasound determination of margin involvement agreed in 81% of cases.

CONCLUSION

Endorectal ultrasound has substantial agreement with MR to measure the closest predicted radial tumor-mesorectal margin. Correlations between observers and modalities for identification of mesorectal dimensions are modest. Further assessment is indicated to confirm endorectal ultrasound mesorectal measurements in a larger sample and to understand the advantages and disadvantages relative to MR.

Magnetic resonance imaging cannot predict histological tumour involvement of a circumferential surgical margin in rectal cancer

AIM

Several recent studies have attempted to evaluate the accuracy of preoperative magnetic resonance imaging (MRI) in predicting the likelihood of tumour involvement of the postoperative circumferential resection margin (CRM) in rectal cancer with the intention of selecting patients who might benefit from neoadjuvant therapy and as a guide to surgery. The aim of this study was to assess whether such studies can provide a valid answer as to whether preoperative MRI can accurately predict CRM involvement by tumour.

METHOD

The study design and methodology of studies on this topic were critically examined.

RESULTS

Features identified as affecting the efficacy of these studies were: representativeness of patients, definition of the margin assessed by MRI and by histology, lack of blinding of surgeons and pathologists to MRI results, effect of neoadjuvant treatment, and number of patients studied.

CONCLUSION

Because of methodological inadequacies in studies completed to date, there is insufficient evidence of the ability of a positive MRI result to predict an involved CRM. Although MRI may be able to identify a tumour that has extended to the mesorectal fascia and/or intersphincteric plane, logically, it cannot indicate where the surgical boundary of the resection will ultimately lie, and therefore cannot validly predict an involved CRM and should not be relied upon for this purpose.

Upfront systemic chemotherapy and preoperative short-course radiotherapy with delayed surgery for locally advanced rectal cancer with distant metastases

BACKGROUND

Choosing the most effective approach for treating rectal cancer with mesorectal fascia (MRF) involvement or closeness and synchronous distant metastases is a current clinical challenge. The aim of this retrospective study was to determine if upfront systemic chemotherapy and short-course radiotherapy (RT) with delayed surgery enables R0 resection.

METHODS

Between March 2009 and October 2009, six patients were selected for upfront chemotherapy and short-course RT (5 × 5 Gy) with delayed surgery. The patients had locally advanced primary tumors with MRF involvement or closeness, as well as synchronous and potentially resectable distant metastases. Chemotherapy was administered to five patients between the end of the RT and surgery. All patients underwent total mesorectal excision (TME).

RESULTS

The median patient age was 54 years (range 39-63). All primary and metastatic lesions were resected simultaneously. The median duration between short-course RT and surgery was 13 weeks (range, 7-18). R0 resection of rectal lesions was achieved in 5 patients. One patient, who had a very low-lying tumor, had an R1 resection. The median follow-up duration for all patients was 16.7 months (range, 15.5-23.5). One patient developed liver metastasis at 15.7 months. There have been no local recurrences or deaths.

CONCLUSIONS

Upfront chemotherapy and short course RT with delayed surgery is a valuable alternative treatment approach for patients with MRF involvement or closeness of rectal cancer with distant metastases.

Magnetic resonance imaging (MRI) in rectal cancer: a comprehensive review

Magnetic resonance imaging (MRI) has established itself as the primary method for local staging in patients with rectal cancer. This is due to several factors, most importantly because of the ability to assess the status of circumferential resection margin. There are several newer developments being introduced continuously, such as diffusion-weighted imaging and imaging with 3 T. Assessment of loco-regional lymph nodes has also been investigated extensively using different approaches, but more work needs to be done. Finally, evaluation of tumours during or after preoperative treatment is becoming an everyday reality. All these new aspects prompt a review of the most recent advances and opinions. In this review, a comprehensive overview of the current status of MRI in the loco-regional assessment and management of rectal cancer is presented. The findings on MRI and their accuracy are reviewed based on the most up-to-date evidence. Optimisation of MRI acquisition and relevant regional anatomy are also presented, based on published literature and our own experience.

Factors related to preoperative assessment of the circumferential resection margin and the extent of mesorectal invasion by magnetic resonance imaging in rectal cancer: a prospective comparison study

BACKGROUND

This study was designed to identify factors related to inaccurate prediction of circumferential resection margin (CRM) and the extent of mesorectal invasion (EMI) in T3 tumors by preoperative magnetic resonance imaging (MRI) in rectal cancer.

METHODS

A total of 66 patients with rectal cancer were enrolled prospectively in this study. CRM was defined as the distance from the outer tumor margin to the mesorectal fascia, and EMI was defined as the distance from the outer surface of the muscularis propria to the outermost tumor margin. CRM and EMI measurements on MRI were compared with corresponding measurements from whole-mount sections using 1-mm and 5-mm reference values, respectively, as prognostic indicators. The following variables were analyzed for relevance to preoperative staging: tumor distance from the anal verge (lower and middle), tumor location (anterior and posterior), tumor (T) and nodal (N) stage, and the thickness of the perirectal fat (anterior, left, right, and posterior positions).

RESULTS

MRI correctly predicted CRM status in 57 of the 66 tumors and EMI status in 51 of the 58 tumors (eight T1 tumors were excluded from EMI analysis). Univariate analysis showed that T3 stage, lymph node involvement, anterior tumor location, and thin perirectal fat thickness at the anterior portion were related to incorrect prediction of CRM. Anterior tumor location and thin perirectal fat thickness at the anterior portion were related to incorrect prediction of EMI.

CONCLUSIONS

Preoperative chemoradiation can be accurately guided by preoperative MRI staging, but CRM and EMI in anterior rectal tumor should be interpreted with caution.

Circumferential resection margin as a prognostic factor in rectal cancer

BACKGROUND

This study examined the prognostic impact of the circumferential resection margin (CRM) in patients with rectal cancer treated by total mesorectal excision (TME) with or without radiotherapy.

METHODS

A national population-based rectal cancer registry included 3196 patients with known CRM status between 1993 and 2004. Some 90.5 per cent of the patients had surgery alone and 9.5 per cent had preoperative radiotherapy. Patients who did not have TME, those in whom the CRM was not measured, patients with intraoperative bowel or tumour perforation and those who received postoperative radiotherapy were excluded.

RESULTS

Five-year local recurrence, distant metastasis and overall survival rates were 23.7, 43.9 and 44.5 per cent respectively for patients with a CRM of 0-2 mm, compared with 8.9, 21.7 and 66.7 per cent respectively for those with wider margins. A CRM of 2 mm or less had an impact on the prognosis of T2 and T3 tumours located 6-15 cm above the anal verge, but not on lower tumours. CRM also had a prognostic impact on the three endpoints in patients who received preoperative radiotherapy, but with less precision.

CONCLUSION

A CRM of 2 mm or less confers a poorer prognosis and patients should be considered for neoadjuvant treatment.

Tumor volume changes assessed by three-dimensional magnetic resonance volumetry in rectal cancer patients after preoperative chemoradiation: the impact of the volume reduction ratio on the prediction of pathologic complete response

PURPOSE

The aim of this study was to determine the correlation between tumor volume changes assessed by three-dimensional (3D) magnetic resonance (MR) volumetry and the histopathologic tumor response in rectal cancer patients undergoing preoperative chemoradiation therapy (CRT).

METHODS AND MATERIALS

A total of 84 patients who underwent preoperative CRT followed by radical surgery were prospectively enrolled in the study. The post-treatment tumor volume and tumor volume reduction ratio (% decrease ratio), as shown by 3D MR volumetry, were compared with the histopathologic response, as shown by T and N downstaging and the tumor regression grade (TRG).

RESULTS

There were no significant differences in the post-treatment tumor volume and the volume reduction ratio shown by 3D MR volumetry with respect to T and N downstaging and the tumor regression grade. In a multivariate analysis, the tumor volume reduction ratio was not significantly associated with T and N downstaging. The volume reduction ratio (>75%, p = 0.01) and the pretreatment carcinoembryonic antigen level (< or =3 ng/ml, p = 0.01), but not the post-treatment volume shown by 3D MR (< or = 5 ml), were, however, significantly associated with an increased pathologic complete response rate.

CONCLUSION

More than 75% of the tumor volume reduction ratios were significantly associated with a high pathologic complete response rate. Therefore, limited treatment options such as local excision or simple observation might be considered after preoperative CRT in this patient population.

The prognostic impact of the number of lymph nodes retrieved after neoadjuvant chemoradiotherapy with mesorectal excision for rectal cancer

BACKGROUND

We aimed to assess factors associated with the number of nodes retrieved and the impact of the number of lymph nodes in rectal cancer patients who underwent neoadjuvant chemoradiation with radical surgery.

METHODS

A total of 258 patients were enrolled. Lymph nodes were retrieved from specimens using a manual dissection technique.

RESULTS

Of the 258 patients, nine patients had an absence of lymph nodes (ypNx), 150 patients had a node-negative status (ypN(-)) and 99 patients had node-positive disease (ypN(+)). An advanced ypT classification (ypT3,4) and larger tumor (>4 cm) were associated with an increased number of nodes retrieved. The pretreatment CEA level (>5 ng/ml) and ypN(+) classification were significant risk factors for cancer specific and recurrence free survival. There was no significant difference of oncological outcomes among ypNx patients and a subset of ypN(-) patients based on the number of nodes retrieved using three cutoff values (1-11, 12-25, and 25-65 nodes).

CONCLUSIONS

In a neoadjuvant setting, ypN(+) disease was an independent risk factor for oncological outcomes. An absence of nodes does not represent an inferior oncological outcome. The number of nodes does not seen to impact survival and recurrence in ypN(-) patients.