Occurrence and prognostic value of circumferential resection margin involvement for patients with rectal cancer

Progress of MRI in predicting the circumferential resection margin of rectal cancer: A narrative review

Rectal cancer (RC) is the third most frequently diagnosed cancer worldwide, and the status of its circumferential resection margin (CRM) is of paramount significance for treatment strategies and prognosis. CRM involvement is defined as tumor touching or within 1 mm from the outermost part of tumor or outer border of the mesorectal or lymph node deposits to the resection margin. The incidence of involved CRM varied from 5.4 % to 36 %, which may associate with an in consistent definition of CRM, the quality of surgeries, and the different examination modalities. Although T and N status are essential factors in determining whether a patient should receive neoadjuvant therapy before surgery, CRM status is a powerful predictor of local and distant recurrence as well as survival rate. This review explores the significance of CRM, the various assessment methods, and the role of magnetic resonance imaging (MRI) and artificial intelligence-based MRI in predicting CRM status. MRI showed potential advantage in predicting CRM status with a high sensitivity and specificity compared to computed tomography (CT). We also discuss MRI advancements in RC imaging, including conventional MRI with body coil, high-resolution MRI with phased-array coil, and endorectal MRI. Along with a discussion of artificial intelligence-based MRI techniques to predict the CRM status of RCs before and after treatments.

The Prognostic Value of Circumferential Resection Margin Involvement in Patients with Extraperitoneal Rectal Cancer

The prognostic influence of circumferential resection margin (CRM) status in extraperitoneal rectal cancer probably differs from that of intraperitoneal rectal cancer because of its different anatomical and biological behaviors. However, previous reports have not provided the data focused on extraperitoneal rectal cancer. Therefore, the aim of this study was to examine the prognostic significance of the CRM status in patients with extraperitoneal rectal cancer. From January 2005 to December 2008, 248 patients were treated for extraperitoneal rectal cancer and enrolled in a pro-spectively collected database. Extraperitoneal rectal cancer was defined based on tumors located below the anterior peritoneal reflection, as determined intraoperatively by a surgeon. Cox model was used for multivariate analysis to examine risk factors of recurrence and mortality in the 248 patients, and multivariate logistic regression analysis was performed to identify predictors of recurrence and mortality in 135 patients with T3 rectal cancer. CRM involvement for extraperitoneal rectal cancer was present in 29 (11.7%) of the 248 patients, and was the identified predictor of local recurrence, overall recurrence, and death by multivariate Cox analysis. In the 135 patients with T3 cancer, CRM involvement was found to be associated with higher probability of local recurrence and mortality. In extraperitoneal rectal cancer, CRM involvement is an independent risk factor of recurrence and survival. Based on the results of the present study, it seems that CRM involvement in extraperitoneal rectal cancer is considered an indicator for (neo)adjuvant therapy rather than conventional TN status.

Significance of R1 resection margin in colon cancer resections in the modern era

AIM

Circumferential resection margin involvement (R1) in rectal cancer is a predictive factor for poor prognosis. The aim of this study was to confirm the prognostic significance of R1 in colon cancer resection and to establish whether the introduction of laparoscopic colorectal surgery influenced this.

METHOD

Prospectively collected data on a patient pathway data manager for sequential patients with colon cancer treated at our specialist unit from January 2005 to December 2010 were analysed. There were 1110 colonic resections (elective 865; emergency 245). A circumferential resection margin involvement of < 1 mm was considered positive.

RESULTS

The total R1 rate was 13.3% (elective 10.4%; emergency 23.6%; P < 0.001). Other statistically significant risk factors for an R1 resection included tumour perforation (P < 0.001), poorly differentiated carcinoma (P < 0.001), T4 tumour (P < 0.001), vascular invasion (P < 0.001), lymph node metastasis (P < 0.001), distant metastasis (P < 0.001) and palliative resection (P < 0.001). Over half of the elective resections were undertaken laparoscopically (486/865; 56.2%). When compared with elective open resection (379/865; 43.8%), the R1 rate was similar (P = 0.491) with similar disease-free survival (DFS) and overall survival (OS). The overall relapse rate was 18.9% in R0 and 55.5% in R1 resections (P < 0.001). Kaplan-Meier survival analysis showed significant improvements in DFS and OS in R0 over R1 patients.

CONCLUSION

The R1 margin in colon cancer resection is an important marker for advanced disease and a prognostic factor for DFS and OS. The introduction of laparoscopic surgery has not influenced the outcome in our unit despite a complex case mix.

Long-term oncologic outcomes of laparoscopic vs open surgery for stages II and III rectal cancer: A retrospective cohort study

AIM: To evaluate the 5-year survival after laparoscopic surgery vs open surgery for stages II and III rectal cancer.

METHODS: This study enrolled 406 consecutive patients who underwent curative resection for stages II and III rectal cancer between January 2000 and December 2009 [laparoscopic rectal resection (LRR), n = 152; open rectal resection (ORR), n = 254]. Clinical characteristics, operative outcomes, pathological outcomes, postoperative recovery, and 5-year survival outcomes were compared between the two groups.

RESULTS: Most of the clinical characteristics were similar except age (59 years vs 55 years, P = 0.033) between the LRR group and ORR group. The proportion of anterior resection was higher in the LRR group than that in the ORR group (81.6% vs 66.1%, P = 0.001). The LRR group had less estimated blood loss (50 mL vs 200 mL, P < 0.001) and a lower rate of blood transfusion (4.6% vs 11.8%, P = 0.019) compared to the ORR group. The pathological outcomes of the two groups were comparable. The LRR group was associated with faster recovery of bowel function (2.8 d vs 3.7 d, P < 0.001) and shorter postoperative hospital stay (11.7 d vs 13.7 d, P < 0.001). The median follow-up time was 63 mo in the LRR group and 65 mo in the ORR group. As for the survival outcomes, the 5-year local recurrence rate (16.0% vs 16.4%, P = 0.753), 5-year disease-free survival (DFS) rate (63.0% vs 63.1%, P = 0.589), and 5-year overall survival (OS) rate (68.1% vs 63.5%, P = 0.682) were comparable between the LRR group and the ORR group. Stage by stage, there were also no statistical differences between the LRR group and the ORR group in terms of the 5-year local recurrence rate (stage II: 6.3% vs 8.7%, P = 0.623; stage III: 26.4% vs 23.2%, P = 0.747), 5-year DFS rate (stage II: 77.5% vs 77.6%, P = 0.462; stage III: 46.5% vs 50.9%, P = 0.738), and 5-year OS rate (stage II: 81.4% vs 74.3%, P = 0.242; stage III: 53.9% vs 54.1%, P = 0.459).

CONCLUSION: LRR for stages II and III rectal cancer can yield comparable long-term survival while achieving short-term benefits compared to open surgery.

The multidisciplinary approach to the treatment of rectal cancer: 2015 update

The multidisciplinary approach to the management of rectal cancer continues to evolve with developments in surgery, radiation therapy as well as systemic chemotherapy. Refinement of surgical techniques to improve organ preservation, selective use of neoadjuvant (or adjuvant) therapies, improvements in staging modalities and emerging criteria for the selection of tailored therapies are some of the advancements made over the last three decades. In addition, neoadjuvant treatment alternatives, multimodality sequencing and adaptive therapies based on treatment response continue to be a subject of clinical investigation. The current article reviews the salient topics related to the multidisciplinary treatment of resectable rectal cancer.

Risk factors of circumferential resection margin involvement in the patients with extraperitoneal rectal cancer

Purpose

Currently, circumferential resection margins (CRM) are used as a clinical endpoint in studies on the prognosis of rectal cancer. Although the concept of a circumferential resection margin in extraperitoneal rectal cancer differs from that in intraperitoneal rectal cancer due to differences in anatomical and biologic behaviors, previous reports have provided information on CRM involvement in all types of rectal cancer including intraperitoneal lesions. Therefore, the aim of this study was to analyze risk factors of CRM involvement in extraperitoneal rectal cancer.

Methods

From January 2005 to December 2008, 306 patients with extraperitoneal rectal cancer were enrolled in a prospectively collected database. Multivariate logistic regression analysis was used to identify predictors of CRM involvement.

Results

The overall rate of CRM involvement was found to be 16.0%. Multivariate analysis showed that male sex, larger tumor size (≥4 cm), stage higher than T3, nodal metastasis, tumor perforation and non-sphincter preserving proctectomy (NSPP) were risk factors for CRM involvement.

Conclusion

Male sex, larger tumor size (≥4 cm), advanced T stage, nodal metastasis, tumor perforation, and NSPP are significant risk factors of CRM involvement in extraperitoneal rectal cancer. Given that postoperative chemoradiotherapy is recommended for patients with a positive CRM, further oncologic studies are warranted to ascertain which patients with these risk factors would require adjuvant therapy.

Primary staging and response assessment postchemoradiotherapy in rectal cancer

SUMMARY Initial assessment of newly diagnosed patients with rectal cancer includes clinical examination, colonoscopy, pelvic MRI and CT scan of the thorax, abdomen and pelvis. Radiological staging can objectively evaluate both surgical and biological prognostic features of rectal cancer. MRI has emerged to be the most useful preoperative prognostic staging tool and it can predict the risk of tumor involvement of surgical circumferential resection margin. An agreed definition of favorable tumor response to chemoradiotherapy is controversial. The importance of detecting and assessing good versus poor responders to chemoradiotherapy is of increasing relevance. MRI has been found to be useful in assessing tumor response postchemoradiotherapy, especially the assessment of potential circumferential resection margin and magnetic resonance tumor regression grade. These imaging markers predict survival outcomes for good and poor responders and provide an opportunity for clinicians to offer additional neoadjuvant and adjuvant treatments to reduce local or distance failure for the poor responders.

Perspectives on current tumor-node-metastasis (TNM) staging of cancers of the colon and rectum

Improvements in classifications of cancers based on discovery and validation of important histopathological parameters and new molecular markers continue unabated. Though still not perfect, recent updates of classification schemes in gastrointestinal oncology by the American Joint Commission on Cancer (tumor-node-metastasis [TNM] staging) and the World Health Organization further stratify patients and guide optimization of treatment strategies and better predict patient outcomes. These updates recognize the heterogeneity of patient populations with significant subgrouping of each tumor stage and use of tumor deposits to significantly "up-stage" some cancers; change staging parameters for subsets of IIIB and IIIC cancers; and introduce of several new subtypes of colon carcinomas. By the nature of the process, recent discoveries that are important to improving even routine standards of patient care, especially new advances in molecular medicine, are not incorporated into these systems. Nonetheless, these classifications significantly advance clinical standards and are welcome enhancements to our current methods of cancer reporting.

Clinical characteristics of rectal cancer involving the anal canal

BACKGROUND

This study evaluates the clinical characteristics of rectal cancer involving the anal canal.

METHODS

A total of 346 consecutive patients with primary low rectal cancer located below the peritoneal reflection were reviewed in this study. Patients were divided into two groups according to whether the lower edge of the tumor came in contact with the anal canal (P group, n = 78) or not (Rb group, n = 268). Clinical and pathological parameters, recurrence rates, and survival rates were compared between the two groups.

RESULTS

The occurrence of uncommon histological types of tumor was significantly higher in the P group than in the Rb group. P group patients also had a significantly higher lateral pelvic node metastasis rate (p < 0.001), lower 5-year overall survival rate (p = 0.0491), and higher 5-year local recurrence rate (p = 0.0171) than Rb group patients. Multivariate analysis revealed that tumor location was a significant risk factor for local recurrence. In the P group, multivariate analysis showed that uncommon histological tumor types were a significant prognostic factor.

CONCLUSION

Rectal cancer involving the anal canal should be treated with special care, considering the particularly high lateral pelvic lymph node metastasis rate and high local recurrence rate.

Multidisciplinary treatment of resectable rectal cancer

This review identifies evidence that influences current practices in the multidisciplinary treatment and shapes future directions in the treatment of resectable rectal cancer. Recent advances in surgery, radiotherapy and systemic chemotherapy have provided measurable improvements in disease control, functional outcomes and quality of life for patients with rectal cancer. However, controversies remain regarding the optimum delivery of adjuvant therapies. Preoperative radiation either with or without concurrent chemotherapy demonstrates lower recurrence, with minimal survival benefit. Currently, the use of neoadjuvant standard fractionation chemoradiation versus short-course radiation without chemotherapy is controversial and under investigation. New combinations of chemotherapeutic agents and targeted therapies are also being evaluated. In addition, criteria for patient selection are being re-evaluated to determine the relative benefit of modern treatments, so that we may better tailor adjuvant therapy recommendations to be patient-specific. Recommendations for adjuvant treatments of rectal cancer are continuing to evolve; however, survival has been only marginally affected despite low incidence of local recurrence. Future trials should aim to address the role of adjuvant therapies utilizing new criteria, such as function, quality of life and impact on development of metastatic disease.