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

Intersphincteric resection for very low rectal cancer: A review of the updated literature

Intersphincteric resection (ISR) has rapidly increased worldwide including laparoscopic surgery. However, there are some concerns for the definition of ISR, surgical technique, oncological outcome, anal function, and quality of life (QoL). The aim of the present study is to evaluate those issues. A review of this surgical technique was carried out by searching English language literature of the PubMed online database and appropriate articles were identified. With regard to open‐ISR, the morbidity rate ranged from 7.5% to 38.3%, with lower mortality rates. Local recurrence rates varied widely from 0% to 22.7%, with a mean follow‐up duration of 40–94 months. Disease‐free and overall 5‐year survival rates were 68–86% and 76–97%, respectively. Those outcomes were equivalent to laparoscopic‐ISR. Surgical and oncological outcomes of ISR were generally acceptable. However, accurate evaluation of anal function and QoL was difficult because of a lack of standard assessment of various patient‐related factors. The surgical and oncological outcomes after ISR seem to be acceptable. The ISR technique seems to be valid as an alternative to abdominoperineal resection in selected patients with a very low rectal cancer. However, both necessity for ISR and expectations of QoL impairment as a result of functional disorder should be fully discussed with patients before surgery.

Diagnostic Accuracy of MRI for Assessment of T Category and Circumferential Resection Margin Involvement in Patients With Rectal Cancer: A Meta-Analysis

BACKGROUND

The prognosis of rectal cancer is directly related to the stage of the tumor at diagnosis. Accurate preoperative staging is essential for selecting patients to receive optimal treatment.

OBJECTIVE

The purpose of this study was to evaluate the diagnostic performance of MRI in tumor staging and circumferential resection margin involvement in rectal cancer.

DATA SOURCES

A systematic literature search was performed in MEDLINE, EMBASE, PubMed, Cochrane Database of Systematic Reviews, and Web of Science database.

STUDY SELECTION

Original articles from 2000 to 2016 on the diagnostic performance of MRI in the staging of rectal cancer and/or assessment of mesorectal fascia status were eligible.

MAIN OUTCOME MEASURES

Pooled diagnostic statistics including sensitivity, specificity, positive likelihood ratio, and negative likelihood ratio were calculated for invasion of muscularis propria, perirectal tissue, and adjacent organs and for circumferential resection margin involvement through bivariate random-effects modeling. Summary receiver operating characteristic curves were fitted, and areas under summary receiver operating characteristic curves were counted to evaluate the diagnostic performance of MRI for each outcome.

RESULTS

Thirty-five studies were eligible for this meta-analysis. Preoperative MRI revealed the highest sensitivity of 0.97 (95% CI, 0.96-0.98) and specificity of 0.97 (95% CI, 0.96-0.98) for muscularis propria invasion and adjacent organ invasion. Areas under summary receiver operating characteristic curves indicated good diagnostic accuracy for each outcome, with the highest of 0.9515 for the assessment of adjacent organ invasion. Significant heterogeneity existed among studies. There was no notable publication bias for each outcome.

LIMITATIONS

This meta-analysis revealed relatively high diagnostic accuracy for preoperative MRI, although significant heterogeneity existed. Therefore, exploration should be focused on standardized interpretation criteria and optimal MRI protocols for future studies.

CONCLUSIONS

MRI showed relatively high diagnostic accuracy for preoperative T staging and circumferential resection margin assessment and should be reliable for clinical decision making.

Urogenital dysfunctions after treatment of rectal cancer

A significant part of rectal cancer survivors will experience urogenital dysfunction induced by the treatment. Significant progress has been made in order to improve the total mesorectal technique through different approaches (open, laparoscopic, robotic, transanal). Rectal cancer surgery is technically difficult notably deep in the pelvis, and therefore the most frequent cause of the postoperative dysfunction is the surgical nerve damage of the autonomic nerves at this level. The main objectives of these efforts were to obtain maximal oncological results and to achieve better functional outcomes including less postoperative urogenital dysfunctions. Our purpose was to build a comprehensive review of the existing literature data regarding this issue from past to present.

Identification of a DNA methylation signature to predict disease-free survival in locally advanced rectal cancer

In locally advanced rectal cancer a preoperative predictive biomarker is necessary to adjust treatment specifically for those patients expected to suffer relapse. We applied whole genome methylation CpG island array analyses to an initial set of patients (n=11) to identify differentially methylated regions (DMRs) that separate a good from a bad prognosis group. Using a quantitative high-resolution approach, candidate DMRs were first validated in a set of 61 patients (test set) and then confirmed DMRs were further validated in additional independent patient cohorts (n=71, n=42). We identified twenty highly discriminative DMRs and validated them in the test set using the MassARRAY technique. Ten DMRs could be confirmed which allowed separation into prognosis groups (p=0.0207, HR=4.09). The classifier was validated in two additional cohorts (n=71, p=0.0345, HR=3.57 and n=42, p=0.0113, HR=3.78). Interestingly, six of the ten DMRs represented regions close to the transcriptional start sites of genes which are also marked by the Polycomb Repressor Complex component EZH2. In conclusion we present a classifier comprising 10 DMRs which predicts patient prognosis with a high degree of accuracy. These data may now help to discriminate between patients that may respond better to standard treatments from those that may require alternative modalities.

Impact of Postoperative Chemoradiotherapy versus Chemotherapy Alone on Recurrence and Survival in Patients with Stage II and III Upper Rectal Cancer: A Propensity Score-Matched Analysis

Purpose

To compare the impact of postoperative chemoradiotherapy (CRT) versus adjuvant chemotherapy alone on recurrence and survival in patients with stage II and III upper rectal cancer undergoing curative resection.

Materials and Methods

From our institutional database, 190 patients who underwent primary curative resection between 2003 and 2010 for stage II or III upper rectal cancer were identified. None of the patients received preoperative CRT. Of these, 136 patients received postoperative chemotherapy alone (the CTx group) and 54 patients received postoperative CRT (the CRT group). The CRT group had poorer prognostic features (pT4, pN2, poor differentiation, or involved resection margin) compared with the CTx group. To reduce the impact of treatment selection bias on treatment outcomes, propensity score-matching analysis was used.

Results

The matched cohort consisted of 50 CRT and 50 CTx patients with a median follow-up period of 76 and 63 months, respectively. In the matched cohort, CRT resulted in an improved 5-year local control (98.0% vs. 85.2%, p = 0.024) and overall survival rate (89.9% vs. 69.8%, p = 0.021) compared with CTx. In the subgroup analysis to identify subpopulations of patients that benefit most from receiving CRT, local recurrence did not occur in patients who did not have poor prognostic features regardless of the receipt of CRT. For patients with any poor prognostic features, CRT resulted in an improved 5-year local control compared with CTx (96.4% vs. 70.7%, p = 0.013).

Conclusions

After adjusting for clinicopathologic factors by propensity score-matching, postoperative CRT was associated with improved local control and overall survival in stage II and III upper rectal cancer. Our results suggest that surgery followed by chemotherapy alone is acceptable for patients who did not have poor prognostic features, while additional radiotherapy should be given for patients who have any poor prognostic features.

Optimizing the selection of patients with low rectal cancer for intersphincteric resection by evaluating vertical invasion to the levator and external sphincter

AIM

The indications for intersphincteric (ISR) anterior resection are not clearly defined. The aim of this study was to evaluate vertical extension of T2 or T3 low rectal cancer treated by rectal amputation to optimize patient selection for ISR.

METHOD

The abdominoperineal excision specimens of T2 or T3 low rectal cancer from 53 patients treated between 1992 and 2004 were retrospectively reviewed. Vertical invasion was quantified by measuring the shortest distance between the tumour and the striated muscle (T-SM), assuming that this represented the surgical margin that would have be achieved had an ISR been performed.

RESULTS

Involvement of the dentate line (DL) and intramural distal spread were independent risk factors for T-SM ≤ 2 mm. The T-SM was less when the inferior border of the tumour was on the distal side of the DL (r = 0.572, P < 0.001). The probability of involvement of the DL, intramural distal spread or either one of these being associated with T-SM ≤ 2 mm was 43, 46 and 43%, respectively. All patients without both intramural distal spread and involvement of the DL had T-SM > 2.

CONCLUSION

We recommend that ISR should only be performed for patients with T2 or T3 low rectal cancer in whom the lowest edge of the tumour is above the DL and there is no intramural distal spread. Such patients are relatively unlikely to have a T-SM ≤ 2 mm.

MRI-based treatment of rectal cancer: is prognostication of the recurrence risk solid enough to render radiation redundant?

BACKGROUND

Most current guidelines recommend neoadjuvant short course radiotherapy (sRT) or radio-chemotherapy (nRCT) for rectal cancer stage II and III. After the introduction of total mesorectal excision (TME) and magnetic resonance imaging (MRI), this proceeding has been questioned and omission of neoadjuvant treatment according to preoperative MRI-criteria has been propagated. Aim of the present paper is to review the state of evidence regarding MRI-based treatment decision depending on the predicted width of the circumferential resection margin (CRM).

METHODS

A comprehensive survey of the literature was performed using the search terms "rectal cancer", "radiotherapy", "radio-chemotherapy", "MRI-based therapy", "circumferential resection margin". Data from lately published observational studies were compared to results from randomized trials and outcome analyses of the Norwegian national cancer registry.

RESULTS

Only one observational study using MRI-based treatment according to the anticipated CRM provided 5 year local recurrence data, however only for 65 patients. The second study did not yet evaluate recurrence rates. Two randomized trials comparing sRT to primary TME showed significantly worse outcome for non-irradiated patients. Data from the Norwegian rectal cancer registry demonstrate that TME alone is associated with higher LRR than achievable with preoperative RT.

CONCLUSIONS

Current evidence does not support the omission of neoadjuvant treatment for stage II-III rectal cancer on the basis of an MRI-predicted negative CRM. Randomized studies are warranted to clarify whether and for which subgroups TME alone is safe in terms of local recurrences.

Consensus statement on the multidisciplinary management of patients with recurrent and primary rectal cancer beyond total mesorectal excision planes

BACKGROUND

The management of primary rectal cancer beyond total mesorectal excision planes (PRC-bTME) and recurrent rectal cancer (RRC) is challenging. There is global variation in standards and no guidelines exist. To achieve cure most patients require extended, multivisceral, exenterative surgery, beyond conventional total mesorectal excision planes. The aim of the Beyond TME Group was to achieve consensus on the definitions and principles of management, and to identify areas of research priority.

METHODS

Delphi methodology was used to achieve consensus. The Group consisted of invited experts from surgery, radiology, oncology and pathology. The process included two international dedicated discussion conferences, formal feedback, three rounds of editing and two rounds of anonymized web-based voting. Consensus was achieved with more than 80 per cent agreement; less than 80 per cent agreement indicated low consensus. During conferences held in September 2011 and March 2012, open discussion took place on areas in which there is a low level of consensus.

RESULTS

The final consensus document included 51 voted statements, making recommendations on ten key areas of PRC-bTME and RRC. Consensus agreement was achieved on the recommendations of 49 statements, with 34 achieving consensus in over 95 per cent. The lowest level of consensus obtained was 76 per cent. There was clear identification of the need for referral to a specialist multidisciplinary team for diagnosis, assessment and further management.

CONCLUSION

The consensus process has provided guidance for the management of patients with PRC-bTME or RRC, taking into account global variations in surgical techniques and technology. It has further identified areas of research priority.

Rectal cancer : when is the local recurrence risk low enough to refrain from the aim to prevent it?

Recently, preliminary results of the OCUM study (optimized surgery and MRI-based multimodal therapy of rectal cancer) were published and raised concern in the scientific community. In this observational study, the circumferential resection margin status assessed in preoperative MRI (mrCRM) was used to decide for either total mesorectal excision (TME) alone or neoadjuvant radiochemotherapy (nRCT). In contrast to current guidelines, neither T3 stage (with negative CRM) nor clinically positive lymph nodes were an indication for nRCT. Pathologically node-positive patients received chemotherapy (ChT). Overall, 230 patients were included, of whom 96 CRM-positive patients received nRCT. The CRM was accurately predicted in MRI, the rate of mesorectal plane resection was high. Recurrence rates have not yet been reported, but an impressive rate of down-staging for both T and N stage after nRCT was observed, while acute side effects were minimal. Nonetheless, the authors conclude that a substantial number of patients could be "spared severe radiation toxicity" and propagate their concept for prospectively replacing current guidelines. This is based on the hypothesis that CRM is a valid surrogate parameter for the risk of local recurrence and in case of a negative CRM, nRCT becomes dispensable. Moreover, it is assumed that lymph node status is no more relevant. Both assumptions are a contradiction to recent data from randomized studies as specified below. As 5-year locoregional recurrence rate (LRR) of only of 5-8% and < 5% in low risk rectal cancer can be achieved by the addition of RT, the noninferiority of surgery alone can not be presumed unless the expected 5-year LRR is ≤ 5-8%, whereas any excess of this range renders the study design inacceptable. Unless a publication explicitly specifies 5-year LRR, results are not exploitable for clinical decisions.

Intersphincteric resection for very low rectal cancer: a systematic review

Radical surgical treatment for very low rectal cancer near the anus has generally involved abdominoperineal resection. Various sphincter-saving operations have been developed for such tumors to optimize the patients' postoperative quality of life. Current protocols focus on intersphincteric resection (ISR), which differs from conventional hand-sewn coloanal anastomosis (CAA) after low anterior resection. However, the efficacy of ISR remains unclear. The surgical, oncologic, and functional outcomes after intersphincteric resection (ISR) were reviewed. This review of the current literature was conducted by searching the PubMed online database. Articles focusing specifically on conventional hand-sewn CAA were excluded from this study. The mean mortality rate is <2 %, and the mean morbidity rate ranges from 7.7 to 38.3 %. The mean local recurrence rate varies widely from 0 to 22.7 %, with a mean follow-up duration of 40-94 months. The mean disease-free and overall 5-year survival rates are 69-86 and 79-97 months, respectively. Functional outcomes are generally acceptable, but accurate evaluation is extremely difficult due to the absence of unified appraisal methods. ISR appears surgically, oncologically and functionally acceptable. However, more experience and better understanding of the oncology, anal physiology, and pelvic anatomy are necessary to achieve successful outcomes without complications, and to improve patient survival.

Rectal Cancer: MR imaging of the mesorectal fascia and effect of chemoradiation on assessment of tumor involvement

PURPOSE

To evaluate the impact of chemoradiation on the reliability of MRI in assessing tumor involvement of the mesorectal fascia in patients with rectal cancer.

MATERIALS AND METHODS

Presurgical MRI was performed in 150 patients; among them 85 had received neoadjuvant long-course chemoradiation. A standardized imaging protocol (1.5 Tesla [T] system, image voxel size 0.6 × 0.4 × 3 mm(3) ), standardized surgery, and histopathological examination were applied for the entire patient population. Images were analyzed to identify potential tumor involvement of the mesorectal fascia (minimum tumor distance to fascia ≤1 mm) and compared with histopathology as the reference standard. Results of nonirradiated and irradiated patients were compared to define the impact of chemoradiation on imaging reliability.

RESULTS

In nonirradiated patients, MRI was reliable in predicting or excluding tumor involvement of the mesorectal fascia, positive predictive value 80%, negative predictive value 89%. The frequency of overestimating tumor involvement was significantly higher in irradiated patients (P = 0.005, positive predictive value 42%).

CONCLUSION

Discussions about MRI assessment of tumor involvement of the mesorectal fascia as a basis for recommending neoadjuvant chemoradiation should focus on investigations that excluded irradiated patients, because MRI is less reliable after chemoradiation and tends to overestimate mesorectal tumor involvement.

Diagnostic accuracy of MRI for assessment of T category, lymph node metastases, and circumferential resection margin involvement in patients with rectal cancer: a systematic review and meta-analysis

BACKGROUND

Magnetic resonance imaging (MRI) is increasingly being used for rectal cancer staging. The purpose of this study was to determine the accuracy of phased array MRI for T category (T1-2 vs. T3-4), lymph node metastases, and circumferential resection margin (CRM) involvement in primary rectal cancer.

METHODS

Medline, Embase, and Cochrane databases were searched using combinations of keywords relating to rectal cancer and MRI. Reference lists of included articles were also searched by hand. Inclusion criteria were: (1) original article published January 2000-March 2011, (2) use of phased array coil MRI, (3) histopathology used as reference standard, and (4) raw data available to create 2×2 contingency tables. Patients who underwent preoperative long-course radiotherapy or chemoradiotherapy were excluded. Two reviewers independently extracted data. Sensitivity, specificity, and diagnostic odds ratio were estimated for each outcome using hierarchical summary receiver-operating characteristics and bivariate random effects modeling.

RESULTS

Twenty-one studies were included in the analysis. There was notable heterogeneity among studies. MRI specificity was significantly higher for CRM involvement [94%, 95% confidence interval (CI) 88-97] than for T category (75%, 95% CI 68-80) and lymph nodes (71%, 95% CI 59-81). There was no significant difference in sensitivity between the three elements as a result of wide overlapping CIs. Diagnostic odds ratio was significantly higher for CRM (56.1, 95% CI 15.3-205.8) than for lymph nodes (8.3, 95% CI 4.6-14.7) but did not differ significantly from T category (20.4, 95% CI 11.1-37.3).

CONCLUSIONS

MRI has good accuracy for both CRM and T category and should be considered for preoperative rectal cancer staging. In contrast, lymph node assessment is poor on MRI.