Adverse features on rectal MRI identify a high-risk group that may benefit from more intensive preoperative staging and treatment

Clinical outcomes of neoadjuvant chemoradiotherapy followed by total mesorectal excision in locally advanced rectal cancer with mesorectal fascia involvement

PURPOSE

For the treatment of locally advanced rectal cancer (LARC), research on primary lesions with mesorectal fascia (MRF) involvement is lacking. This study analyzed the clinical outcomes and efficacy of dose-escalated neoadjuvant concurrent chemoradiotherapy (NCRT) to patients with LARC involving MRF.

MATERIALS AND METHODS

We retrospectively reviewed 301 patients who were diagnosed with LARC involving MRF and underwent NCRT followed by total mesorectal excision (TME). Patients who received radiotherapy (RT) doses of ≤50.4 Gy were defined as the non-boost group, while ≥54.0 Gy as the boost group. Pathological tumor response and survival outcomes, including intrapelvic recurrence-free survival (IPRFS), distant metastases-free survival (DMFS) and overall survival (OS), were analyzed.

RESULTS

A total of 269 patients (89.4%) achieved a negative pathological circumferential resection margin and 104 (34.6%) had good pathological tumor regression grades. With a median follow-up of 32.4 months, IPRFS, DMFS, and OS rates at 5-years were 88.6%, 78.0%, and 91.2%, respectively. In the subgroup analysis by RT dose, the boost group included more advanced clinical stages of patients. For the non-boost group and boost group, 5-year IPRFS rates were 90.3% and 87.0% (p = 0.242), 5-year DMFS rates were 82.0% and 71.3% (p = 0.105), and 5-year OS rates were 93.0% and 80.6% (p = 0.439), respectively. Treatment related toxicity was comparable between the two groups (p = 0.211).

CONCLUSION

Although this retrospective study failed to confirm the efficacy of dose-escalated NCRT, favorable IPRFS and pathological complete response was achieved with NCRT followed by TME. Further studies combining patient customized RT dose with systemic therapies are needed.

Neoadjuvant treatment of colorectal cancer: comprehensive review

BACKGROUND

Neoadjuvant therapy has an established role in the treatment of patients with colorectal cancer. However, its role continues to evolve due to both advances in the available treatment modalities, and refinements in the indications for neoadjuvant treatment and subsequent surgery.

METHODS

A narrative review of the most recent relevant literature was conducted.

RESULTS

Short-course radiotherapy and long-course chemoradiotherapy have an established role in improving local but not systemic disease control in patients with rectal cancer. Total neoadjuvant therapy offers advantages over short-course radiotherapy and long-course chemoradiotherapy, not only in terms of increased local response but also in reducing the risk of systemic relapses. Non-operative management is increasingly preferred to surgery in patients with rectal cancer and clinical complete responses but is still associated with some negative impacts on functional outcomes. Neoadjuvant chemotherapy may be of some benefit in patients with locally advanced colon cancer with proficient mismatch repair, although patient selection is a major challenge. Neoadjuvant immunotherapy in patients with deficient mismatch repair cancers in the colon or rectum is altering the treatment paradigm for these patients.

CONCLUSION

Neoadjuvant treatments for patients with colon or rectal cancers continue to evolve, increasing the complexity of decision-making for patients and clinicians alike. This review describes the current guidance and most recent developments.

An MRI-based scoring system for pretreatment risk stratification in locally advanced rectal cancer

BACKGROUND

Accurately assessing the risk of recurrence in patients with locally advanced rectal cancer (LARC) before treatment is important for the development of treatment strategies. The purpose of this study is to develop an MRI-based scoring system to predict the risk of recurrence in patients with LARC.

METHODS

This was a multicenter observational study that enrolled participants who underwent neoadjuvant chemoradiotherapy. To evaluate the risk of recurrence in these patients, we developed the mrDEC scoring system and assessed inter-reader agreement. Additionally, we plotted Kaplan-Meier curves to compare the 3-year disease-free survival (DFS) and 5-year overall survival (OS) rates among patients with different mrDEC scores.

RESULTS

A total of 1287 patients with LARC were included in this study. We observed substantial inter-reader agreement for mrDEC. Based on the mrDEC scores ranging from 0 to 3, the patients were categorized into four groups. The 3-year DFS rates for the groups were 91.0%, 79.5%, 65.5%, and 44.0% (P < 0.0001), respectively, and the 5-year OS rates were 92.9%, 87.1%, 74.8%, and 44.5%, respectively (P < 0.0001).

CONCLUSIONS

The mrDEC scoring system proved to be an effective tool for predicting the prognosis of patients with LARC and can assist clinicians in clinical decision-making.

Minimum radial margin in pelvic exenteration for locally advanced or recurrent rectal cancer

PURPOSE

The aim of this study was to clarify the suitable radial margin (RM) for favourable outcomes after pelvic exenteration (PE), focusing on the discrepancy between the concepts of circumferential resection margin (CRM) and traditional R status.

METHODS

Seventy-three patients with locally advanced (LARC, n = 24) or locally recurrent rectal cancer (LRRC, n = 49) who underwent PE between 2006 and 2018 were retrospectively analysed. Patients were histologically classified into the following 3 groups; wide RM (≥1 mm, n = 45), narrow RM (0-1 mm, n = 10), and exposed RM (n = 18). The analysis was performed not only in the entire cohort but also in each disease group separately.

RESULTS

The rates of traditional R0 (RM > 0 mm) and wide RM were 75.3% and 61.6%, respectively, resulting in the discrepancy rate of 13.7% between the two concepts. Preoperative radiotherapy was given in 12.3%. In the entire cohort, the local recurrence and overall survival (OS) rates for narrow RMs were significantly worse than those for wide RMs (p < 0.001 and p = 0.002), but were similar to those for exposed RMs. In both LARC and LRRC, RM < 1 mm resulted in significantly worse local recurrence and OS rates compared to the wide RMs. Multivariate analysis showed that RM < 1 mm was an independent risk factor for local recurrence in both LARC (HR 15.850, p = 0.015) and LRRC (HR 4.874, p = 0.005).

CONCLUSIONS

Narrow and exposed RMs had an almost equal impact on local recurrence and poor OS after PE. Preoperative radiotherapy might have a key role to ensure a wide RM.

Induction chemotherapy with capecitabine and oxaliplatin followed by chemoradiotherapy before surgery in patients with locally advanced rectal cancer

BACKGROUND

Locally advanced rectal cancer (LARC) has a high incidence of local and distant relapse even after adequate treatment. The emerging role of neoadjuvant induction chemotherapy may allow initial down staging of the primary tumor, less toxicity and early treatment of micrometastatic disease followed by chemoradiation with the hope of increased complete response rates before surgery OBJECTIVES: To identify the effect of induction chemotherapy before concurrent chemoradiation (CCRTH) in locally advanced rectal cancer in terms of response and toxicity. Primary end point is assessment of pathological complete response rate after surgery. Secondary end points are disease free survival (DFS) and overall survival (OS) after 3 years follow up.

PATIENTS AND METHODS

Patients with MRI based criteria for staging high-risk LARC (T4 tumors, tumors within 2 mm of mesorectal fascia, T3 tumors at or below levators and T2-4 with LN +ve tumors) were included. Thirty-five patients were recruited. Patients received 12 weeks of induction capecitabine/oxaliplatin followed by concomitant capecitabine and conventional 3D-conformal radiotherapy. Surgery was done at least 6 weeks later .

RESULTS

Five patients (20.8%) had a pathological complete response (TRG 0) (ypT0N0). Another three patients (12.5%) had near complete pathological response (TRG 1). Regarding OS and pathological complete response corrlelation, it was statistically not significant in relation to patients with incomplete pathological response (p = 1).

CONCLUSION

Induction chemotherapy could be a promising option for better response rates either clinical or pathological for high risk LARC patients with acceptable toxicity.

ACR Appropriateness Criteria® Staging of Colorectal Cancer: 2021 Update

Preoperative imaging of rectal carcinoma involves accurate assessment of the primary tumor as well as distant metastatic disease. Preoperative imaging of nonrectal colon cancer is most beneficial in identifying distant metastases, regardless of primary T or N stage. Surgical treatment remains the definitive treatment for colon cancer, while organ-sparing approach may be considered in some rectal cancer patients based on imaging obtained before and after neoadjuvant treatment. The American College of Radiology Appropriateness Criteria are evidence-based guidelines for specific clinical conditions that are reviewed annually by a multidisciplinary expert panel. The guideline development and revision include an extensive analysis of current medical literature from peer reviewed journals and the application of well-established methodologies (RAND/UCLA Appropriateness Method and Grading of Recommendations Assessment, Development, and Evaluation or GRADE) to rate the appropriateness of imaging and treatment procedures for specific clinical scenarios. In those instances where evidence is lacking or equivocal, expert opinion may supplement the available evidence to recommend imaging or treatment.

Oncologic Outcomes Associated With MRI-detected Extramural Venous Invasion (mrEMVI) in Rectal Cancer: A Systematic Review and Meta-analysis

BACKGROUND

The role of MRI-detected EMVI (mrEMVI) as a reliable prognostic factor in rectal cancer has been emphasized in recent years but this finding remains underreported by many institutions.

OBJECTIVE

This review aimed to demonstrate the importance of pre- and post-treatment MRI-detected EMVI as independent prognostic factors of adverse oncologic outcomes in patients undergoing neoadjuvant therapy followed by total mesorectal excision.

METHODS

This review was designed using the PRISMA guidelines. The following electronic databases were searched from January 2002 to January 2020: CENTRAL, Ovid MEDLINE, PubMed, and Ovid Embase. Main outcomes included DFS and overall survival (OS). Other outcomes of interest comprised positive resection margin and synchronous metastases.

RESULTS

Seventeen studies involving a total of 3821 patients were included for data synthesis. For preneoadjuvant treatment mrEMVI, pooled hazard ratio (HR) estimate for DFS was 2.30 (95% confidence intervals (CI) 1.54-3.44) for higher recurrence in mrEMVI-positive patients. mrEMVI-positive patients were found to have a lower OS with a pooled HR of 1.68 (95%CI 1.27-2.22). Pooled risk ratio for synchronous metastasis was 4.11 (95%CI 2.80-6.02) for mrEMVI-positivity. For postneoadjuvant treatment EMVI (ymrEMVI), positive status showed a lower DFS with a pooled HR of 2.04 (95%CI 1.55-2.69). Risk ratio of having a positive resection margin status was 2.95 (95%CI 1.75-4.98) for ymrEMVI-positive patients.

CONCLUSIONS

This review showed that oncologic outcomes are significantly worse for both pre- and post-neoadjuvant treatment mrEMVI-positive patients. MRI-detected EMVI should be consistently reported in rectal cancer staging and may provide guidance for the targeted use of additional systemic therapy.

Prognostic Significance of EMVI in Rectal Cancer in a Tertiary Cancer Hospital in India

Background  Presence of extramural venous invasion (EMVI) is a poor prognostic factor for rectal cancer as per literature. However, India-specific data are lacking.

Aim  The aim of the study is to determine the prognostic significance of EMVI in locally advanced rectal cancer on baseline MRI.

Materials and Methods  We retrospectively reviewed 117 MRIs of operable non-metastatic locally advanced rectal cancers in a tertiary cancer institute. Three dedicated oncoradiologists determined presence or absence of EMVI, and its length and thickness, in consensus. These patients were treated as per standard institutional protocols and followed up for a median period of 37 months (range: 2–71 months). Kaplan-Meier curves (95% CI) were used to determine disease-free survival (DFS), distant-metastases free survival (DMFS), and overall survival (OS). Univariate analysis was performed by comparing groups with log-rank test.

Results  EMVI positive cases were 34/114 (29%). More EMVI-positive cases developed distant metastasis compared with EMVI-negative cases (14/34–41% vs. 22/83–26%). The difference, however, was not statistically significant ( p  = 0.146). After excluding signet-ring cell cancers ( n  = 14), EMVI showed significant correlation with DMFS ( p  = 0.046), but not with DFS or OS. The median thickness and length of EMVI was 6 and 14 mm, respectively in patients who developed distant metastasis, as compared with 5 and 11 mm in those who did not, although this difference was not statistically significant.

Conclusion  EMVI is a predictor of distant metastasis in locally advanced non-metastatic, non-signet ring cell rectal cancers. EMVI can be considered another high-risk feature to predict distant metastasis.

Value of Primary Rectal Tumor PET/MRI in the Prediction of Synchronic Metastatic Disease

PURPOSE

To analyze the associations between positron emission tomography (PET)/magnetic resonance imaging (MRI) features for primary rectal tumors and metastases.

PROCEDURES

Between November 2016 and April 2018, 101 patients with rectal adenocarcinoma were included in this prospective study (NCT02537340) for whole-body PET/MRI for baseline staging. Two readers analyzed the PET/MRI; they assessed the semiquantitative PET features of the primary tumor and the N- and M-stages. Another reader analyzed the MRI features for locoregional staging. The reference standard for confirming metastatic disease was biopsy or imaging follow-up. Non-parametric tests were used to compare the PET/MRI features of the participants with or without metastatic disease. Binary logistic regression was used to evaluate the associations between the primary tumor PET/MRI features and metastatic disease.

RESULTS

A total of 101 consecutive participants (median age 62 years; range: 33-87 years) were included. Metastases were detected in 35.6% (36 of 101) of the participants. Among the PET/MRI features, higher tumor lesion glycolysis (352.95 vs 242.70; P = .46) and metabolic tumor volume (36.15 vs 26.20; P = .03) were more frequent in patients with than in those without metastases. Additionally, patients with metastases had a higher incidence of PET-positive (64% vs 32%; P = .009) and MRI-positive (56% vs 32%; P = .03) mesorectal lymph nodes, extramural vascular invasion (86% vs 49%; P > .001), and involvement of mesorectal fascia (64% vs 42%; P = .04); there were also differences between the mrT stages of these two groups (P = .008). No differences in the maximum standardized uptake values for the primary tumors in patients with and without metastases were observed (18.9 vs 19.1; P = .56). Multivariable logistic regression showed that extramural vascular invasion on MRI was the only significant predictor (adjusted odds ratio, 3.8 [95% CI: 1.1, 13.9]; P = .001).

CONCLUSION

PET/MRI facilitated the identification of participants with a high risk of metastatic disease, though these findings were based mainly on MRI features.

MRI-detected extramural venous invasion of rectal cancer: Multimodality performance and implications at baseline imaging and after neoadjuvant therapy

MRI is routinely used for rectal cancer staging to evaluate tumor extent and to inform decision-making regarding surgical planning and the need for neoadjuvant and adjuvant therapy. Extramural venous invasion (EMVI), which is intravenous tumor extension beyond the rectal wall on histopathology, is a predictor for worse prognosis. T2-weighted images (T2WI) demonstrate EMVI as a nodular-, bead-, or worm-shaped structure of intermediate T2 signal with irregular margins that arises from the primary tumor. Correlative diffusion-weighted images demonstrate intermediate to high signal corresponding to EMVI, and contrast enhanced T1-weighted images demonstrate tumor signal intensity in or around vessels. Diffusion-weighted and post contrast images may increase diagnostic performance but decrease inter-observer agreement. CT may also demonstrate obvious EMVI and is potentially useful in patients with a contraindication for MRI. This article aims to review the spectrum of imaging findings of EMVI of rectal cancer on MRI and CT, to summarize the diagnostic accuracy and inter-observer agreement of imaging modalities for its presence, to review other rectal neoplasms that may cause EMVI, and to discuss the clinical significance and role of MRI-detected EMVI in staging and restaging clinical scenarios.

Prognostic Implications of MRI-Detected EMVI and Tumor Deposits and Their Response to Neoadjuvant Therapy in cT3 and cT4 Rectal Cancer

PURPOSE

Magnetic resonance imaging-detected extramural venous invasion (mrEMVI) and tumor deposits (TDs) are risk factors for the development of local recurrence and distant metastases (DMs) in rectal cancer. However, little is known about their response to neoadjuvant treatment and its relation to oncologic outcomes. This study evaluated the incidence and features of mrEMVI and TDs before and after neoadjuvant treatment in relation to the development of local recurrence and DMs.

METHODS AND MATERIALS

Patients with cT3/4 rectal cancer without synchronous metastases who underwent surgery in a tertiary referral hospital were retrospectively analyzed. MRI scans were re-evaluated for the presence of mrEMVI, the occurrence of TDs, and response to neoadjuvant therapy (mr-vTRG).

RESULTS

In total, 277 patients were included, of whom 163 (58.8%) presented with mrEMVI. TDs were present in 56.4% of mrEMVI-positive and 9.6% of mrEMVI-negative patients (P < .001). The 5-year DM rate was significantly higher in mrEMVI-positive patients with and without TDs (45.2% and 35.9%, respectively) compared with mrEMVI-negative patients (25.7%; P = .012). After neoadjuvant treatment, the 5-year DM rate of patients with mr-vTRG 3-5 was 46.1%, whereas good responders (mr-vTRG 1-2) had a DM rate similar to mrEMVI-negative patients (25.7% and 25.7%, respectively; P = .002). The occurrence of TDs and larger mrEMVI size resulted in a lower likelihood of regression of mrEMVI.

CONCLUSIONS

The prevalence of mrEMVI and TDs in cT3-4 rectal cancer is high and is associated with worsened oncologic outcomes. mrEMVI regression (mr-vTRG 1-2), which occured in 25% of the cases, leads to oncologic outcomes similar to those in patients without mrEMVI on baseline MRI.

Single-centre evaluation and staging of rectal carcinoma on a 3-Tesla magnetic resonance imaging and correlation with histological profile

Purpose

To assess magnetic resonance imaging (MRI) features of rectal carcinoma in correlation with pathology, and to evaluate the diagnostic accuracy of 3-Tesla MRI.

Material and methods

A total of 86 patients were included. 3T MR imaging was conducted pre-operatively, with imaging data correlated to pathology results. High-resolution, 2-dimensional, T2-weighted fast-spin echo sequences in the sagittal, axial, and coronal planes used to tumour staging. Diffusion-weighted images were used to increase the accuracy of tumour evaluation.

Results

Rectal carcinoma was staged as T3 in 45.3% of all patients (n = 39), without involvement of the mesorectal fascia in 31.4% (n = 27), and with a possible or obvious invasion in 14% of patients (n = 12). The diagnostic accuracy of 3T MRI was 97.6% for the T1 stage, 92.1% for T2, 89% for T3, and 90% for T4 tumours. MR-derived extramural vascular invasion (EMVI) was found in 16.2% (n = 14), with an estimated diagnostic accuracy of 95%. Diffusion-weighted images and apparent diffusion coefficient were estimated for the different histology types of rectal carcinoma. The average apparent diffusion coefficient for adenocarcinoma was 0.846 ± 0.17, for mucinous adenocarcinoma it was 1.17 ± 0.08, and for signet cell and squamous carcinomas it was 0.91 ± 0.11 and 0.796 ± 0.21 mm²/s, respectively.

Conclusions

3T MRI enables high levels of diagnostic accuracy in local rectal carcinoma staging, including assessment of mesorectal fascia infiltration and EMVI-status with high accuracy.

MRI-defined high-risk rectal cancer patients: outcome comparison between neoadjuvant chemoradiotherapy plus TME and TME plus adjuvant chemotherapy or TME alone

OBJECTIVE

The goal of this study was to investigate whether neoadjuvant chemoradiotherapy (NCRT) plus total mesorectal excision (TME) would improve the outcome of patients with MRI-defined high-risk rectal cancer compared with TME plus adjuvant chemotherapy (ACT) or TME alone.

METHODS

We retrospectively enrolled 362 patients with MRI-defined high-risk rectal cancer who were treated with NCRT plus TME, TME plus ACT, or TME alone between January 2008 and August 2018. Cases with a high-risk tumor stage, positive extramural venous invasion, or mesorectal fascia involvement on baseline MRI were considered cases of high-risk rectal cancer. We matched patients treated with NCRT plus TME to patients treated with TME plus ACT and to those treated with TME alone. Kaplan-Meier curves were used to compare local recurrence (LR), disease-free survival (DFS), and overall survival (OS) rates.

RESULTS

The cumulative 3 year LR rate in the matched NCRT plus TME group was more favorable than in the TME plus ACT group (0% vs 5.1%; p = 0.037; n = 98) and in the TME alone group (0% vs 11.5%; p = 0.016; n = 61). Patients who received NCRT plus TME demonstrated better cumulative 3 year DFS rates than patients treated with TME plus ACT (85.7% vs 65.3%; p = 0.009) or with TME alone (86.9% vs 68.9%; p = 0.046). No difference in OS was observed among the groups.

CONCLUSION

NCRT may improve DFS and LR rates in patients with MRI-defined high-risk rectal cancer when compared with TME plus ACT or TME alone.

ADVANCES IN KNOWLEDGE

This study illustrated the specific benefit of NCRT on the outcome measures of MRI-defined high-risk rectal cancer compared with TME plus ACT or TME alone, which was not clearly clarified in previous studies enrolling all patients with Stage II/III rectal cancer.

CT-detected extramural venous invasion is corelated with presence of lymph node metastasis and progression-free survival in gastric cancer

OBJECTIVE

This study aimed to investigate if CT-detected extramural venous invasion (ctEMVI) was associated with the presence of lymph node metastasis (LNM) and survival outcomes in patients with gastric cancer.

METHODS

We retrospectively reviewed 105 patients with pathologically proved gastric cancer who underwent pre-operative CT examinations and received radical gastrectomy with extended lymphadenectomy. Differences in CT characteristics between the LNM-positive and -negative groups were assessed by two observers. Binary logistic regression analysis was performed to determine the risk factors of lymph node metastasis in gastric cancer. Progression-free survival analysis was performed by Kaplan-Meier method.

RESULTS

Two observers reached good inter-reader agreements in ctEMVI and ctN status with κ values of 0.711 and 0.751, respectively. The frequency of ctEMVI-positive status was 58.1% (61/105) in patients with gastric cancer. The LNM-positive group showed higher possibility of ctEMVI-positive status (81.7% vs 26.7%, p＜0.001), larger tumor volume (mean volume, 40.77 vs 22.09 mL, p＜0.001), poor tumor margin (45.0% vs 26.7% , p = 0.054) and high enhancement on arterial phase (43.3% vs 26.7%, p = 0.023) and venous phase (60.0% vs 44.4%, p = 0.048), than LNM-negative group. In multivariate analysis, ctEMVI status and tumor volume were identified as independent risk factors for lymph node metastasis with odds ratio (OR) of 9.804 (95% CI, 3.076－31.246; p＜0.001) and 1.030 (95% CI, 1.001－1.060; p = 0.044). CT-detected EMVI presented better diagnostic efficiency for lymph node metastasis than CT-defined N status, with sensitivity (81.7% vs 70.0%), specificity (73.3% vs 71.1%), accuracy (78.1% vs 70.5), PPV (80.3% vs 76.4%), and NPV (75.0% vs 64.0%), respectively. Kaplan-Meier curves showed that patients with positive ctEMVI findings has lower PFS rate than patients with negative ctEMVI findings (Log-rank test, p = 0.007).

CONCLUSION

CT-detected EMVI was significantly associated with lymph node metastasis and progression free survival in patients with gastric cancer. Compared to CT-defined N status, ctEMVI provided superior diagnostic performance to predict pathologic Nstatus.

ADVANCES IN KNOWLEDGE

Our study proved that CT-detected EMVI is a promising imaging marker to predict lymph node metastasis and poor prognosis, which may contribute to the precise evaluation of gastric cancer before surgery.

The prognostic importance of MRI detected extramural vascular invasion (mrEMVI) in locally advanced rectal cancer

BACKGROUND

MRI detected extramural vascular invasion (mrEMVI) is a poor prognostic factor in rectal cancer patients. The objectives of this study were to assess survival outcomes in patients with and without mrEMVI and to compare the prognostic value of mrEMVI with other rectal cancer features.

METHODS

In a Dutch high volume rectal cancer center cohort of sixty-seven locally advanced rectal cancer patients, an independent radiologist reviewed all primary staging MRI scans. The presence of mrEMVI was correlated to tumor specific and survival outcomes.

RESULTS

20/67 patients had mrEMVI positive rectal cancer. 55% (11/20) developed metachronous metastases, compared with 23% (11/47) in the mrEMVI negative group (OR 4.0, p = 0.01). Overall survival was also decreased with a Hazard ratio of 3.3 (p = 0.01). A multivariable logistic regression with a backward selection procedure was conducted including cT-stage, c-N-stage, extramural tumor invasion depth, mesorectal fascia involvement, distance to anorectal junction, tumor length, mrEMVI, CEA level, and synchronous metastases. After stepwise removal based on p value, only positive mrEMVI remained as a single significant predictor for metachronous metastases (OR: 4.16 , p < 0.05).

CONCLUSION

Positive mrEMVI is a poor prognostic factor in locally advanced rectal cancer with a 4-fold increased risk of developing metachronous metastases after surgery and a worsened overall survival. mrEMVI also appeared an independent risk factor, with a stronger prediction for metachronous metastases than other MRI-detectable tumor characteristics. mrEMVI should be incorporated in all risk stratification guidelines for rectal cancer.

Beware of Early Relapse in Rectal Cancer Patients Treated With Preoperative Chemoradiotherapy

Purpose

Recurrence patterns in rectal cancer patients treated with preoperative chemoradiotherapy (PCRT) are needed to evaluate for establishing tailored surveillance protocol.

Methods

This study included 2,215 patients with locally-advanced mid and low rectal cancer treated with radical resection between January 2005 and December 2012. Recurrence was evaluated according to receipt of PCRT; PCRT group (n = 1,258) and no-PCRT group (n = 957). Early recurrence occurred within 1 year of surgery and late recurrence after 3 years. The median follow-up duration was 65.7 ± 29 months.

Results

The overall recurrence rate was similar between the PCRT and no-PCRT group (25.8% vs. 24.9%, P = 0.622). The most common initial recurrence site was the lungs in both groups (50.6% vs. 49.6%, P = 0.864), followed by the liver, which was more common in the no-PCRT group (22.5% vs. 33.6%, P = 0.004). Most of the recurrence occurred within 3 years after surgery in both groups (85.3% vs. 85.8%, P = 0.862). Early recurrence was more common in the PCRT group than in the no-PCRT group (43.1% vs. 32.4%, P = 0.020). Recurrence within the first 6 months after surgery was significantly higher in the PCRT group than in the no-PCRT group (18.8% vs. 7.6%, P = 0.003). Lung (n = 27, 44.3%) and liver (n = 22, 36.1%) were the frequent the first relapsed site within 6 months after surgery in PCRT group.

Conclusion

Early recurrence within the first 1 year after surgery was more common in patients treated with PCRT. This difference would be considered for surveillance protocols and need to be evaluated in further studies.

Grey areas and evidence gaps in the management of rectal cancer as revealed by comparing recommendations from clinical guidelines

BACKGROUND

While the management of nonmetastatic and oligometastatic rectal cancer has rapidly evolved over the last few decades, many grey areas and highly debated topics remain that foster significant variation in clinical practice. We aimed to identify controversial points and evidence gaps in this disease setting by systematically comparing recommendations from national and international clinical guidelines.

METHODS

Twenty-six clinical questions reflecting practical challenges in the routine management of nonmetastatic and oligometastatic rectal cancer patients were selected. Recommendations from the ESMO, NCCN, JSCCR, Australian and Ontario guidelines were extrapolated and compared using a 4-tier classification system (i.e., identical/very similar, similar, slightly different, different). Overall agreement between guidelines (i.e., substantial/complete disagreement, partial disagreement, partial agreement, substantial/complete agreement) was assessed for each clinical question and compared against the highest level of available evidence by using the χ² statistic test.

RESULTS

Guidelines were in substantial/complete agreement, partial agreement, partial disagreement, and substantial/complete disagreement for 8 (30.8%), 2 (7.7%), 7 (26.9%), and 9 (34.6%) clinical questions, respectively. High level of evidence supported clinical recommendations in 3/10 cases (30%) where guidelines were in agreement and in 10/16 cases (62.5%) where guidelines were in disagreement (χ² = 2.6, p = 0.106). Agreement was frequently reached for questions regarding diagnosis, staging, and radiology/pathology pro-forma reporting, while disagreement characterised most of the treatment-related topics.

CONCLUSIONS

Substantial variation exists across clinical guidelines in the recommendations for the management of nonmetastatic and oligometastatic rectal cancer. This variation is only partly explained by the lack of supporting, high-level evidence.

The prognostic significance of MRI-detected extramural venous invasion, mesorectal extension, and lymph node status in clinical T3 mid-low rectal cancer

The purpose of this study was to evaluate the prognostic significance of the magnetic resonance imaging-detected extramural venous invasion (MR-EMVI), the depth of mesorectal extension (MR-DME), and lymph node status (MR-LN) in clinical T3 mid-low rectal cancer. One hundred and forty-six patients with clinical T3 mid-low rectal cancer underwent curative surgery were identified. Pretreatment high-resolution MRI was independently reviewed by two experienced radiologists to evaluate MR-EMVI score (0–4), MR-DME (≤4 mm or >4 mm), and MR-LN (positive or negative). The Cox-multivariate regression analysis revealed that the MR-EMVI was the only independent prognostic factor that correlated with overall 3-year disease-free survival (DFS) (p = 0.01). The survival analysis showed that patients with positive MR-EMVI, MR-DME > 4 mm, and positive MR-LN had a poorer prognosis in the overall 3-year DFS (HR 3.557, 95% CI 2.028 to 13.32, p < 0.01; HR 3.744, 95% CI:1.165 to 5.992, p = 0.002; HR 2.946, 95% CI: 1.386 to 6.699, p < 0.01). By combining MR-EMVI with MR-DME or MR-LN, the prognostic significance was more remarkable. Our study suggested that the MR-EMVI, MR-DME, and MR-LN were the important prognostic factors for patients with clinical T3 mid-low rectal cancer and the MR-EMVI was an independent prognostic factor.

Determining the use of preoperative (chemo)radiotherapy in primary rectal cancer according to national and international guidelines

BACKGROUND

Pre-operative radiotherapy (RT) or chemoradiotherapy (CRT) is frequently used prior to rectal cancer surgery to improve local control and survival. The treatment is administered according to guidelines, but these recommendations vary significantly between countries. Based on the stage distribution and risk factors of rectal cancers as determined by magnetic resonance imaging (MRI) in an unselected Swedish population, the use of RT/CRT according to 15 selected guidelines is described.

MATERIALS AND METHODS

Selected guidelines from different countries and regions were applied to a well-characterized unselected population-based material of 686 primary non-metastatic rectal cancers staged by MRI. The fraction of patients assigned to surgery alone or surgery following pre-treatment with (C)RT was determined according to the respective guideline. RT/CRT administered to rectal cancer patients for other reasons, for example, for organ preservation or palliation, was not considered.

RESULTS

The fraction of patients with a clear recommendation for pre-treatment with (C)RT varied between 38% and 77% according to the different guidelines. In most guidelines, CRT was recommended to all patients who were not operated directly, and, in others, short-course RT was also recommended to patients with intermediate risk tumours. If only non-resectable or difficult to resect tumours were recommended pre-treatment, as stated in many Japanese publications, 9% would receive CRT followed by a delay to surgery.

CONCLUSIONS

According to most guidelines, well over 50% of primary non-metastatic rectal cancer patients from a general population, in which screening for colorectal cancer is not practised, are recommended treatment with pre-operative/neo-adjuvant therapy.

Comparative Outcomes of Preoperative Chemoradiotherapy and Selective Postoperative Chemoradiotherapy in Clinical Stage T3N0 Low and Mid Rectal Cancer

Purpose/aim: Preoperative chemoradiotherapy (pre-CRT) and total mesorectal excision (TME) have become the standard of care for patients with locally advanced rectal cancer (LARC). Nevertheless, it is a controversial issue whether pre-CRT in cT3N0M0 patients would result in potential overtreatment. Materials and methods: In total, 183 clinical stage IIA rectal cancer patients treated with and without pre-CRT between 2011 and 2014 were retrospectively analyzed. Capecitabine/FOLFOX/CAPOX chemotherapy was co-administered with preoperative radiotherapy. Surgical resection with laparoscopic or open TME was conducted 8-12 weeks after completion of the pre-CRT. Postoperative radiotherapy was routinely given to patients with pT4 lesion or circumferential margin (CRM) and/or distal resection margin (DRM) involvement. Results: In total, 108 (59%) patients received pre-CRT and 75 (41%) underwent surgery first. The pre-CRT patients presented with less-advanced pathological T stage tumors compared with the surgery-first patients (p < 0.001). However, the pathological N stage was not significantly different between the two groups (p = 0.065). The 3-year overall survival (OS), disease-free survival (DFS), and 2-year local recurrence (LR) rate were similar in the pre-CRT and surgery-first patients (88.4 versus 88.7%, p = 0.552; 79.6 versus 83.3%, p = 0.797; 2.8 versus 2.7%, p = 0.960, respectively). Cox regression analysis showed that pN stage and CRM/DRM involvement were independently correlated with an unfavorable DFS. Conclusions: In this study, the omission of pre-CRT in cT3N0M0 patients did not translate into a worse oncological outcome. Postoperative radiotherapy should remain a standard option for patients with CRM/DRM involvement and pathological T4 tumors. A generalized indication for pre-CRT in cT3N0 patients is likely to result in overtreatment.

Prognostic implications of MRI-detected lateral nodal disease and extramural vascular invasion in rectal cancer

BACKGROUND

Lateral nodal disease in rectal cancer remains a subject of debate and is treated differently in the East and the West. The predictive value of lateral lymph node and MRI-detected extramural vascular invasion (mrEMVI) features on oncological outcomes was assessed in this study.

METHODS

In this retrospective cohort study, data on patients with cT3-4 rectal cancer within 8 cm from the anal verge were considered over a 5-year period (2009-2013). Lateral lymph node size, malignant features and mrEMVI features were evaluated and related to oncological outcomes.

RESULTS

In total, 192 patients were studied, of whom 30 (15·6 per cent) underwent short-course radiotherapy and 145 (75·5 per cent) received chemoradiotherapy. A lateral lymph node short-axis size of 10 mm or more was associated with a significantly higher 5-year lateral/presacral local recurrence rate of 37 per cent, compared with 7·7 per cent in nodes smaller than 10 mm (P = 0·041). Enlarged nodes did not result in a higher 5-year rate of distant metastasis (23 per cent versus 27·7 per cent in nodes smaller than 10 mm; P = 0·563). However, mrEMVI positivity was related to more metastatic disease (5-year rate 43 versus 26·3 per cent in the mrEMVI-negative group; P = 0·014), but not with increased lateral/presacral recurrence. mrEMVI occurred in 46·6 per cent of patients with nodes smaller than 10 mm, compared with 29 per cent in patients with nodes of 10 mm or larger (P = 0·267).

CONCLUSION

Although lateral nodal disease is more a local problem, mrEMVI mainly predicts distant recurrence. The results of this study showed an unacceptably high local recurrence rate in patients with a short axis of 10 mm or more, despite neoadjuvant (chemo)radiotherapy.

Is the accuracy of preoperative MRI stage in rectal adenocarcinoma influenced by tumour height?

AIM

To our knowledge, no prior studies have addressed the possible effects of tumour height on the accuracy of preoperative magnetic resonance imaging (MRI)-based staging relative to postoperative histopathological assessments in patients with adenocarcinoma of the rectum (RC). This study aimed to investigate whether the accuracy of preoperative MRI stage in RC is influenced by tumour height.

METHODS

A total of 489 consecutive RC patients scheduled for curative treatment between 2009 and 2013 were included. Of the 489 patients, 133 patients had preoperative chemoradiotherapy (CRT), and 356 patients underwent primary surgery. Low, mid and high RC were defined as a tumour <5 cm, 5-10 cm and >10 cm from the anal verge, respectively. Diagnostic MRI and, for patients with CRT, re-staging MRI features including tumour T-stage (mrT), distance between the tumour border and the distance to the mesorectal fascia (mrMRF), extramural tumour depth (mrEMD), extramural vascular invasion (mrEMVI) and nodal involvement (mrN) were correlated with the corresponding postoperative histopathological findings.

RESULTS

There were 115, 186 and 188 patients with low RC, mid RC and high RC, respectively. For all patients, the correlations between mrT and pT and between mrMRF and pCRM were not influenced by tumour height. None of the correlations between mrEMD, mrEMVI and mrN and the corresponding postoperative histopathological findings significantly differed for tumours of different heights. For patients with CRT, a remarkable proportion with low RC were overstaged as ymrT3 compared to ypT0-2.

CONCLUSIONS

The ability to preoperatively use MRI to accurately stage is not influenced by tumour height. For patients with preoperative CRT, low RC may be MRI overstaged due to post-radiation fibrosis. We found that mrEMD predicts pEMD reliably and should therefore be considered in treatment decisions. Although new MRI techniques are emerging, preoperative RC staging remains incompletely definitive in daily clinical practice.

ACR Appropriateness Criteria® Pretreatment Staging of Colorectal Cancer

Colorectal cancers are common tumors in the United States and appropriate imaging is essential to direct appropriate care. Staging and treatment differs between tumors arising in the colon versus the rectum. Local staging for colon cancer is less integral to directing therapy given radical resection is often standard. Surgical options for rectal carcinoma are more varied and rely on accurate assessment of the sphincter, circumferential resection margins, and peritoneal reflection. These important anatomic landmarks are best appreciated on high-resolution imaging with transrectal ultrasound or MRI. When metastatic disease is suspected, imaging modalities that provide a global view of the body, such as CT with contrast or PET/CT may be indicated. Rectal cancer often metastasizes to the liver and so MRI of the liver with and without contrast provides accurate staging for liver metastases. This article focuses on local and distant staging and reviews the appropriateness of different imaging for both variants. The American College of Radiology Appropriateness Criteria are evidence-based guidelines for specific clinical conditions that are reviewed annually by a multidisciplinary expert panel. The guideline development and revision include an extensive analysis of current medical literature from peer reviewed journals and the application of well-established methodologies (RAND/UCLA Appropriateness Method and Grading of Recommendations Assessment, Development, and Evaluation or GRADE) to rate the appropriateness of imaging and treatment procedures for specific clinical scenarios. In those instances where evidence is lacking or equivocal, expert opinion may supplement the available evidence to recommend imaging or treatment.

Extramural vascular invasion detected by contrast-enhanced multiple-row detectors computed tomography (ceMDCT) as a predictor of synchronous metastases in colon cancer

Background

Extramural Vascular Invasion (EMVI) is histologically defined as the presence of tumor cells beyond the muscularis propria in vessels resulting in disease metastases.

Objective

To determine whether EMVI, detected by contrast-enhanced multiple-row detectors computed tomography (MDCT), has closely association with synchronous metastases in colon cancer.

Methods

Patients with pathology proven colon cancer were included in this retrospective study. Preoperative imaging status, including Extramural tumor depth, Lymph nodes, tumor location, and ctEMVI status, were defined on MDCT. Postoperative pathological tumor stage, lymph node stage, and tumor differentiation, were defined in accordance with the American Joint Committee on Cancer (AJCC) 7^th Edition. Synchronous metastases were detected on follow-up MDCT 3 months after initial diagnosis or by surgery, if available. Associations between ctEMVI and other preoperative and postoperative factors were analyzed using Chi-squared tests. Logistic regression analyses were performed to analyze the preoperative and postoperative factors of synchronous metastases in colon cancer.

Results

ctEMVI was observed in 96 patients (96/241, 39.8%). The presence of ctEMVI varied significantly depending on ctEMD (χ2 = 66.557, P<0.001), lymph nodes status on MDCT (χ2 =24.533, P=0.001), pathological tumor status (χ2 = 36.267, P <0.001) and pathological lymph nodes status analyses (χ2 =32.103, P <0.001). Synchronous metastases were seen in 36 patients (36/96, 37.5%) with ctEMVI and 11 (11/145, 7.6%) patients without ctEMVI. The incidence of synchronous metastases was significantly higher in the cohort of positive ctEMVI with odds ratio (OR) of 7.309 (95% CI 3.485∼15.330, P<0.001). Positive ctEMVI (Odds ratio 4.654, 95%CI: 1.987∼10.898, P <0.001) and ctEMD larger than 5 mm (Odds ratio 2.654, 95%CI: 1.116∼6.309, P =0.027) were demonstrated to be significant preoperative factors in predicting synchronous metastases.

Conclusion

MDCT-detected EMVI could be used as a preoperative factor to predict synchronous metastases in colon cancer.

Laparoscopic versus open surgery for rectal cancer after neoadjuvant chemoradiation: Long-term outcomes of a propensity score matched study

BACKGROUND AND OBJECTIVES

Laparoscopic resection for rectal cancer has short-term benefits when compared to open resection. The aim of this study was to compare the long-term oncological outcomes of laparoscopic and open resection for rectal cancer following neoadjuvant chemoradiation (NCRT).

METHODS

In this propensity matched study, a series of 72 patients who underwent laparoscopic surgery for rectal cancer following NCRT between 2004 and 2010 (Lap group) were matched with 72 patients who underwent open surgery for rectal cancer in the same period (Open group). The survival and recurrence patterns were compared between the two groups.

RESULTS

After a median follow-up of 69.5 months (range 1-138 months), local recurrence rate was observed in 4 patients (5.5%) and 7 patients (9.7%) in the Lap and Open groups, respectively (P = 0.35). The 5- and 10-year disease-free survival in the Lap and Open groups were 61.3% versus 47.9% and 48.8% versus 41%, respectively (P = 0.16). The 5- and 10-year overall survival was 66.9% versus 60.2% and 49% versus 46.2% in the Lap and Open groups, respectively (P = 0.38).

CONCLUSION

Laparoscopic surgery following NCRT for low and mid third rectal cancers was associated with similar long-term oncological outcomes when compared to open surgery.

A meta-analysis comparing the risk of metastases in patients with rectal cancer and MRI-detected extramural vascular invasion (mrEMVI) vs mrEMVI-negative cases

BACKGROUND

Pathological extramural vascular invasion (EMVI) is an independent prognostic factor in rectal cancer, but can also be identified on MRI-detected extramural vascular invasion (mrEMVI). We perform a meta-analysis to determine the risk of metastatic disease at presentation and after surgery in mrEMVI-positive patients compared with negative tumours.

METHODS

Electronic databases were searched from January 1980 to March 2016. Conventional meta-analytical techniques were used to provide a summative outcome. Quality assessment of the studies was performed.

RESULTS

Six articles reported on mrEMVI in 1262 patients. There were 403 patients in the mrEMVI-positive group and 859 patients in the mrEMVI-negative group. The combined prevalence of mrEMVI-positive tumours was 0.346(range=0.198-0.574). Patients with mrEMVI-positive tumours presented more frequently with metastases compared to mrEMVI-negative tumours (fixed effects model: odds ratio (OR)=5.68, 95% confidence interval (CI) (3.75, 8.61), z=8.21, df=2, P<0.001). Patients who were mrEMVI-positive developed metastases more frequently during follow-up (random effects model: OR=3.91, 95% CI (2.61, 5.86), z=6.63, df=5, P<0.001).

CONCLUSIONS

MRI-detected extramural vascular invasion is prevalent in one-third of patients with rectal cancer. MRI-detected extramural vascular invasion is a poor prognostic factor as evidenced by the five-fold increased rate of synchronous metastases, and almost four-fold ongoing risk of developing metastases in follow-up after surgery.

Extramural venous invasion detected by MDCT as an adverse imaging feature for predicting synchronous metastases in T4 gastric cancer

Background Extramural venous invasion (EMVI) is defined histologically as the active invasion of tumor cells to the lumens of mesenteric vessels beyond the muscularis propria in advanced gastrointestinal cancer, resulting in distant metastases. Purpose To determine the association between synchronous metastatic disease in patients with T4 gastric cancer and EMVI detected on contrast-enhanced multiple-row detector computed tomography (MDCT). Material and Methods A total of 152 patients with T4 gastric carcinoma were retrospectively reviewed and divided into EMVI-positive and EMVI-negative groups where EMVI, as detected on MDCT, was defined as a tubular or nodular soft tissue thickening extending from the tumor along the vessels of the mesentery. Synchronous metastases were detected by MDCT and/or confirmed by postoperative diagnosis. Logistic regression analyses were performed to analyze the predictive factors of synchronous metastases in gastric cancer. Results Synchronous metastases were found in 47 of 152 (30.9%) patients with T4 gastric cancer. Thirty-one of 77 (40.3%) patients in the EMVI-positive group had evidence of metastases compared to 16 (21.3%) of 75 patients in the EMVI-negative group ( P = 0.019). Synchronous metastases were significantly associated with EMVI with an odds ratio (OR) of 2.250 (95% CI, 1.072-4.724). Conclusion EMVI-positive tumors, as an adverse imaging feature, were significantly associated with synchronous metastases in patients with T4 gastric cancer.

Risk factor assessment to predict the likelihood of a diagnosis of metastasis for indeterminate hepatic lesions found at computed tomography in patients with rectal cancer

AIM

To assess the significant factors on rectal magnetic resonance imaging (MRI) to predict the likelihood of a diagnosis of metastasis for indeterminate hepatic lesions found at computed tomography (CT) in patients with rectal cancer.

MATERIALS AND METHODS

A total of 207 patients with rectal cancer who underwent preoperative contrast-enhanced abdominopelvic CT, and rectal and liver MRI were included. Univariate analysis and multivariate logistic regression were used to evaluate the determining factors for the significance of indeterminate hepatic lesions on CT in patients with rectal cancer.

RESULTS

Hepatic metastases were diagnosed in 29 (20.9%) of 139 patients who had indeterminate hepatic lesions on preoperative CT obtained for rectal cancer. On univariate analysis, carcinoembryonic antigen level, N stage, mesorectal fascia (MRF) invasion, diameter of superior haemorrhoidal vein, and mesorectal vascular lesion (MVL) grade on rectal MRI (p<0.05) were associated with the possibility of metastasis for indeterminate hepatic lesions on CT. On multivariate analysis, MVL grade and MRF invasion on rectal MRI were independent factors associated with the possibility of metastasis for indeterminate hepatic lesions on CT (p<0.0005 and p=0.0066, respectively).

CONCLUSION

MVL grade and MRF invasion on rectal MRI are independent factors for estimating hepatic metastasis among indeterminate hepatic lesions on CT in patients with rectal cancer.

The potential predictive value of MRI and PET-CT in mucinous and nonmucinous rectal cancer to identify patients at high risk of metastatic disease

OBJECTIVE

To correlate imaging parameters from baseline MRI diffusion-weighted imaging (DWI) and fludeoxyglucose (FDG) positron emission tomography (PET)-CT with synchronous and metachronous metastases in mucinous carcinoma (MC) and non-mucinous carcinoma (NMC) rectal cancer.

METHODS

111 patients with extraperitoneal locally advanced rectal cancer, who underwent pelvic MRI, DWI and FDG PET-CT, were stratified into MC (n = 23) and NMC (n = 88). We correlated adverse morphologic features on MRI [mT4, mesorectal fascia involvement, extramural venous invasion (mEMVI), mN2] and quantitative imaging parameters [minimum apparent diffusion coefficient (ADC_min), maximum standardized uptake value, total lesion glycolysis, metabolic tumour volume, T₂ weighted and DWI tumour volumes] with the presence of metastatic disease. All patients underwent pre-operative chemoradiation therapy (CRT); 100/111 patients underwent surgery after CRT and were classified as pathological complete response (PCR) and no PCR [tumour regression grade (TRG)1 vs TRG2-5] and as ypN0 and ypN1-2. Median follow-up time was 48 months. Metastases were confirmed on FDG PET-CT and contrast-enhanced multidetector CT.

RESULTS

The percentage of mucin measured by MRI correlates with that quantified by histology. On multivariate analysis, the synchronous metastases were correlated with mEMVI [odds ratio (OR) = 21.48, p < 0.01] and low ADC_min (OR = 0.04, p = 0.038) in NMC. The difference of metachronous recurrence between the MC group (10-90% mucin) and NMC group was significant (p < 0.01) (OR = 21.67, 95% confidence interval 3.8-120.5). Metachronous metastases were correlated with ypN2 (OR = 8.24, p = 0.01) in MC and in NMC. In NMC, mEMVI correlated with no PCR (p = 0.018) and ypN2 (p < 0.01).

CONCLUSION

mEMVI could identify patients with NMC, who are at high risk of synchronous metastases. The MC group is at a high risk of developing metachronous metastases. Advances in knowledge: Patients at high risk of metastases are more likely to benefit from more aggressive neoadjuvant therapy.

Pre-operative staging of rectal cancer: a review of imaging techniques

INTRODUCTION

The treatment of rectal cancer has diversified in recent years, presenting the clinician and patient with increasingly challenging management decisions. At the heart of this decision-making process are two competing interests; more radical but more morbid treatments which optimize oncological outcome, and less radical treatments which preserve organs and function but may pose a greater risk of disease recurrence.

AREAS COVERED

Imaging plays a vital role informing this decision-making process, both by providing prognostic details about the cancer before the start of treatment and by updating this picture as the cancer responds or fails to respond to treatment. There is a range of available imaging modalities, each with its strengths and weaknesses. Optimizing rectal cancer treatment requires a clear understanding of the important questions that imaging needs to answer and the optimum imaging strategy. Expert Commentary: This article provides an evidence-based review of the available imaging techniques and an expert commentary on the best imaging strategy.

Imaging oligometastatic cancer before local treatment

With the advent of novel treatment strategies to help widen the therapeutic window for patients with oligometastatic cancer, improved biomarkers are needed to reliably define patients who can benefit from these treatments. Multimodal imaging is one such option and should be optimised to comprehensively assess metastatic sites, disease burden, and response to neoadjuvant treatment in each disease setting. These features will probably remain important prognostic biomarkers, and are crucial in planning multidisciplinary treatment. There are opportunities to extract additional phenotypic information from conventional imaging, while novel imaging techniques can also reveal specific aspects of tumour biology. Imaging can both characterise and localise the phenotypic heterogeneity of multiple tumour sites. Novel approaches to existing imaging datasets and correlation with tumour biology will be important in realising the potential of imaging to guide treatment in the oligometastatic setting. In this Personal View, we discuss the current status and future directions of imaging before treatment in patients with extracranial oligometastases.

Beyond Histologic Staging: Emerging Imaging Strategies in Colorectal Cancer with Special Focus on Magnetic Resonance Imaging

Imaging plays an increasingly important role in the staging and management of colorectal cancer. In recent years, magnetic resonance imaging (MRI) has supplanted transrectal ultrasound as the preferred modality for the locoregional staging of rectal cancer. Furthermore, the advent of both diffusion-weighted imaging and hepatobiliary contrast agents has significantly enhanced the ability of MRI to detect colorectal liver metastases. In clinical practice, MRI routinely provides prognostic information, helps to guide surgical strategy, and determines the need for neoadjuvant therapies related to both the primary tumor and metastatic disease. Expanding on these roles for MRI, positron emission tomography (PET)/MRI is the newest clinical hybrid imaging modality and combines the metabolic information of PET with the high soft tissue contrast of MRI. The addition of PET/MRI to the clinical staging armamentarium has the potential to provide comprehensive state-of-the-art colorectal cancer staging in a single examination.

The prognostic significance of extramural venous invasion detected by multiple-row detector computed tomography in stage III gastric cancer

PURPOSE

To determine the 1-year progression-free survival (PFS) of extramural venous invasion (EMVI), detected with contrast-enhanced multiple-row detector computed tomography (ceMDCT), in patients with stage III gastric cancer.

METHODS

Between January 2009 and December 2013, 117 patients with pathological-proved stage III gastric cancer based on the criteria of the AJCC 7th were included in this retrospective study. All patients underwent adjuvant chemotherapy postoperatively and had been monitored with the follow-up chest/abdomen/pelvis ceMDCT on 3, 6, and 12 months post-operation. Two radiologists reviewed preoperative images regarding the presence of EMVI, categories of tumor and categories of lymph node. Conventional prognostic histological factors including pathological T/N status, tumor location/growth pattern, histological type/tumor differentiation, and tumor size were also recorded. Disease progression was defined as the presence of radiological or/and pathology-confirmed metachronous metastases, local recurrence, or gastric cancer-related death. The 1-year PFS for both EMVI-positive and EMVI-negative was calculated using the Kaplan-Meier product limit. Hazard ratios for 1-year PFS were generated using a Cox proportional hazard regression on ceMDCT tumor characteristics.

RESULTS

The prevalence of EMVI detected with ceMDCT was 43.6% (51/117) in patients with stage III gastric cancer. The EMVI-positive patients had significantly lower 1-year PFS rates (45.1%), than the EMVI-negative patients (75.8%), (Log-rank test, P = 0.0008). In a Cox proportional hazards regression analysis, EMVI and tumor location/growth pattern were identified as independent prognostic factors of 1-year PFS with hazard ratio of 2.272 (95% CI 1.133-4.556, P = 0.021) and 1.982 (95% CI 1.040-3.780, P = 0.039), respectively.

CONCLUSION

EMVI status, detected with ceMDCT, could be used to counsel patients regarding ongoing risks of metastatic disease, implications for surveillance, and systemic chemotherapy.

PAN-EX: a pooled analysis of two trials of neoadjuvant chemotherapy followed by chemoradiotherapy in MRI-defined, locally advanced rectal cancer

BACKGROUND

EXPERT and EXPERT-C were phase II clinical trials of neoadjuvant chemotherapy (NACT) followed by chemoradiotherapy (CRT) in high-risk, locally advanced rectal cancer (LARC).

DESIGN

We pooled individual patient data from these trials. The primary objective was overall survival (OS) in the intention-to-treat (ITT) population. Prognostic factors were also analysed.

RESULTS

A total of 269 patients were included. Of these, 91.1% completed NACT, 88.1% completed CRT and 240 (89.2%) underwent curative surgery (R0/R1). After a median follow-up of 71.9 months, 5-year progression-free survival (PFS) and OS were 66.4% and 73.3%, respectively. In the group of R0/R1 resection patients, 5-year relapse-free survival (RFS) and OS were 71.6% and 77.2%, respectively, with local recurrence occurring in 5.5% and distant metastases in 20.6% of cases. Significant prognostic factors after multivariate analyses included age, tumour grade and MRI extramural venous invasion (mrEMVI) at baseline, MRI tumour regression grade (mrTRG) after CRT, ypT stage after surgery and adherence to study treatment. mrTRG after NACT was associated with PFS (P = 0.002) and OS (P = 0.018) and appeared to stratify patients based on the incremental benefit from sequential CRT. Among the outcome measures considered, in the subgroup of R0/R1 resection patients, ypT and ypStage had the highest predictive accuracy for RFS (concordance index: 0.6238 and 0.6252, respectively) and OS (concordance index: 0.6094 and 0.6132, respectively).

CONCLUSIONS

Administering NACT before CRT could be a potential strategy for high-risk LARC. In this setting, mrTRG after CRT is an independent prognostic factor, while mrTRG after NACT should be tested as a parameter for treatment selection in trials of NACT ± CRT. ypT stage may be a valuable surrogate end point for future phase II trials investigating intensified neoadjuvant treatments in similar patient populations.

MRI Detection of Extramural Venous Invasion in Rectal Cancer: Correlation With Histopathology Using Elastin Stain

OBJECTIVE

The purpose of this article is to evaluate the diagnostic performance of MRI for detection of extramural venous invasion (EMVI) compared with histopathologic analysis using elastin stain.

MATERIALS AND METHODS

Forty-nine patients with rectal cancer who had undergone surgical resection with preoperative MRI were identified. Thirty-seven patients had received preoperative chemoradiation therapy (CRT). Sixty-nine MRI studies were independently reviewed by two blinded radiologists for EMVI using a score of 0-4. Comparison was made with histopathologic results obtained by two pathologists reviewing the elastin-stained slides in consensus. EMVI status was also correlated with other tumoral and prognostic features on imaging and pathologic analysis. Statistical analysis was performed using Fisher exact and McNemar tests.

RESULTS

EMVI was present in 31% of the pathology specimens. An MRI EMVI score of 3-4 was 54% sensitive and 96% specific in detecting EMVI in veins 3 mm in diameter or larger. Inclusion of a score of 2 as positive for EMVI increased the sensitivity to 79% but decreased the specificity to 74%, with poor positive predictive value. Preoperative CRT had no significant effect on the diagnostic performance of MRI. Contrast-enhanced MRI increased reader confidence for diagnosis or exclusion of EMVI compared with T2-weighted imaging. EMVI status correlated with depth of extramural invasion and proximity to mesorectal fascia.

CONCLUSION

Despite an anticipated increase in sensitivity for EMVI detection by histopathologic analysis using elastin compared with H and E staining, MRI maintains a high specificity and moderate sensitivity for the detection of EMVI.

MRI Risk Stratification for Tumor Relapse in Rectal Cancer Achieving Pathological Complete Remission after Neoadjuvant Chemoradiation Therapy and Curative Resection

Purpose

Rectal cancer patients achieving pCR are known to have an excellent prognosis, yet no widely accepted consensus on risk stratification and post-operative management (e.g., adjuvant therapy) has been established. This study aimed to identify magnetic resonance imaging (MRI) high-risk factors for tumor relapse in pathological complete remission (pCR) achieved by rectal cancer patients who have undergone neoadjuvant concurrent chemoradiation therapy (CRT) and curative resection.

Materials and Methods

We analyzed 88 (male/female = 55/33, median age, 59.5 years [range 34–78]) pCR-proven rectal cancer patients who had undergone pre-CRT MRI, CRT, post-CRT MRI and curative surgery between July 2005 and December 2012. Patients were observed for post-operative tumor relapse. We analyzed the pre/post-CRT MRIs for parameters including mrT stage, mesorectal fascia (mrMRF) status, tumor volume, tumor regression grade (mrTRG), nodal status (mrN), and extramural vessel invasion (mrEMVI). We performed univariate analysis and Kaplan-Meier survival analysis.

Results

Post-operative tumor relapse occurred in seven patients (8.0%, n = 7/88) between 5.7 and 50.7 (median 16.8) months. No significant relevance was observed between tumor volume, volume reduction rate, mrTRG, mrT, or mrN status. Meanwhile, positive mrMRF (P_pre-CRT = 0.018, P_pre/post-CRT = 0.006) and mrEMVI (P_pre-CRT = 0.026, P_{pre-/post-CRT} = 0.008) were associated with higher incidence of post-operative tumor relapse. Kaplan-Meier survival analysis revealed a higher risk of tumor relapse in patients with positive mrMRF (P_pre-CRT = 0.029, P_{pre-/post-CRT} = 0.009) or mrEMVI (P_pre-CRT = 0.024, P_{pre-/post-CRT} = 0.003).

Conclusion

Positive mrMRF and mrEMVI status was associated with a higher risk of post-operative tumor relapse of pCR achieved by rectal cancer patients, and therefore, can be applied for risk stratification and to individualize treatment plans.

Current imaging of rectal cancer

Recent advances in rectal cancer surgery and treatment as well as new developments in magnetic resonance imaging (MRI) technique have led to extensive research in the field of preoperative imaging of rectal cancer and to an abundant literature. Pelvic MRI has indeed become an important part of the decision-making process for patients with rectal cancer. The aim of this article is to give current guidelines in terms of which imaging method to perform and also to review the role of imaging, with emphasis on MRI, not only for tumor primary staging but also for reevaluation of the tumor after neoadjuvant therapy, highlighting the role of new so-called "functional MR techniques". Future trends are also discussed.

How can we determine the best neoadjuvant chemoradiotherapy regimen for rectal cancer?

SUMMARY 

The current management of patients with clinically defined ‘locally advanced rectal cancer’ often involves fluoropyrimidine-based preoperative chemoradiotherapy (CRT) followed by total mesorectal excision. The focus remains primarily on reducing local recurrence, and improving survival, with organ preservation an increasing target. The best neoadjuvant CRT is the most effective regimen, balanced against the tolerability and late functional consequences, which should be selected for the individual according to their individual risk of local and distant recurrence. Hence, what makes the best neoadjuvant treatment depends on the activity and toxicity of the particular schedule, the aims of treatment, the individual disease characteristics and the individual patient pharmacogenomics. Current research efforts focus on enhancing the efficacy of CRT by integrating additional cytotoxics and biologically targeted agents.

Magnetic resonance imaging and endorectal ultrasound for diagnosis of rectal lesions

Endorectal ultrasonography (ERUS) and magnetic resonance imaging (MRI) allow exploring the morphology of the rectum in detail. Use of such data, especially assessment of the rectal wall, is an important tool for ascertaining the perianal fistula localization as well as stage of the cancer and planning it appropriate treatment, as stage T3 tumors are usually treated with neoadjuvant therapy, whereas T2 tumors are initially managed surgically. The only advantage of ERUS over MRI is the possibility of assessing T1 tumors that could be treated by transanal endoscopic microsurgery. However, MRI is better for visualizing most radiological prognostic features in rectal or anal cancer such as a circumferential resection margin less than 1 mm, T stage at T1-T2 or T3 tumors with extramural extension less than 5 mm, absence of extramural vascular invasion, N stage at N0/N1, and tumors located in the middle or upper third of the rectum. It can also evaluate the intersphincteric space or levator ani muscle involvement. Increased signal on diffusion weighted imaging (DWI) and low apparent diffusion coefficient (ADC) values as well as an irregular contour and heterogeneous internal signal intensity seem to predict the involvement of pelvic lymphatic nodes better than their size alone. Computed tomography as well as other examination techniques, including digital rectal examination, contrast edema, recto- and colonoscopy, are less useful in staging of rectal cancer but still are very important screening tools.

MRI-detected extramural vascular invasion is an independent prognostic factor for synchronous metastasis in patients with rectal cancer

OBJECTIVES

To determine whether magnetic resonance imaging (MRI)-detected extramural vascular invasion (EMVI) could predict synchronous distant metastases in rectal cancer.

METHODS

Patients who underwent rectal MRI between July 2011 and December 2012 were screened. This study included 447 patients with pathologically confirmed rectal adenocarcinoma who had undergone MRI without previous treatment. Distant metastases were recorded at the initial work-up and over a 6-month follow-up. Univariate/multivariate logistic regression models were used to determine the risk of metastasis. The diagnostic performance was calculated using pathologic lymphovascular invasion (LVI) as a gold standard.

RESULTS

Among 447 patients, 79 patients (17.7 %) were confirmed to have distant metastases. Three MRI features are significantly associated with a high risk of distant metastasis: positive EMVI (odds ratio 3.02), high T stage (odds ratio 2.10) and positive regional lymph node metastasis (odds ratio 6.01). EMVI in a large vessel (≥3 mm) had a higher risk for metastasis than EMVI in a small vessel (<3 mm). Sensitivity, specificity and accuracy of MRI-detected EMVI were 28.2 %, 94.0 % and 80.3 %, respectively.

CONCLUSIONS

MRI-detected EMVI is an independent risk factor for synchronous metastasis in rectal cancer. EMVI in large vessels is a stronger risk factor for distant metastasis than EMVI in small vessels.

KEY POINTS

• EMVI, LN metastasis and T staging on MRI are risk factors for metastasis. • EMVI in large vessels has greater risk for metastasis than in small vessels. • Regional LN metastasis on MRI has highest risk for predicting metastasis. • MR findings could be helpful for selecting patients at high risk for metastasis.

Neoadjuvant chemotherapy without radiotherapy for locally advanced rectal cancer

ABSTRACT 

Chemoradiotherapy or short-course radiotherapy followed by surgery is a standard treatment for locally advanced rectal cancer. This multimodality strategy has reduced the risk of local recurrence but failed to improve survival. Moreover, mid- and long-term side effects of radiotherapy have been reported. Alternative strategies have been investigated in an attempt to minimize treatment-related toxicities and improve outcome. Neoadjuvant chemotherapy without radiotherapy is an attractive therapeutic option that yields theoretical advantages. Moreover, if carefully selected, patients may be spared the effects of radiotherapy without compromising the oncology outcome. The authors review the available evidence on neoadjuvant chemotherapy without radiotherapy in locally advanced rectal cancer and try to anticipate potential algorithms of treatment selection to implement in clinical practice in the future.

A practical review of the performance and interpretation of staging magnetic resonance imaging for rectal cancer

OBJECTIVES

The purpose of this article was to outline key technical considerations in performing rectal magnetic resonance imaging (MRI) along with a practical, systematic approach to the interpretation of rectal MRI.

CONCLUSIONS

Following validation by the Magnetic Resonance Imaging and Rectal Cancer European Equivalence Study group, rectal MRI is mandatory for the local staging of rectal cancer in many countries. The systematic interpretation of high-quality, high-resolution T2-weighted images should form the basis for discussing the management of patients with rectal cancer, including aiding surgical planning and enabling the appropriate use of neoadjuvant therapy. In this article, we discuss the methods for obtaining high-quality rectal magnetic resonance images and a systematic approach for the accurate interpretation of these images.

Primary rectal cancer local staging

The treatment of patients with a malignant rectal tumor has evolved over the past few years. The role of medical imaging techniques, notably MRI, has become increasingly important in the preoperative assessment of rectal tumors. Radiologists are finding that their presence is requested more and more frequently at multidisciplinary team meetings for decision-making on the treatment of these tumors and therefore they must have a grounding in the therapeutic issues involved. Locoregional assessment of malignant rectal tumors may be performed prior to initiating treatment or as a re-evaluation following neoadjuvant therapy. We are interested in the assessment of the initial locoregional extension of these rectal tumors and we place much emphasis on the ability to identify MRI criteria which determine the patient's prognosis and treatment. We will also examine the advantages of MRI as well as its limits in this assessment.

Magnetic resonance imaging in rectal cancer: A surgeon’s perspective

Magnetic resonance imaging (MRI) in rectal cancer was first investigated in 1999 and has become almost mandatory in planning rectal cancer treatment. MRI has a high accuracy in predicting circumferential resection margin involvement and is used to plan neoadjuvant therapy. The accuracy of MRI in assessing mesorectal lymph nodes remains moderate, as there are no reliable criteria to assess nodal involvement. MRI seems to be good in assessing peritoneal involvement in upper rectal cancer; this however has been assessed in only a few studies and needs further research. For low rectal cancers, mesorectum is thin at the level of levator ani especially in relation to prostate; so predicting circumferential resection margin involvement is not easy. However high spatial resolution coronal imaging shows levator muscles, sphincter complex and intersphincteric plane accurately. This is used to stage low rectal tumors and plan plane of surgery (standard surgery, intersphincteric resection, Extralevator abdominoperineal resection). While most centres perform MRI post chemoradiotherapy, its role in accurate staging post neoadjuvant therapy remains debatable. THe role of Diffusion weighted MRI post neoadjuvant therapy is being evaluated in research settings.