Staging Of Rectal Cancer Research Articles

ThTP4.13 Discrepancy between preoperative MRI staging and post-operative histopathology staging in rectal cancer patients who had primary surgery. A retrospective study at a District General Hospital

Abstract Aim The aim of this retrospective study was to analyse the discrepancy between preoperative MRI staging and post-operative histopathology staging of rectal cancer patients who had primary surgery. Methods A retrospective cohort study analysed the records of 47 patients with histology confirmed rectal cancer over the period of 5 years from 2017 to 2022. Data was collected from the hospital database. Results Forty-seven patients were evaluated. The mean age of presentation was 72 years. Out of 47 patients 65.95% (n=31/47) were men; 34.05 % (n=16/47) were women. Discrepancy in T staging and N staging were found in 44% (n=21/47) and 49% (n=22/45) patients respectively. Two patients had inconclusive N staging on preoperative MRI. In T stage discrepancy, 86 % ( n=18/21) were upstaged and 14% (n=3/21) were downstaged. In N stage discrepancy, 73%(n=16/22) were upstaged and 27% (n=6/22) were downstaged. Conclusion There was significant discrepancy in preoperative MRI staging and post-operative histopathology staging in our study. Discrepancy in rectal cancer staging has critical effects on management, outcomes, and survival rates of patients. Appropriate and accurate clinical radiological staging enables multi-disciplinary teams to plan optimal management approaches.

ThTP4.5 Outcomes of colorectal cancers can be improved - 10 year Results from a South Asian Tertiary Center

Abstract Introduction Colorectal cancers are the most common gastrointestinal cancers and continue to rise in numbers. We aimed to compare the outcomes of all colorectal cancers after a five year period of change in practice. Methods We compared the demographic, clinical, treatment, and outcomes parameters of all rectal cancer patients registered at our hospital in the year 2013 to those in 2018. A total of 1442 patients, 511 in 2013 and 931 in 2018 were included. Results Median age reduced from 46 years to 40 years, with the proportion of young rectal cancers (≤45 years) increasing from 49% to 70% in 2018. A shift towards low rectal cancers, poorly differentiated and signet-ring cell histology was also observed in 2018. More patients in 2018 presented with advanced T and N stage with similar rates of distant metastatic disease at initial diagnosis. Curative intent treatment was offered to 1179 patients, and neoadjuvant radiation was offered to similar proportions with an increasing use of short-course radiation in 2018. Higher default and progression rates were observed in 2018 (30.2% vs 40.8%), and fewer patients could receive definitive surgery. At a median follow up of 96 months for the 2013 group and 32 months for the 2018 cohort, the 3-year OS was 47.5% and 73.3% for the 2013 and 2018 registered patients, respectively. Conclusions The increase in survival for every stage of rectal cancer in five years interval despite more advanced and aggressive tumours, suggest the augmentation and improvement in services offered at the colorectal unit.

ThTP4.4 Textural Analysis as a Predictive Biomarker in Rectal Cancer

Abstract Background Colorectal cancer (CRC) is common and accurate staging enhances a better prognosis. Pelvic MRI is the gold standard for Rectal cancer staging. Textural analysis (TA) is a radiomic process that quantifies lesions’ heterogenicity by measuring pixel distribution in digital imaging. MRI TA of rectal cancer images is considered a future predictor of its outcomes. This review summarizes the potential role of TA in rectal cancer’s prognosis. Methods Searches were done using Medline, Embase, and PubMed. Only English articles and human studies were included. Key findings and future research suggestions were highlighted to delineate the gap in TA use. Review analysis Some studies established a correlation between TA and rectal cancer outcomes, such as treatment response, survival, and distant spread. Research showed that TA of MRI could differentiate complete from partial responders to Neo-adjuvant radio-chemotherapy. The response was higher in the mid-treatment MRI but lower in the pre-treatment. The pre-and post-treatment MRIs were significant markers of overall survival, disease-free survival, and relapse-free survival in Locally Advanced Rectal Cancer patients.MR morphological features showed the ability to define either local or distant recurrence. TA showed an ability to predict liver metastasis in CRC; Entropy and uniformity were significant predictors of patients’ liver metastases compared to patients with normal liver. Conclusion Medical images TA could predict important clinical outcomes in rectal cancer; eventually, this could change rectal cancer management into more personalized treatment options (watchful waiting). More prospective and randomized trials are mandatory to overcome TA standardization challenges.

Radiomic Features Are Predictive of Response in Rectal Cancer Undergoing Therapy.

Rectal cancer is a major mortality cause in the United States (US), and its treatment is based on individual risk factors for recurrence in each patient. In patients with rectal cancer, accurate assessment of response to chemoradiotherapy has increased in importance as the variety of treatment options has grown. In this scenario, a controversial non-operative approach may be considered in some patients for whom complete tumor regression is believed to have occurred. The recommended treatment for locally advanced rectal cancer (LARC, T3-4 ± N+) is total mesorectal excision (TME) after neoadjuvant chemoradiotherapy (nCRT). Magnetic resonance imaging (MRI) has become a standard technique for local staging of rectal cancer (tumor, lymph node, and circumferential resection margin [CRM] staging), in both the US and Europe, and it is getting widely used for restaging purposes. In our study, we aimed to use an MRI radiomic model to identify features linked to the different responses of chemoradiotherapy of rectal cancer before surgery, and whether these features are helpful to understand the effectiveness of the treatments. We retrospectively evaluated adult patients diagnosed with LARC who were subjected to at least 2 MRI examinations in 10-12 weeks at our hospital, before and after nCRT. The MRI acquisition protocol for the 2 exams included T2 sequence and apparent diffusion coefficient (ADC) map. The patients were divided into 2 groups according to the treatment response: complete or good responders (Group 1) and incomplete or poor responders (Group 2). MRI images were segmented, and quantitative features were extracted and compared between the two groups. Features that showed significant differences (SF) were then included in a LASSO regression method to build a radiomic-based predictive model. We included 38 patients (26 males and 12 females), who are classified from T2 and T4 stages in the rectal cancer TNM. After the nCRT, the patients were divided into Group 1 (13 patients), complete or good responders, and Group 2 (25 patients), incomplete or poor responders. Analysis at baseline generated the following significant features for the Mann-Whitney test (out of a total of 107) for each sequence. Also, the analysis at the end of the follow-up yielded a high number of significant features for the Mann-Whitney test (out of a total of 107) for each image. Features selected by the LASSO regression method for each image analyzed; ROC curves relative to each model are represented. We developed an MRI-based radiomic model that is able to differentiate and predict between responders and non-responders who went through nCRT for rectal cancer. This approach might identify early lesions with high surgical potential from lesions potentially resolving after medical treatment.

Optimal examined lymph node number for accurate staging and long-term survival in rectal cancer: a population-based study.

Although the recommended minimal examined lymph node (ELN) number in rectal cancer (RC) is 12, this standard remains controversial because of insufficient evidence. We aimed to refine this definition by quantifying the relationship between ELN number, stage migration and long-term survival in RC. Data from a Chinese multi-institutional registry (2009-2018) and the Surveillance, Epidemiology, and End Results (SEER) database (2008-2017) on stages I-III resected RC were analysed to determine the relationship between ELN count, stage migration, and overall survival (OS) using multivariable models. The series of odds ratios (ORs) for negative-to-positive node stage migration and hazard ratios (HRs) for survival with more ELNs were fitted using a Locally Weighted Scatterplot Smoothing (LOWESS) smoother, and structural breakpoints were determined using the Chow test. The relationship between ELN and survival was evaluated on a continuous scale using restricted cubic splines (RCS). The distribution of ELN count between the Chinese registry ( n =7694) and SEER database ( n =21332) was similar. With increasing ELN count, both cohorts exhibited significant proportional increases from node-negative to node-positive disease (SEER, OR, 1.012, P <0.001; Chinese registry, OR, 1.016, P =0.014) and serial improvements in OS (SEER: HR, 0.982; Chinese registry: HR, 0.975; both P <0.001) after controlling for confounders. Cut-point analysis showed an optimal threshold ELN count of 15, which was validated in the two cohorts, with the ability to properly discriminate probabilities of survival. A higher ELN count is associated with more precise nodal staging and better survival. Our results robustly conclude that 15 ELNs are the optimal cut-off point for evaluating the quality of lymph node examination and stratification of prognosis.

MRI in Evaluation of Rectal Cancer pre- and post-Chemo-Radiation Treatment.

Rectal cancer is associated with a high risk of metastases and local recurrence; local recurrence rates after surgical treatment being up to 32%. An accurate local staging at the time of initial diagnosis is therefore very important. Magnetic Resonance Imaging (MRI) is already established as an accurate tool for the preoperative staging of rectal cancer and has resulted in marked improvements in staging accuracy.&#x0D; Material and Methods: This study used MRI in comparing the morphologic features of rectal cancer before and after 8 weeks of chemo-radiation treatment (CRT) and to correlate the post treatment MRI appearances with the histological findings in resected tumors. 45 patients with histo-pathologically proven rectal adenocarcinoma received standardized 8 weeks chemo-radiation therapy and subjected to MRI before and after treatment for clinical staging. A correlation between pathological response and MRI findings was done.&#x0D; Results: The MRI diagnostic accuracy to diagnose T2 is 74.2% with relatively low specificity (64.7%). The diagnostic accuracy of MRI in evaluation of stage T3 and T4, the MRI sensitivity was 96.2% however of low specificity 26.3%. The diagnostic accuracy was 66.7%. Additionally, in evaluation of T2 stage, the sensitivity of MRI was very low 27.3% and specificity relatively high 94.7%. Diagnostic accuracy was 70%.&#x0D; Post RCT, based on downstaging after CRT, the sensitivity of MRI to show no tumor was very low 0% with diagnostic accuracy 88.9%. However, to evaluate stage T2, the sensitivity was 84.6% with low specificity 66.7% and the diagnostic accuracy was 74.2%.&#x0D; Conclusion: MRI had an accuracy average of 81.6% in T stage and 68.9% in N stage in re-staging rectal tumors after CRT. Over-staging results of majority of the inaccuracy. The statistical agreement between post-CRT MRI and the pathologic staging involving T and N stages was not satisfactory. In view of the above, Post CRT, restaging rectal cancer remains a challenge.

Complete response rates in rectal cancer: Temporal changes over a decade in a population-based nationwide cohort

IntroductionIn the past decade many changes in neoadjuvant treatment for patients with rectal cancer have taken place and are expected to impact complete response rates. The aim of this study was to investigate the impact on pathological, and overall, complete response rates in a nationwide population-based cohort, in relation to changes in neoadjuvant treatment and the start of a Watch & Wait (WoW) study. Materials and methodsA nationwide register study using prospectively collected data from the Swedish Colorectal Cancer Register between 2009 and 2020. Patients with rectal cancer stage I-III with a ypT0N0 in the resected specimen after neoadjuvant treatment and clinical complete responders from the yearly inclusion data of the national WoW study were included. Temporal changes in pathological and overall complete response rates were analysed, and differences in neoadjuvant treatment regimens over time and per region were studied. ResultsBetween 2009 and 2020 the pathological complete response rate for rectal cancer remained similar (Mann-Kendall tau of 0.091, p = 0.68) while the overall complete response rate increased significantly from 3.0% to 9.6% (Mann-Kendall tau of 0.818, p < 0.001). The pathological complete response rate for patients receiving short course radiotherapy followed by chemotherapy was reduced by 50% after the introduction of the WoW study. ConclusionsDuring the studied time period the overall complete response rate increased significantly presumably due to changes in national neoadjuvant treatment regimens. Since the start of the national WoW study clinical complete response seem to partly replace pathological complete response.

The experience of the COMRE group (REctal COMmittee): can magnetic resonance imaging and endosonography really help the clinical pathway after NCRT in rectal cancer?

MRI and rectal endosonography (EUS) are routinely used for preoperative tumor staging and assessment of response to therapy in patients with rectal cancer. This study aimed to evaluate the accuracy of the two techniques in predicting the pathological response compared to the resected specimen and the agreement between MRI and EUS and to define the factors that could affect the ability of EUS and MRI to predict pathological responses. This study included 151 adult patients with middle or low rectal adenocarcinoma treated with neoadjuvant chemoradiotherapy, followed by curative intent elective surgery in the Oncologic Surgical Unit of a hospital in the north of Italy between January 2010 and November 2020. All patients underwent MRI and rectal EUS. The accuracy of EUS to evaluate the T stage was 67.48%, and for the N stage was 75.61%; the accuracy of MRI to evaluate the T stage was 75.97%, and that for the N stage was 51.94%. The agreement in detecting the T stage between EUS and MRI was 65.14% with a Cohen's kappa of 0.4070 and that for the evaluation of the lymph nodes between EUS and MRI was 47.71% with a Cohen's kappa of 0.2680. Risk factors that affect the ability of each method to predict pathological response were also investigated using logistic regression. EUS and MRI are accurate tools for rectal cancer staging. However, after RT-CT, neither method is reliable for establishing the T stage. EUS seems significantly better than MRI for assessing the N stage. Both methods can be used as complementary tools in the preoperative assessment and management of rectal cancer, but their role in the assessment of residual rectal tumors cannot predict the complete clinical response.

Restaging of rectal cancer with hybrid positron emission tomography magnetic resonance imaging after preoperative chemoradiotherapy.

This study determines the sensitivity and specificity of positron emission tomography/magnetic resonance imaging (PET/MRI) parameters in predicting treatment response in patients with localised rectal cancer who have undergone preoperative chemoradiotherapy (CRT). Patients with stage I-III adenocarcinoma of the rectum planned for preoperative CRT followed by surgery were recruited. Patients had PET/MRI scans at baseline and 6-8 weeks post-CRT. Functional MRI and PET parameters were assessed for their diagnostic accuracy for tumour regression grade (TRG). Nonparametric receiver operating characteristic analysis was employed to determine the area under the ROC curve (AUC), and the sensitivity and specificity of each quantile cut-off. A total of 31 patients were recruited, of whom 20 completed study protocol. All patients included had mid or lower rectal tumours. There were 16 patients (80%) with node-positive disease at presentation. The median time to surgery was 75.5 days (range 52-106 days). Histopathological assessment revealed 20% good responders (TRG 1/2), and the remaining 80% of patients had a poor response (TRG 3/4). When predicting good responders, the AUC values for percent maximum thickness reduction and percent apparent diffusion coefficient (ADC) change were 0.82 and 0.73, respectively. A maximum thickness reduction cut-off of >47% and a percent ADC change of >20% yielded a sensitivity and specificity of 75%/95% and 75%/73%, respectively. Parameters such as percent maximum thickness reduction and percent ADC change may be useful for predicting good responders in patients undergoing preoperative CRT for rectal cancer. Larger studies are warranted to establish the utility of PET/MRI in rectal cancer staging.

How reliable is restaging MRI after neoadjuvant therapy in rectal cancer?

Despite the pivotal role of magnetic resonance imaging (MRI) in rectal cancer staging and evaluation, the reliability of restaging MRI after neoadjuvant therapy is still debatable. This study aimed to assess the accuracy of restaging MRI by comparing post-neoadjuvant MRI findings with those of the final pathology. This study was a retrospective review of the medical records of adult rectal cancer patients who had restaging MRI following neoadjuvant therapy and prior to rectal cancer resection in a NAPRC-certified rectal cancer centre between 2016 and 2021. The study compared findings of preoperative, post-neoadjuvant MRI with final pathology relative to T stage, N stage, tumour size, and circumferential resection margin (CRM) status. A total of 126 patients were included in the study. We found fair concordance (kappa -0.316) for T stage between restaging MRI and pathology report, and slight concordance for N stage and CRM status (kappa -0.11, kappa = 0.089, respectively). Concordance rates were lower for patients following total neoadjuvant treatment (TNT) or with a low rectal tumour. In total, 73% of patients with positive N pathology status had negative N status in the restaging MRI. Sensitivity and specificity regarding positive CRM in post-neoadjuvant treatment MRI were 45.45% and 70.4%, respectively. We found low concordance levels between restaging MRI and pathology regarding TN stage and CRM status. Concordance levels were even lower for patients after TNT regimen and with a low rectal tumour. In the era of TNT and watch-and-wait approach, we should not rely solely on restaging MRI to make post-neoadjuvant treatment decisions.

Radiologic T staging of colon cancer: renewed interest for clinical practice.

Radiologic imaging, especially MRI, has long been the mainstay for rectal cancer staging and patient selection for neoadjuvant therapy prior to surgical resection. In contrast, colonoscopy and CT have been the standard for colon cancer diagnosis and metastasis staging with T and N staging often performed at the time of surgical resection. With recent clinical trials exploring the expansion of the use of neoadjuvant therapy beyond the anorectum to the remainder of the colon, the current and future state of colon cancer treatment is evolving with a renewed interest in evaluating the role radiology may play in the primary T staging of colon cancer. The performance of CT, CT colonography, MRI, and FDG PET-CT for colon cancer staging will be reviewed. N staging will also be briefly discussed. It is expected that accurate radiologic T staging will significantly impact future clinical decisions regarding the neoadjuvant versus surgical management of colon cancer.

Applying a neoscore in locally advanced rectal cancer is beneficial in predicting local recurrences after surgery.

The current study was undertaken to provide more detailed prognostic models for early prediction of local recurrences and local recurrence free survival (RFS) using different radiologic and pathologic features of locally advanced rectal carcinomas treated with neoadjuvant chemoradiation (CRT). One hundred patients with locally advanced rectal carcinomas decided to receive neoadjuvant CRT were retrospectively recruited, Hazard ratios (HR) were determined in the two cox regression models and only significant ratios were considered for pointing, Models were built to determine their important effects of different predictors including: pathologic T (T), pathologic N (N), grade (G), clinical stage (cTNM), site (S), perineural invasion (PNI), and response to CRT (R) on 3-year RFS, goodness of performance of each model was measured by Harrell's C index. HR of 1st group of models: T+N, T+N+G, T+N+G+S, T+N+G+S+PNI, and T+N+G+S+PNI+R were summated and categorized into scores, these scores were significantly correlated with the risk of recurrence (Somer's D = 0.5, p<0.0001) & Harrell's C index = 0.751, (Somer's D = 0.6, p<0.0001) & its Harrell's C index = 0.794, (Somer's D = 0.7, p<0.0001) & C index = 0.826, Somer's D = 0.7, p<0.0001) & C index = 0.827, and (Somer's D = 0.7, p<0.0001) & C index = 0.843 respectively. The 2nd group of models including: cTNM stage, cTNM+G, cTNM+G+S, cTNM+G+S+PNI, cTNM+G+S+PNI+R scores which were significantly correlated with the HR of LRR (Somer's D = 0.2, 0.5, 0.6, 0.6, & 0.6 respectively), (p = 0.006, <0.0001, <0.0001, <0.0001, <0.0001 respectively), the corresponding Harrell's C indices were 0.595, 0.743, 0.782, 0.795, & 0.813 respectively. We propose that the addition of biologic factors to staging of rectal cancer provide precise stratification and association with local recurrences in patients received preoperative CRT.

Feasibility of high-resolution readout-segmented echo-planar imaging with simultaneous multislice imaging in assessing rectal cancer.

To investigate the feasibility of high-resolution readout-segmented echo-planar imaging (rs-EPI) with simultaneous multislice (SMS) imaging to predict well-differentiated rectal cancer.Kindly check and confirm whether the Author Name 'Hongyun Huang ' is correctly identified.confirm METHODS: A total of eighty-three patients with nonmucinous rectal adenocarcinoma received both prototype SMS high-spatial-resolution and conventional rs-EPI sequences. Image quality was subjectively assessed by two experienced radiologists using a 4-point Likert scale (1 = poor, 4 = excellent). The signal-to-noise ratio (SNR) and contrast-to-noise ratio (CNR) and apparent diffusion coefficient (ADC) of the lesion were measured by two experienced radiologists in the objective assessment. Paired t tests or Mann‒Whitney U tests were used to compare the two groups. The areas under the receiver operating characteristic (ROC) curves (AUCs) were used to determine the predictive value of the ADCs in discriminating well-differentiated rectal cancer in the two groups. A two-sided p value < 0.05 represented statistical significance.Please check and confirm if the authors and affiliation details have been correctly identified. Amend if necessary.confirm RESULTS: In the subjective assessment, high-resolution rs-EPI had better image quality than conventional rs-EPI (p < 0.001). High-resolution rs-EPI also had a significantly higher SNR and CNR (p < 0.001). The T stage of rectal cancer was inversely correlated with the ADCs measured on high-resolution rs-EPI (r = -0.622, p < 0.001) and rs-EPI (r = -0.567, p < 0.001). The AUC of high-resolution rs-EPI in predicting well-differentiated rectal cancer was 0.768. High-resolution rs-EPI with SMS imaging provided significantly higher image quality, SNRs, and CNRs and more stable ADC measurements than conventional rs-EPI. Additionally, the pretreatment ADC on high-resolution rs-EPI could discriminate well-differentiated rectal cancer.

AB046. SOH23ABS_167. Comparing neoadjuvant therapy followed by local excision to total mesorectal excision in the treatment of early, clinical stage rectal cancer: a meta-analysis

AB046. SOH23ABS_167. Comparing neoadjuvant therapy followed by local excision to total mesorectal excision in the treatment of early, clinical stage rectal cancer: a meta-analysis

Segmentation of rectal tumor from multi-parametric MRI images using an attention-based fusion network.

Accurate segmentation of rectal tumors is the most crucial task in determining the stage of rectal cancer and developing suitable therapies. However, complex image backgrounds, irregular edge, and poor contrast hinder the related research. This study presents an attention-based multi-modal fusion module to effectively integrate complementary information from different MRI images and suppress redundancy. In addition, a deep learning-based segmentation model (AF-UNet) is designed to achieve accurate segmentation of rectal tumors. This model takes multi-parametric MRI images as input and effectively integrates the features from different multi-parametric MRI images by embedding the attention fusion module. Finally, three types of MRI images (T2, ADC, DWI) of 250 patients with rectal cancer were collected, with the tumor regions delineated by two oncologists. The experimental results show that the proposed method is superior to the most advanced image segmentation method with a Dice coefficient of [Formula: see text], which is also better than other multi-modal fusion methods. Framework of the AF-UNet. This model takes multi-modal MRI images as input, and integrates complementary information using attention mechanism and suppresses redundancy.

The optimized rectal cancer MRI protocol: choosing the right sequences, sequence parameters, and preparatory strategies.

Pelvic MRI plays a critical role in rectal cancer staging and treatment response assessment. Despite a consensus regarding the essential protocol components of a rectal cancer MRI, substantial differences in image quality persist across institutions and vendor software/hardware platforms. In this review, we present image optimization strategies for rectal cancer MRI examinations, including but not limited to preparation strategies, high-resolution T2-weighted imaging, and diffusion-weighted imaging. Our specific recommendations are supported by case studies from multiple institutions. Finally, we describe an ongoing initiative by the Society of Abdominal Radiology's Disease-Focused Panel (DFP) on Rectal and Anal Cancer to create standardized rectal cancer MRI protocols across scanner platforms.

Diagnostic performance of magnetic resonance imaging in preoperative local staging of rectal cancer after neoadjuvant chemoradiotherapy

This paper aims to investigate the diagnostic performance of magnetic resonance imaging (MRI) in predicting the pathologic stage of locally advanced rectal cancer (LARC) after neoadjuvant chemoradiotherapy (CRT) and the role of MRI in selecting patients with a pathologic complete response (ypCR). Restaging MRI (yMRI) examinations of 136 patients with LARC treated with neoadjuvant CRT followed by surgery were retrospectively analyzed by two radiologists. All examinations were performed on a 1.5 Tesla MRI machine with a pelvic phased-array coil. T2-weighted turbo spin-echo images and diffusion-weighted imaging were obtained. Histopathologic reports of the surgical specimens were the reference standard. The accuracy, sensitivity, specificity, positive and negative predictive values (PPV and NPV) of yMRI in predicting the pathologic T-stage (ypT), N-stage, and ypCR were calculated. The inter-observer agreement was evaluated using kappa statistics. The yMRI results showed 67% accuracy, 59% sensitivity, 80% specificity, 81% PPV, and 56% NPV in identifying ypT (ypT0-2 versus ypT3-4). In predicting the nodal status, the yMRI results revealed 63% accuracy, 60% sensitivity, 65% specificity, 47% PPV, and 75% NPV. In predicting ypCR, the yMRI results showed 84% accuracy, 20% sensitivity, 92% specificity, 23% PPV, and 90% NPV. The kappa statistics revealed substantial agreement between the two radiologists. Utilization of yMRI showed high specificity and PPV in predicting the tumor stage and high NPV in predicting the nodal stage; in addition, yMRI revealed moderate accuracy in the T and N classifications, mainly due to underestimating the tumor stage and overestimating the nodal status. Finally, yMRI revealed high specificity and NPV but low sensitivity in predicting the complete response.

Planned organ preservation for elderly patients with rectal cancer using short course radiotherapy and a contact brachytherapy boost-an International multi-institution analysis.

The use of external beam radiotherapy (EBRT) and contact X-Ray brachytherapy (CXB) is emerging as an effective alternative in patients with early stage rectal cancer with the intent of organ preservation (OP). Short course radiotherapy (SCRT) is an alternative EBRT schedule for patients not fit for chemotherapy or for longer courses of EBRT. There are no multicentre studies that have reported on the outcomes of SCRT with a CXB boost, therefore we present these from patients from centres from the UK and Sweden. From the Guildford Colorectal Database or local databases, 258 patients who underwent SCRT and CXB with the intent of OP from five centres treated between 2007 and 2019 were identified. Response and survival data was analysed and presented. With a median age of 81, 226 patients were treated with radiotherapy alone (RTA) and 32 immediately after local excision (ILE). Median follow-up was 24 months. 70% and 97% of patients in the RTA and ILE groups respectively had a complete clinical response (cCR) after SCRT with CXB. Of those, local relapse was seen in 16% of the RTA and 3% of the ILE group. Median survival was 40 months after CXB in the RTA and 52 months in the ILE group. 94% of patients remained stoma-free to the point of latest follow-up. This data suggests that CXB when combined with SCRT, in a mainly elderly and comorbid population, provides good palliation with stoma-avoidance. Oncological outcomes compare with previously published work. A greater focus is required on quality of life outcomes after OP.

High-resolution integrated dynamic shimming diffusion-weighted imaging (DWI) in the assessment of rectal cancer.

To investigate the feasibility of high-resolution integrated dynamic shimming echo planar imaging (iEPI) applied to rectal cancer. A total of seventy-eight patients with non-mucinous rectum adenocarcinoma were enrolled in this study. Using a prototype high-resolution iEPI sequence, high-resolution single-shot EPI (sEPI) sequence, and sEPI sequence, subjective and objective assessment and apparent diffusion coefficient (ADC) value were measured for comparison. The spearman rank correlation analysis test and the receiver operating characteristic curve were performed to evaluate correlation between tumor ADC values, corresponding T stage, and differentiation degree of rectal cancer. The subjective assessment of the image quality (IQ) of high-resolution iEPI was rated superior to high-resolution sEPI and sEPI by both readers (p < 0.001). Signal-to-noise ratio, contrast-to-noise, and signal-intensity ratio were significantly higher in high-resolution iEPI than the other two sequences (p < 0.001). There was no significant difference of tumor ADC values among three EPI sequences in the group of low- to well-differentiated rectal cancer. An inverse correlation was noted between ADC values on three DWI sequences and pathological T stage of rectal cancer (r = - 0.693, - 0.689, - 0.640, p < 0.001). The AUC values of high-resolution iEPI, high-resolution sEPI, and sEPI in predicting well-differentiated rectal cancer were 0.910, 0.761, and 0.725 respectively. In conclusion, the high-resolution iEPI provided significantly higher IQ and stable ADC compared to another two sequences. High-resolution iEPI has the highest efficacy among three examined sequences in differentiation of rectal cancer with different degrees of differentiation. • High-resolution iEPI provided a significantly better IQ than high-resolution sEPI and sEPI when assessing rectal cancer. • The AUC of high-resolution sEPI was the highest among three EPI sequences in predicting well-differentiated rectal cancer.

A prospective translational study investigating the association of gut microbiome (GM) diversity with pathological complete response (pCR) after neoadjuvant treatment in early stage rectal and esophageal cancers.

TPS819 Background: The gut microbiome (GM) is thought to influence host immunity by modulating multiple immunologic pathways. Studies have suggested that dysbiosis of the GM confers a predisposition to certain malignancies and influences response to immune checkpoint inhibitors. However, little is known about how the GM diversity influences complete pathological response to neoadjuvant therapy in gastrointestinal (GI) tumours. We hypothesize that a more diverse GM constitution at baseline will lead to improved pathological response at the time of definitive surgery. Methods: We designed a cross-institutional multi-center translational study investigating the impact of the GM diversity on the efficacy of neoadjuvant therapy in GI cancers by assessing its association with pathological response. The study population will consist of patients with an early-stage rectal or esophageal cancer due to commence neoadjuvant therapy (including chemotherapy and chemoradiation) and planned for definitive surgery. Patients who received prior chemotherapy/monoclonal antibodies/immune checkpoint inhibitors or radiation will be excluded. The study assessments will include fecal sampling of the GM prior to neoadjuvant therapy, upon completion and again six months post completion of therapy. Fecal samples will be analysed by 16S RNA sequencing. Pathological response will be examined at time of surgery and patients will be classified as responders (complete pathological response) or non-responders. The primary endpoint of the study is to examine the association between the GM diversity and pathological response. 120 patients will be recruited over 18 months. Results: Species richness (Alpha Diversity) will be analysed using the Shannon diversity index and Jaccard similarity index to calculate beta diversity. Classification and clustering analysis will be performed with Principal Component Analysis (PCA) and Random Forest analysis. Comparison of taxa or functions between clinical cohorts will be performed using the two tailed Z test and corrected using the false discovery rate to determine Q-values. The association between GM and complete pathological response will be examined using logistic regression analysis adjusting for potential confounding factors. Adjusted odds ratios (OR) and 95% confidence intervals will be presented. Conclusions: This study will show preliminary insights into the role of GM as a potential biomarker for neoadjuvant therapy efficacy in patients with GI cancers. Recruitment is on-going.