Depth and lateral spread of microscopic residual rectal cancer after neoadjuvant chemoradiation: implications for treatment decisions

Short-term outcomes of transanal endoscopic intersphincteric resection for locally advanced rectal cancer after neoadjuvant chemoradiotherapy: A single-center retrospective cohort study

OBJECTIVE

To compare the perioperative safety and specimen characteristics after transanal endoscopic intersphincteric resection (taE-ISR) versus classical intersphincteric resection (cISR) in patients with locally advanced rectal cancer (LARC) treated with neoadjuvant chemoradiotherapy (nCRT).

METHODS

Clinicopathological data of 145 patients (75 undergoing taE-ISR and 70 undergoing cISR after nCRT) were retrospectively analyzed. Baseline characteristics, perioperative details, and pathological specimen quality of the two groups were compared.

RESULTS

Intraoperative blood loss was lower in the taE-ISR group compared to cISR (50.0 (40.0-100.0) ml vs. 70.0 (50.0-100.0) ml, P = 0.034). Two patients (2.6 %) in the taE-ISR group and eight patients (11.4 %) in the cISR group sustained adjacent organ injury (P = 0.037). There was no statistically significant difference in the prevalence of postoperative complications between the two groups (17.3 % vs. 30.0 %, P = 0.072). However, pelvic abscess (1.3 % vs. 8.6 %, P = 0.042) and rectovaginal fistula (0.0 % vs. 5.7 %, P = 0.036) occurred less often in taE-ISR compared to cISR. The complete resection rate was higher in taE-ISR compared to cISR (98.7 % vs. 91.4 %, P = 0.042). No patients in taE-ISR had positive distal resection margins (DRM), while four patients in cISR had positive DRM (0.0 % vs. 5.7 %, P = 0.036).

CONCLUSION

taE-ISR after nCRT was associated with higher-quality specimens, reduced intraoperative blood loss, and fewer perioperative complications, attesting to the feasibility and safety of taE-ISR In low-LARC patients.

Measurement of the distance between tumor micro-foci and gross tumor in rectal cancer pathological specimens: implication on margin distance of clinical target volume treated with high-dose radiotherapy for rectal cancer

PURPOSE

To measure the micro-foci distance away from gross tumor and to provide reference to create the clinical target volume (CTV) margin for boost radiotherapy in rectal adenocarcinoma.

METHODS

Twenty-eight rectal cancer surgical specimens of only total mesorectal excision were collected. The pathological specimens were retrospectively measured, and the nearest distance between the tumor micro-foci and gross tumor was microscopically measured. The "in vivo-in vitro" retraction factor was calculated as the ratio of the deepest thickness laterally and the vertical height superior/inferiorly of the rectal tumor measured in MRI and those measured in immediate pathological specimens. The retraction factor during pathological specimen processing was calculated as the distance ratio before and after dehydration in the lateral, superior, and inferior sides by the "knot marking method." The distances of tumor micro-foci were individually corrected with these two retraction factors.

RESULTS

The mean "in vivo-in vitro" tumor retraction factors were 0.913 peripherally and 0.920 superior/inferiorly. The mean tumor specimen processing retraction factors were 0.804 peripherally, 0.815 inferiorly, and 0.789 superiorly. Of 28 patients, 14 cases (50.0%) had 24 lateral micro-foci, 8 cases (28.6%) had 13 inferior micro-foci, and 7 cases (25.0%) had 19 superior micro-foci. The 95th percentiles of the micro-foci distance for 28 patients were 6.44 mm (peripheral), 5.54 mm (inferior), and 5.42 mm (superior) after retraction correction.

CONCLUSION

The micro-foci distances of 95% of rectal adenocarcinoma patients examined were within 6.44 mm peripherally, 5.54 mm inferiorly, and 5.42 mm superiorly. These findings provide reference to set the boost radiotherapy CTV margin for rectal cancer.

Identification of radiologic and clinicopathologic variables associated with tumor regression pattern and distribution of cancer cells after short-course radiotherapy and consolidation chemotherapy in patients with rectal cancer

Background

Knowledge of the pattern of regression and distribution of residual tumor cells may assist in the selection of candidates for rectum-sparing strategies.

Objective

To investigate and identify factors associated with tumor regression pattern and distribution of residual tumor cells.

Methods

We conducted a prospective study of patients with T3/T4 N0/N+ adenocarcinoma of the middle and lower third of the rectum (≤10 cm) treated with radiotherapy (5×5 Gy) followed by 6 cycles of CAPOX chemotherapy. The pattern of tumor regression was classified as fragmented or solid. Microscopic intramural spread was measured. We used a model of distribution of residual tumor cells not yet applied to rectal cancer, defined as follows: type I (luminal), type II (invasive front), type III (concentric), and type IV (random).

Results

Forty patients were included with a median age of 66 years; 23 (57.5%) were men. A fragmented pattern was identified in 18 patients (45.0%), and a solid pattern in 22 (55.0%). Microscopic intramural spread was identified in 25 patients (62.5%), extending from 1 to 18 mm (median, 4 mm). There were 14 cases (35.0%) of microscopic intramural spread ≥10 mm. All cases of fragmented regression pattern, except one, showed microscopic intramural spread. Within the fragmented pattern, microscopic intramural spread was 4-8 mm in 4 cases and ≥10 mm in the remaining cases. All cases of microscopic intramural spread ≥ 10 mm were within the fragmented pattern. Regarding the distribution pattern of residual tumor cells, 11 cases (31.5%) were classified as type I, 14 (40.0%) as type II, 10 (28.5%) as type III, and none as type IV. Carcinoembryonic antigen levels >5 ng/mL, downsizing <50%, residual mucosal abnormality >20 mm, and anatomopathologic lymph node involvement were significantly associated with the occurrence of fragmentation (P<0.05). Having received all 6 cycles of CAPOX chemotherapy and absence of microscopic intramural spread were significantly associated with the type I distribution pattern (P<0.05).

Conclusion

The occurrence of a fragmented regression pattern is common, as is the presence of microscopic intramural spread. We could identify radiologic and clinicopathologic factors associated with the pattern of tumor regression and a type I distribution pattern.

Tumor regression and safe distance of distal margin after neoadjuvant therapy for rectal cancer

Neoadjuvant therapy has been widely employed in the treatment of rectal cancer, demonstrating its utility in reducing tumor volume, downstaging tumors, and improving patient prognosis. It has become the standard preoperative treatment modality for locally advanced rectal cancer. However, the efficacy of neoadjuvant therapy varies significantly among patients, with notable differences in tumor regression outcomes. In some cases, patients exhibit substantial tumor regression, even achieving pathological complete response. The assessment of tumor regression outcomes holds crucial significance for determining surgical approaches and establishing safe margins. Nonetheless, current research on tumor regression patterns remains limited, and there is considerable controversy surrounding the determination of a safe margin after neoadjuvant therapy. In light of these factors, this study aims to summarize the primary patterns of tumor regression observed following neoadjuvant therapy for rectal cancer, categorizing them into three types: tumor shrinkage, tumor fragmentation, and mucinous lake formation. Furthermore, a comparison will be made between gross and microscopic tumor regression, highlighting the asynchronous nature of regression in the two contexts. Additionally, this study will analyze the safety of non-surgical treatment in patients who achieve complete clinical response, elucidating the necessity of surgical intervention. Lastly, the study will investigate the optimal range for safe surgical resection margins and explore the concept of a safe margin distance post-neoadjuvant therapy.

The ypT may better predict the efficacy of neoadjuvant chemoradiotherapy than tumor regression grade in locally advanced rectal cancer patients diagnosed ypT1-4N0

PURPOSE

This study aimed to assess the impact of ypT stage and tumor regression grade (TRG) on the long-term prognosis of patients with locally advanced rectal cancer (LARC) stage ypT1-4N0 after neoadjuvant chemoradiotherapy (NCRT).

METHODS

We retrospectively analyzed 585 patients with histologically diagnosed middle-low LARC (cT3-4 or cN + by pelvic MRI) from 2014 to 2019. All patients underwent NCRT, followed by total mesorectal excision. Disease-free survival (DFS) rates were compared among patients with different ypT stages and TRGs by Kaplan-Meier survival analysis. The chi-square test was used to analyze the relationship between clinicopathological or therapeutic factors and ypT stage.

RESULTS

The median follow-up was 35.8 months (range 2.8-71.8 months). The 3-year DFS was 79.5%. A better 3-year DFS was achieved in patients with a pathologic complete response (94.0% vs. 74.3%, p < 0.001) and those in the ypT0-2 (86.5% vs. 66.6%, p < 0.001), ypN0 (85.0% vs. 60.2%, p < 0.001), and TRG0 + 1 (83.1% vs. 73.0%, p = 0.004) subgroups. A total of 309 patients (52.8%) achieved stage ypT1-4N0 after surgery. Among these patients, the ypT1-2N0 subgroup achieved a significantly higher 3-year DFS than the ypT3-4N0 subgroup (85.4% vs. 72.8%, p = 0.018); in contrast, the 3-year DFS did not significantly differ between the TRG1 and TRG2 + 3 subgroups (79.9% vs. 81.1%, p = 0.833). In the ypT1-2N0 or ypT3-4N0 subgroup, different TRG had no significant effect on failure patterns.

CONCLUSIONS

For LARC patients with a ypT1-4N0 status after NCRT, ypT stage may be a more effective predictor of long-term prognosis than TRG.

Essentials of macroscopic evaluation of specimens from gastrointestinal tract

An astute macroscopic examination, coupled with correlating the gross findings with clinical indication and operative notes along with judicious, yet all pertinent sectioning for pathological examination is crucial for an accurate histopathological diagnosis, eventually leading to optimal patient care. This succinct review highlights the general concepts that lay the foundation of evaluating and grossing specimens from the luminal gastrointestinal (GI) tract. We also discuss the gross evaluation and sectioning of small therapeutic resections, along with a systematic approach and rationale when grossing and submitting histological sections from larger oncological resections from the luminal GI tract. Selected site-specific considerations, for example, grossing treated rectal and oesophageal cancers or taking sections from mucinous tumours of the appendix, among others, are also discussed.

Clinical Tools for Rectal Cancer Response Assessment following Neoadjuvant Treatment in the Era of Organ Preservation

Local tumor response evaluation following neoadjuvant treatment(s) in rectal adenocarcinoma requires a multi-modality approach including physical and endoscopic evaluations, rectal protocoled MRI, and cross-sectional imaging. Clinical tumor response exists on a spectrum from complete clinical response (cCR), defined as the absence of clinical evidence of residual tumor, to near-complete response (nCR), which assumes a significant reduction in tumor burden but with increased uncertainty of residual microscopic disease, to incomplete clinical response (iCR), which incorporates all responses less than nCR that is not progressive disease. This article aims to review the clinical tools currently routinely available to evaluate treatment response and offers a potential management approach based on the extent of local tumor response.

Total Neoadjuvant Treatment for Locally Advanced Rectal Cancer Patients: Where Do We Stand?

The therapeutic landscape in locally advanced rectal cancer (LARC) has undergone a significant paradigm shift in recent years with the rising adoption of total neoadjuvant treatment (TNT). This comprehensive approach entails administering chemotherapy and radiation therapy before surgery, followed by optional adjuvant chemotherapy. To establish and deliver the optimal tailored treatment regimen to the patient, it is crucial to foster collaboration among a multidisciplinary team comprising healthcare professionals from various specialties, including medical oncology, radiation oncology, surgical oncology, radiology, and pathology. This review aims to provide insights into the current state of TNT for LARC and new emerging strategies to identify potential directions for future research and clinical practice, such as circulating tumor-DNA, immunotherapy in mismatch-repair-deficient tumors, and nonoperative management.

The Impact of Narrow and Infiltrated Distal Margin After Proctectomy for Rectal Cancer on Patients' Outcomes: a Systematic Review and Meta-analysis

Rectal cancer is a common tumor within a difficult anatomic constraint. Total mesorectal excision with longitudinal and circumferential free margins is considered imperative for good prognosis. In this article, the authors systematically reviewed all published literature with specific Mesh terms until the end of year 2019. Thereafter, retrieved articles were assessed using the Newcastle-Ottawa Scale and meta-analysis was conducted comparing local recurrence among 1-cm, 5-mm, and narrow (< 1-mm)/infiltrated margins. Thirty-nine articles were included in the study. Macroscopic distal margin < 1 cm carried a higher incidence of recurrence for those who did not receive neoadjuvant radiation, without affecting neither estimated overall nor disease-free survival. Less than 5-mm margin after radiation therapy is accepted oncologically. Infiltrated margins and narrow margins (< 1 mm) microscopically are associated with higher incidence of local recurrence and shorter overall and disease-free survival. Surgeons should aim at 1-cm safety margin in radiotherapy-naïve patients and microscopic free margin > 1 mm for those who received neoadjuvant therapy. The cost/benefit of reoperation for patients with infiltrated margins is still inadequately studied.

Association of levels of metabolites with the safe margin of rectal cancer surgery: a metabolomics study

Background

Rectal cancer is one of the most lethal of gastrointestinal malignancies. Metabonomics has gradually developed as a convenient, inexpensive and non-destructive technique for the study of cancers.

Methods

A total of 150 tissue samples from 25 rectal cancer patients were analyzed by liquid chromatography–mass spectrometry (LC–MS), and 6 tissue samples were collected from each patient (group 1: tumor; group 2: 0.5 cm from tumor; group 3:1 cm from tumor; group 4:2 cm from tumor; group 5:3 cm from tumor and group 6:5 cm from tumor). The differential metabolites of tumor tissues and 5 cm from the tumor (normal tissues) were first selected. The differential metabolites between tumor tissues and normal tissues were regrouped by hierarchical clustering analysis, and further selected by discriminant analysis according to the regrouping of clustering results. The potential safe margin of clinical T(cT)1,cT2 stage rectal cancer and cT3,cT4 stage rectal cancer at the metabolomic level was further identified by observing the changes in the level of differential metabolites within the samples from group 1 to group 6.

Results

We found 22 specific metabolites to distinguish tumor tissue and normal tissue. The most significant changes in metabolite levels were observed at 0.5 cm (cT1, cT2) and 2.0 cm (cT3, cT4) from the tumor, while the changes in the tissues afterwards showed a stable trend.

Conclusions

There are differential metabolites between tumor tissues and normal tissues in rectal cancer. Based on our limited sample size, the safe distal incision margin for rectal cancer surgery in metabolites may be 0.5 cm in patients with cT1 and cT2 stage rectal cancer and 2.0 cm in patients with cT3 and cT4 stage rectal cancer.

Rectal cancer: Maximizing local control and minimizing toxicity

Adoption of multimodality treatment approach for rectal cancer has resulted in significant improvements in oncologic outcomes. The roles of chemotherapy, radiation, and surgery in rectal cancer treatment are continuously evolving with the goal of achieving the best possible oncologic and functional outcome while minimizing treatment toxicity. The aim of this review is to summarize the most recent trials focusing on organ-sparing treatment strategies and the optimal selection of patients for neoadjuvant radiation therapy.

Impact of the distal resection margin on local recurrence after neoadjuvant chemoradiation and rectal excision for locally advanced rectal cancer

We aimed to evaluate whether a short distal resection margin (< 1 cm) was associated with local recurrence in patients with locally advanced rectal cancer who underwent preoperative chemoradiotherapy. Patients with rectal cancer who underwent preoperative chemoradiotherapy followed by curative surgery were divided into two groups based on the distal resection margin (≥ 1 cm and < 1 cm). In total, 507 patients were analyzed. The median follow-up duration was 48.9 months. The 3-year local recurrence rates were 2% and 8% in the ≥ 1 cm and < 1 cm groups, respectively (P < 0.001). Multivariable analysis revealed that a distal resection margin of < 1 cm was a significant risk factor for local recurrence (P = 0.008). Subgroup analysis revealed that a distal resection margin of < 1 cm was not an independent risk factor for local recurrence in the ypT0-1 group. However, among patients with tumor stages ypT2-4, the cumulative 3-year incidences of local recurrence were 2.3% and 9.8% in the ≥ 1 cm and < 1 cm groups, respectively (P = 0.01). A distal resection margin of < 1 cm might influence local recurrence rates in patients with locally advanced rectal cancer undergoing preoperative chemoradiotherapy, especially in patients with tumor stages ypT2-4.

Evaluation and Predictive Factors of Complete Response in Rectal Cancer after Neoadjuvant Chemoradiation Therapy

The response to neoadjuvant chemoradiation therapy is an important prognostic factor for locally advanced rectal cancer. Although the majority of the patients after neoadjuvant therapy are referred to following surgery, the clinical data show that complete clinical or pathological response is found in a significant proportion of the patients. Diagnostic accuracy of confirming the complete response has a crucial role in further management of a rectal cancer patient. As the rate of clinical complete response, unfortunately, is not always consistent with pathological complete response, accurate diagnostic parameters and predictive markers of tumor response may help to guide more personalized treatment strategies and identify potential candidates for nonoperative management more safely. The management of complete response demands interdisciplinary collaboration including oncologists, radiotherapists, radiologists, pathologists, endoscopists and surgeons, because the absence of a multidisciplinary approach may compromise the oncological outcome. Prediction and improvement of rectal cancer response to neoadjuvant therapy is still an active and challenging field of further research. This literature review is summarizing the main, currently known clinical information about the complete response that could be useful in case if encountering such condition in rectal cancer patients after neoadjuvant chemoradiation therapy, using as a source PubMed publications from 2010–2021 matching the search terms “rectal cancer”, “neoadjuvant therapy” and “response”.

MRI Assessment of Complete Response to Preoperative Chemoradiation Therapy for Rectal Cancer: 2020 Guide for Practice from the Korean Society of Abdominal Radiology

Objective

To provide an evidence-based guide for the MRI interpretation of complete tumor response after neoadjuvant chemoradiation therapy (CRT) for rectal cancer using visual assessment on T2-weighted imaging (T2) and diffusion-weighted imaging (DWI).

Materials and Methods

PubMed MEDLINE, EMBASE, and Cochrane Library were searched on November 28, 2019 to identify articles on the following issues: 1) sensitivity and specificity of T2 or DWI for diagnosing pathologic complete response (pCR) and the criteria for MRI diagnosis; 2) MRI alone vs. MRI combined with other test(s) in sensitivity and specificity for pCR; and 3) tests to select patients for the watch-and-wait management. Eligible articles were selected according to meticulous criteria and were synthesized.

Results

Of 1615 article candidates, 55 eligible articles (for all three issues combined) were identified. Combined T2 and DWI performed better than T2 alone, with a meta-analytic summary sensitivity of 0.62 (95% confidence interval [CI], 0.43–0.77; I² = 80.60) and summary specificity of 0.89 (95% CI, 0.80–0.94; I² = 92.61) for diagnosing pCR. The criteria for the complete response on T2 in most studies had the commonality of remarkable tumor decrease to the absence of mass-like or nodular intermediate signal, although somewhat varied, as follows: (near) normalization of the wall; regular, thin, hypointense scar in the luminal side with (near) normal-appearance or homogeneous intermediate signal in the underlying wall; and hypointense thickening of the wall. The criteria on DWI were the absence of a hyperintense signal at high b-value (≥ 800 sec/mm²) in most studies. The specific algorithm to combine T2 and DWI was obscure in half of the studies. MRI combined with endoscopy was the most utilized means to select patients for the watch-and-wait management despite a lack of strong evidence to guide and support a multi-test approach.

Conclusion

This systematic review and meta-analysis provide an evidence-based practical guide for MRI assessment of complete tumor response after CRT for rectal cancer.

Local excision following chemoradiotherapy in T2-T3 rectal cancer: current status and critical appraisal

Local excision following chemoradiotherapy in rectal cancer is an organ-preserving procedure which aims at reducing morbidity and functional disorders associated with total mesorectal excision (TME) in selected patients. Although TME after chemoradiotherapy remains the gold standard for locally advanced mid and low rectal cancer, in the last years multicenter research trials have offered encouraging oncologic results which have allowed to preserve the rectum in patients with a pathologic complete response after chemoradiotherapy. A review of the available literature on this topic was conducted to define the state of the art of this conservative approach and to focus on the most controversial aspects concerning local excision performed after chemoradiotherapy, in particular tumor scatter and lymph node status, completion and salvage surgery, morbidity and quality of life. The analysis of these topics should be considered, in trial setting or in current practice, for their clinical implications. Oncologic outcomes of recent trials are encouraging for part of the patients presenting T2 rectal cancer; however, TME still remains the standard treatment in clinical practice. In such cases, local excision should include a surgical safety margin of at least 1 cm from the resection margin to achieve a true negative margin from residual tumor cells. The selection of the patients should be carefully performed and their consensus extremely detailed because TME is necessary in about 30% of cases. Failing that, morbidity and quality of life are negatively affected. However, about half of these patients refuse radical surgery (45%), thus undergoing only palliative care.

How to measure tumour response in rectal cancer? An explanation of discrepancies and suggestions for improvement

Various methods categorize tumour response after neoadjuvant therapy, including down-staging and tumour regression grading. Response categories allow comparison of different treatments within clinical trials and predict outcome. A reproducible response categorization could identify subgroups with high or low risk for the most appropriate subsequent treatments, like watch and wait. Lack of standardization and interpretation difficulties currently limit the usability of these approaches. In this review we describe these difficulties for the evaluation of chemoradiation in rectal cancer. An alternative approach of tumour response is based on patterns of residual disease, including fragmentation. We summarise the evidence behind this alternative method of response categorisation, which explains a number of very relevant clinical discrepancies. These issues include differences between downstaging and tumour regression, high local regrowth in advanced tumours during watchful waiting procedures, the importance of resection margins, the limited value of post-treatment biopsies and the relatively poor outcome of patients with a near complete pathological response. Recognition of these patterns of response can allow meaningful development of novel biomarkers in the future.

Non-operative management of rectal cancer: understanding tumor biology

The management of locally-advanced rectal cancer involves a combination of chemotherapy, chemoradiation, and surgical resection to provide excellent local tumor control and overall survival. However, aspects of this multimodality approach are associated with significant morbidity and long-term sequelae. In addition, there is growing evidence that patients with a clinical complete response to chemotherapy and chemoradiation treatments may be safely offered initial non-operative management in a rigorous surveillance program. Weighed against the morbidity and significant sequelae of rectal resection, recognizing how to best optimize non-operative strategies without compromising oncologic outcomes is critical to our understanding and treatment of this disease.

Pathologic assessment of gastrointestinal tract and pancreatic carcinoma after neoadjuvant therapy

Neoadjuvant therapy is increasingly used to treat patients with a wide variety of malignancies. Histologic evaluation of treated specimens provides important prognostic information and may guide subsequent chemotherapy. Neoadjuvant therapy is commonly employed in the treatment of locally advanced rectal adenocarcinoma, hepatic colorectal metastases, esophageal/esophagogastric junction carcinoma, and pancreatic ductal adenocarcinoma. Numerous tumor regression schemes have been used in these tumors and standardized approaches to evaluate these specimens are needed. In this review, the various tumor regression scoring systems that have been used in these organs are described and their associations with clinical outcomes are discussed. Recommendations regarding how to handle and report the histologic findings in these resections specimens are provided.

Organ-Preserving Strategies for the Management of Near-Complete Responses in Rectal Cancer after Neoadjuvant Chemoradiation

In recent years, organ preservation has been considered a feasible alternative to total mesorectal excision for patients with locally advanced rectal cancer with a clinical complete response to neoadjuvant therapy. However, the degree of tumor response to neoadjuvant therapy is variable. A fraction of the patients who did not achieve a complete response had grossly visible tumors. These patients, with clearly incomplete clinical response, need a total mesorectal excision. In addition, some patients with a significant tumor response still have some abnormalities in the bowel wall, such as superficial ulceration or tissue nodularity, which, while not conclusive for the presence of a tumor, are indicative of the possibility of a residual tumor in the bowel wall or in mesorectal lymph nodes. The management of patients with a so-called near-complete clinical response to neoadjuvant therapy is controversial. In this article, we will review the clinical and radiological criteria that define a clinical response to neoadjuvant therapy, possible treatment strategies, and follow-up protocols. We will also discuss patient and tumor characteristics that in our opinion can be useful in selecting the most appropriate treatment alternative. Although organ preservation and quality of life are important, the primary goal of treatment for these patients should be local tumor control and long-term survival.

New Strategies in Rectal Cancer

In recent years, our understanding of rectal cancer has improved, including how locally advanced disease responds to chemotherapy and radiation. This has led to new innovations and advances in the treatment of rectal cancer, which includes organ-preserving strategies for responsive disease, and minimally invasive approaces for the performance of total mesorectal excision/protectomyh for persistently advanced disease. This article discusses new strategies for rectal cancer therapy, including Watch and Wait, local excision, minimally invasive proctectomy, and transanal total mesorectal excision particularly in the setting of preoperative multimodality treatment.

Local Excision Techniques for Rectal Cancer After Neoadjuvant Chemoradiotherapy: What Are We Doing?

BACKGROUND

Recent evidence shows that the majority of rectal cancers demonstrate occult tumor scatter after neoadjuvant chemoradiotherapy that can extend for several centimeters under adjacent normal-appearing mucosa beside the residual mucosal abnormality or scar.

OBJECTIVE

This systematic review aimed to determine all of the published selection criteria and technical descriptions for local excision to date with regard to this phenomenon.

DATA SOURCES

PubMed, MEDLINE, and Embase were searched using the following key words: rectal cancer, local excision, radiotherapy, and neoadjuvant.

STUDY SELECTION

Studies that assessed local excision of rectal cancer after neoadjuvant chemoradiotherapy were included. Duplicate series were excluded from final analysis.

INTERVENTION

All of the data points were tabulated and analyzed using Microsoft Excel.

MAIN OUTCOME MEASURES

Criteria for patient selection, surgical technique, clinical restaging, pathologic assessment, and indications for completion surgery were analyzed.

RESULTS

After exclusions, data from 25 studies that in total evaluated local excision in 1001 patients were included. Compared with the single accepted technique of total mesorectal excision, described techniques for local excision after neoadjuvant therapy demonstrate significant variability in many critical technical issues, such as marking/tattooing original tumor margins before neoadjuvant therapy, using pretreatment tumor size/stage as exclusion criteria, and specifically stating lateral excision margins. Where detailed, the majority of local recurrences occurred in patients with clear pathological margins, yet significant variation existed for pathological assessment and reporting, with few studies detailing R status and some not reporting margin status at all. Significant variability also existed for adverse tumor features that mandated completion surgery, and, importantly, many series describe patients refusing completion surgery where indicated.

LIMITATIONS

We were unable to perform meta-analysis because studies lacked sufficient methodologic homogeneity to synthesize.

CONCLUSIONS

The observations from this study prompt additional study, standardization of technique, and cautious use of local excision of rectal cancer in the setting of neoadjuvant chemoradiotherapy.

Transanal Endoscopic Microsurgery (TEM) Following Neoadjuvant Chemoradiation for Rectal Cancer: Outcomes of Salvage Resection for Local Recurrence

BACKGROUND

Transanal endoscopic microsurgery (TEM) has been considered an alternative for selected patients with rectal cancer following neoadjuvant chemoradiation (CRT). Immediate total mesorectal completion for all patients with unfavorable pathological features would result in unnecessary protectomies in a significant proportion of patients. Instead, salvage total mesorectal excision (TME) could be restricted for patients developing local recurrence. The aim of the present study is to determine oncological outcomes of salvage resection for local recurrences following CRT and TEM.

METHODS

Consecutive patients undergoing TEM following neoadjuvant CRT for rectal cancer were reviewed. Patients with "near" complete response to CRT (≤3 cm; ycT1-2N0) were offered TEM. Salvage surgery was attempted in the event of a local recurrence.

RESULTS

A total of 53 patients were managed by CRT followed by TEM. Unfavorable pathological features were present in 36 patients (68 %). None of the patients underwent immediate completion TME. There were 12 patients who developed local recurrence resulting in a 2-year local recurrence-free survival of 77 % (95 % CI, 53-100 %). Of these patients, 9 developed exclusively local recurrences, and all had at least 1 unfavorable pathological feature in the specimen after TEM (100 %). Eight patients (8 of 9) underwent salvage resection (abdominoperineal resection [APR] in 87 %) with CRM+ in 7 of 8 patients (87 %). Four patients developed local re-recurrence after a median 36 months of follow-up. The 2-year local re-recurrence free survival was 60 %.

CONCLUSIONS

Salvage resection for local recurrence following CRT and TEM is associated with high rates of R1 resection (CRM+) and local re-recurrence. Immediate completion of TME should be considered for patients with unfavorable pathological features after TEM.

The value of forceps biopsy and core needle biopsy in prediction of pathologic complete remission in locally advanced rectal cancer treated with neoadjuvant chemoradiotherapy

Patients with pathological complete remission (pCR) after treated with neoadjuvant chemoradiotherapy (nCRT) have better long-term outcome and may receive conservative treatments in locally advanced rectal cancer (LARC). The study aimed to evaluate the value of forceps biopsy and core needle biopsy in prediction of pCR in LARC treated with nCRT. In total, 120patients entered this study. Sixty-one consecutive patients received preoperative forceps biopsy during endoscopic examination. Ex vivo core needle biopsy was performed in resected specimens of another 43 consecutive patients. The accuracy for ex vivo core needle biopsy was significantly higher than forceps biopsy (76.7% vs. 36.1%; p < 0.001). The sensitivity for ex vivo core needle biopsy was significantly lower in good responder (TRG 3) than poor responder (TRG ≤ 2) (52.9% vs. 94.1%; p = 0.017). In vivo core needle biopsy was further performed in 16 patients with good response. Eleven patients had residual cancer cells in final resected specimens, among whom 4 (36.4%) patients were biopsy positive. In conclusion, routine forceps biopsy was of limited value in identifying pCR after nCRT. Although core needle biopsy might further identify a subset of patients with residual cancer cells, the accuracy was not substantially increased in good responders.

Organ preservation in rectal cancer: current status and future perspectives

With the introduction of population screening initiatives, more patients may be amenable to local, transanal excision (LE) of early-stage rectal cancer. The most important drawback of LE is the risk of understaging node-positive disease. The most powerful predictors of node-positive disease are lymphatic invasion, submucosal invasion depth and width, tumor budding and poor differentiation. Therefore, LE should be reserved for low-risk T1 tumors in those reluctant or unable to undergo major surgery. Neoadjuvant chemoradiation followed by LE for T2 tumors allows adequate local control, and is currently being compared with anterior resection alone in randomized trials. A mere watchful waiting approach has been proposed in clinical complete responders to chemoradiation. However, given the very poor accuracy of current imaging modalities to predict a true pathological complete response, this strategy should not be offered outside of well-controlled trials.

Assessment of a novel, full-thickness incisional biopsy model to restage rectal tumours after neoadjuvant chemoradiotherapy: results of an ex vivo pilot study

BACKGROUND

There is currently no reliable means to restage rectal cancers after neoadjuvant chemoradiation. Recent histological evidence shows that the epicentre for residual cancer cells is focussed directly underneath any residual mucosal abnormality (RMA). This proof-of-concept study aimed to determine the utility of a novel, minimally invasive method of incisional biopsy as a restaging tool. A secondary aim was to compare its performance to clinical response assessment.

METHODS

After surgical resection, 0.5 × 0.5 cm, full-thickness incisional biopsy was performed in 15 rectal cancers. Of these, 13 had RMA and 2 had mucosal cCR but a palpable intramural abnormality. In all patients, a full-thickness incisional biopsy was taken through the centre of these areas. The ypT stage of the incisional biopsy and the final total specimen were compared. Complete mucosal clinical response was deemed to have occurred when either no residual tumour or only a flat mucosal scar remained.

RESULTS

Incisional biopsy correctly identified all patients that had been downstaged to ypT0; however, it also falsely identified 5 of 10 patients (50%) with yp residual disease as ypT0. Overall performance of incisional biopsy to detect residual cancer was 50% sensitivity, 100 % specificity, 100% PPV, and 50% NPV with an accuracy of 66%. A complete mucosal clinical response occurred in only one of five patients downstaged to ypT0 (20% sensitive). It also occurred in one patient, which was ultimately staged as ypT3.

CONCLUSION

This prospective data demonstrates that incisional biopsy is not suitable as a stand-alone method to restage rectal cancer after CRT. Alternate or complementary means of restaging are needed.