MRI-Based Use of Neoadjuvant Chemoradiotherapy in Rectal Carcinoma: Surgical Quality and Histopathological Outcome of the OCUM Trial

Rectal Cancer and Radiation in Colitis

Inflammatory bowel disease (IBD) is associated with an increased risk of colorectal cancer. When IBD patients develop a rectal cancer, this should be treated with the same oncological principles and guidelines as the general population. Rectal cancer treatment includes surgery, chemotherapy, and radiation therapy (RT). Many IBD patients will require a total proctocolectomy with an ileal-pouch anal anastomosis (IPAA) and others, restoration of intestinal continuity may not be feasible or advisable. The literature is scarce regarding outcomes of IPAA after RT. In the present review, we will summarize the evidence regarding RT toxicity in IBD patients and review surgical strategies and outcomes of IPAA after RT.

A contemporary assessment of total neoadjuvant therapy (TNT) protocols for locally advanced rectal cancer: adoption and expert perspectives at German Cancer Society (DKG)-certified colorectal cancer centers

PURPOSE

The treatment paradigm for locally advanced rectal cancer (LARC) is shifting toward the total neoadjuvant therapy (TNT) concept, which administered systemic chemotherapy in the neoadjuvant setting, either before or after chemoradiotherapy (CRT) or short-course radiotherapy (SCRT). First results have shown higher pathologic complete response (pCR) rates and a favorable impact on disease-free survival (DFS). Our study aimed to evaluate the current clinical practice and expert opinion regarding TNT for locally advanced rectal cancer across DKG (German Cancer Society)-certified colorectal cancer centers.

METHODS

A comprehensive online questionnaire, constituted of 14 TNT-focused queries targeting patients with locally advanced rectal cancer, was conducted among DKG-certified colorectal cancer centers registered within the database of the Addz (Arbeitsgemeinschaft Deutscher Darmzentren) between December 2022 and January 2023.

RESULTS

A significant majority (68%) indicated that they treated between 0 and 10 patients using a TNT protocol. Only a third (36%) of these centers participated in patient enrollment for a TNT study. Despite this, 84% of centers reported treating patients in a manner analogous to a TNT study, with the RAPIDO regimen being the most prevalent approach, employed by 60% of the respondents. The decision to adopt a TNT approach was primarily influenced by factors, such as the lower third of the rectum (93% of centers), cT4 stage (86% of centers), and a positive circumferential resection margin (80% of centers). Regarding concerns, 65% of the survey respondents expressed no reservations about the TNT concept, while 35% had concerns. In particular, there appears to be disagreement and uncertainty in regard to a clinical complete response and the "Watch and Wait" approach. While some centers adopt the watch-and-wait approach (42%), others only utilize it when extirpation is otherwise necessary (39%), and a portion still proceeds with surgery as initially planned (19%). The survey also addressed unmet needs, which were elaborated in the free-text responses. Overall, there was high interest in participating in planned observational studies.

CONCLUSIONS

This study presents an overview of current clinical practice and unmet needs within DKG-certified German colorectal cancer centers. It is noteworthy that total neoadjuvant therapy (TNT) is predominantly performed outside of clinical trials. Moreover, across the centers, there is significant heterogeneity in handling clinical complete response and adopting the "watch and wait" approach. Further research is needed to establish standardization in the care of locally advanced rectal cancer.

Multimodal Treatment of Rectal Cancer

BACKGROUND

Colorectal cancer is one of the three most common types of cancer in Germany. Approximately 30% of these cancers are located in the rectum, corresponding to about 18 000 new cases per year.

METHODS

This review is based on publications retrieved by a selective search in the PubMed database, including current guidelines and recommendations.

RESULTS

Specialized imaging, particularly magnetic resonance imaging, is essential for treatment planning. In very early stages of this disease, tumors without risk factors can be excised locally. Otherwise, radical surgical resection with lymphadenectomy remains the standard treatment, and can be performed either minimally invasive or open. At present, neoadjuvant treatment plans are evolving in the direction of total neoadjuvant therapy. In addition, recent studies investigate whether the improved efficacy of neoadjuvant therapy might now enable patients with a complete clinical remission to be spared from surgical resection (organ-preserving watch-and-wait strategy).

CONCLUSION

The treatment of rectal cancer is a prime example of an interdisciplinary, multimodal approach. In the past, the focus was mainly on improving oncologic outcomes; at present, increasing attention is being devoted to the patients' quality of life as well and the functional aspects of the various modes of treatment.

Involvement of tissue changes induced by neoadjuvant treatment in total mesorectal excision (TME): novel suggestions for determining TME quality

BACKGROUND

Few studies to date have investigated morphological changes after neoadjuvant treatment (NAT) and their implications in total mesorectal excision (TME). This study was primarily designed to evaluate whether tissue changes associated with NAT affected the quality of TME and additionally to suggest a more objective method evaluating TME quality.

METHODS

This study enrolled 1322 consecutive patients who underwent curative robot-assisted surgery for rectal cancer. Patients who did and did not receive NAT were subjected to propensity-score matching, yielding 402 patients in each group.

RESULTS

NAT independently reduced complete achievement of TME [odds ratio (OR) = 2.056, p = 0.017]. Intraoperative evaluation identified seven tissue changes significantly associated with NAT, including tumor perforation, mucin pool, necrosis, fibrosis, fat degeneration, and rectal or perirectal edema NAT (p < 0.001-0.05). Tumor perforation (OR = 5.299, p = 0.001) and mucin pool (OR = 14.053, p = 0.002) were independently associated with inappropriate (near-complete + incomplete) TME. Complete TME resulted in significantly reduced local recurrence (4.3% vs 15.3%, p = 0.003) and increased 5-year DFS rate (80.6% vs 67.6%, p = 0.047) compared with inappropriate one. By contrast, two tiers of complete and near-complete TMEs vs incomplete TME did not. Notably, among patients with complete TME, those who received NAT had a lower 5-year DFS than those who did not (77.8% vs 83.3%, p = 0.048).

CONCLUSIONS

NAT-associated tissue changes, somewhat interrupting complete TME, may provide unsolved clue to the relative inability of NAT to improve overall survival. The conventional three-tier grading of TME seems to be simplified into two tiers as complete and inappropriate.

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.

[Locally advanced rectal cancer - Standards and new multimodality treatment concepts]

Treatment strategies for locally advanced rectal cancer are changing dramatically. The treatment recommended in the guidelines for locally advanced tumors of neoadjuvant radio(chemo)therapy (RChT), followed by surgery and, if necessary, adjuvant therapy, are increasingly be abandoned in favor of the following concepts: (i) prolonged neoadjuvant (RChT (i. e. "more chemotherapy before resection", referred to as total neoadjuvant therapy, TNT); (ii) omission of radiotherapy in tumors with a low risk of local recurrence; (iii) organ preservation in patients with a complete clinical response after neoadjuvant radiochemotherapy. Herein, current strategies and study concepts are to be discussed based on the guideline-based status quo.

MRI Evaluation of Complete Response of Locally Advanced Rectal Cancer After Neoadjuvant Therapy: Current Status and Future Trends

Complete tumor response can be achieved in a certain proportion of patients with locally advanced rectal cancer, who achieve maximal response to neoadjuvant therapy (NAT). For these patients, a watch-and-wait (WW) or nonsurgical strategy has been proposed and is becoming widely practiced in order to avoid unnecessary surgical complications. Therefore, a non-invasive, reliable diagnostic tool for accurately evaluating complete tumor response is needed. Magnetic resonance imaging (MRI) plays a crucial role in both primary staging and restaging tumor response to NAT in rectal cancer without relying on resected specimen. In recent years, numerous efforts have been made to research the value of MRI in predicting and evaluating complete response in rectal cancer. Current MRI evaluation is mainly based on morphological and functional images. Morphologic MRI yields high soft tissue resolution, multiplanar images, and provides detailed depictions of rectal cancer and its surrounding structures. Functional MRI may help to distinguish residual tumor from fibrosis, therefore improving the diagnostic performance of morphologic MRI in identifying complete tumor response. Both morphologic and functional MRI have several promising parameters that may help accurately evaluate and/or predict complete response of rectal cancer. However, these parameters still have limitations and the results remain inconsistent. Recent development of new techniques, such as textural analysis, radiomics analysis and deep learning, demonstrate great potential based on MRI-derived parameters. This article aimed to review and help better understand the strengths, limitations, and future trends of these MRI-derived methods in evaluating complete response in rectal cancer.

[The importance of radiotherapy in rectal cancer-an update from a surgeon's perspective]

BACKGROUND

Neoadjuvant chemoradiotherapy was implemented in the treatment of rectal cancer for UICC stages II and III in 2004. Recent studies have provided new insights with respect to the indications and sequence of radiotherapy in the concept of multimodal treatment.

OBJECTIVE

The aim of the study was to review the status of radiotherapy in the context of current developments in the treatment of rectal cancer, such as magnetic resonance imaging (MRI)-based surgery, total neoadjuvant therapy and the watch and wait strategy for complete clinical remission.

RESULTS

The indications for neoadjuvant radiotherapy based on the clinical T and N stages are not exact and can lead to overtreatment in 18-27% of cases. Radiotherapy is associated with a worsening of anorectal and urogenital functions. Local recurrence rates of 3% with surgery alone can be achieved in patients with negative circumferential resection margins (low risk cancer) in MRI. For rectal cancer with high-risk features, such as cT4 tumor, positive circumferential resection margins and extramural vascular invasion, an improved disease-free survival and a lower rate of distant metastases could be achieved with total neoadjuvant therapy compared to standard neoadjuvant chemoradiotherapy in recent phase III randomized trials. Pathological complete remission is achieved in 28% of patients after total neoadjuvant therapy.

CONCLUSION

The high rate of complete remission has fired the debate regarding watch and wait after total neoadjuvant therapy; however, no prospective randomized phase III trials comparing total mesorectal resection vs. watch and wait in complete clinical remission have been published. Hence, resection remains the gold standard in this scenario given the excellent long-term oncological results.

Association of certification, improved quality and better oncological outcomes for rectal cancer in a specialized colorectal unit

PURPOSE

Centralization of cancer care is expected to yield superior results. In Germany, the national strategy is based on a voluntary certification process. The effect of centre certification is difficult to prove because quality data are rarely available prior to certification. This observational study aims to assess outcomes for rectal cancer patients before and after implementation of a certified cancer centre.

PATIENTS AND METHODS

All consecutive patients treated for rectal cancer in our certified centre from 2009 to 2017 were retrieved from a prospective database. The dataset was analyzed according to a predefined set of 19 quality indicators comprising 36 quality goals. The results were compared to an identical cohort of patients, treated from 2000 to 2008 just before centre implementation.

RESULTS

In total, 1059 patients were included, 481 in the 2009-2017 interval and 578 in the 2000-2008 interval. From 2009 to 2017, 25 of 36 quality goals were achieved (vs. 19/36). The proportion of anastomotic leaks in low anastomoses was improved (13.5% vs. 22.1%, p = 0.018), as was the local 5-year recurrence rate for stage (y)pIII rectal cancers (7.7% vs. 17.8%, p = 0.085), and quality of mesorectal excision (0.3% incomplete resections vs. 5.5%, p = 0.002). Furthermore, a decrease of abdominoperineal excisions was noted (47.1% vs. 60.0%, p = 0.037). For the 2009-2017 interval, local 5-year recurrence rate in stages (y)p0-III was 4.6% and 5-year overall survival was 80.2%.

CONCLUSIONS

Certification as specialized centre and regular audits were associated with an improvement of various quality parameters. The formal certification process has the potential to enhance quality of care for rectal cancer patients.

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.

Avoidance of Overtreatment of Rectal Cancer by Selective Chemoradiotherapy: Results of the Optimized Surgery and MRI-Based Multimodal Therapy Trial

BACKGROUND

Neoadjuvant chemoradiotherapy (nCRT) in patients with rectal cancer carries a high risk of adverse effects. The aim of this study was to examine the selective application of nCRT based on patient risk profile, as determined by MRI, to find the optimal range between undertreatment and overtreatment.

STUDY DESIGN

In this prospective multicenter observational study, nCRT before total mesorectal excision (TME) was indicated in high-risk patients with involved or threatened mesorectal fascia (≤1 mm), or cT4 or cT3 carcinomas of the lower rectal third. All other patients received primary surgery.

RESULTS

Of the 1,093 patients, 878 (80.3%) were treated according to the protocol, 526 patients (59.9%) underwent primary surgery, and 352 patients (40.1%) underwent nCRT followed by surgery. The 3-year locoregional recurrence (LR) rate was 3.1%. Of 604 patients with clinical stages II and III, 267 (44.2%) had primary surgery; 337 (55.8%) received nCRT followed by TME. The 3-year LR rate was 3.9%, without significant differences between groups. In patients with clinical stages II and III who underwent primary surgery, 27.3% were diagnosed with pathological stage I.

CONCLUSIONS

The results justify the restriction of nCRT to high-risk patients with rectal cancer classified by pretreatment MRI. Provided that a high-quality MRI diagnosis, TME surgery, and standardized examination of the resected specimen are performed, nCRT, with its adverse effects, costs, and treatment time can be avoided in more than 40% of patients with stage II or III rectal cancer with minimal risk of undertreatment. (clinicaltrials.gov NCT325649).