Advancing Personalized Medicine in the Treatment of Locally Advanced Rectal Cancer

Rectal cancer presents a significant burden globally, often requiring multimodal therapy for locally advanced cases. Long-course chemoradiotherapy (LCRT) and short-course radiotherapy (SCRT) followed by surgery have been conventional neoadjuvant approaches. Recent trials favor LCRT due to improved local control. However, distant tumor recurrence remains a concern, prompting the exploration of total neoadjuvant therapy (TNT) as a comprehensive treatment strategy. Immune checkpoint inhibitors (ICIs) show promise, particularly in mismatch repair-deficient (dMMR) or microsatellite instability-high (MSI-H) tumors, potentially revolutionizing neoadjuvant regimens. Nonoperative management (NOM) represents a viable alternative post-neoadjuvant therapy for selected patients achieving complete clinical response (cCR). Additionally, monitoring minimal residual disease (MRD) using circulating tumor DNA (ctDNA) emerges as a non-invasive method for the assessment of treatment response. This review synthesizes current evidence on TNT, ICIs, NOM, and ctDNA, elucidating their implications for rectal cancer management and highlighting avenues for future research and clinical application.

Recent advances in rectal cancer treatment - are we on the right track?

Background

Staging and treatment of rectal cancer have evolved over several decades with considerably fewer locoregional recurrences but no marked improved survival since systemic recurrence risks remain virtually unchanged. This development will briefly be summarised followed by a thorough discussion of two recent developments.

Methods

A systematic approach towards the literature is aimed at focusing on organ preservation and the delivery of all non-surgical treatments prior to surgery or total neoadjuvant treatment (TNT).

Results

Organ preservation, that is to defer surgery if the tumour happens to disappear completely after any pre-treatment given to locally advanced tumours to decrease recurrence risks has increased in popularity and is, if not universally, widely accepted. To give neo-adjuvant treatment to intentionally obtain a clinically complete remission to avoid surgery is practised in some environments but is mostly still experimental. TNT, that is to provide both radiotherapy and chemotherapy aimed at killing microscopic disease in the pelvis or elsewhere has been subject to several trials. Collectively, they show that the chance of achieving a complete response, pathologically or clinically, has approximately doubled, increasing the chance for organ preservation, and the risk of distant metastasis has decreased at least in some trials. The best schedule remains to be established.

Conclusions

To obtain substantial progress and also improve survival, the systemic treatments need to be improved even if preoperative delivery is more effective and better tolerated than postoperative. The locoregional treatment may be further optimised through better risk prediction.

Rectal cancer - avoiding surgery?

Nonoperative treatment of rectal cancer is gaining popularity. Several trials recently demonstrated advantages in disease-free survival with total neoadjuvant treatment (TNT) with the addition of the watch and wait (WW) strategy for locally advanced rectal cancer. On longer follow-up, an unexpected increased risk in local recurrence in the TNT group at the RAPIDO trial suggested early surgery for nonresponding tumours. The WW option is globally accepted for a complete clinical response; however, a high rate of regrowth was found in a registry with an increased risk of distant metastases, questioning the deleterious effect of deferral of surgery in this group. The short- and long-term toxic effects of neoadjuvant treatment are costs to consider in the National Comprehensive Cancer Network guidelines compared with the European Society for Medical Oncology guidelines, which favour surgery alone if good mesorectal resection is assured with increasing surgical proficiency adjusted to the precise anatomical location.

Radiotherapy in the preoperative neoadjuvant treatment of locally advanced rectal cancer

Radiotherapy and chemotherapy are effective treatments for patients with locally advanced rectal cancer (LARC) and can significantly improve the likelihood of R0 resection. Radiotherapy can be used as a local treatment to reduce the size of the tumor, improve the success rate of surgery and reduce the residual cancer cells after surgery. Early chemotherapy can also downgrade the tumor and eliminate micrometastases throughout the body, reducing the risk of recurrence and metastasis. The advent of neoadjuvant concurrent radiotherapy (nCRT) and total neoadjuvant treatment (TNT) has brought substantial clinical benefits to patients with LARC. Even so, given increasing demand for organ preservation and quality of life and the disease becoming increasingly younger in its incidence profile, there is a need to further explore new neoadjuvant treatment options to further improve tumor remission rates and provide other opportunities for patients to choose watch-and-wait (W&W) strategies that avoid surgery. Targeted drugs and immunologic agents (ICIs) have shown good efficacy in patients with advanced rectal cancer but have not been commonly used in neoadjuvant therapy for patients with LARC. In this paper, we review several aspects of neoadjuvant therapy, including radiation therapy and chemotherapy drugs, immune drugs and targeted drugs used in combination with neoadjuvant therapy, with the aim of providing direction and thoughtful perspectives for LARC clinical treatment and research trials.

Locoregional Failure During and After Short-course Radiotherapy Followed by Chemotherapy and Surgery Compared With Long-course Chemoradiotherapy and Surgery: A 5-Year Follow-up of the RAPIDO Trial

OBJECTIVE

To analyze risk and patterns of locoregional failure (LRF) in patients of the RAPIDO trial at 5 years.

BACKGROUND

Multimodality treatment improves local control in rectal cancer. Total neoadjuvant treatment (TNT) aims to improve systemic control while local control is maintained. At 3 years, LRF rate was comparable between TNT and chemoradiotherapy in the RAPIDO trial.

METHODS

A total of 920 patients were randomized between an experimental (EXP, short-course radiotherapy, chemotherapy, and surgery) and a standard-care group (STD, chemoradiotherapy, surgery, and optional postoperative chemotherapy). LRFs, including early LRF (no resection except for organ preservation/R2 resection) and locoregional recurrence (LRR) after an R0/R1 resection, were analyzed.

RESULTS

Totally, 460 EXP and 446 STD patients were eligible. At 5.6 years (median follow-up), LRF was detected in 54/460 (12%) and 36/446 (8%) patients in the EXP and STD groups, respectively ( P =0.07), in which EXP patients were more often treated with 3-dimensional-conformed radiotherapy ( P =0.029). In the EXP group, LRR was detected more often [44/431 (10%) vs. 26/428 (6%); P =0.027], with more often a breached mesorectum (9/44 (21%) vs. 1/26 (4); P =0.048). The EXP treatment, enlarged lateral lymph nodes, positive circumferential resection margin, tumor deposits, and node positivity at pathology were the significant predictors for developing LRR. Location of the LRRs was similar between groups. Overall survival after LRF was comparable [hazard ratio: 0.76 (95% CI, 0.46-1.26); P =0.29].

CONCLUSIONS

The EXP treatment was associated with an increased risk of LRR, whereas the reduction in disease-related treatment failure and distant metastases remained after 5 years. Further refinement of the TNT in rectal cancer is mandated.

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

BACKGROUND

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.

METHODS

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.

RESULTS

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.

CONCLUSION

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.

Total neoadjuvant treatment and PD-1/PD-L1 checkpoint inhibitor in locally advanced rectal cancer

For local advanced rectal cancer (LARC), total neoadjuvant treatment (TNT) has shown more complete response (CR), reduced risk of distant metastasis (DM) and increase of the sphincter preservation rate. Now it is the one and only recommendation for high-risk group of LARC according to National Comprehensive Cancer Network (NCCN) rectal cancer guideline, while it is also preferentially recommended for low-risk group of LARC. TNT is also beneficial for distant rectal cancer patients who have need for organ preservation. Even though the prognostic value of programmed cell death-ligand 1 (PD-L1) in the neoadjuvant chemoradiotherapy (NACRT) of LARC patients is undetermined yet, the combination of NACRT and programmed cell death-1 (PD-1)/PD-L1 antibodies seem bring new hope for mismatch repair proficient (pMMR)/microsatellite stable (MSS) LARC patients. Accumulating small sample sized studies have shown that combining NACRT with PD-1/PD-L1 antibody yield better short-term outcomes for pMMR/MSS LARC patients than historic data. However, ideal total dose and fractionation of radiotherapy remains one of unresolved issues in this combination setting. Thorough understanding the impact of radiotherapy on the tumor microenvironment and their interaction is needed for in-depth understanding and exquisite design of treatments combination model.

Predicting Response to Total Neoadjuvant Treatment (TNT) in Locally Advanced Rectal Cancer Based on Multiparametric Magnetic Resonance Imaging: A Retrospective Study

Purpose

To investigate the potential value of magnetic resonance imaging (MRI) in predicting response relevance to total neoadjuvant treatment (TNT) in locally advanced rectal cancer.

Methods

We analyzed MRI of 71 patients underwent TNT from 2015 to 2017 retrospectively. We categorized the response of TNT as CR (complete response) vs non-CR, and high vs moderate vs low sensitivity. Logistic regression analysis was used to identify the best predictors of response. Diagnostic performance was assessed using receiver operating characteristic curve analysis.

Results

Post-ICT (induction chemotherapy) ∆TL (tumor length), post-CRT (concurrent chemoradiotherapy) ∆LNN (the numbers of lymph node metastases), post-CCT (consolidation chemotherapy) ∆S_DWI (maximum cross-sectional area of tumor on diffusion-weighted imaging), post-CCT ADC_T (the mean apparent diffusion coefficient values of tumor) and post-CCT ∆LNV (volume of lymph node) were the best CR predictors. Post-ICT ∆TL, post-CRT EMVI (extramural vascular invasion) and post-CCT ∆S_T2 (S on T2-weight) were the best significant factors for high sensitivity.

Conclusion

Post-ICT ∆TL may be an early predictor of CR and high sensitivity to TNT. Dynamic analysis based on MRI between baseline and post-CCT could provide the most valuable prediction of CR. The grouping modality of CR vs non-CR may be more suitable for treatment response prediction than high vs moderate vs low sensitivity.

Tailored total neoadjuvant therapy for locally advanced rectal cancer: One size may not fit for all!

While current neoadjuvant protocols have proven benefits on local control for majority of patients with locally advanced rectal cancer, there are certain clinical conditions that require future advances for improving the outcomes. Total neoadjuvant therapy incorporates systemic chemotherapy planned within standard neoadjuvant protocols either before or after radiotherapy for locally advanced rectal cancer as a whole. Enhanced compliance with planned oncological therapy, tumour downstaging, administration of chemotherapy at the earliest time in the disease course to help assessing chemosensitivity are the proposed benefits of total neoadjuvant therapy in patients with locally advanced rectal cancer. Patient selection criteria for administration of total neoadjuvant therapy in the recent guidelines are unclear. Since current literature is inconclusive for the optimal sequence and type of radiotherapy and chemotherapy, premature incorporation of total neoadjuvant therapy for all locally advanced rectal cancers may result in overtreatment and subsequently toxicity. This article aims to discuss the current literature and to propose a future perspective by considering real-life scenarios reflecting patients' needs for treatment of locally advanced rectal cancer.

Acute Ischemic Gangrene of the Rectosigmoid Colon in a Patient With Rectal Cancer in the "Watch-and-Wait" Protocol

Acute rectal ischemia is a rare entity because the rectum has abundant blood supply from the inferior mesenteric, internal iliac, internal pudendal, and marginal artery with rich collaterals.

We present a case of an acute ischemic proctosigmoiditis with a history of rectal cancer who completely recovered after total neoadjuvant treatment and was in the “watch-and-wait” protocol. Urgent laparoscopic low anterior resection and protective ileostomy were performed. Causes of acute rectosigmoid ischemia include old age, diabetes, atherosclerosis, previous aortic surgery due to aneurysm, vasculitis, and radiotherapy. Ischemia may be present as only involving the mucosa, which can be managed conservatively, but full-thickness necrosis requires urgent surgical intervention. Endoscopic examination is the gold standard in initial diagnosis. Ischemic gangrene of the rectosigmoid colon is a rare condition and can be life-threatening unless an urgent surgical intervention is performed.

Neoadjuvant Chemotherapy in Locally Advanced Rectal Cancer

Simple Summary

The outcome for patients with rectal cancer has significantly improved over the last thirty years. Previously, local relapses in the pelvis occurred in more than one third of all patients with apparently localized tumors. Total mesorectal excision was the first step to improve local control by reducing local relapses to less than 5%. Preoperative radiation, either short-course or long-course with concurrent administration of chemotherapy, was a second important step for reducing local relapses to a minimum, even in locally advanced tumors where a clean surgical resection was not possible or would not be curative. Magnetic resonance imaging is a very useful tool for locoregional staging and for properly selecting patients for preoperative treatment. Nowadays, we know that preoperative chemotherapy also provides better control of systemic relapses. Moreover, surgery can be avoided in 25% of patients and the watch and wait strategy is considered safe and curative.

Abstract

Most clinical practice guidelines recommend a selective approach for rectal cancer after clinical staging. In low-risk patients, upfront surgery may be an appropriate option. However, in patients with MRI-defined high-risk features such as extramural vascular invasion, multiple nodal involvement or T4 and/or tumors close to or invading the mesorectal fascia, a more intensive preoperative approach is recommended, which may include neoadjuvant or preoperative chemotherapy. The potential benefits include better compliance than postoperative chemotherapy, a higher pathological complete remission rate, which facilitates a non-surgical approach, and earlier treatment of micrometastatic disease with improved disease-free survival compared to standard preoperative chemoradiation or short-course radiation. Two recently reported phase III randomized trials, RAPIDO and PRODIGE 23, show that adding neoadjuvant chemotherapy to either standard short-course radiation or standard long-course chemoradiation in locally advanced rectal cancer patients reduces the risk of metastasis and significantly prolongs disease-related treatment failure and disease-free survival. This review discusses these potentially practice-changing trials and how they may affect our current understanding of treating locally advanced rectal cancers.

Total Neoadjuvant Treatment for Rectal Cancer: Preliminary Experience

INTRODUCTION

Administration of chemotherapeutic regimens such as FOLFOX or CAPEOX with chemoradiation in the neoadjuvant setting, termed total neoadjuvant treatment (TNT), was introduced in recent years. By increasing the complete pathologic and clinical responses, patients with locally advanced rectal cancer may have better oncologic outcomes and potentially abstain from undergoing a proctectomy.

METHODS

All patients who underwent TNT at a single National Accreditation Program for Rectal Cancer accredited referral center were included. A retrospective analysis was performed using a computerized Institutional Review Board-approved database. Patient demographics, diagnostic workup, treatment regimens, and surgical and pathological reports were reviewed. Complete pathological response was the primary outcome. Univariable and multivariable logistic regression analyses were performed to identify potential factors predisposing to complete pathological response.

RESULTS

Thirty patients met the inclusion criteria, 14(46.6%) of whom had complete pathologic response. There was no difference in baseline demographic characteristics between patients who achieved complete pathological response and those who did not. Pathology revealed a 92% intact mesorectum rate in the complete pathologic response group and a mean of 24 harvested lymph nodes in the entire study cohort. Both univariable and multivariable logistic regression analyses failed to demonstrate statistically significant factors predicting complete pathologic response, magnetic resonance imaging (MRI) tumor size, and posttreatment MRI lymph node positivity.

CONCLUSION

TNT is safe and efficient for patients with locally advanced rectal cancer. It increases complete pathological and clinical response rates and may more widely evolve to be the treatment of choice in this group of patients in the near future.

Challenges and shifting treatment strategies in the surgical treatment of locally advanced rectal cancer

The current standard treatment for locally advanced rectal cancer (LARC) in Korea and Western countries is a multimodal approach incorporating preoperative long-course chemoradiotherapy (LCRT) followed by total mesorectal excision (TME) and adjuvant chemotherapy. This approach has significantly improved local control and reduced recurrence rates; however, the overall survival benefit has not been established. Although LCRT is a good option, there remain challenging unresolved problems for colorectal surgeons. We focused on four challenging issues in this review article. The first is LARC with resectable liver metastases, for which there has been no consensus regarding optimal management and practice thus far. The second is cancer progression at the time of restaging after completion of preoperative LCRT. To date, there have been few reports on this issue. The third is early recurrence after TME following preoperative LCRT, the reason for which is thought to be the delayed systemic chemotherapy in the preoperative LCRT protocol. The fourth is cost-effectiveness. The preoperative LCRT protocol takes 5 weeks. After a 6-8-week waiting period, surgery is performed. Therefore, it is more time-consuming than short-course chemoradiotherapy. To overcome these issues, total neoadjuvant treatment (TNT) modalities, performed using various protocols, have been conducted globally based on cumulative experience. We also attempted to discuss previous TNT protocols in this article. One treatment strategy is not sufficient for patients with varying clinical characteristics. Therefore, we should revisit current treatment strategies based on recent clinical experience.

Report from the 20th annual Western Canadian Gastrointestinal Cancer Consensus Conference; Saskatoon, Saskatchewan; 28-29 September 2018

The 20th annual Western Canadian Gastrointestinal Cancer Consensus Conference was held in Saskatoon, Saskatchewan, 28-29 September 2018. This interactive multidisciplinary conference is attended by health care professionals from across Western Canada (British Columbia, Alberta, Saskatchewan, and Manitoba) who are involved in the care of patients with gastrointestinal cancers. In addition, invited speakers from other provinces participate. Surgical, medical, and radiation oncologists, and allied health care professionals participated in presentations and discussion sessions for the purpose of developing the recommendations presented here. This consensus statement addresses current issues in the management of colorectal cancers.

Total neoadjuvant treatment of locally advanced rectal cancer with high risk factors in Slovenia. Radiol Oncol. 2019;53:465-472. [PMID: 31652124 PMCID: PMC6884932 DOI: 10.2478/raon-2019-0046]

Background In the light of a high rate of distant recurrence and poor compliance of adjuvant chemotherapy in high risk rectal cancer patients the total neoadjuvant treatment was logical approach to gaining acceptance. We aimed to evaluate toxicity and efficiency of this treatment in patients with rectal cancer and high risk factors for local or distant recurrence. Patients and methods Patients with rectal cancer stage II and III and with at least one high risk factor: T4, presence of extramural vein invasion (EMVI), positive extramesorectal lymph nodes or mesorectal fascia (MRF) involvement were treated with four cycles of induction CAPOX/FOLFOX, followed by capecitabine-based radiochemotherapy (CRT) and two consolidation cycles of CAPOX/FOLFOX before the operation. Surgery was scheduled 8-10 weeks after completition of CRT. Results From November 2016 to July 2018 66 patients were evaluable. All patients had stage III disease, 24 (36.4%) had T4 tumors, in 46 (69.7%) EMVI was present and in 47 (71.2%) MRF was involved. After induction chemotherapy, which was completed by 61 (92.4%) of patients, radiologic downstaging of T, N, stage, absence of EMVI or MRF involvement was observed in 42.4%, 62.1%, 36.4%, 69.7% and 68.2%, respectively. All patients completed radiation and 54 (81.8%) patients received both cycles of consolidation chemotherapy. Grade 3 adverse events of neoadjuvant treatment was observed in 4 (6%) patients. Five patients rejected surgery, 3 of them with radiologic complete clinical remissions. One patient did not have definitive surgery of primary tumor due to unexpected cardiac arrest few days after sigmoid colostomy formation. Among 60 operated patients pathological complete response rate was 23.3%, the rate of near complete response was 20% and in 96.7% radical resection was achieved. Pathological T, N and stage downstaging was 65%, 96.7% and 83.4%, respectively. Grade ≥ 3 perioperative complications were anastomotic leakage in 3, pelvic abscess in 1 and paralytic ileus in 2 patients. The rate of pathologic complete response (pCR) in patients irradiated with 3D conformal technique was 12.1% while with IMRT and VMAT it was 37% (p < 0.05). Hypofractionation with larger dose per fraction and simultaneous integrated boost used in the latest two was the only factor associated with pCR. ConclusionsTotal neoadjuvant treatment of high risk rectal cancer is well tolerated and highly effective with excellent tumor and node regression rate and with low toxicity rate. Longer follow up will show if this strategy will improve distant disease control and survival.