Management of the Complete Clinical Response

Total neoadjuvant therapy followed by a watch-and-wait strategy for patients with rectal cancer (TOWARd): protocol for single-arm phase II/III confirmatory trial (JCOG2010)

BACKGROUND

Radical surgery is the standard treatment for rectal cancer, but can impact quality of life. Recently, the concept of total neoadjuvant therapy with a watch-and-wait strategy has been proposed in which patients with a cCR after total neoadjuvant therapy do not proceed to surgery. However, most investigations of a watch-and-wait strategy have reported cases where cCR was achieved coincidentally via total neoadjuvant therapy. The aim is to assess whether total neoadjuvant therapy is effective in early-stage rectal cancer in patients that achieve cCR and are offered a watch-and-wait strategy.

METHODS

JCOG2010 (TOWARd) is a multi-institutional, single-arm phase II/III confirmatory investigation of the safety and efficacy of total neoadjuvant therapy followed by a watch-and-wait strategy for rectal cancer. Key eligibility criteria include cT2-3 N0 M0 rectal adenocarcinoma, tumour diameter less than or equal to 5 cm, age 18-75 years, performance status 0-1, and no history of pelvic irradiation or rectal surgery. Total neoadjuvant therapy involves neoadjuvant chemoradiotherapy (capecitabine and radiotherapy: 45 Gy/25 fractions to the whole pelvis plus boost of 5.4 Gy/3 fractions to the primary tumour) followed by consolidation chemotherapy (four cycles of capecitabine/oxaliplatin). Patients will be re-staged every 8 weeks after total neoadjuvant therapy, and those who achieve cCR will undergo a watch-and-wait strategy, those with near complete response will undergo a watch-and-wait strategy or local resection, and those with an incomplete response will undergo radical surgery. The primary endpoint is the cCR rate in phase II and 5-year overall survival in phase III. Secondary endpoints include postoperative anal, urinary, and sexual function. A total of 105 patients (phase II, 40 patients; phase III, 65 patients) will be enrolled over 3.5 years.

CONCLUSION

This trial will determine whether total neoadjuvant therapy and a watch-and-wait strategy is an effective alternative to radical surgery for early-stage rectal cancer in patients with cT2-3 N0 M0 and tumour size less than or equal to 5 cm.

REGISTRATION NUMBER

jRCTs031220288 (https://jrct.niph.go.jp/en-latest-detail/jRCTs031220288).

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”.

ctDNA on liquid biopsy for predicting response and prognosis in locally advanced rectal cancer: A systematic review

BACKGROUND

The management of locally advanced rectal cancer (LARC) requires a multidisciplinary approach, with an increasing interest for non-operative strategies. Liquid biopsy for obtaining circulating tumor DNA (ctDNA) can provide information on neoadjuvant chemoradiotherapy (nCRT) pathological response and cancer-specific prognosis, and therefore might be a promising guide for these treatments.

METHODS

A systematic review of the studies available in literature has been performed to assess the role of ctDNA as a predictive and prognostic biomarker in LARC patients.

RESULTS

We retrieved 21 publications, of which 17 full-text articles and 4 abstracts. Results have been labelled into two groups: predictive and prognostic. Data about the usefulness of liquid biopsy in this setting is still inconclusive. However, baseline higher levels of longer fragments of cell-free DNA and integrity index, tumor-specific mutations and certain methylated genes could predict non-responders. Also, undetectable baseline ctDNA and decrease of common rectal cancer mutations throughout treatment (dynamic monitoring) were predictive factors of pathological complete response. The continuous detection of ctDNA in different timepoints of treatment (minimal residual disease) was consistently associated with worse prognosis.

CONCLUSIONS

ctDNA is a promising biomarker that could assist predicting treatment response to nCRT and prognosis in patients with LARC. The ideal methods and timings for the liquid biopsy still have to be defined.

Long-term outcomes of real world 'watch and wait' data for rectal cancer after neoadjuvant chemoradiotherapy

AIM

A 'watch and wait' (W&W) strategy after neoadjuvant long-course chemoradiotherapy (NACRT) remains controversial. Whilst encouraging short-term data exist, the strategy will be judged on long-term data. We present long-term, real-world UK data from a single National Health Service trust.

METHODS

An analysis was performed of a prospectively maintained W&W database over 9 years between 2010 and 2018. Outcome measures include incidence and time to regrowth and overall and disease-free survival.

RESULTS

We diagnosed 563 rectal cancers in 9 years. In all, 283 patients underwent rectal resection (50.3%). NACRT was used in 155 patients for margin-threatened tumours on staging MRI. Forty-nine patients (31.6%) experienced either a 'near complete' or a complete clinical response (cCR) at their 10 weeks post-NACRT assessment (MRI and endoscopy). The median age was 69 years (range 44-83), and the male to female ratio was 32:17. The median follow-up was 38 months (range 12-96). The median tumour distance from the anal verge was 7 cm (1-15 cm). Twenty-two patients had a cCR on initial assessment and 27 patients had a 'near' cCR. Of those 27 who experienced a 'near' cCR, 17 (63%) progressed to cCR on repeat assessment and 10 (37%) did not. Of these 10 patients, seven underwent standard surgical resection and three were unfit for surgery. R0 for the seven with delayed resection was 100%. Of 39 patients (22 cCR and 17 'near' cCR who progressed to cCR) (25.2% of those receiving NACRT), six patients experienced local regrowth (15.4%). The median time to local regrowth was 29 months (15-60 months). One of these six patients underwent salvage abdominoperineal resection, one was advised to have contact radiotherapy and four opted against surgery and also had contact radiotherapy. The overall survival was 100% at 2 years and 90% at 5 years. Disease-free survival was 90.47% at 2 years and 74.8% at 5 years.

CONCLUSION

A W&W treatment strategy was employed safely in this patient cohort with acceptable rates of local regrowth and survival.

Potential of miR-21 to Predict Incomplete Response to Chemoradiotherapy in Rectal Adenocarcinoma

Background: Patients with locally advanced rectal adenocarcinoma (LARC) are treated with neoadjuvant chemoradiotherapy (CRT). However, biomarkers for patient selection are lacking, and the association between miRNA expression and treatment response and oncological outcomes is unclear.

Objectives: To investigate miRNAs as predictors of response to neoadjuvant CRT and its association with oncological outcomes.

Methods: This retrospective study analyzed miRNA expression (miR-16, miR-21, miR-135b, miR-145, and miR-335) in pre- and post-chemoradiation rectal adenocarcinoma tissue and non-neoplastic mucosa in 91 patients treated with neoadjuvant CRT (50.4 Gy) and proctectomy. Two groups were defined: a pathological complete responders group (tumor regression grade—TRG 0) and a pathological incomplete responders group (TRG 1, 2, and 3).

Results: miR-21 and miR-135b were upregulated in tumor tissue of incomplete responders comparing with non-neoplastic tissue (p = 0.008 and p < 0.0001, respectively). Multivariate analysis showed significant association between miR-21 in pre-CRT tumor tissue and response, with a 3.67 odds ratio (OR) of incomplete response in patients with higher miR-21 levels (p = 0.04). Although with no significance, patients treated with 5-fluorouracil (5-FU) presented reduced odds of incomplete response compared with those treated with capecitabine (OR = 0.19; 95% confidence interval (CI) 0.03–1.12, p = 0.05). Moreover, significant differences were seen in overall survival (OS) in relation to clinical TNM stage (p = 0.0004), cT (p = 0.0001), presence of distant disease (p = 0.002), mesorectal tumor deposits (p = 0.003), and tumor regression grade (p = 0.04).

Conclusion: miR-21 may predict response to CRT in rectal cancer (RC).

Unintended consequences of treating early rectal cancers for complete clinical response with chemoradiotherapy

The aim was to examine the current trend in rectal cancer, which is to extend ’watch-and-wait’ to earlier-stage tumors, not normally treated with chemoradiotherapy, to define the up-side and down-side regarding quality of life (QOL) and anorectal/sexual/urinary function from this approach. We reviewed the literature regarding a ‘watch-and-wait’ strategy after neoadjuvant chemoradiotherapy. The primary outcome measure was complete clinical response. Secondary measures included colostomy rate, functional outcomes and QOL. There is a trend to use chemoradiotherapy in earlier tumors using dose-escalation of radiation and/or additional chemotherapy, resulting in high rates of complete clinical response, which may impact adversely on QOL if radical surgery is subsequently required. Focusing on organ-preservation as the primary goal of treatment rather than overall functional outcomes and QOL for the whole population, may not provide patients with sufficient information for optimal decision-making.

Liquid biopsy for rectal cancer: A systematic review

BACKGROUND

The management of locally advanced rectal cancer (RC) is an evolving clinical field where the multidisciplinary approach can reach its best, and liquid biopsy for obtaining tumor-derived component such as circulating tumor DNA (ctDNA) might provide complementary informations.

METHODS

A systematic review of studies available in literature of liquid biopsy in non-metastatic RC has been performed according to PRISMA criteria to assess the role of ctDNA as a diagnostic, predictive and prognostic biomarker in this setting.

RESULTS

Twenty-five publications have been retrieved, of which 8 full-text articles, 7 abstracts and 10 clinical trials. Results have been categorized into three groups: diagnostic, predictive and prognostic. Few but promising data are available about the use of liquid biopsy for early diagnosis of RC, with the main limitation of sensitivity due to low concentrations of ctDNA in this setting. In terms of prediction of response to chemoradiation, still inconclusive data are available about the utility of a pre-treatment liquid biopsy, whereas some studies report a positive correlation with a dynamic (pre/post-treatment) monitoring. The presence of minimal residual disease by ctDNA was consistently associated with worse prognosis across studies.

CONCLUSIONS

The use of liquid biopsy for monitoring response to chemoradiation and assess the risk of disease recurrence are the most advanced potential applications for liquid biopsy in RC, with implications also in the context of non-operative management strategies.

A Non-Operative Approach to Rectal Cancer after Chemo-Radiotherapy: Case Series and Review

INTRODUCTION

Chemotherapy administered concurrently with radiotherapy for locally-advanced rectal cancer prior to surgery is a standard of care approach. A fraction of patients after chemo-radiotherapy achieve pathological complete remission. Our aim was to evaluate patients treated only with a non-operative approach of only chemo-radiotherapy followed by observation at a community cancer center.

METHODS

Medical charts of the patients who were treated for locally advanced rectal cancer and treated with chemo-radiation therapy alone from January 1, 2000 through May 1, 2017 at a Midwestern cancer center were reviewed. The clinical course of the patients was followed from the time of the cancer diagnosis through their last available clinical record.

RESULTS

A series of three cases were reviewed with locally-advanced distal rectal cancers treated with a non-operative approach.

CONCLUSIONS

Watchful waiting for patients with locally advanced distal rectal cancer who have complete clinical response with neoadjuvant chemotherapy and radiation might be an effective treatment strategy.

[Assessment of individualized treatment of rectal carcinoma]

Individualized and tailored treatment plays a crucial role in the rating of special operation techniques or certain treatment strategies following defined quality criteria and indicators. Deviations from clearly defined recommendations in guidelines must therefore be justified, documented and evaluated as precisely as possible. The aim of this leading article is to examine the individualized treatment of rectal cancer based on existing evidence and to discuss its role in the light of routinely used treatment algorithms. In addition to a web-based literature search the current German national S3 guidelines on colorectal cancer were also included. In the treatment of cancer in the middle and lower third of the rectum, individual, patient and tumor-related parameters are of decisive importance from the pretreatment stage to the actual surgery up to aftercare and adjuvant therapy to enable interdisciplinary decision making for optimal treatment.

Delta radiomics for rectal cancer response prediction with hybrid 0.35 T magnetic resonance-guided radiotherapy (MRgRT): a hypothesis-generating study for an innovative personalized medicine approach

The aim of this study was to evaluate the variation of radiomics features, defined as "delta radiomics", in patients undergoing neoadjuvant radiochemotherapy (RCT) for rectal cancer treated with hybrid magnetic resonance (MR)-guided radiotherapy (MRgRT). The delta radiomics features were then correlated with clinical complete response (cCR) outcome, to investigate their predictive power. A total of 16 patients were enrolled, and 5 patients (31%) showed cCR at restaging examinations. T2*/T1 MR images acquired with a hybrid 0.35 T MRgRT unit were considered for this analysis. An imaging acquisition protocol of 6 MR scans per patient was performed: the first MR was acquired at first simulation (t0) and the remaining ones at fractions 5, 10, 15, 20 and 25. Radiomics features were extracted from the gross tumour volume (GTV), and each feature was correlated with the corresponding delivered dose. The variations of each feature during treatment were quantified, and the ratio between the values calculated at different dose levels and the one extracted at t0 was calculated too. The Wilcoxon-Mann-Whitney test was performed to identify the features whose variation can be predictive of cCR, assessed with a MR acquired 6 weeks after RCT and digital examination. The most predictive feature ratios in cCR prediction were the L_least and glnu ones, calculated at the second week of treatment (22 Gy) with a p value = 0.001. Delta radiomics approach showed promising results and the quantitative analysis of images throughout MRgRT treatment can successfully predict cCR offering an innovative personalized medicine approach to rectal cancer treatment.

Neoadjuvant chemoradiation for locally advanced rectal cancer: a systematic review of the literature with network meta-analysis

Background

Neoadjuvant chemoradiotherapy (CRT) prior to surgery is a standard therapy for locally advanced rectal cancer, but the optimum regime is not conclusive. This meta-analysis evaluated various CRT regimens with regard to the rate of pathologic complete response (pCR) and toxic effects of grade ≥3.

Methods

The databases PubMed, Cochrane Library, and Embase were searched for randomized controlled trials (RCTs) that compared neoadjuvant CRT regimes for treating patients with locally advanced rectal cancer, published before 28 December 2017. The primary end points were pCR and toxic effects. A network meta-analysis was applied.

Results

Fourteen RCTs (with 5,599 participants) involving the following eight regimens were included: fluorouracil (5FU) alone, or 5FU with oxaliplatin (OXA), cisplatin, or irinotecan (CPT-11); capecitabine (CAP) alone, or CAP with OXA or CPT-11; and CPT-11 with combined tegafur, 5-chloro-2,4-dihydroxypyridine, and potassium oxonate. The rate of pCR associated with CAP + OXA was significantly higher compared with 5FU alone; there were no significant differences among the other regimens. The toxicity of 5FU + OXA or CAP + OXA was significantly worse than that of 5FU alone or CAP alone. CAP + OXA and CAP were ranked, respectively, the most and second most effective regimens in terms of pCR rate. 5FU alone and CAP alone likely had the lowest and second lowest toxicity, respectively.

Conclusion

Among the currently available CRT regimens for locally advanced rectal cancer, this meta-analysis indicated that CAP + OXA provides the superior clinical results. Adding OXA to 5FU or CAP significantly increases toxicity.

Critical and Challenging Issues in the Surgical Management of Low-Lying Rectal Cancer

Despite innovative advancements, the management of distally located rectal cancer (RC) remains a formidable endeavor. The critical location of the tumor predisposes it to a circumferential resection margin that tends to involve the sphincters and surrounding organs, pelvic lymph node metastasis, and anastomotic complications. In this regard, colorectal surgeons should be aware of issues beyond the performance of total mesorectal excision (TME). For decades, abdominoperineal resection had been the standard of care for low-lying RC; however, its association with high rates of tumor recurrence, tumor perforation, and poorer survival has stimulated the development of novel surgical techniques and modifications, such as extralevator abdominoperineal excision. Similarly, difficult dissections and poor visualization, especially in obese patients with low-lying tumors, have led to the development of transanal TME or the "bottom-to-up" approach. Additionally, while neoadjuvant chemoradiotherapy has allowed for the execution of more sphincter-saving procedures without oncologic compromise, functional outcomes remain an issue. Nevertheless, neoadjuvant treatment can lead to significant tumor regression and complete pathological response, permitting the utilization of organ-preserving strategies. At present, an East and West dualism pervades the management of lateral lymph node metastasis, thereby calling for a more global and united approach. Moreover, with the increasing importance of quality of life, a tailored, individualized treatment approach is of utmost importance when taking into account oncologic and anticipated functional outcomes.

Meta-analysis of the prognostic value of CpG island methylator phenotype in rectal cancer

PURPOSE

The pathological and prognostic importance of CpG island methylator phenotype (CIMP) in rectal cancer, as a sub-population of colorectal cancer, is unknown. A meta-analysis was preformed to estimate the prognostic significance of CIMP in rectal cancer.

METHODS

A systematic search was performed of PubMed, Embase, MEDLINE, PubMed Central, and Cochrane electronic databases for articles pertaining to CIMP and rectal cancer. Articles were analysed and data extracted according to PRISMA standards.

RESULTS

Six studies including 1529 patients were included in the analysis. Following dichotomisation, the prevalence of CIMP-positive tumours was 10 to 57%, with a median of 12.5%. Meta-analysis demonstrated the pooled odds ratio for all-cause death for CIMP-positive tumours vs CIMP-negative tumours was 1.24 (95% CI 0.88-1.74). Z test for overall effect was 1.21 (p = 0.23). Heterogeneity between the studies was low (X2 5.96, df 5, p = 0.31, I2 = 16%). A total of 15 different loci were used for assessing CIMP across the studies, with a median of 6.5 loci (range 5-8).

CONCLUSIONS

No significant association between CIMP and poor outcomes in rectal cancer was demonstrated. There was a high degree of heterogeneity in CIMP assessment methodologies and in study populations. Rectal cancer datasets were frequently not extractable from larger colorectal cohorts, limiting analysis.