Radiotherapy and concurrent radiochemotherapy for rectal cancer

Circulating Tumor DNA for Prediction of Complete Pathological Response to Neoadjuvant Radiochemotherapy in Locally Advanced Rectal Cancer (NEORECT Trial)

BACKGROUND/OBJECTIVES

Locally advanced rectal cancer is treated with neoadjuvant chemoradiotherapy (nCRT) followed by total mesorectal excision (TME). As this approach achieves complete pathologic remissions (pCR) in approximately 30% of patients, it raises the question of whether surgery is always necessary. Non-surgical strategies, such as "watch and wait" (W&W), have shown similarly promising outcomes. However, there is an unmet need for reliable biomarkers predicting pCR. Analysis of circulating tumor DNA (ctDNA) has shown potential for monitoring treatment response and detecting minimal residual disease. We hypothesized that monitoring ctDNA changes during nCRT might facilitate the identification of individuals who achieve pCR.

METHODS

In the prospective single-center NEORECT trial, the plasma of forty rectal cancer patients was collected before, during, and after nCRT and before TME. Informative somatic mutations were identified in tissue biopsies by NGS and subsequently used for ctDNA quantification by dPCR.

RESULTS

The results identified three distinct ctDNA patterns: increase, decrease, and absence. Remarkably, undetectable DNA was observed in good responders, while a tenfold ctDNA increase was associated with the emergence of new metastases. Despite these insights, ctDNA alone demonstrated low specificity, with no significant correlation to pCR or long-term prognosis. A multimodal approach incorporating routinely available clinical parameters remains inadequate for accurately predicting pCR prior to TME.

CONCLUSIONS

In conclusion, the NEORECT trial establishes the feasibility of ctDNA-based personalized monitoring for rectal cancer patients undergoing nCRT. However, the utility of ctDNA in enhancing pCR prediction for a W&W strategy warrants further investigation. Larger studies integrating multi-gene analyses and expanded clinical datasets are essential in the future.

Association of fascin-1 with mortality, disease progression and metastasis in carcinomas: a systematic review and meta-analysis

BACKGROUND

Fascin-1 is an actin-bundling protein expressed in many human carcinomas, although absent from most normal epithelia. Fascin-1 promotes filopodia formation, migration and invasion in carcinoma cells; in mouse xenograft tumor models it contributes to metastasis. Fascin-1 is an interesting candidate biomarker for aggressive, metastatic carcinomas but data from individual studies of human tumors have not yet been pooled systematically.

METHODS

This systematic review was conducted in accordance with PRISMA guidelines, using fixed and random effects models, as appropriate, to undertake meta-analysis.

RESULTS

A total of 26 immunohistochemical studies of 5 prevalent human carcinomas were identified for meta-analysis. Fascin-1 was associated with increased risk of mortality for breast (pooled hazard ratio, (HR) = 2.58; 95% confidence interval (CI) 1.48 to 4.52; P = 0.001), colorectal (HR = 1.60 (1.37 to 1.86; P <0.001) and esophageal carcinomas (HR = 1.35; CI 1.13 to 1.60; P = 0.001). There was no evidence of association of fascin-1 with mortality in gastric and lung carcinomas. Fascin-1 was associated with increased risk of disease progression in breast (HR = 2.48; CI 1.38 to 4.46; P = 0.002) and colorectal carcinomas (HR = 2.12; CI 1.00 to 4.47; P = 0.05), but not with progression of lung carcinomas (HR = 0.95; CI 0.49 to 1.85; P = 0.9). Fascin-1 was associated with increased risk of lymph node metastasis in colorectal (pooled risk ratio (RR) = 1.47; CI 1.26 to 1.71; P <0.001) and gastric carcinomas (RR = 1.43; CI 1.21 to 1.70; P <0.001). There was no evidence of association of fascin-1 with lymph node metastasis in lung or esophageal carcinomas. Fascin-1 was associated with increased risk of distant metastasis in colorectal (RR = 1.70; CI 1.18 to 2.45; P = 0.004) and gastric carcinomas (RR = 1.93; CI 1.21 to 3.33; P = 0.02). No association with distant metastasis in esophageal carcinomas was observed. Pooling across all the carcinomas provided strong evidence for association of fascin-1 with increased risk of mortality (HR = 1.44; CI 1.24 to 1.68; P <0.001; n = 3,645), lymph node metastasis (RR = 1.36; CI 1.18 to 1.55; P <0.001; n = 2,906) and distant metastasis (1.76; 1.34 to 2.32; P <0.001; n = 1,514).

CONCLUSIONS

Fascin-1 is associated consistently with increased risk of mortality in breast, colorectal and esophageal carcinomas and with metastasis in colorectal and gastric carcinomas. The results were stable to various sensitivity analyses and did not vary by predefined subgroups. These data will assist rational decision making for focusing investigations of fascin-1 as a biomarker or therapeutic target onto the most relevant carcinomas.

Novel substituted (Z)-5-((N-benzyl-1H-indol-3-yl)methylene)imidazolidine-2,4-diones and 5-((N-benzyl-1H-indol-3-yl)methylene)pyrimidine-2,4,6(1H,3H,5H)-triones as potent radio-sensitizing agents

A series of (Z)-5-((N-benzyl-1H-indol-3-yl)methylene)imidazolidine-2,4-dione (9a-9m) and 5-((N-benzyl-1H-indol-3-yl)methylene)pyrimidine-2,4,6(1H,3H,5H)-trione (10a-10i) derivatives that incorporate a variety of aromatic substituents in both the indole and N-benzyl moieties have been synthesized. These analogs were evaluated for their radiosensitization activity against the HT-29 cell line. Three analogs, 10a, 10b, and 10c were identified as the most potent radiosensitizing agents.

Current evidence-based opinions in the management of adenocarcionoma of the rectum

The management of rectal cancer has drastically evolved over the past two decades as a result of implementation of circular stapling devices and the introduction of neoadjuvant chemoradiation. In spite of current aggressive multimodality treatments, the recurrence rate remains unacceptably high and the expected 5-year survival in patients who develop recurrent disease is dismal. The management of rectal cancer must involve a multidisciplinary approach. An understanding of the biology of rectal tumours may allow for selection of patients who may have an aggressive phenotype allowing for alterations in the operative and neoadjuvant planning. Efforts to improve local control and survival in rectal cancer are the focus of multiple current clinical and preclinical research efforts. Preoperative chemoradiation for and surgical management of rectal cancer, including the laparoscopic approach are areas of dynamic progression. In the present report, we review the current evidence in the new strategies pertaining to the multimodality approach in the management of rectal cancer.

Rectal cancer and importance of chemoradiation in the treatment

Neoadjuvant chemoradiation is used as a preoperative standard treatment for the majority of patients with Stage II/III rectal cancers and, in attempt to facilitate surgical intervention, reduce the rate of local recurrence and improve overall outcomes in patients suffering from this malignancy. However, this modality results in a wide range of clinical responses. In many cases, a pathological complete response is achieved, while in others, receiving the same form of treatment, the tumor continues to grow. The specific phenotype of the tumor plays a major role in rendering tumor cells a survival advantage to the cytotoxic effects of chemoradiation. Several factors participating in proliferation, cell cycle, apoptosis and hypoxiahave been investigated under a variety of conditions in pre-irradiated tissues and post-irradiated tumors. Mutations in the genes of these pathways have shown to lead to resistance to chemoradiation. This chapter describes colon cancer with emphasis on the molecular mechanisms that may lead to chemoradio-resistance of cells with cytotoxically induced DNA injury in rectal cancer.

Factors associated with sphincter-preserving surgery for rectal cancer at national comprehensive cancer network centers

OBJECTIVE

To determine rate and predictors of sphincter-preserving surgery (SPS) for rectal cancer patients treated at specialty institutions.

SUMMARY BACKGROUND DATA

SPS has been considered a surrogate for surgical quality, and sphincter preservation is tremendously important to patients. Evidence of association between case volume and SPS rate has prompted recommendations that all rectal cancer patients undergo surgery at specialty institutions. However, rates of SPS, and the factors associated with ability to perform SPS, have not been well-characterized.

METHODS

A prospective registry of all colorectal cancer patients treated at 7 National Comprehensive Cancer Network institutions was used to identify patients with clinical stage I-III rectal cancer undergoing surgery (n = 674) between September 2005 and October 2007. Patient, tumor and treatment factors were abstracted; patients' clinical characteristics with and without SPS were compared using descriptive statistics and multivariable logistic regression.

RESULTS

Of 674 identified patients (median age, 58.2; 60% male), 520 (77%) had SPS. Of these, 240 had low anterior resection with coloanal anastomosis, 268 low anterior resection without coloanal anastomosis; 12 had other SPS procedures. Sixty-two percent had a temporary diverting stoma. On multivariable analyses, independent predictors of SPS included younger age at diagnosis, proximal location in the rectum, nonfixed tumor, and institution.

CONCLUSIONS

SPS rates at National Comprehensive Cancer Network institutions exceed those seen in population-based samples and clinical trials. In addition to expected variation in SPS rates based on patient and tumor characteristics, we identified variation among institutions. Although the optimal rate of SPS remains unknown, this provides areas for further research and potential performance improvement.

Radiosensitization of HT-29 cells and xenografts by the nitric oxide donor DETANONOate

BACKGROUND

Mechanisms of radioresistance in rectal cancer remain unclear.

OBJECTIVES

To determine mechanisms of radioresistance in rectal cancer cells and to assess the role of the nitric oxide donor DETANONOate as a radiosensitizing agent.

METHODS

Survival was determined by clonogenic assays, apoptosis by PARP-1 cleavage, and phenotypic differences by Western blot analysis. SCID mice bearing HT-29 xenografts were treated with ionizing radiation (IR) [2.0 Gy x 5], DETANONOate [0.4 mg/kg i.p.], or combination treatment.

RESULTS

Colorectal cancer HT-29-p53-null cells were resistant and HCT-116-p53 wild-type cells sensitive to IR, which correlated with cleaved PARP-1. Increased levels of p21 occurred in HCT-116 cells, while Bcl-2 and survivin were elevated in HT-29 cells. Radiosensitization was achieved with a substantial elevation of cleaved PARP-1 in DETANONOate-HT-29-treated versus control cells, which was accompanied by elevation of p21, p27, and BAX, and a concomitant decrease in Bcl-2. SCID mice bearing HT-29 xenografts demonstrated a 37.6%, 51.1%, and 70.1% inhibition in tumor growth in mice receiving IR, DETANONOate, and combination treatment versus control, respectively.

CONCLUSIONS

Radioresistant HT-29 cells are p53-null and have substantially decreased levels of p21. DETANONOate radiosensitized HT-29 cells in vitro and in vivo by an additive effect in apoptosis.

Irinophore C, a novel nanoformulation of irinotecan, alters tumor vascular function and enhances the distribution of 5-fluorouracil and doxorubicin

PURPOSE

To examine the antitumor effects of Irinophore C, a nanopharmaceutical formulation of irinotecan, on the tissue morphology and function of tumor vasculature in HT-29 human colorectal tumors.

EXPERIMENTAL DESIGN

Fluorescence microscopy was used to map and quantify changes in tissue density, tumor vasculature, hypoxia, and the distribution of Hoechst 33342, a perfusion marker, and the anticancer drug, doxorubicin. Noninvasive magnetic resonance imaging was used to quantify Ktrans, the volume transfer constant of a solute between the blood vessels and extracellular tissue compartment of the tumor, as a measure of vascular function. Following treatment with Irinophore C, 19F magnetic resonance spectroscopy was used to monitor the delivery of 5-fluorouracil (5-FU) to the tumor tissue, whereas scintigraphy was used to quantify the presence of bound [14C]5-FU.

RESULTS

Irinophore C decreased cell density (P = 8.42 x 10(-5)), the overall number of endothelial cells in the entire section (P = 0.014), tumor hypoxia (P = 5.32 x 10(-9)), and K(trans) (P = 0.050). However, treatment increased the ratio of endothelial cells to cell density (P = 0.00024) and the accumulation of Hoechst 33342 (P = 0.022), doxorubicin (P = 0.243 x 10(-5)), and 5-FU (P = 0.0002) in the tumor. Vascular endothelial growth factor and interleukin-8, two proangiogenic factors, were down-regulated, whereas the antiangiogenic factor TIMP-1 was up-regulated in Irinophore C-treated tumors.

CONCLUSIONS

Irinophore C treatment improves the vascular function of the tumor, thereby reducing tumor hypoxia and increasing the delivery and accumulation of a second drug. Reducing hypoxia would enhance radiotherapy, whereas improving delivery of a second drug to the tumor should result in higher cell kill.

Preoperative therapy for lower rectal cancer and modifications in distance from anal sphincter

PURPOSE

To assess the frequency and magnitude of changes in lower rectal cancer resulting from preoperative therapy and its impact on sphincter-saving surgery. Preoperative therapy can increase the rate of preserving surgery by shrinking the tumor and enhancing its distance from the anal sphincter. However, reliable data concerning these modifications are not yet available in published reports.

METHODS AND MATERIALS

A total of 98 cases of locally advanced cancer of the lower rectum (90 Stage uT3-T4N0-N+ and 8 uT2N+M0) that had undergone preoperative therapy were studied by endorectal ultrasonography. The maximal size of the tumor and its distance from the anal sphincter were measured in millimeters before and after preoperative therapy. Surgery was performed 6-8 weeks after therapy, and the histopathologic margins were compared with the endorectal ultrasound data.

RESULTS

Of the 90 cases, 82.5% showed tumor downsizing, varying from one-third to two-thirds or more of the original tumor mass. The distance between the tumor and the anal sphincter increased in 60.2% of cases. The median increase was 0.73 cm (range, 0.2-2.5). Downsizing was not always associated with an increase in distance. Preserving surgery was performed in 60.6% of cases. It was possible in nearly 30% of patients in whom the cancer had reached the anal sphincter before the preoperative therapy. The distal margin was tumor free in these cases.

CONCLUSION

The results of our study have shown that in very low rectal cancer, preoperative therapy causes tumor downsizing in >80% of cases and in more than one-half enhances the distance between the tumor and anal sphincter. These modifications affect the primary surgical options, facilitating or making sphincter-saving surgery possible.

Sphincter-preserving R0 total mesorectal excision with resection of internal genitalia combined with pre- or postoperative chemoradiation for T4 rectal cancer in females

AIM: To evaluate the impact of chemoradiation admi-nistered pre- or postoperatively on prognosis in females following R0 extended resection with sphincter-preserving total mesorectal excision (TME) for locally advanced rectal cancer and to assess the association between chemoradiation and intra- and postoperative variables.

METHODS: Twenty-one females were treated for locally advanced but preoperatively assessed as primarily resectable rectal cancer involving reproductive organs. Anterior resection with TME and excision of internal genitalia was combined with neo- or adjuvant chemoradiation. Two-year disease-free survival analysis was performed with the Kaplan-Meier method and log-rank test. The association between chemoradiation and other variables was evaluated with the Fisher’s exact test and Mann-Whitney test.

RESULTS: Survival rate decreased in anaemic females (51.5% vs 57.4%), in patients older than 60 years (41.8% vs 66.7%) with poorly differentiated cancers (50.0% vs 55.6%) and tumors located ≤ 7 cm from the anal verge (42.9% vs 68.1%) but with the lack of importance. Patients with negative lymph nodes and women chemoradiated preoperatively had significantly favourable prognosis (85.7% vs 35.7%; P = 0.03 and 80.0% vs 27.3%; P = 0.01, respectively). Preoperative chemoradiation compared to adjuvant radiochemotherapy was not significantly associated with the duration of surgery, incidence of intraoperative bowel perforation and blood loss ≥ 1 L, rate of postoperative bladder and anorectal dysfunction, and minimal distal resection margin. It significantly influenced minimal radial margin (mean 4.2 mm vs 1.1 mm; P < 0.01).

CONCLUSION: Despite involving internal genitalia, long-term disease-free survival and sphincter preservation may be achieved with combined-modality therapy for females with T4 locally advanced rectal carcinoma. Neoadjuvant chemoradiation does not compromise functional results and may significantly improve oncological outcomes probably due to enhanced radial clearance.

Independent prognostic value of fascin immunoreactivity in stage III-IV colonic adenocarcinoma

Fascin, an actin-bundling protein involved in cell motility, has been shown to be upregulated in several types of carcinomas. In this study, we investigated the expression of fascin in 228 advanced colonic adenocarcinoma patients with a long follow-up. Fascin expression was compared with several clinicopathologic parameters and survival. Overall, fascin immunoreactivity was detected in 162 (71%) tumours with a prevalence for right-sided tumours (P<0.001). Fascin correlated significantly with sex, tumour grade and stage, mucinous differentiation, number of metastatic lymph nodes, extranodal tumour extension, and the occurrence of distant metastases. Patients with fascin-expressing tumours experienced a shorter disease-free and overall survival in comparison with those with negative tumours, and fascin immunoreactivity emerged as an independent prognostic factor in the multivariate analysis. Moreover, patients with the same tumour stages could be stratified in different risk categories for relapse and progression according to fascin expression. Our findings suggest that fascin is a useful prognostic marker for colonic adenocarcinomas.

Alternative clinical end points in rectal cancer--are we getting closer?

BACKGROUND

In rectal cancer a high risk of local recurrence has been reported for patients treated by surgery alone. It is also recognised that 20%-40% of rectal cancer patients continue to develop distant metastases and die, even when a very low risk of local recurrence has been achieved with the use of preoperative radiotherapy and total mesorectal excision (TME). Hence, the current design of randomised trials in rectal cancer continues to use the standard end points of local control and survival. This strategy is time-consuming. The recently published EORTC 22921 trial, which compared radiotherapy with chemoradiotherapy and tested the role of postoperative adjuvant chemotherapy, has taken 14 years from planning to results. The aim of this review was to use the evidence from both phase II and phase III trials to provide a comprehensive survey of alternative clinical trial end points in rectal cancer, where preoperative chemoradiation has now become the standard treatment. We describe their strengths and weaknesses. Some are clearly defined, easy to assess and can be obtained early, because surgical resection usually takes place within 6-8 weeks of the completion of treatment. Some pathological response end points reflect biological activity, although their effect on survival has yet to be validated in randomised controlled trials. We will propose measurement and analytical techniques for minimising bias and intra- and inter-observer variability of the non-validated end points in the hope of basing these judgements on as firm a ground as possible.

METHODS

A literature search identified both randomised and non-randomised trials of preoperative radiation therapy (RT) and chemoradiation therapy (CRT) in rectal cancer from 1993 to 2005. The aim was to find those studies that documented potential alternative end points.

RESULTS

Pathological parameters have been used as early end points to compare studies of preoperative radiotherapy or chemoradiation. In the light of the German CAO/ARO/AIO-94 study, which demonstrated an improved therapeutic ratio for preoperative treatment, enthusiasm for preoperative chemoradiation in the management of rectal cancer is increasing. Current evidence cannot indicate whether the degree of response to chemoradiation (e.g. complete pathological response; downsizing the primary tumour; sterilizing the regional nodes; tumour regression grades or residual cell density) or the achievement of a curative resection (CRM/R0 resection) is the best early clinical end point. Problems with these end points include lack of structured measurement and analysis techniques to control for intra- and inter-observer variation and lack of validation as surrogates for long-term clinical end points such as local control and survival. However, retrospective studies in rectal cancer have confirmed a strong association between the presence of microscopic tumour cells within 1 mm of the CRM and increased risks of both local recurrence and distant metastases. Further end points of current clinical relevance for which adequate methodologies for assessment are lacking include sphincter sparing end points, and assessment of long-term toxicities, ano-rectal function and their specific impact on quality of life. Recommendations are made as to the most appropriate information, which should be documented in future trials.

CONCLUSIONS

Pathological complete response following preoperative chemoradiation does not reliably predict late outcome. There are other events not mediated through this end point and there are also unintended effects (often an excess of non-cancer related deaths). Disease-free survival currently remains the best (because it is relatively quick) primary end point in designing randomised phase III studies of preoperative chemoradiation in rectal cancer, although it is necessary to control for postoperative adjuvant chemotherapy. However, the CRM status can substantially account for effects on disease-free and overall survival after chemoradiation, radiation or surgery alone. Hopefully, randomised controlled trials, which utilise these alternative clinical end points, will in future determine the precise percentages of the effect of different chemoradiation schedules on disease-free and overall survival.