The advantage of circulating tumor cells over serum carcinoembryonic antigen for predicting treatment responses in rectal cancer

Rectal Cancer: Exploring Predictive Biomarkers Through Molecular Pathways Involved in Carcinogenesis

In 2022, colorectal cancer (CCR) had the second-highest incidence in Europe, preceded only by breast cancer [...].

The Role of Frailty in the Treatment of Locally Advanced Rectal Cancer

Owing to the gradual aging of today's population, an increase in the prevalence of frailty syndrome has been noticed. This complex state of health, characterized by decreased resilience and tolerance with concurrent increased vulnerability to stressors and adverse health-related factors, has drawn researchers' attention in recent years. Rectal cancer, which constitutes ~30% of all colorectal cancers, is a disease noticeably related to the elderly. In its locally advanced form, it is conventionally treated with trimodal therapy-neoadjuvant chemoradiotherapy followed by total mesorectal excision and adjuvant chemotherapy. Despite its good clinical outcomes and improvement in rectal cancer local control, as evidenced by clinical trials, it remains unclear if all frail patients benefit from that approach since it may be associated with adverse side effects that cannot be handled by them. As old patients, and frail ones even more noticeably, are poorly represented in the clinical trials describing outcomes of the standard treatment, this article aims to review the current knowledge on the trimodal therapy of rectal cancer with an emphasis on novel approaches to rectal cancer that can be implemented for frail patients.

The Crying Need for a Better Response Assessment in Rectal Cancer

OPINION STATEMENT

Since total neoadjuvant treatment achieves almost 30% pathologic complete response, organ preservation has been increasingly debated for good responders after neoadjuvant treatment for patients diagnosed with rectal cancer. Two organ preservation strategies are available: a watch and wait strategy and a local excision strategy including patients with a near clinical complete response. A major issue is the selection of patients according to the initial tumor staging or the response assessment. Despite modern imaging improvement, identifying complete response remains challenging. A better selection could be possible by radiomics analyses, exploiting numerous image features to feed data characterization algorithms. The subsequent step is to include baseline and/or pre-therapeutic MRI, PET-CT, and CT radiomics added to the patients' clinicopathological data, inside machine learning (ML) prediction models, with predictive or prognostic purposes. These models could be further improved by the addition of new biomarkers such as circulating tumor biomarkers, molecular profiling, or pathological immune biomarkers.

MicroRNAs as Predictive Biomarkers in Patients with Colorectal Cancer Receiving Chemotherapy or Chemoradiotherapy: A Narrative Literature Review

Colorectal cancer (CRC) is one of the most common malignancies and is associated with high mortality rates worldwide. The underlying mechanism of tumorigenesis in CRC is complex, involving genetic, lifestyle-related, and environmental factors. Although radical resection with adjuvant FOLFOX (5-fluorouracil, leucovorin, and oxaliplatin) chemotherapy and neoadjuvant chemoradiotherapy have remained mainstays of treatment for patients with stage III CRC and locally advanced rectal cancer, respectively, the oncological outcomes of these treatments are often unsatisfactory. To improve patients' chances of survival, researchers are actively searching for new biomarkers to facilitate the development of more effective treatment strategies for CRC and metastatic CRC (mCRC). MicroRNAs (miRs), small, single-stranded, noncoding RNAs, can post-transcriptionally regulate mRNA translation and trigger mRNA degradation. Recent studies have documented aberrant miR levels in patients with CRC or mCRC, and some miRs are reportedly associated with chemoresistance or radioresistance in CRC. Herein, we present a narrative review of the literature on the roles of oncogenic miRs (oncomiRs) and tumor suppressor miRs (anti-oncomiRs), some of which can be used to predict the responses of patients with CRC to chemotherapy or chemoradiotherapy. Moreover, miRs may serve as potential therapeutic targets because their functions can be manipulated using synthetic antagonists and miR mimics.

Biomarkers of Favorable vs. Unfavorable Responses in Locally Advanced Rectal Cancer Patients Receiving Neoadjuvant Concurrent Chemoradiotherapy

Colorectal cancer is the second leading cause of cancer death globally. The gold standard for locally advanced rectal cancer (LARC) nowadays is preoperative concurrent chemoradiation (CCRT). Approximately three quarters of LARC patients do not achieve pathological complete response and hence suffer from relapse, metastases and inevitable death. The exploration of trustworthy and timely biomarkers for CCRT response is urgently called for. This review focused upon a broad spectrum of biomarkers, including circulating tumor cells, DNA, RNA, oncogenes, tumor suppressor genes, epigenetics, impaired DNA mismatch repair, patient-derived xenografts, in vitro tumor organoids, immunity and microbiomes. Utilizing proper biomarkers can assist in categorizing appropriate patients by the most efficient treatment modality with the best outcome and accompanied by minimal side effects. The purpose of this review is to inspect and analyze accessible data in order to fully realize the promise of precision oncology for rectal cancer patients.

Current State of Neoadjuvant Radiotherapy for Rectal Cancer

Colorectal cancer is the third most commonly diagnosed cancer, with rectal cancer accounting for 30% of cases. The current standard of care curative treatment for locally advanced rectal cancer is (chemo)radiotherapy followed by surgery and adjuvant chemotherapy. Although neoadjuvant radiotherapy has reduced the risk of local recurrence to less than 10%, the risk of distant metastasis remained high at 30% affecting patient survival. In addition, there is a recognition that there is heterogeneity in tumor biology and treatment response with good responders potentially suitable for treatment de-escalation. Therefore, new treatment sequencing and regimens were investigated. Here, we reviewed the evidence for current neoadjuvant treatment options in patients with locally advanced rectal adenocarcinoma, and highlight the new challenges in this new treatment landscape.

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”.

Biomarkers and cell-based models to predict the outcome of neoadjuvant therapy for rectal cancer patients

Rectal cancer constitutes approximately one-third of all colorectal cancers and contributes to considerable mortality globally. In contrast to colon cancer, the standard treatment for localized rectal cancer often involves neoadjuvant chemoradiotherapy. Tumour response rates to treatment show substantial inter-patient heterogeneity, indicating a need for treatment stratification. Consequently researchers have attempted to establish new means for predicting tumour response in order to assist in treatment decisions. In this review we have summarized published findings regarding potential biomarkers to predict neoadjuvant treatment response for rectal cancer tumours. In addition, we describe cell-based models that can be utilized both for treatment prediction and for studying the complex mechanisms involved.

Radiation therapy for rectal cancer

Radiotherapy (RT) has remained an important pillar in the multi-modality management of rectal cancer. Adjuvant RT with concurrent chemotherapy (chemo-RT) was once the standard of care for locally advanced rectal cancer, but with time, that has now changed and neoadjuvant chemo-RT followed by total mesorectal excision (TME) surgery is the new standard. Alternatively, neoadjuvant RT alone remains an option and clinicians are tasked to choose between the two. In an era of personalised oncological management, it is unsurprising that the treatment for rectal cancer is following suit and upcoming trials are studying ways to improve outcomes and minimise toxicity for patients while tailoring treatments specific to each patient's tumour. We review the evolution of the role of RT in rectal cancer and look forward to what the future holds.

Circulating Biomarkers for Response Prediction of Rectal Cancer to Neoadjuvant Chemoradiotherapy

Rectal cancer response to neoadjuvant Chemoradiotherapy (pCRT) is highly variable. In fact, it has been estimated that only about 21 % of patients show pathologic Complete Response (pCR) after therapy, while in most of the patients a partial or incomplete tumour regression is observed. Consequently, patients with a priori chemoradioresistant tumour should not receive the treatment, which is associated with substantial adverse effects and does not guarantee any clinical benefit. For Locally Advanced Rectal Cancer Patients (LARC), a standardized neoadjuvant treatment protocol is applied, the identification and the usefulness of prognostic or predictive biomarkers can improve the antitumoural treatment strategy, modifying the sequence, dose, and combination of radiotherapy, chemotherapy and surgical resection. For these reasons, a growing number of studies are actually focussed on the discovery and investigation of new predictive biomarkers of response to pCRT. In this review, we have selected the most recent literature (2012-2017) regarding the employment of blood-based biomarkers potentially predicting pCR in LARC patients and we have critically discussed them to highlight their real clinical benefit and the current limitations of the proposed methodological approaches.

Liquid Biopsy in Solid Malignancy

The clinical utility of tissue biopsies in cancer management will continue to expand, especially with the evolving role of targeted therapies. "Liquid biopsy" refers to testing a patient's biofluid samples such as blood or urine to detect tumor-derived molecules and cells that can be used diagnostically and prognostically in the assessment of cancer. Many proof-of-concept and pilot studies have shown the clinical potential of liquid biopsies as diagnostic and prognostic markers which would provide a surrogate for the conventional "solid biopsy". In this review, we focus on three methods of liquid biopsy-circulating tumor cells, extracellular vesicles, and circulating tumor DNA-to provide a landscape view of their clinical applicability in cancer management and research.

Clinical indications for, and the future of, circulating tumor cells

Circulating tumor cells (CTCs) are cells that have detached from the primary tumor and entered circulation with potential to initiate a site of metastasis. Currently, CTC detection using CellSearch is cleared by the Food and Drug Administration for monitoring metastatic breast, prostate, and colorectal cancers as a prognostic biomarker for progression-free and overall survival. Accumulating evidence suggests CTCs have similar prognostic value in other metastatic and non-metastatic settings. Current research efforts are focused on extending the utility of CTCs beyond a prognostic biomarker to help guide clinical decision-making. These include using CTCs as a screening tool for diagnosis, liquid biopsy for molecular profiling, predictive biomarker to specific therapies, and monitoring tool to assess response and guide changes to treatment. CTCs have unique advantages vs circulating tumor DNA in this endeavor. Indications for CTCs in daily practice will expand as isolation techniques improve and clinical studies validating their utility continue to grow.

Predictive and Prognostic Molecular Biomarkers for Response to Neoadjuvant Chemoradiation in Rectal Cancer

The standard of care in locally advanced rectal cancer is neoadjuvant chemoradiation (nCRT) followed by radical surgery. Response to nCRT varies among patients and pathological complete response is associated with better outcome. However, there is a lack of effective methods to select rectal cancer patients who would or would not have a benefit from nCRT. The utility of clinicopathological and radiological features are limited due to lack of adequate sensitivity and specificity. Molecular biomarkers have the potential to predict response to nCRT at an early time point, but none have currently reached the clinic. Integration of diverse types of biomarkers including clinicopathological and imaging features, identification of mechanistic link to tumor biology, and rigorous validation using samples which represent disease heterogeneity, will allow to develop a sensitive and cost-effective molecular biomarker panel for precision medicine in rectal cancer. Here, we aim to review the recent advance in tissue- and blood-based molecular biomarker research and illustrate their potential in predicting nCRT response in rectal cancer.

The Role of CTCs as Tumor Biomarkers

Detection of Circulating Tumor Cells (CTCs) in peripheral blood can serve as a "liquid biopsy" approach and as a source of valuable tumor markers. CTCs are rare, and thus their detection, enumeration and molecular characterization are very challenging. CTCs have the unique characteristic to be non-invasively isolated from blood and used to follow patients over time, since these cells can provide significant information for better understanding tumour biology and tumour cell dissemination. CTCs molecular characterization offers the unique potential to understand better the biology of metastasis and resistance to established therapies and their analysis presents nowadays a promising field for both advanced and early stage patients. In this chapter we focus on the latest findings concerning the clinical relevance of CTC detection and enumeration, and discuss their potential as tumor biomarkers in various types of solid cancers. We also highlight the importance of performing comparison studies between these different methodologies and external quality control systems for establishing CTCs as tumor biomarkers in the routine clinical setting.

Circulating tumor cells in breast cancer beyond the genotype of primary tumor for tailored therapy

Although TNM staging based on tumor, node lymph status and metastasis status-is the most widely used method in the clinic to classify breast cancer (BC) and assess prognosis, it offers limited information for different BC subgroups. Circulating tumor cells (CTCs) are regarded as minimal residual disease and are proven to have a strong relationship with BC. Detection of ≥5 CTCs per 7.5 mL in peripheral blood predicts poor prognosis in metastatic BC irrespective of other clinical parameters, whereas, in early-stage BC, detection of CK19(+) CTCs are also associated with poor prognosis. Increasing data and clinical trials show that CTCs can improve prognostic accuracy and help tailor treatment for patients with BC. However, heterogeneous CTCs in the process of an epithelial-mesenchymal transition (EMT) in BC makes it a challenge to detect these rare cells. Moreover, the genotypic and phenotypic features of CTCs are different from primary BC tumors. Molecular analysis of CTCs in BC may benefit patients by identifying those amenable to tailored therapy. We propose that CTCs should be used alongside the TNM staging system and the genotype of primary tumor to guide tailored BC diagnosis and treatment.

Circulating microRNA-21 as a biomarker for the detection of various carcinomas: an updated meta-analysis based on 36 studies

Cancer is a class of diseases with high mortality rate, characterized by unregulated cell growth. Early diagnosis of cancer is currently the most effective method to prevent cancer development and improve the survival rate of patients. Traditional diagnostic methods such as biopsy usually provoke discomfort and unpleasant experience. Recently, microRNAs (miRNAs) were widely reported to be potential biomarkers to detect cancers without invasiveness. MicroRNA-21 (miRNA-21, miR-21) is one of the most prevalent miRNAs. This meta-analysis aims to make a comprehensive analysis of the potential role of circulating miR-21 as a biomarker in human carcinoma diagnosis. A total of 36 articles involving 2920 cancer patients and 1986 healthy controls with regard to the diagnostic value of the circulating miR-21 for cancer detection were selected from online bibliographic databases. For pooled analysis, the sensitivity, specificity, and other basic characteristics were extracted from the 36 included articles. Then, bivariate random-effects model was selected to gain pooled results. Furthermore, to explore the sources of heterogeneity, we conducted stratified and meta-regression analyses based on different race/sample groups. The pooled characteristics of all included articles were as follows: sensitivity, 0.78 (95% confidence intervals (CI), 0.73-0.82); specificity, 0.82 (95% CI, 0.79-0.86); positive likelihood ratio (PLR), 4.4 (95% CI, 3.6-5.4); negative likelihood ratio (NLR), 0.26 (95% CI, 0.21-0.33); diagnostic odds ratio (DOR), 17 (95% CI, 12-24); and area under the curve (AUC), 0.87 (95% CI, 0.84-0.90). The subgroup analyses results based on different ethnic populations revealed that the diagnostic accuracy of miR-21 tends to be higher in Asian populations than in Caucasian populations. Furthermore, another subgroup analysis performed on sample types suggested that the serum-based specimen used in cancer diagnosis appeared to be more accurate than the plasma-based specimen. Our meta-analysis shows that the circulating miR-21 may be a potential biomarker as diagnostic tool for early-stage cancer diagnosis.