Immunotherapy for gastroenteropancreatic neuroendocrine neoplasms (GEP-NENs): a 2021 update.

Neuroendocrine neoplasms (NENs) are a group of heterogeneous malignancies, arising from the neuroendocrine system. These neoplasms are divided into two distinct groups, the low-proliferating, well-differentiated neuroendocrine tumors (NETs), and the highly-proliferating, poorly-differentiated neuroendocrine carcinomas (NECs). Recent data demonstrate that the incidence of gastroenteropancreatic (GEP) neuroendocrine neoplasms, GEP-NETs and GEP-NECs, has increased exponentially over the last three decades. Although surgical resection is considered the best treatment modality, patients with GEP-NETs often present with advanced disease at diagnosis associated with a 5-year survival rate of 57% for well-differentiated tumors, and only 5.2% for small-cell tumors. Immunotherapy is a novel treatment approach, which has demonstrated effective and promising therapeutic results against several types of cancers. In the present study, we review the current ongoing clinical trials and to evaluate the efficacy of immunotherapy in GEP-NENs. Furthermore, we analyze the importance of tumor genetic profiling and its clinical implications in immunotherapy response.

Radiation-Induced Esophageal Cancer: Investigating the Pathogenesis, Management, and Prognosis.

One of the most serious late side effects of irradiation is the promotion of tumorigenesis. Radiation-induced esophageal cancer (RIEC) can arise in a previously irradiated field, mostly in patients previously irradiated for thoracic malignancies such as breast cancer, Hodgkin and non-Hodgkin lymphomas, head and neck cancers, lung cancer, or previous esophageal cancer. RIEC is rare and accounts for less than 1% of all carcinomas of the esophagus. There are little data available in the current literature regarding pathogenesis, diagnosis, treatment, and outcome of esophageal cancer developed in a previously irradiated field. RIEC seems to represent a biologically aggressive disease with a poor prognosis. Although it is difficult to perform radical surgery on a previously irradiated field, R0 resection remains the mainstay of treatment. The use of neoadjuvant and adjuvant chemoradiotherapy remains very helpful in RIEC, similarly to conventional esophageal cancer protocols. The aim of this article is to elucidate this rare but challenging entity.

Current and potential biomarkers in gastric cancer: a critical review of the literature.

Gastric cancer is the fourth most common type of cancer worldwide and the second most lethal. Gastric cancer biomarkers can be used for diagnosis, prediction of sensitivity to treatment, and prognosis. The following search terms were applied to PubMed as of December 2020: 'gastric cancer classification', 'gastric cancer epidemiology', 'cancer metastasis' and 'gastric cancer biomarker'. Only experimental studies were reported in the 'biomarkers' section. Some biomarkers can serve as therapeutic targets for antitumoral drugs. The genes analyzed include E-cadherin, RPRM, XAF1, MINT25, TFF1, p16 and p53. The miRNAs analyzed include miR-18a, miR185-5p, miR-125b and miR-21. Some molecules were associated with metastasis of gastric cancer, specifically those involved with EMT process and tissue degradation.

Lay abstract Gastric cancer is the fourth most common type of cancer worldwide and the second most lethal. Gastric cancer biomarkers are molecules that have different expressions in tumor cells than in normal body cells, and can be used for diagnosis, prediction of sensitivity to treatment, and prognosis. Biomarkers in gastric cancer can include genes that suppress tumor progression, genes that increase tumor progression by binding to growth molecules, molecules related to the body's immune response to the tumor, and non-coding RNA molecules (RNA molecules that do not produce proteins but regulate the cell's genetic material). Some biomarkers can serve as therapeutic targets for anti-tumoral drugs.

Impact of Radiation Therapy on Pain Relief of Cancer Patients Affected by on Malignant Psoas Syndrome: 26 Years of Experience.

AIM: The malignant psoas syndrome (MPS) is a rare and complex cancer-related clinical entity, with a significant impact on cancer patients' quality of life. The literature describing malignant infiltration of the psoas muscle as well as its management is limited. The primary endpoint of the study was the assessment of pain relief in symptomatic terminal-stage MPS patients. MATERIALS AND METHODS: Patients underwent hypofractionated (two- or three-dimensional conformal) radiotherapy as palliative treatment. A dose of 42.5 Gy in 17 daily fractions (2.5 Gy/fraction) was prescribed. Pain response was measured before 3 and 6 months after radiation delivery. RESULTS: Between May 1992 and April 2019, eight patients were treated. The median age was 75 years (range: 59-87 years). All patients had distant metastatic disease at the time of treatment. We found a significant pain relief (median duration of response of 105 days) and an improvement in health-related quality of life. CONCLUSIONS: Radiotherapy had a favorable outcome and can be considered an effective analgesic treatment in case of painful MPS.

Actionable Locoregional Relapses after Therapy of Localized Esophageal Cancer: Insights from a Large Cohort.

OBJECTIVE: The goal of surveillance after therapy of localized esophageal cancer (LEC) is to identify actionable relapses amenable to salvage; however, the current surveillance algorithms are not optimized. We report on a large cohort of LEC patients with actionable locoregional relapses (LRRs). METHODS: Between 2000 and 2013, 127 (denominator = 752) patients with actionable LRR were identified. Histologic/cytologic confirmation was the gold standard. All surveillance tools (imaging, endoscopy, fine needle aspiration) were assessed. RESULTS: Most patients were men (89%), had adenocarcinoma (79%), and had no new symptoms (72%) when diagnosed with LRR. In trimodality patients, endoscopic confirmation of positron emission tomography-computed tomography-suspected LRR occurred in only 44%, and 56% required additional tools (e.g., fine needle aspiration). Alternatively, in bimodality patients, endoscopy confirmed LRRs in 81%. Trimodality patients had a higher risk of subsequent LRR/distant metastases after the first LRR than the bimodality patients (p = 0.03). In all patients, 78% of the subsequent relapses were distant. For patients who were salvaged, survival was significantly prolonged (50.6 vs. 25.1 months, p < 0.01). CONCLUSIONS: Patients live longer after successful salvage of the LRR than if salvage is not possible. After LRR, patients have a high risk of subsequent distant metastasis and whether the second relapse is local or distant, survival is uniformly poor.

The role of surgical treatment in isolated organ recurrence of esophageal cancer-a systematic review of the literature.

BACKGROUND: Despite the improvements in the early detection and treatment of non-metastatic esophageal cancer, more than half of patients undergoing a curative treatment for esophageal cancer will develop recurrence within three years. The prognosis of these patients is poor. However, a wide range in overall survival has been reported, depending on the pattern of recurrence, and no optimal treatment strategy following recurrence has yet been uniformly accepted. AIM: In this article, we aimed to systematically review the literature for the role of surgical resection of metachronous distant metastasis following primary treatment of esophageal cancer. Furthermore, we discuss possible factors that could possibly predict which patients may benefit from a surgical approach. A comprehensive literature search was conducted in PubMed using combinations of keywords. RESULTS: Patients with recurrence may benefit of a multimodality treatment. Regarding the isolated recurrence of esophageal cancer in solid visceral organs, operative intervention has been proposed as a treatment that may offer a survival benefit in an individual basis. No definitive conclusions regarding the potential survival advantage offered by the surgical treatment of solitary recurrent lesions can be drawn. However, recent improvements in surgical treatment and optimization of perioperative management guarantee an acceptable operative risk, making surgical resection of solitary recurrence lesions a considerable therapeutic option. CONCLUSIONS: It can be conferred from the available studies that the surgical treatment of isolated recurrence from esophageal cancer may offer a survival benefit for properly selected patients. Prospective, multicenter studies might be useful to gain a better insight into those factors that affect selection of patients to take benefit from an operative intervention.

Utilizing Yoga in Oncologic Patients Treated with Radiotherapy: Review.

PURPOSE: Several trials on noncancer population indicate that yoga is associated with meaningful clinical effects. This study evaluated the physical and psychosocial outcomes of yoga in oncologic patients treated with radiotherapy. METHODS: We focused on a research through Cochrane Register of Controlled Trials (CENTRAL), BioMed Central, and MEDLINE studies up to May 2017. RESULTS: Yoga was found to have a substantial benefit in cancer patients' distress, anxiety, and depression. It also demonstrated a moderate impact on fatigue and emotional function and a small and insignificant effect on functional well-being and sleep disturbances. As far as the effects on psychological outcomes are concerned, there was insufficient evidence. CONCLUSIONS: This systematic review of randomized controlled trials showed that yoga has strong beneficial effects on oncologic patients' quality of life. Results of the current review must be interpreted with caution due to the relative small sample sizes of most of the included studies, while a prospective randomized study stands in need for the confirmation of our results.

Co-morbidities Rather than Age Impact Outcomes in Patients Receiving Preoperative Therapy for Gastroesophageal Adenocarcinoma.

BACKGROUND: Older patients with localized gastric adenocarcinoma (LGAC) have substantial postoperative morbidity and mortality; however, postoperative outcomes of the patients who receive preoperative chemotherapy and/or chemoradiation have not been reported. We examined the impact of age at baseline on potential predictors of postoperative outcomes. METHODS: Patients with LGAC who were treated with chemotherapy and/or chemoradiation followed by surgery (n = 203) formed two groups: (1) ≥65 years old (n = 70) and (2) <65 years old (n = 133). We assessed postoperative morbidity and mortality as well as overall survival (OS) and progression-free survival (PFS). Potential predictors of 90-day postoperative outcomes were identified i) by age groups and ii) other clinical covariates. Descriptive statistics and survival analyses were utilized. RESULTS: 90-day postoperative morbidity was similar in older and younger patients (61 % vs 58 %; P = 0.655). 90-day mortality was similar (3 % vs 0 %; P = 0.118). Major Clavien grade III/IV complications were similar (17 % vs 12 %; P = 0.392). OS and PFS were also similar for both groups (P = 0.863 and P = 0.558, respectively). Other factors, such as Charlson comorbidity index (P < 0.001) and median operative time (P = 0.002) were strongly associated with postoperative complications. CONCLUSION: Our data show that older patients with LGAC generally have similar outcomes as do younger patients after preoperative therapy but comorbidity indices have significant impact on complications and the long-term outcomes rather than age.

The Proportion of Signet Ring Cell Component in Patients with Localized Gastric Adenocarcinoma Correlates with the Degree of Response to Pre-Operative Chemoradiation.

BACKGROUND: Patients with localized gastric adenocarcinoma (LGAC), who get pre-operative therapy, have heterogeneous/unpredictable outcomes. Predictive clinical variables/biomarkers are not established. METHODS: We analyzed 107 LGAC patients who had chemoradiation and surgery. LGACs were grouped for (1) presence/absence of signet ring cell histology (SRC) and (2) histologic grade: G2 or G3. %SRC was assessed (0, 1-10, 11-49, and 50-100%) and correlated with pathologic complete response (pathCR) or

A Nomogram to Predict Distant Metastases After Multimodality Therapy for Patients With Localized Esophageal Cancer.

BACKGROUND: Among patients with localized esophageal cancer (LEC), 35% or more develop distant metastases (DM) as first relapse, most in the first 24 months after local therapy. Implementation of novel strategies may be possible if DM can be predicted reliably. We hypothesized that clinical variables could help generate a DM nomogram. PATIENTS AND METHODS: Patients with LEC who completed multimodality therapy were analyzed. Various statistical methods were used, including multivariate analysis to generate a nomogram. A concordance index (c-index) was established and validated using the bootstrap method. RESULTS: Among 629 patients analyzed (356 trimodality/273 bimodality), 36% patients developed DM as first relapse. The median overall survival from DM was only 8.6 months (95% CI, 7.0-10.2). In a multivariate analysis, the variables associated with a higher risk for developing DM were poorly differentiated histology (hazard ratio [HR], 1.76; P<.0001), baseline T3/T4 primary (HR, 3.07; P=.0006), and baseline N+ LEC (HR, 2.01; P<.0001). Although variables associated with a lower risk for DM were age of 60 years or older (HR, 0.75; P=.04), squamous cell carcinoma (HR, 0.54; P=.013), and trimodality therapy (HR, 0.58; P=.0001), the bias-corrected c-index was 0.67 after 250 bootstrap resamples. CONCLUSIONS: Our nomogram identified patients with LEC who developed DM with a high probability. The model needs to be refined (tumor and blood biomarkers) and validated. This type of model will allow implementation of novel strategies in patients with LEC.

Early versus Delayed Therapy of Advanced Gastric Cancer Patients--Does It Make a Difference?

BACKGROUND: Nearly 50% of gastric cancer patients are diagnosed with advanced gastric cancer (AGC). Therapy is palliative but results in ill effects. The median overall survival (OS) of AGC patients is often <12 months. It is unclear if the early initiation of therapy in all AGC patients is beneficial. METHODS: A retrospective analysis of AGC patients in our database was carried out. The patients were divided into two groups: asymptomatic or symptomatic. We sought to assess whether the delay of systemic therapy was harmful in asymptomatic patients. RESULTS: A total of 135 patients were analyzed. Most patients were symptomatic (68%), males (67%), and had low ECOG scores (0-1; 85%). In univariate analyses, ECOG performance status 0 (p = 0.005), delayed initiation of therapy (p = 0.03), and lack of symptoms (p = 0.03) were associated with a longer OS. The multivariate model for OS identified only ECOG performance status as an independent prognosticator of longer OS (p = 0.02). Asymptomatic patients who had delayed (≥ 4 weeks) systemic therapy had an OS rate of 77% at 1 year compared to 58% for patients treated within 4 weeks (p = 0.47). CONCLUSION: Symptomatic AGC patients had a poor outcome compared to asymptomatic AGC patients. Treatment delay in asymptomatic patients had no detrimental effect on OS, suggesting that the timing of therapy can be based on patient selection.

Initial Standardized Uptake Value of Positron Emission Tomography Influences the Prognosis of Patients with Localized Gastric Adenocarcinoma Treated Preoperatively.

BACKGROUND: In patients with localized gastric adenocarcinoma (LGAC) who receive preoperative therapy, tools to predict response or prognosticate outcome before therapy are lacking. We used initial standardized uptake value (iSUV) of positron emission tomography (PET) to evaluate its association with overall survival (OS). METHODS: We identified 60 patients with confirmed LGAC who were treated with preoperative chemoradiation and had a baseline PET in addition to other routine staging. Fisher's exact test and Wilcoxon's rank sum test were used to determine the association between iSUV and other variables, and the log-rank test and Cox proportional hazards model were used for survival analysis. RESULTS: The median iSUV was 6 (range, 0-28). The presence of signet ring cells in pretreatment biopsies correlated highly with low iSUV (≤ 6; p = 0.0017). Patients with a high iSUV (> 6) had a longer OS compared to those with a low iSUV (≤ 6; p = 0.0344). iSUV was not an independent predictor (p = 0.12); however, the risk of death was reduced for patients with an iSUV > 6 (hazard ratio = 0.26). CONCLUSION: Our novel findings show that among LGAC patients treated with preoperative chemoradiation and surgery, those with a high iSUV have longer OS than patients with a low iSUV. iSUV appears to have a predictive role in patients with LGAC when treated with preoperative chemoradiation.

Distribution of Resistant Esophageal Adenocarcinoma in the Resected Specimens of Clinical Stage III Patients after Chemoradiation: Its Clinical Implications.

BACKGROUND: We have limited knowledge of the geographic distribution of resistant esophageal adenocarcinoma (EAC) in resected specimens, but its clinical importance can be enormous. METHOD: We selected patients with baseline stage III EAC who had had chemoradiation followed by surgery and had residual EAC (resistant cases only). Outcomes were correlated with various endpoints (percentage of resistant EAC and anatomic distribution). RESULTS: A total of 100 clinical stage III patients were studied; 90% had an R0 resection, and 99% had either moderate or poorly differentiated EAC. Twelve percent had >50% residual cancer, 31% had 11-50% residual cancer, 53% had 1-10% residual cancer, and 3% had positive nodes only. Each compartment was frequently involved: mucosa/submucosa (66%), muscularis propria (76%), and serosa (62%); all compartments were involved in 35% of the cases. Lack of EAC (meaning response) was observed in the mucosa/submucosa (34%), muscularis propria (24%), serosa (38%), and nodes (42%). Although the endoscopic biopsies prior to surgery showed no EAC in 79% of the patients, in the surgical specimens, resistant EAC was frequently occurring in the mucosa/submucosa (66%). CONCLUSION: Contrary to our hypothesis that resistant EAC would be frequent in the nodes, our data show that its distribution is heterogeneous and unpredictable. Most importantly, the postchemoradiation biopsies are misleading, and a decision to delay/avoid surgery based on negative biopsies can be detrimental for the patients.

Non-alcoholic Wernicke Encephalopathy in a Young Patient with Adenocarcinoma of the Colon: A Case Report and Review of the Literature.

INTRODUCTION: Wernicke Encephalopathy (W.E.) is an acute neurological disorder induced by thiamine deficiency. Alcohol abuse is considered to be the leading cause of the disease; however, numerous other conditions, such as malnutrition or cancer, have been identified as potential risk factors. CASE PRESENTATION: Clinical manifestations include a typical triad of mental status alteration, nystagmus, and ataxia and are attributed to damage in brain regions of high thiamine demand. The diagnosis is mainly clinical and further supported by the immediate response of neurological signs to parenteral thiamine administration. Among paraclinical examinations, brain MRI is considered substantial for diagnosis and is supported by the determination of thiamine blood levels. CONCLUSION: Non-alcoholic W.E. is trickier to diagnose due to its atypical clinical course and risk factors. We herein describe a case of non-alcoholic W.E. in a woman with colon cancer who gradually developed the classic symptoms of thiamine deficiency.

Primary Paraganglioma of the Prostate: A Systematic Review of the Literature for A Rare Entity.

BACKGROUND: Paragangliomas of the urinary tract are exceptionally uncommon, and sporadic case reports of primary paraganglioma of the prostate have been reported in the literature. METHODS: Systematic research in PubMed/Medline and Scopus databases concerning primary prostatic paraganglioma was performed by two independent investigators. RESULTS: This analysis included 25 adult males, with a mean age of 49.8 ± 22.4 years. 32% of included patients had a history of hypertension. Problems during urination (52%), blood loss (44%), either as hematuria or hemospermia, and catecholamine-related symptoms (36%) comprised the most frequently reported clinical manifestations. Digital rectal examination found a palpable nodule in 36% of patients, while prostatic specific antigen (PSA) was normal in all tested patients. Abdominal ultrasound (44%), computed tomography (44%) and magnetic resonance imaging (28%) helped to identify the primary lesion. 24-hour urine epinephrine, norepinephrine and vanillylmandelic acid (VMA) levels were elevated in 90%, 80% and 90% of included patients. Open surgical excision of the mass was performed in 40%, transurethral resection in 8%, open radical prostatectomy in 24%, transurethral resection of the prostate in 16% and robot-assisted radical prostatectomy in 4% of included patients. CONCLUSION: Due to atypical clinical manifestation and scarcity of prostatic paraganglioma, urologists should be aware of this extremely rare entity.

Progastrin: An Overview of Its Crucial Role in the Tumorigenesis of Gastrointestinal Cancers.

Defining predictive biomarkers for targeted therapies and optimizing anti-tumor immune response is a main challenge in ongoing investigations. Progastrin has been studied as a potential biomarker for detecting and diagnosing various malignancies, and its secretion has been associated with cell proliferation in the gastrointestinal tract that may promote tumorigenesis. Progastrin is a precursor molecule of gastrin, synthesized as pre-progastrin, converted to progastrin after cleavage, and transformed into amidated gastrin via biosynthetic intermediates. In cancer, progastrin does not maturate in gastrin and becomes a circulating and detectable protein (hPG80). The development of cancer is thought to be dependent on the progressive dysregulation of normal signaling pathways involved in cell proliferation, thus conferring a growth advantage to the cells. Understanding the interaction between progastrin and the immune system is essential for developing future cancer strategies. To that end, the present review will approach the interlink between gastrointestinal cancers and progastrin by exploring the underlying molecular steps involved in the initiation, evolution, and progression of gastrointestinal cancers. Finally, this review will focus on the clinical applications of progastrin and investigate its possible use as a diagnostic and prognostic tumor circulating biomarker for disease progression and treatment effectiveness, as well as its potential role as an innovative cancer target.

Is the Patient Actually Failing on Enzalutamide? A Case Report and Issues to Consider in Enzalutamide-Resistant Oligoprogressive Metastatic Castrate-Resistant Prostate Cancer.

BACKGROUND: Metastatic castrate-resistant prostate cancer (mCRPC) is a challenging disease, especially in heavily pretreated patients. Androgen pathway inhibitors have contributed to a notable improvement in the overall survival and quality of life in patients with mCRPC during the last decade. Still, a considerable percentage of patients are unable to draw benefits from this drug category and are deprived of a treatment that offers limited toxicity and preserves a good quality of life. The mechanisms leading to this pre-existing or acquired resistance, as well as the possible strategies to overcome this resistance have been put at the center of scientists' attention. CASE PRESENTATION: With the present report we present the case of a 70-year-old patient with mCRPC, who was apparently an enzalutamide non-responder, but a multimodal approach with enzalutamide continuation and irradiation to his symptomatic oligoprogressive disease converted him to a responder with clinical, biochemical and imaging response; furthermore, we discuss the existing data providing evidence for the use of metastasis-directed therapy in combination with androgen pathway inhibitors in order to overcome drug resistance in patients with oligoprogressive disease. CONCLUSION: A considerable proportion of patients with oligometastatic or oligoprogressive prostate cancer who seem not to respond to androgen pathway inhibitors, such as enzalutamide, due to preexisting or acquired resistance, could benefit from MDT with a multimodal treatment approach. This strategy allows androgen pathway inhibitor continuation beyond biochemical progression and delays the switch to next-line systemic treatment.

Identification of a Novel TSC2 c.170G>A Missense Variant: A Case Report and Elaboration on the Yield of Targeted Options against Tuberous Sclerosis Complex Manifestations.

BACKGROUND: Tuberous sclerosis complex (TSC) is a rare genetic disease that affects multiple organs and affects the quality of life. Mutations in TSC1 and TSC2 genes are causing dysregulations in the mammalian target of the rapamycin (mTOR) pathway, inducing mostly benign but also malignant tumors, including renal cell carcinoma (RCC). The diagnosis of TSC, based on established clinical and genetic criteria, is essential for the optimal surveillance and management of patients. CASE PRESENTATION: With the current report, we present the case of two sisters who were consequently diagnosed with early-stage chromophobe-like RCC, possibly familial given their young age. The younger sister also had a previous diagnosis of differentiated thyroid carcinoma, for which she had been treated properly. Genetic testing of both revealed the same heterozygous TSC2 variant that is currently regarded as a variant of unknown significance, while both patients did not fulfill the clinical criteria for the diagnosis of TSC. Owing to these data, we opted to manage and surveil both sisters as TSC patients, while we also considered the specific TSC2 variant to be pathogenic - but of low penetrance - based on clinical judgment and functional analyses. Furthermore, we discussed the implementation of mTOR inhibitors for the treatment of TSC complications. CONCLUSION: As novel pathogenic variants of TSC genes are constantly being explored, the identification of TSC variants of unknown significance in combination with absent clinical diagnostic criteria cannot exclude a TSC diagnosis. We support the implementation of clinical judgment in assisting the diagnosis of TSC, as well as the enrollment of patients in clinical trials due to the rarity of the disease.

Immune checkpoint inhibitors and combinations with other agents in cholangiocarcinoma.

Cholangiocarcinoma consists of a heterogeneous group of malignancies with generally poor prognoses. Immunotherapy has emerged in the treatment landscape of many tumors, offering survival benefits, but data regarding the use of immunotherapy for cholangiocarcinoma remain vague. In this review, the authors analyze differences in the tumor microenvironment and various immune escape mechanisms and discuss available immunotherapy combinations with other agents among completed and ongoing clinical trials, such as chemotherapy, targeted agents, antiangiogenic drugs, local ablative therapies, cancer vaccines, adoptive cell therapy and PARP and TGF-ß inhibitors. Ongoing research to identify appropriate biomarkers is warranted.

Cholangiocarcinomas are a group of rare tumors. Survival time is limited, due to late diagnosis and advanced symptoms. The small number of patients makes it difficult to carry out clinical trials and find new medicines. Another issue is that there are many different subtypes of this tumor. Each one requires a different approach. Despite these setbacks, new treatment choices have appeared. Medicines that stimulate the immune system to fight cancer cells have changed the current treatment landscape for many tumor types and are very promising in cholangiocarcinomas.

Metformin: A Promising Radiosensitizer in Neoadjuvant Rectal Cancer Treatment.

BACKGROUND: Neoadjuvant chemoradiotherapy (nCRT) decreases the risk of local recurrence after surgery in patients with locally advanced rectal cancer (LARC) and metformin is constantly gaining scientific interest due to its potentially radiosensitizing effect. OBJECTIVE: This review article aims to better clarify the role of metformin as a radiosensitizer in patients with LARC undergoing neoadjuvant concurrent chemoradiotherapy. METHODS: We used the PubMed database to retrieve journal articles and the inclusion criteria were all human studies that illustrated the effective role of metformin in the neoadjuvant setting of locally advanced rectal cancer. RESULTS: Our search resulted in 17 citations, of which 10 eventually fulfilled the inclusion criteria of our study. Promising results (improved tumor and nodal regression as well as higher pathologic complete response rate) have been occasionally documented with metformin use in some of the included studies. However, regarding survival and all-cause mortality, no significant difference has been found. CONCLUSION: Metformin might constitute a highly promising radiosensitizer in neoadjuvant LARC treatment attracting much scientific interest. Due to the lack of studies with high evidence, further advanced research is required to enhance the existing knowledge about its potential value in this field.