Tissue-Based Markers as a Tool to Assess Response to Neoadjuvant Radiotherapy in Rectal Cancer-Systematic Review.

According to current guidelines, the current treatment for locally advanced rectal cancer is neoadjuvant therapy, followed by a total mesorectal excision. However, radiosensitivity tends to differ among patients due to tumor heterogeneity, making it difficult to predict the possible outcomes of the neoadjuvant therapy. This review aims to investigate different types of tissue-based biomarkers and their capability of predicting tumor response to neoadjuvant therapy in patients with locally advanced rectal cancer. We identified 169 abstracts in NCBI PubMed, selected 48 reports considered to meet inclusion criteria and performed this systematic review. Multiple classes of molecular biomarkers, such as proteins, DNA, micro-RNA or tumor immune microenvironment, were studied as potential predictors for rectal cancer response; nonetheless, no literature to date has provided enough sufficient evidence for any of them to be introduced into clinical practice.

Late gastrointestinal toxicity after radiotherapy for rectal cancer: a systematic review.

PURPOSE: Although the multimodal cancer treatment techniques have greatly improved over the years, irradiation-induced late gastrointestinal toxicity remains a great concern as it may highly affect the quality of life of a patient. The aim of this study was to define the prevalence of late gastrointestinal toxicities. METHODS: Electronic databases of Cochrane Library, Embase, Web of Science, CENTRAL and PubMed were searched until September 2019. We used the following keywords: radiotherapy, radiation therapy, irradiation, rectal cancer, gastrointestinal toxicity, adverse effects, late effects, pelvic radiation and pelvic radiation disease. RESULTS: Nine studies were included into this review out of 4785 that were preidentified as potentially relevant. Overall prevalence of severe (Grade 3 or higher) late irradiation-induced gastrointestinal toxicities was up to 19%. Most frequent toxicities of any grade were reported to be diarrhoea (up to 35%), faecal incontinence (22%), incontinence to gas (71%), rectal bleeding (9%), rectal pain (13%) and obstruction (7.4%). Preoperative treatment approaches and more advance radiotherapy techniques such as intensity-modulated and image-guided radiotherapy (IMRT) and volumetric modulated arc therapy (VMAT) turn out to result in lower late gastrointestinal toxicity rates. CONCLUSION: After great improvements in rectal cancer treatment, late gastrointestinal toxicity after radiotherapy is experienced less frequent and less severe; however, it remains a great concern associated with worse quality of life.