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Rectal cancer management necessitates a rigorous multidisciplinary strategy, emphasizing precise staging and detailed risk stratification to inform optimal therapeutic decision-making. Obtaining an accurate histological diagnosis before initiating treatment is essential. Comprehensive staging integrates clinical evaluation, thorough medical history analysis, assessment of carcinoembryonic antigen (CEA) levels, and computed tomography (CT) imaging of the abdomen and thorax. High-resolution pelvic magnetic resonance imaging (MRI), utilizing dedicated rectal protocols, is critical for identifying recurrence risks and delineating precise anatomical relationships. Endoscopic ultrasound further refines staging accuracy by determining the tumor infiltration depth in early-stage cancers, while preoperative colonoscopy effectively identifies synchronous colorectal lesions. In early-stage rectal cancers (T1–T2, N0, and M0), radical surgical resection remains the standard of care, although transanal local excision can be selectively indicated for certain T1N0 tumors. In contrast, locally advanced rectal cancers (T3, T4, and N+) characterized by microsatellite stability or proficient mismatch repair are optimally managed with total neoadjuvant therapy (TNT), which combines chemoradiotherapy with oxaliplatin-based systemic chemotherapy. Additionally, tumors exhibiting high microsatellite instability or mismatch repair deficiency respond favorably to immune checkpoint inhibitors (ICIs). The evaluation of tumor response following neoadjuvant therapy, utilizing MRI and endoscopic assessments, facilitates individualized treatment planning, including non-operative approaches for patients with confirmed complete clinical responses who comply with rigorous follow-up. Recent advancements in molecular characterization, targeted therapies, and immunotherapy highlight a significant evolution towards personalized medicine. The effective integration of these innovations requires enhanced interdisciplinary collaboration to improve patient prognosis and quality of life. Full article

Standard treatments of localized rectal cancer are surgery or the multimodal approach with neoadjuvant treatments (chemo-radiotherapy, short-course radiotherapy, induction, or consolidation chemotherapy) followed by surgery. In metastatic colorectal cancer (mCRC), immune checkpoint inhibitors (ICIs) are now the first choice in patients with a deficient mismatch repair system/microsatellite instability (dMMR/MSI-H) and are being explored in combination with chemotherapy to rewire the immune system against malignant cells in subjects with proficient mismatch repair system/microsatellite low (pMMR/MSI-L) cancers, with promising signals of efficacy. Recently, some efforts have been made to translate ICIs in earlier stages of CRC, including localized rectal cancer, with breakthrough efficacy and an organ preservation rate of mono-immunotherapy in dMMR/MSI-H patients and promising anti-tumor activity of immunotherapy plus neoadjuvant (chemo)radiotherapy in pMMR/MSI-L subjects. Here, we present the rationale, results, and limitations of the most remarkable trials assessing ICIs in dMMR/MSI-H and pMMR/MSI-L localized rectal cancer patients, at the same time highlighting the most promising research perspectives that have followed these studies. Full article

In metastatic colorectal cancer (mCRC), remarkable advances have been achieved with immune checkpoint inhibitors (ICIs) targeting PD-1/PD-L1 and CTLA-4, only in a small subset of tumours (4–5%), harbouring a deficient mismatch repair system (dMMR)/microsatellite instability–high (MSI-H) or mutations in the catalytic subunit of polymerase epsilon (POLE). Within this framework, several combination strategies have been investigated to sensitize proficient mismatch repair (pMMR)/microsatellite stable (MSS) mCRC to ICIs, with disappointing results so far. However, at the last ESMO meeting, two phase II trials AtezoTRIBE and MAYA provided promising results in this field. In the comparative AtezoTRIBE trial, the addition of atezolizumab to FOLFOXIRI (5-fluoruracil, oxaliplatin and irinotecan) and bevacizumab led to a significant advantage in terms of progression free survival (PFS) in a population of untreated mCRC patients, not selected according to MMR/MSI status. In the single-arm MAYA trial, immune priming with temozolomide in pMMR/MSS chemo-resistant mCRC patients with silencing of O6-methylguanine-DNA methyltransferase (MGMT) allowed reporting signals of sensitivity to the subsequent therapy with nivolumab and a low dose of ipilimumab in some patients. Here, we discuss the rationale, results, criticisms and research perspectives opened by these two studies. Full article