Background: Age- and cancer-related sarcopenia and malnutrition are common in older patients with colorectal cancer (CRC) and may negatively influence treatment tolerance and prognosis. However, the comparative prognostic value of post-chemotherapy changes in CT-based body composition parameters at the third lumbar vertebra (L3) and the twelfth thoracic vertebra (T12) levels, and their associations with nutritional indices, remain unclear. This study aimed to examine and compare the prognostic relevance of post-chemotherapy body composition changes at L3 and T12 and to assess their relationship with nutritional indices in older patients with metastatic CRC (mCRC). Methods: This retrospective study included 87 older patients with mCRC. Baseline and ~3-month follow-up CT scans were analyzed at L3 and T12 using 3D Slicer to quantify skeletal muscle index (SMI), subcutaneous adipose tissue index (SATI), visceral adipose tissue index (VATI), visceral-to-subcutaneous fat ratio (VSR), and intramuscular adipose tissue index (IMATI). Changes (Δ) in CT-derived body composition after chemotherapy were calculated as percentage change using ((follow-up − baseline)/baseline) × 100. Prognostic Nutritional Index (PNI) and Geriatric Nutritional Index (GNRI), which are established nutritional assessment tools, were calculated from baseline laboratory/anthropometric data. Agreement between T12 and L3 was assessed, and associations with grade ≥ 3 toxicity, progression-free survival (PFS), and overall survival (OS) were evaluated using multivariable models and ROC analyses. Results: Mean age was 69.0 ± 4.5 years (59 male/28 female), and 26.4% developed grade ≥ 3 adverse events. Over 3 months, mean SMI declined significantly at both L3 (46.7 ± 8.8 → 42.8 ± 9.8 cm²/m²) and T12 (34.6 ± 8.2 → 31.6 ± 8.1 cm²/m²) (p < 0.001 for both), accompanied by decreases in VATI and VSR; T12-IMATI increased significantly. Baseline PNI showed a weak positive correlation with L3-SMI (r = 0.302, p = 0.033), whereas GNRI showed moderate correlations with SMI at L3 (r = 0.502, p < 0.001) and T12 (r = 0.317, p = 0.025) and was associated with longitudinal changes in muscle metrics. T12-SMI consistently yielded lower values than L3-SMI, and agreement varied by compartment (best for SATI; weakest for VSR). Lower GNRI and greater L3-SMI loss were independently associated with grade ≥ 3 toxicity; ΔL3-SMI showed the highest discrimination (AUC = 0.79, 95% CI = 0.69–0.87, p < 0.001; cut-off >5.1% loss). All patients progressed (median PFS 7.6 months); mortality was 82.8% (median follow-up: 25 months). In multivariable analysis, PFS, CRP, GNRI, and ΔL3-SMI remained independently associated with OS. ΔL3-SMI provided the strongest mortality discrimination (AUC = 0.85, 95% CI = 0.74–0.94, p < 0.001; cut-off >10.4% loss), while ΔIMATI was also informative (AUC = 0.71, 95% CI = 0.59–0.82, p = 0.023). Conclusions: In older patients with mCRC, early post-chemotherapy skeletal muscle loss—particularly at the L3 level—showed the strongest prognostic association with severe toxicity and mortality. GNRI provided complementary prognostic information as a marker of baseline immunonutritional reserve. Although T12-derived measurements were correlated with L3-derived values, systematic bias suggests that they should not be interpreted interchangeably for longitudinal risk stratification.

Background: Radiotracer- and magnetic seed-based targeted axillary staging techniques are increasingly used after neoadjuvant chemotherapy (NAC) in patients with initially node-positive breast cancer who convert to clinical node-negative (ycN0) status. However, these technologies remain unavailable in many centres worldwide. We evaluated the effectiveness of radiotracer-free axillary staging using dual-tracer sentinel lymph node biopsy (SLNB) with indocyanine green (ICG) and methylene blue, with particular focus on the clinical implications of clipped node non-retrieval. Methods: This retrospective single-centre cohort study included 49 patients with biopsy-proven cN1 breast cancer who achieved ycN0 status following NAC and underwent dual-tracer SLNB using ICG and methylene blue between 2021 and 2024. Clipped node retrieval rates, tracer-specific detection patterns, recurrence outcomes, and disease-free survival (DFS) were analysed. Clinical outcomes, including recurrence and disease-free survival, were compared between patients with successful and unsuccessful clipped node retrieval. Results: Clipped node retrieval was achieved in 41 of 49 patients (83.7%). ICG outperformed methylene blue for clipped node identification (80.5% vs. 61.0%) and was the sole detecting tracer in 39.0% of cases. Using methylene blue alone would have reduced the retrieval rate to 51.0% (p = 0.001). ICG identified the clipped node in all six patients with axillary micrometastases (ypN1mi). Clipped node non-retrieval occurred in eight patients, all of whom had negative SLNB findings and did not undergo completion axillary lymph node dissection. Recurrence rates were similar between the retrieval and non-retrieval groups (17.1% vs. 12.5%, p = 1.000), and no isolated axillary recurrences were observed. Baseline tumour size was the only independent predictor of disease-free survival in multivariable analysis (HR 2.05, 95% CI 1.20–3.51; p = 0.008). Conclusions: Radiotracer-free axillary staging using ICG and methylene blue achieved a high clipped node retrieval rate in patients with ycN0 breast cancer after neoadjuvant chemotherapy. ICG significantly improved clipped node identification compared with methylene blue alone and identified the clipped node in all patients with residual nodal micrometastatic disease. Among patients with negative SLNB findings, clipped node non-retrieval was not associated with higher recurrence rates or worse disease-free survival during follow-up. However, given the small number of clipped node non-retrieval cases (n = 8) and recurrence events (n = 8), these findings should be interpreted with caution and require confirmation in larger prospective studies. These findings support the feasibility of a radiotracer-free dual-tracer approach in settings where radiotracer-based techniques are not available. Prospective multicentre studies are warranted to validate both the oncological performance of radiotracer-free axillary staging and the clinical implications of clipped node non-retrieval.