Background: The determination of renal function is crucial for the clinical management of patients with cancer. The glomerular filtration rate (GFR) serves as a key parameter, estimated by creatinine clearance determination in 24-h collected urine (CrCl) as well as equation-based approaches (eGFR) relying on serum creatinine (eGFR CKD EPIcrea) or serum cystatin C (eGFR cystatin C). Serum creatinine and serum cystatin C levels differentially depend on muscle and tumor mass, respectively. Although muscle and tumor mass may thus represent confounding factors, comparative studies for eGFR estimate approaches in cancer patients are lacking. Methods: The present study retrospectively analyzed GFR estimates based on equations of creatinine (eGFRcr), cystatin C (eGFRcys) and combined creatinine-cystatin C levels (eGFRcr-cys) in a subset of patients. The associations of LDH with cystatin C or LDH with eGFRcr, eGFRcys and GFRcr-cys were explored. Results: The laboratory values of 123 consecutive patients were included. The median age was 59 (24–87) and 47.2% were female. There was a statistically significant difference in the mean of CKD EPIcrea (85.17 ± 21.63 mL/min/1.73 m²), CKD EPIcys (61.16 ± 26.03 mL/min/1.73 m²) and CKD EPIcrea-cys (70.42 ± 23.89 mL/min/1.73 m²) (p < 0.0001). Spearman’s correlation analysis revealed a significant correlation of elevated plasma LDH >1.5 UNV and cystatin C values (r = 0.270, p < 0.01, n = 123). LDH values >1.5 UNV were associated with significantly lower CKD EPIcys (r = 0.184, p < 0.01) or CKD EPIcrea-cys (r = 0.226, p < 0.05) estimates compared to CKD EPIcrea. Conclusions: The inclusion of cystatin C as a biomarker led to a lower eGFR estimates compared to creatinine alone or in a combination of both cystatin C and creatinine. The level of cystatin C correlated with the level of LDH, suggesting that the use of cystatin C-based calculations of GFR in cancer patients with elevated LDH should be used with caution.

Zusammenfassung: Dargestellt wird der Krankheitsverlauf einer 66-jährigen Patientin mit der Erstdiagnose einer akuten myeloischen Leukämie. Als paraneoplastisches Syndrom zeigten sich eine Hypernatriämie sowie Polyurie infolge eines zentralen Diabetes insipidus (CDI), welcher mittels Desmopressingabe kontrolliert werden konnte. Nach Einleitung einer Induktionstherapie kam es im Verlauf nach Beendigung der Desmopressintherapie noch vor Anstieg des Blastenanteils zu einer erneuten Hypernatriämie und Polyurie als Hinweis auf eine primäre Refraktärität.

Background/Objectives: Primary central nervous system lymphoma (PCNSL) is a rare but aggressive tumor, primarily affecting elderly patients. Radiotherapy (RT) remains an important treatment option, particularly for patients who are ineligible for systemic chemotherapy. This study aims to identify prognostic factors and evaluate recurrence patterns in a real-world cohort of PCNSL patients treated with RT. Methods: We retrospectively analyzed 64 PCNSL patients treated with radiotherapy at our institution between 2000 and 2022. Clinical characteristics, treatment details, and outcomes were collected by chart review. Overall survival (OS) was analyzed using Kaplan–Meier and Cox regression methods. Recurrence patterns were assessed based on available post-treatment imaging. Results: Median patient age was 71 years (range: 31–83); 53.1% had an Eastern Cooperative Oncology Group (ECOG) performance status ≥2. Radiotherapy was used as first-line treatment in 62.5% of cases, primarily due to contraindications to chemotherapy. Median OS was 10 months from diagnosis. Age, poor performance status, seizures at presentation, absence of systemic therapy, incomplete radiotherapy, and <80% applied dose of planned radiotherapy were associated with inferior OS in our univariable analysis. Multivariable analysis confirmed age, systemic therapy, seizures, and radiotherapy dose <80% as independent predictors. Among twenty-nine patients with imaging follow-up, eight recurrences after RT were documented: six of those within, and two outside of the initially affected areas. All recurrences occurred within previously irradiated areas. Conclusions: This study confirms known negative prognostic factors in PCNSL and underscores the importance of systemic chemotherapy for curatively intended treatments aiming for prolonged survival. The recurrence patterns observed question the added benefit of whole-brain irradiation in preventing distant relapses. These findings support the need for prospective trials to optimize radiotherapy strategies while balancing efficacy and neurotoxicity.

Background: Intravenous high-dose methotrexate (MTX ≥ 1 g/m²) is frequently used in patients with cerebral lymphoma or other malignancies. In addition to its potent efficacy, it is known to have pronounced toxicity and life-threatening side effects. Regular-level monitoring at short and defined intervals is mandatory. This study aimed to evaluate the possibility of replacing peripheral blood sampling with blood samples from central venous catheters for therapeutic monitoring of MTX in adults. Methods: A total of 6 patients and 7 cycles of chemotherapy (6 females; 5 with cerebral non-Hodgkin lymphoma and 1 with osteosarcoma, median age 51 years; range 33–62 years) were included. An immunoassay was used for quantitative analysis of MTX levels. The measurement points were obtained in the time intervals of 24, 42, 48, and 72 hours, and afterward, every 24 hours until the level was below <0.1 µmol/L. After flushing with 10 mL of saline solution and discarding 10 mL of venous blood, blood was drawn from the central venous access through which MTX had previously been administered. Simultaneously, MTX levels were obtained from peripheral venipuncture. Results: Methotrexate levels from central venous access and MTX levels from peripheral venipuncture showed a significant correlation (r = 0.998; P < 0.01; n = 35). During withdrawal from the central access group, 17 values showed a lower MTX level, 10 showed a higher level, and 8 showed no difference. However, the MTX level difference was not significant (P = 0.997, linear mixed model). No increase in the dose of calcium folinate was necessary based on the collected MTX levels. Conclusions: In adults, MTX monitoring from central venous access is not inferior to monitoring from peripheral venipuncture. Repeated venipuncture to measure MTX levels can be replaced after establishing standardized instructions for proper sampling by a central venous catheter.