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Long-term stability of pleural fluid carcinoembryonic antigen and its effect on the diagnostic accuracy for malignant pleural effusion.

Author(s): Yang DN, Niu Y, Wen JX, Wen XH, Wang YF, Yan L, Jiang TW, Huang JH, Chen H, Lippi G, Zheng WQ, Hu ZD

Publication: Thorac Cancer, 2023, Vol. 14, Page 2077-2084

PubMed ID: 37314828 PubMed Review Paper? No

Purpose of Paper

Conclusion of Paper

Studies

1. Study Purpose

   This study compared levels of CEA in pleural fluid collected from two cohorts prior to (fresh) and after storage at -70°C to -80°C for 1-3 years. Pleural fluid was collected into anticoagulant-free tubes at two sites from patients with undiagnosed pleural effusion who underwent a diagnostic thoracentesis. The Affiliated Hospital of Inner Mongolia Medical University from Hohhot collected pleural fluid from 152 patients (65 malignant pathologies and 87 benign) in its respiratory and intensive care department between September 2018 and July 2021. Pleural fluid was also collected from 58 patients (26 malignant pathologies and 32 benign) who visited the Changshu No. 2 People’s Hospital between June 2020 and July 2021. Pleural fluid was centrifuged (details not provided) and the supernatant was stored at -70°C to -80°C from collection until analysis in January-April 2022. CEA levels were measured in fresh and frozen CEA using an Abbott I2000SR immunoassay.

   Summary of Findings:

   When all specimens were considered (both cohorts) CEA levels were slightly higher in frozen than fresh pleural fluid (P<0.01). Interestingly, while CEA levels were slightly higher in frozen than fresh benign pleural fluid (1.35 versus 1.29, P<0.01), they were non-significantly lower in frozen than fresh malignant pleural fluid (41.23 versus 47.46, P=0.07).  In specimens from the Hohhot cohort, CEA levels were higher in frozen pleural fluid than fresh (2.61 versus 2.23, P<0.01) when all specimens were considered (malignant and benign), higher in benign frozen specimens than fresh (1.41 versus 1.18, P<0.01), but lower in frozen than fresh malignant specimens (36.86 versus 40.77, P<0.01). In specimens from the Changshu cohort, CEA levels were lower in frozen pleural fluid than fresh when all specimens were considered (2.44 versus 2.78, P<0.01) and in benign (1.19 versus 1.36, P=0.02) and malignant specimens (46.55 versus 51.98, P=0.03).  Storage duration and CEA levels were not correlated, and overall there was good agreement between CEA levels in fresh and frozen specimens; for the Hohhot cohort, the 95% confidence interval for the intercept of the Deming regression did not cover 1. The receiver operating characteristic curves were similar for fresh and frozen pleural specimens, with an overall sensitivity of 89% and 88%, respectively, and comparable sensitivities in fresh and frozen specimens from the Hohhot (87% and 86%, respectively) and Changshu cohorts (93% and 91%, respectively).

   Biospecimens

   • Bodily Fluid - Pleural Fluid

   Preservative Types

   • None (Fresh)
   • Frozen

   Diagnoses:

   • Neoplastic - Not specified
   • Other diagnoses
   • Neoplastic - Carcinoma
   • Neoplastic - Benign

   Platform:

   Analyte	Technology Platform
   Protein	Clinical chemistry/auto analyzer

   Pre-analytical Factors:

   Classification	Pre-analytical Factor	Value(s)
   Biospecimen Preservation	Type of fixation/preservation	Frozen None (fresh)
   Storage	Storage duration	0 years 1-3 years
   Biospecimen Acquisition	Locale of biospecimen collection	Affiliated Hospital of Inner Mongolia Medical University from Hohhot Changshu No. 2 People’s Hospital

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