Blood-sampling collection prior to surgery may have a significant influence upon biomarker concentrations measured

Abstract

Background: Biomarkers can be subtle tools to aid the diagnosis, prognosis and monitoring of therapy and disease progression. The validation of biomarkers is a cumbersome process involving many steps. Serum samples from lung cancer patients were collected in the framework of a larger study for evaluation of biomarkers for early detection of lung cancer. The analysis of biomarker levels measured revealed a noticeable difference in certain biomarker values that exhibited a dependence of the time point and setting of the sampling. Biomarker concentrations differed significantly if taken before or after the induction of anesthesia and if sampled via venipuncture or arterial catheter.

Methods: To investigate this observation, blood samples from 13 patients were drawn 1-2 days prior to surgery (T1), on the same day by venipuncture (T2) and after induction of anesthesia via arterial catheter (T3). The biomarkers Squamous Cell Carcinoma antigen (CanAG SCC EIA, Fujirebio Diagnostics, Malvern, USA), Carcinoembrionic Antigen (CEA), and CYFRA 21-1 (Roche Diagnostics GmbH, Mannheim, Germany) were analyzed.

Results: SCC showed a very strong effect in relation to the sampling time and procedure. While the first two points in time (T1; T2) were highly comparable (median fold-change: 0.84; p = 0.7354; correlation ρ = 0.883), patients showed a significant increase (median fold-change: 4.96; p = 0.0017; correlation ρ = -0.036) in concentration when comparing T1 with the sample time subsequent to anesthesia induction (T3). A much weaker increase was found for CYFRA 21-1 at T3 (median fold-change: 1.40; p = 0.0479). The concentration of CEA showed a very small, but systematic decrease (median fold-change: 0.72; p = 0.0039).

Conclusions: In this study we show the unexpectedly marked influence of blood withdrawal timing (before vs. after anesthesia) and procedure (venous versus arterial vessel puncture) has on the concentration of the protein biomarker SCC and to a less extent upon CYFRA21-1. The potential causes for these effects remain to be elucidated in subsequent studies, however these findings highlight the importance of a standardized, controlled blood collection protocol for biomarker detection.

Keywords: Anesthesia induction; Biomarker; Blood specimens; CEA; CYFRA 21-1; Lung cancer; SCC; SPREC coding; Sampling time points.

Fig. 1

Results of SCC measurement in two centers in respect to whether the patient underwent surgery (OP) or not (no OP). There is an increase in SCC concentrations in center 2 that can be attributed to the presences or absence of surgery independent from common clinical variables like gender, stage, age and histology.

Fig. 2

Individual time courses for each marker.

Fig. 3

Boxplot of ratios of tumor marker levels at points in time T1–T3.

Fig. 4

Scatterplots of marker concentrations at various points in time. The plots show marker concentrations at T1 versus T2, T1 versus T3 and T2 versus T3 for each marker together with fitted regression lines according to Passing Bablok [17].