The proportion of cancer patients with tumours that harbour a potentially targetable genomic alteration is growing considerably. The diagnosis of these genomic alterations can lead to tailored treatment at the onset of disease or on progression and to obtaining additional predictive information on immunotherapy efficacy. However, in up to 25% of cases, the initial tissue biopsy is inadequate for precision oncology and, in many cases, tumour genomic profiling at progression is not possible due to technical limitations of obtaining new tumour tissue specimens. Efficient diagnostic alternatives are therefore required for molecular stratification, which includes liquid biopsy. This technique enables the evaluation of the tumour genomic profile dynamically and captures intra-patient genomic heterogeneity as well. To date, there are several diagnostic techniques available for use in liquid biopsy, each one of them with different precision and performance levels. The objective of this consensus statement of the Spanish Society of Pathology and the Spanish Society of Medical Oncology is to evaluate the viability and effectiveness of the different methodological approaches in liquid biopsy in cancer patients and the potential application of this method to current clinical practice. The experts contributing to this consensus statement agree that, according to current evidence, liquid biopsy is an acceptable alternative to tumour tissue biopsy for the study of biomarkers in various clinical settings. It is therefore important to standardise pre-analytical and analytical procedures, to ensure reproducibility and generate structured and accessible clinical reports. It is essential to appoint multidisciplinary tumour molecular boards to oversee these processes and to enable the most suitable therapeutic decisions for each patient according to the genomic profile.

Adenoviruses have been implicated in childhood cancers, primarily leukemia, yet prior neonatal investigations have rarely examined other pediatric tumor types. This study evaluated whether adenoviral early region (E1A) sequences can be detected in archival neonatal Guthrie cards from children who later developed diverse pediatric tumors and in corresponding paraffin-embedded tissues. DNA extraction was optimized for long-stored dried blood spots, and PCR conditions were refined for both Guthrie card and paraffin-derived DNA. Adenoviral E1A was analyzed using conventional and nested PCR, and sequencing of representative amplicons confirmed correspondence to human adenovirus species C. E1A PCR positivity was found in 43% of Guthrie cards from cases (n = 54) and 34% of controls (n = 32), and in 41% of tumor tissues (n = 75) compared with 5% of non-tumor paraffin controls (n = 20). Detection occurred across multiple tumor categories without a clear association with tumor type. Partial concordance was observed between paired neonatal and tumor samples, and cytomegalovirus markers were detected in a subset of E1A-positive specimens. These findings confirm the suitability of Guthrie cards for retrospective viral DNA detection and extend previous leukemia-focused neonatal studies to broader pediatric tumors. The data suggest a potential association between birth-stage adenoviral detection and childhood cancer, though a causal link remains unproven and requires further longitudinal investigation.

The article Liquid biopsy in oncology.