Biomarkers vs conventional histological analysis to detect lymph node micrometastases in bladder cancer: a real improvement?

UNLABELLED: Study Type - Therapy (case series) Level of Evidence 4. What's known on the subject? and What does the study add? Muscle invasive bladder cancer has a mortality rate at 5 years of 50%, despite radical therapy, as a result of tumour progression and dissemination. This suggests that half of patients have disseminated disease at the time of diagnosis, which is not detected by the staging techniques currently used. The prognostic factors (histological grade and tumour stage) and current staging techniques do not discriminate between those patients who will be cured with surgical treatment and those who will die from metastatic spread. New diagnostic and prognostic tools that complement the existing methods and provide a proper assessment of carcinoma invading bladder muscle are therefore essential. Molecular staging techniques using specific biomarkers have been applied in various solid tumours to determine the presence of missed tumour cells in lymph nodes (LNs) during routine pathological examination. These techniques could identify patients with LN micrometastases who may potentially benefit from early treatment with chemotherapy. This study compares the performance of conventional histological analysis and molecular biomarkers in detecting bladder cancer LN micrometastases and predicting patient's clinical outcome. The study found that, even though a clear trend to a worse outcome was shown in those patients who became node-positive after molecular analysis, no statistical differences were found in cancer-specific and recurrence-free survival analysis between those patients who were negative by histology but positive by molecular analysis and those who were negative by both techniques. We concluded that molecular analysis of LN spreading in bladder cancer has a better detection rate than conventional histological examination.
OBJECTIVE: • To improve the sensitivity of histological examination in detecting occult lymph node (LN) dissemination of bladder cancer using gene expression analysis. PATIENTS AND METHODS: • We carried out a retrospective study that included 504 formalin-fixed paraffin-embedded LNs from 90 patients with muscle invasive bladder cancer and 35 controls. • Gene expression values of two molecular biomarkers (FXYD3 and KRT20) were analysed using reverse transcription real-time quantitative PCR (RT-qPCR). • Molecular results were compared with histological status and patients' clinical outcomes.
RESULTS: • Of the 90 patients analysed, 16 were positive and 74 were negative by histological analysis. Of these 74, 19 were classified as positive using RT-qPCR. • Significant differences in cancer-specific (P= 0.011) and recurrence-free (P= 0.009) survival were found between the three patient groups (patients positive by both techniques, patients negative by both techniques, and patients negative by histological but positive by molecular analysis). • A significant difference was not found between histologically negative but molecularly positive patients and patients who were negative by both techniques, but a clear trend to a worse outcome was found in those patients who became node-positive after molecular analysis.
CONCLUSIONS: • The analysis of FXYD3 and KRT20 could improve current pathological examination for the detection of micrometastases in LNs. • Further and more extensive studies will determine the real prognostic value of such LN micrometastases.