Molecular Cytology by One-Step Nucleic Acid Amplification (OSNA) Assay of Peritoneal Washings during D2 Gastrectomy in Advanced Gastric Cancer Patients: Preliminary Results

The presence of peritoneal free cancer cells (FCC) in gastric cancer (GC) patients is a poor prognostic factor. D2 gastrectomy may induce exfoliated FCC spread from the primary tumour or involved lymph nodes (LN). Conventional cytology for FCC detection has several limitations, whereas prophylactic use of extensive intraoperative peritoneal lavage (IPL) does not improve survival. A prospective single-arm observational study was conducted to verify whether D2 gastrectomy causes an intraoperative increase of FCC in peritoneal fluid. Twenty-seven GC patients underwent D2 gastrectomy, followed by objective quantitative measurements of CK19 mRNA level reflecting FCC with One-Step Nucleic Acid Amplification (OSNA) assay. The IPL with 3000 mL of saline was performed twice: (1) after gastrectomy with D2 lymphadenectomy and (2) after alimentary tract reconstruction. The IPL samples were analysed by initial cytology and four (1–4) consecutive OSNA assays. Initial OSNA measurement (1) revealed positive results (≥24.6 cCP/μL) in 7 (29.6%) patients. Subsequent OSNA measurements showed a significant decrease in the FCC level after D2 gastrectomy (1 vs. 2; p = 0.0012). The first IPL induced a non-significant increase in the FCCs (2 vs. 3, p = 0.3300), but the second IPL reversed it to normal levels (3 vs. 4, p = 0.0.0574). The OSNA assay indicates a temporal intraoperative increase in the peritoneal FCC in advanced GC patients undergoing D2 gastrectomy. Two consecutive IPLs are necessary to reverse the increase of CK19 mRNA level in peritoneal washings.

Rapid Detection of Free Cancer Cells in Intraoperative Peritoneal Lavage Using One-Step Nucleic Acid Amplification (OSNA) in Gastric Cancer Patients

Cytokeratin-19 (CK19) has been proven to be commonly expressed by cancer cells in a variety of solid tumors and may serve as a suitable marker of metastases in gastric cancer (GC). Since objective assessment of peritoneal lavage or fluid for free cancer cells (FCC) is essential for clinical decision making in patients with GC, it is important to develop a quantitative and reproducible method for such evaluation. We assessed the possible application of One-Step Nucleic Acid amplification (OSNA) assay as a rapid method for FCC detection in intraoperative peritoneal lavage or fluid of GC patients. Seventy-eight intraoperative peritoneal lavage or fluid samples were eligible for the analysis by conventional cytology and OSNA examination. The concentration of CK19 mRNA in intraoperative peritoneal lavage and fluid was compared with the conventional cytological assessment. CK19 mRNA concentration was detected by OSNA assay. For peritoneal lavage samples, sensitivity and specificity were 83.3% and 87.8%, respectively. In peritoneal fluid, significantly higher CK19 values were observed in patients with serosal infiltration (medians: 100 copies/µL vs. 415.7 copies/µL; p = 0.0335) and lymph node metastases (medians: 2.48 copies/µL vs. 334.8 copies/µL). OSNA assay turns out to be an objective, fast, and reproducible quantitative method of FCC assessment.

A prospective validation cohort study of a prediction model on non-sentinel lymph node involvement in early breast cancer.

559 Background: Early breast cancer (cT1-2N0) with one or two sentinel lymph node (SLN) involved may avoid axillary lymph node dissection (ALND) if follow by radiotherapy supported by Z0011 and AMAROS trials. However, only less than one-third of those patients have positive non-sentinel lymph node (nSLN) and can truly benefit from radiotherapy or ALND in those two trials. It is necessary to identify the risk of nSLN metastasis before local treatment decision. We previously developed a predictive model for nSLN involvement using circulating CK19 mRNA level combined with contrast-enhanced ultrasound (CEUS) score (ASCO2017 poster 239, NCT02992067) in a training set. To evaluate the predict effect of this model, we designed a further study using the model prospectively in a validation set (NCT03280134). Methods: We identified early breast cancer cases in Zhejiang Cancer Hospital from July 2017 to June 2018. The level of circulating CK19 mRNA tested by qRT-PCR and CEUS scores were collected before surgery in each case. Patients with 1~2 SLN involved were enrolled and continued for ALND. The estimated percentage of nSLN-involved were calculated both by our model formula and the Memorial Sloan-Kettering Cancer Center (MSKCC) nomogram. The predictive accuracy and false negative rates (FNR) were evaluated and the area under curve (AUC) was compared between two predictive models. Results: Totally, 235 patients diagnosed as early breast cancer with 1~2 SLN involved were enrolled and 35.36% of them were nSLN involved after ALND. The total accuracy and FNR by our model for nSLN-involved prediction was 94.89% and 6.02%, respectively. The AUC was 0.952 (95%CI, 0.922~0.982), significantly higher than that in MSKCC model 0.880 (95%CI, 0.833~0.927). Furthermore, only CK19 mRNA level (HR = 40.091, 95%CI, 13.663~117.635) and CEUS score (HR = 2.009, 95%CI 1.158~3.485) are significantly related to nSLN involvement in both univariate and multivariate analysis, adjusted by age, menopause statue, tumor size, histological grade, estrogen receptor, progesterone receptor and human epidermalgrowth factor receptor-2 expression. Conclusions: Our model using CK19 mRNA and CEUS score showed potential predictive value of nSLN before surgery in early breast cancer patients. Further validation in larger multicenter cohort is warranted before changing clinical practice.