Evaluation of focused sentinel lymph node RT-qPCR screening for micrometastases with the use of the Maruyama computer program

Could the immune response in the sentinel lymph nodes of gastric cancer patients be the key to tailored surgery?

BACKGROUND

Precise detection of downstream, nonsentinel lymph node metastases is the key to implementation of the sentinel lymph node concept in gastric cancer. To overcome the problem of complex lymphatic drainage, micrometastases, and skip metastases, we investigated the feasibility of tumor cell detection in sentinel lymph nodes, using flow cytometry as well as studied immune suppression in the sentinel lymph node as a potential marker of downstream lymph node metastases.

METHODS

In 21 patients with gastric cancer, the sentinel lymph nodes extracted during operation subjected to frozen sections and flow cytometry. The tumor cells were defined with the cell surface markers CEACAM and EpCAM. Simultaneously, the cell densities of different subsets of T cells were determined.

RESULTS

The sensitivity and specificity of the determination of nodal status with flow cytometry for tumor cell detection was 100% and 63%, respectively, as seen in frozen sections. Correlations with nonsentinel lymph node metastases were seen for CD127(low)CD25(high) and CD45(neg)CD127(low)CD25(high) cell densities, relative proportion of CD45RA(neg)CD127(low)CD25(high) cells, frozen sections results, lymphangial invasion, and tumor size (P ≤ .043 each). Multivariate analysis identified the relative proportions of CD45RA(neg)CD127(low)CD25(high) cells as the only significant predictor for downstream nonsentinel lymph node metastases (P = .028; 95% confidence interval, 1.107-5.780). The predictive value of combined detection of flow cytometry tumor cells and the relative proportion of CD45RA(neg)CD127(low)CD25(high) cells for nodal stage determination was 91%.

CONCLUSION

Combined detection of tumor cells and CD45RA(neg)CD127(low)CD25(high) cells in sentinel lymph nodes with flow cytometry predicts accurately nonsentinel lymph node metastases.

CA19-9 serum levels predict micrometastases in patients with gastric cancer

Background

We explored the prognostic value of the up-regulated carbohydrate antigen (CA19-9) in node-negative patients with gastric cancer as a surrogate marker for micrometastases.

Patients and methods

Micrometastases were determined using reverse transcription quantitative polymerase chain reaction (RT-qPCR) for a subgroup of 30 node-negative patients. This group was used to determine the cut-off for preoperative CA19-9 serum levels as a surrogate marker for micrometastases. Then 187 node-negative T1 to T4 patients were selected to validate the predictive value of this CA19-9 threshold.

Results

Patients with micrometastases had significantly higher preoperative CA19-9 serum levels compared to patients without micrometastases (p = 0.046). CA19-9 serum levels were significantly correlated with tumour site, tumour diameter, and perineural invasion. Although not reaching significance, subgroup analysis showed better five-year survival rates for patients with CA19-9 serum levels below the threshold, compared to patients with CA19-9 serum levels above the cut-off. The cumulative survival for T2 to T4 node-negative patients was significantly better with CA19-9 serum levels below the cut-off (p = 0.04).

Conclusions

Preoperative CA19-9 serum levels can be used to predict higher risk for haematogenous spread and micrometastases in node-negative patients. However, CA19-9 serum levels lack the necessary sensitivity and specificity to reliably predict micrometastases.