Gastric carcinoma: applying the sentinel node paradigm to improve the understanding of metastatic patterns and the possible role of selective lymphadenectomy

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.

The accuracy of sentinel node mapping according to T stage in patients with gastric cancer

BACKGROUND

Sentinel lymph node (SLN) mapping has been recently introduced to the field of gastric cancer. To the best of our knowledge, no study has dealt with the accuracy of SLN mapping according to the T stage of the primary tumor. The aim of the present study was to evaluate SLN status according to the T stage of the primary tumors.

METHODS

Eighty patients with gastric cancer underwent SLN mapping with patent blue dye during gastric resection.

RESULTS

Forty-seven patients underwent distal subtotal gastrectomy; 17 patients, proximal gastrectomy; 14, total gastrectomy; and 2, gastric stump resection. SLNs were stained in 61/80 patients (76.3%). The number of stained SLNs varied from 1 to 16 (mean, 3.3). Patients undergoing proximal gastrectomy had a mean of 3 stained SLNs, whereas patients undergoing distal subtotal gastrectomy had a mean of 2.8 stained SLNs. In 55/61 patients (90.2%) with stained SLNs a positive correlation was found between the presence of metastases and stained or non-stained SLNs. Ten out of 11 patients (90.9%) with T1 tumors (mean, 3.27 SLNs per patient) and 15/17 patients with T2 tumors (88.2%; mean, 3 SLNs per patient) had stained SLNs as compared to only 33/48 (68.8%) of patients with T3 tumors (mean, 3.3 SLNs per patient). The positive predictive value of the SLN mapping was 100%, the negative predictive value was 76.9%, and sensitivity was 85.4%.

CONCLUSION

While in T1 and T2 tumors sentinel node mapping may be of assistance in the decision-making process regarding the extent of lymphadenectomy (sensitivity, 100%; negative predictive value, 90%-100%), SLN mapping in patients with T3 tumors will be misleading in a third of the patients and should not be attempted.

Routine modified D2 lymphadenectomy performance in pT1-T2N0 gastric cancer

AIM: To evaluate routine modified D2 lymphadenectomy in gastric cancer, based on immunohistochemically detected skip micrometastases in level II lymph nodes.

METHODS: Among 95 gastric cancer patients who were routinely submitted to curative modified D2 lymphadenectomy, from January 2004 to December 2008, 32 were classified as pN0. All level I lymph nodes of these 32 patients were submitted to immunohistochemistry for micrometastases detection. Patients in whom micrometastases were detected in the level I lymph node stations (n = 4) were excluded from further analysis. The level II lymph nodes of the remaining 28 patients were studied immunohistochemically for micrometastases detection and constitute the material of the present study.

RESULTS: Skip micrometastases in the level II lymph nodes were detected in 14% (4 out of 28) of the patients. The incidence was further increased to 17% (4 out of 24) in the subgroup of T1-2 gastric cancer patients. All micrometastases were detected in the No. 7 lymph node station. Thus, the disease was upstaged from stage IA to IB in one patient and from stage IB to II in three patients.

CONCLUSION: In gastric cancer, true R0 resection may not be achieved without modified D2 lymphadenectomy. Until D2+/D3 lymphadenectomy becomes standard, modified D2 lymphadenectomy should be performed routinely.