Detailed examination of lymph nodes improves prognostication in colorectal cancer

Node negative colorectal cancer patients: assesment of high-risk features on recurrence

BACKGROUND

The introduction of population-based screening programs for colorectal cancer (CRC) results in less patients with advanced disease. There is an increase in the amount of node negative CRC, which makes adequate risk stratification for this particular group of patients necessary. The addition of more risk factors to the conventional histological high-risk factors is investigated in this retrospective study.

PATIENTS AND METHODS

A cohort of 227 node negative (stage I and II) CRC patients who were not treated with adjuvant chemotherapy were selected from two previously conducted cohort studies. Detailed histopathological examination was performed by two independent observers and molecular background (BRAF/RAS mutations, microsatellite status (MSI)) was studied. Univariate analyses were used to analyse differences in histological and mutational characteristics between patients with and without recurrence. P-values below 0.05 were considered statistically significant.

RESULTS

Poorly differentiated histology (p:0.002), BRAF mutation (p:0.002) and MSI status (p:0.006) were found significant relevant risk factors that were related to recurrent disease. Poorly differentiated histology was associated with intermediate/high tumor budding (TB) (p:0.001), a BRAF mutation (p:0.001) and MSI status (p:0.001). A combination of all three features (poorly differentiated histology, BRAF and MSI) was more often present in the recurrence group.

CONCLUSIONS

Recurrence in node negative CRC patients could be better predicted when molecular features such as, BRAF mutation and MSI status are incorporated into a model with poorly differentiated CRC. Therefore, these features might help in the selection of patients who possibly will benefit from adjuvant treatment.

Ex vivo sentinel node mapping in colon cancer combining blue dye staining and fluorescence imaging

BACKGROUND

The sentinel lymph node procedure has been proposed to improve nodal staging in colon cancer patients. The aim of this study was to assess the added value of near-infrared (NIR) fluorescence imaging to conventional blue dye staining for ex vivo sentinel lymph node mapping.

MATERIALS AND METHODS

We included 22 consecutive patients undergoing surgery for colon cancer. After tumor resection, we submucosally injected a premixed cocktail of the near-infrared lymphatic tracer HSA800 and blue dye around the tumor for detection of sentinel lymph nodes. We used the Mini-FLARE imaging system for fluorescence imaging.

RESULTS

In 95% of patients, we identified at least one sentinel lymph node. Overall, a total of 77 sentinel lymph nodes were identified, 77 of which were fluorescent (100%) and 70 of which were blue (91%). Sentinel lymph nodes that were located deeper in the mesenteric fat could easily be located by NIR fluorescence. In four of five patients with lymph node metastases, tumor cells were present in at least one of the sentinel lymph nodes.

CONCLUSIONS

This study shows the successful use and added value of the NIR fluorescence tracer HSA800 to conventional blue dye for the ex vivo sentinel lymph node procedure in colon cancer.

Log odds of positive lymph nodes in colon cancer: a meaningful ratio-based lymph node classification system

BACKGROUND

The log odds of positive lymph nodes (LODDS), defined as the log of the ratio between the numbers of positive and negative lymph nodes, has recently been proposed as a new prognostic index in surgical oncology. The aim of the present study was to investigate whether the LODDS system of lymph node classification was a more accurate prognostic tool than the tumor node metastasis (TNM) and lymph node ratio (LNR) classifications in colon cancer patients.

MATERIALS AND METHODS

Clinicopathologic data from 258 colon cancer patients who had undergone surgical resection were reviewed. Lymph node parameters were categorized according to the Internation Union Against Cancer/American Joint Cancer Commission (UICC/AJCC) TNM staging system, the LNR (LNR0 with ratio ≤ 0.05, LNR1 with 0.05 < ratio ≤ 0.20, LNR2 with ratio > 0.20), and the log odds ratio (LODDS0 ≤ -1.36, -1.36 < LODDS1 ≤ -0.53, and LODDS2 > -0.53).

RESULTS

The LODDS was able to identify patients who would have been included in different prognostic categories, according to both the TNM and LNR. In addition, LODDS was significantly related to the number of positive and negative lymph nodes, as well as the number of examined lymph nodes. In multivariate analysis, LODDS classification (LODDS0: HR 1; LODDS1: HR 3.687, p = 0.003; LODDS2: HR 9.440, p < 0.001) was identified as an independent prognostic factor.

DISCUSSION

The LODDS system is a highly reliable staging system with strong predictive ability for patient outcome. Compared with other nodal staging systems, the prognostic power of LODDS is less influenced by the number of lymph nodes dissected and examined.

Clinical translation of ex vivo sentinel lymph node mapping for colorectal cancer using invisible near-infrared fluorescence light

Background

Sentinel lymph node (SLN) mapping in colorectal cancer may have prognostic and therapeutic significance; however, currently available techniques are not optimal. We hypothesized that the combination of invisible near-infrared (NIR) fluorescent light and ex vivo injection could solve remaining problems of SLN mapping in colorectal cancer.

Methods

The FLARE imaging system was used for real-time identification of SLNs after injection of the NIR lymphatic tracer HSA800 in the colon and rectum of (n = 4) pigs. A total of 32 SLN mappings were performed in vivo and ex vivo after oncologic resection using an identical injection technique. Guided by these results, SLN mappings were performed in ex vivo tissue specimens of 24 consecutive colorectal cancer patients undergoing resection.

Results

Lymph flow could be followed in real-time from the injection site to the SLN using NIR fluorescence. In pigs, the SLN was identified in 32 of 32 (100%) of SLN mappings under both in vivo and ex vivo conditions. Clinically, SLNs were identified in all patients (n = 24) using the ex vivo strategy within 5 min after injection of fluorescent tracer. Also, 9 patients showed lymph node involvement (N1 disease). In 1 patient, a 3-mm mesenteric metastasis was found adjacent to a tumor-negative SLN.

Conclusions

The current pilot study shows proof of principle that ex vivo NIR fluorescence-guided SLN mapping can provide high-sensitivity, rapid, and accurate identification of SLNs in colon and rectum. This creates an experimental platform to test optimized, non-FDA-approved NIR fluorescent lymphatic tracers in a clinical setting.