Impact on Prognosis of Lymph Node Micrometastasis and Isolated Tumor Cells in Stage II Colorectal Cancer

Lymph Node Micrometastasis Cannot be Considered as Positive Lymph Node in Nonmetastatic Colorectal Cancer

The prognostic value of micrometastasis in colorectal cancer (CRC) remains controversial. The study investigated whether lymph node (LN) micrometastasis can have prognostic value in CRC as compared with macrometastasis. The study included 488 patients with curatively resected stage I, II, or III CRC treated between 2004 and 2011. Immuohistochemical staining with monoclonal antibody CAM 5.2 was performed on negative LNs by hematoxylin-eosin staining. The prognostic value of LN micrometastasis was investigated in multivariate analysis. Regression analysis was performed to identify a causal relationship between micro- and macrometastasis. Survival differences were compared between conventional N staging and hypothetic N staging taking micrometastasis in the positive node. A total of 93 patients (19.1%) showed LN micrometastasis. Patients with micrometastasis had more advanced tumor characteristics in terms of tumor size, grade, T stage, N stage, lymphatic invasion, and vascular invasion. In multivariate analysis, micrometastasis was not related with recurrence. Preoperative carcinoembryonic antigen level, neural invasion, and macrometastasis were independent risk factors in the analysis. Regression analysis showed that there was not a causal relationship between micro- and macrometastasis (R2= 0.004, P = 0.153). When the cumulative numbers of micro- and macrometastatic LNs were calculated together, the discriminative power of survival difference between each node stage became less prominent, compared with conventional N staging. LN micrometastasis is related with advanced tumor characteristics, but does not reflect poor prognosis in nonmetastatic CRC. Micrometastasis cannot be considered as positive LN to predict poor prognosis.

Prognostic significance of histologically detected lymph node micrometastases of sizes between 0.2 and 2 mm in colorectal cancer

PURPOSE

Minimal lymph node involvement is a potential prognostic factor in colorectal cancer. The International Union Against Cancer defined tumour deposits between 0.2 and 2 mm as micrometastases and clusters and single-cell infiltrations below this cutoff as isolated tumour cells. Nevertheless, only a minority of studies discriminated metastatic involvements according to this definition.

METHODS

In order to investigate the prognostic significance of micrometastases (0.2-2 mm), we performed a retrospective study enrolling 44 routinely diagnosed micrometastatic cases within 15 years which represent about 1% of our cases. These cases have been re-evaluated.

RESULTS

Seven of the micrometastatic cases turned out to be macrometastases after step sectioning. Complete follow-up was available in 33 remaining cases. Collections of node-negative and macrometastatic cases served as control groups. The Kaplan-Meier curves of macro- and micrometastatic cases showed a similar adverse course (p = 0.830) especially during the first 40 months. The 5-year-survival rates were 51, 60 and 64 months for macro-, micrometastatic and node-negative cases, respectively. The difference in overall survival, however, reached only a statistical trend and was not significant (p = 0.137). After re-evaluation with step sections and cytokeratin immunohistochemistry out of an initial 91 node-negative cases, 11 (12%) cases were identified with isolated tumour cells and one (1%) case with a micrometastasis.

CONCLUSIONS

Our data show that micro- and macrometastatic colorectal cancers show very similar survival rates. Therefore, efforts to improve the detection of lymph node micrometastases seem to be justified.

Lymph node micrometastasis in gastrointestinal tract cancer--a clinical aspect

Lymph node micrometastasis (LNM) can now be detected thanks to the development of various biological methods such as immunohistochemistry (IHC) and reverse transcription-polymerase chain reaction (RT-PCR). Although several reports have examined LNM in various carcinomas, including gastrointestinal (GI) cancer, the clinical significance of LNM remains controversial. Clinically, the presence of LNM is particularly important in patients without nodal metastasis on routine histological examination (pN0), because patients with pN0 but with LNM already in fact have metastatic potential. However, at present, several technical obstacles are impeding the detection of LNM using methods such as IHC or RT-PCR. Accurate evaluation should be carried out using the same antibody or primer and the same technique in a large number of patients. The clinical importance of the difference between LNM and isolated tumor cells (≤0.2 mm in diameter) will also be gradually clarified. It is important that the results of basic studies on LNM are prospectively introduced into the clinical field. Rapid diagnosis of LNM using IHC and RT-PCR during surgery would be clinically useful. Currently, minimally invasive treatments such as endoscopic submucosal dissection and laparoscopic surgery with individualized lymphadenectomy are increasingly being performed. Accurate diagnosis of LNM would clarify issues of curability and safety when performing such treatments. In the near future, individualized lymphadenectomy will develop based on the establishment of rapid, accurate diagnosis of LNM.

Prognostic significance of isolated tumor cells in patients with colorectal cancer in recent 10-year studies

Circulating tumor cells (CTCs) that detach from the primary tumor and move into the circulation are detected in patients with metastatic cancer. The discovery of such cancer cells has been used as a predictor of recurrence and prognosis, although a consensus regarding such applications has not been reached. Peritoneal cytology may be used for identifying high risk of recurrence or mortality, whereas the intraoperative presence of tumor cells in drainage veins, bone marrow, or the liver is not always useful for evaluating the prognosis. The reported positive rate for tumor cells in the peripheral blood of patients with colorectal cancer, including metastasis, has varied from 10 to 80%; however, numerous studies have demonstrated significant differences in the recurrence and mortality rates between patients with and without isolated tumor cells (ITCs) in the peripheral blood. However, the clinical significance of CTCs as an absolute prognostic factor has not been elucidated, since the measurement methodologies and/or the number of cases differed between the studies. Future prospective studies including larger patient populations may elucidate the utility of routine detection of ITCs in daily practice.

Prognostic and survival analysis of 837 Chinese colorectal cancer patients

AIM: To develop a prognostic model to predict survival of patients with colorectal cancer (CRC).

METHODS: Survival data of 837 CRC patients undergoing surgery between 1996 and 2006 were collected and analyzed by univariate analysis and Cox proportional hazard regression model to reveal the prognostic factors for CRC. All data were recorded using a standard data form and analyzed using SPSS version 18.0 (SPSS, Chicago, IL, United States). Survival curves were calculated by the Kaplan-Meier method. The log rank test was used to assess differences in survival. Univariate hazard ratios and significant and independent predictors of disease-specific survival and were identified by Cox proportional hazard analysis. The stepwise procedure was set to a threshold of 0.05. Statistical significance was defined as P < 0.05.

RESULTS: The survival rate was 74% at 3 years and 68% at 5 years. The results of univariate analysis suggested age, preoperative obstruction, serum carcinoembryonic antigen level at diagnosis, status of resection, tumor size, histological grade, pathological type, lymphovascular invasion, invasion of adjacent organs, and tumor node metastasis (TNM) staging were positive prognostic factors (P < 0.05). Lymph node ratio (LNR) was also a strong prognostic factor in stage III CRC (P < 0.0001). We divided 341 stage III patients into three groups according to LNR values (LNR1, LNR ≤ 0.33, n = 211; LNR2, LNR 0.34-0.66, n = 76; and LNR3, LNR ≥ 0.67, n = 54). Univariate analysis showed a significant statistical difference in 3-year survival among these groups: LNR1, 73%; LNR2, 55%; and LNR3, 42% (P < 0.0001). The multivariate analysis results showed that histological grade, depth of bowel wall invasion, and number of metastatic lymph nodes were the most important prognostic factors for CRC if we did not consider the interaction of the TNM staging system (P < 0.05). When the TNM staging was taken into account, histological grade lost its statistical significance, while the specific TNM staging system showed a statistically significant difference (P < 0.0001).

CONCLUSION: The overall survival of CRC patients has improved between 1996 and 2006. LNR is a powerful factor for estimating the survival of stage III CRC patients.

Prognostic significance of EpCAM-positive disseminated tumor cells in rectal cancer patients with stage I disease

Here we evaluated the prevalence and prognostic impact of epithelial cell adhesion molecule (EpCAM)-positive disseminated tumor cells (DTCs) in stage I rectal cancer. Further we tested the association of these single tumor cells or small tumor cell groups with the extent of peritumoral lymphangiogenesis. A total of 845 regional lymph nodes (LN) of 44 patients classified as negative on conventional histopathology were retrospectively reanalyzed with immunohistochemistry (IHC) using the monoclonal antibody Ber-Ep4 directed against EpCAM for the detection of DTCs. The degree of lymphangiogenesis in the primary tumors was assessed by IHC of the primary tumor tissue using the monoclonal antibody D2-40, which reacts with the lymphatic endothelium. The IHC results were correlated with clinico-pathologic parameters and clinical follow-up data. EpCAM-positive DTCs in LNs were detected in 8 (18.2%) of the 44 patients. During a median follow-up of 59 months, 3 (37.5%) of the 8 patients with EpCAM-positive DTCs relapsed, whereas none of the DTC-negative patients developed tumor recurrence (P=0.004). Survival analysis revealed a significant effect of the prevalence of DTCs on overall survival (P=0.0009) and on recurrence-free survival (P=0.0001). Finally, the prevalence of EpCAM-positive DTCs in perirectal LNs was significantly correlated with a high density of peritumoral lymphatic vessels (P=0.015). Our results show that DTCs may occur in stage I of rectal cancer and are associated with poor prognosis. Their occurrence seems to be linked to a high density of newly formed lymphatic vessel at the primary tumor site. According to our data, patients with DTCs in their LN might benefit from adjuvant therapy.

Prognostic significance of the lymph node ratio regarding recurrence and survival in rectal cancer patients treated with postoperative chemoradiotherapy

Background/Aims

To evaluate the prognostic impact of the lymph node ratio (LNR: the ratio of positive lymph nodes to the total number of lymph nodes examined) on disease recurrence and survival among rectal cancer patients who received curative surgery and postoperative chemoradiotherapy (CRT).

Methods

Between 1995 and 2008, 124 patients with pathologic T3-4 or node-positive rectal cancer underwent curative surgery and postoperative CRT. Postoperative radiotherapy was delivered at a median dose of 50.4 Gy (range, 45 to 59.4 Gy) for 6 weeks. Chemotherapy consisted of a bolus injection of 5-fluorouracil and leucovorin in the first and last week of radiotherapy (91.9%) or daily capecitabine during radiotherapy (8.1%). Further adjuvant chemotherapy was administered after chemoradiation.

Results

The median follow-up was 5.1 years. In the multivariate analysis, pathologic N (pN) stage and lymphovascular invasion were significantly associated with disease-free survival and disease-specific survival (p<0.05). However, when the LNR with a cutoff value of 0.2 was included as a covariate in the model, the LNR was highly significant (p<0.001), and the pN stage lost its significance (p>0.05).

Conclusions

The LNR predicts recurrence and survival more accurately than pN stage. The pN stage and the LNR should be considered together when estimating the risk of disease recurrence among rectal cancer patients.

Molecular detection of tumor cells in regional lymph nodes is associated with disease recurrence and poor survival in node-negative colorectal cancer: a systematic review and meta-analysis

PURPOSE

Up to 25% of patients with node-negative colorectal cancer (CRC) on conventional histopathologic analysis ultimately die of recurrent disease. We performed a systematic review with meta-analyses to clarify whether molecular detection of isolated tumor cells or micrometastases in regional lymph nodes indicates high risk of disease recurrence and poor survival in node-negative CRC.

METHODS

The following databases were searched in August 2011 to identify studies on the prognostic significance of molecular tumor-cell detection in regional lymph nodes of node-negative CRC: MEDLINE, BIOSIS, Science Citation Index, EMBASE, CCMed, and publisher databases. We extracted hazard ratios (HRs) and associated 95% CIs from the identified studies and performed random-effects model meta-analyses on overall survival, disease-specific survival, and disease-free survival.

RESULTS

A total of 39 studies with a cumulative sample size of 4,087 patients were included. Immunohistochemistry, reverse transcriptase polymerase chain reaction, and both techniques were applied in 30, seven, and two studies, respectively. Thirteen studies were graded with low risk of bias. Meta-analyses revealed that molecular tumor-cell detection in regional lymph nodes was associated with poor overall survival (HR, 2.20; 95% CI, 1.43 to 3.40), disease-specific survival (HR, 3.37; 95% CI, 2.31 to 4.93), and disease-free survival (HR, 2.24; 95% CI, 1.57-3.20). Subgroup analyses showed the prognostic significance of molecular tumor-cell detection of being independent of the applied detection method, molecular target, and number of retrieved lymph nodes.

CONCLUSION

Molecular detection of occult disease in regional lymph nodes is associated with an increased risk of disease recurrence and poor survival in patients with node-negative CRC.