Adjuvant treatment of early colon cancer with micrometastases: results of a national survey

Superior Effect of the Combination of Carbon-Ion Beam Irradiation and 5-Fluorouracil on Colorectal Cancer Stem Cells in vitro and in vivo

Background

The aim of this study was to investigate whether carbon-ion beam irradiation in combination with 5-fluorouracil (5-FU) is superior to carbon-ion beam irradiation alone in targeting colorectal cancer stem-like cells (CSCs).

Materials and Methods

Human colorectal cancer (CRC) cells, HCT116 and HT29, were treated with carbon-ion beam irradiation alone or in combination with 5-FU. Cell viability assay, colony and spheroid formation assay, apoptotic assay, and quantitative real-time PCR analysis of apoptosis- and autophagy-related gene expression were performed.

Results

Carbon-ion beam irradiation dose-dependently decreased CRC cell viability and showed significantly enhanced cell killing effect when combined with 5-FU. Carbon-ion beam irradiation in combination with 5-FU significantly increased the percentage of apoptotic cells. The expression of some apoptotic and autophagy-related genes such as Bax, Bcl2, Beclin1 and ATG7 was significantly induced by carbon-ion beam irradiation alone and was further enhanced when the beam was combined with 5-FU. The spheroid forming capacity of CD133+ cell subpopulations was significantly inhibited by carbon-ion beam in combination with 5-FU. Histopathologically, the combination of carbon-ion beam irradiation and 5-FU destroyed more xenograft tumor cells, and resulted in increased necrosis, cavitation, and fibrosis, compared to carbon-ion beam irradiation alone.

Conclusion

In conclusion, carbon-ion beam treatment combined with 5-FU has the potential to kill CRC cells including CSCs by inducing increased apoptosis and autophagy.

Value of primary tumor gene signatures in colon cancer when national quality standards are adhered to: preliminary results of an international prospective multicenter trial

BACKGROUND

The purpose of this study was to determine if gene signatures are informative in colon cancer (CC) when National Quality Standards (NQS) are adhered to. Several studies have demonstrated the prognostic potential of gene signatures in primary CC. This has never been evaluated prospectively with adherence to NQS.

METHODS

This was a prospective, international, multicenter trial. Eligibility criteria were: no distant metastasis, ≥12 lymph nodes (LNs), and no adjuvant chemotherapy for LN-negative CC. RNA from frozen tumor samples was considered reliable if RNA Integrity Number >9. Using an Agilent whole human genome array, 44,000 genes were analyzed in primary tumors for differential gene expression (DGE). ANOVA applied at 2-fold expression level was performed in at least 8 experiments to obtain the DGEs.

RESULTS

Molecular analysis was completed in 113 of 128 patients. With median follow-up of 27 months, 11.5 % recurred within 3 years after surgery. Significant DGE was identified in recurrent tumors reflected by upregulation (UR) in cellular proliferation and by downregulation (DR) in prodifferentiating panel of 9 genes, independent of T or N classification. By multivariate analysis 3-year disease-free survival was 12.5 % in the UR/DR group versus 93.4 % in the non-UR/DR group (p < .0001; HR = 24.2; 95 % CI 4.8-120.4).

CONCLUSIONS

This is the first prospective trial to evaluate gene signatures in CC with adherence to a 12-node minimum quality standard. Certain molecular pathways may be prognostically relevant if both surgery and pathology are standardized, regardless of T or N classification. Careful consideration should be made to include surgical quality measures when planning clinical trials to evaluate the true effect of molecular markers in CC.

The prognostic value of micrometastases and isolated tumour cells in histologically negative lymph nodes of patients with colorectal cancer: a systematic review and meta-analysis

INTRODUCTION

Detection of occult tumour cells in lymph nodes of patients with stage I/II colorectal cancer is associated with decreased survival. However, according to recent guidelines, occult tumour cells should be categorised in micrometastases (MMs) and isolated tumour cells (ITCs). This meta-analysis evaluates the prognostic value of MMs and of ITCs, separately.

METHODS

PubMed, Embase, Biosis and the World Health Organization International Trials Registry Platform were searched for papers published until April 2013. Studies on the prognostic value of MMs and ITCs in lymph nodes of stage I/II colorectal cancer patients were included. Odds ratios (ORs) for the development of disease recurrence were calculated to analyse the predictive value of MMs and ITCs.

RESULTS

From five papers, ORs for disease recurrence could be calculated for MMs and ITCs separately. In patients with colorectal cancer, disease recurrence was significantly increased in the presence of MMs in comparison with absent occult tumour cells (OR 5.63; 95%CI 2.4-13.13). This was even more pronounced in patients with colon cancer (OR 7.25 95% CI 1.82-28.97). In contrast, disease recurrence was not increased in the presence of ITCs (OR 1.00 95% CI 0.53-1.88).

CONCLUSION

Patients with stage I/II colorectal cancer and MMs have a worse prognosis than patients without occult tumour cells. However, ITCs do not have a predictive value. The distinction between ITCs and MMs should be made if the detection of occult tumour cells is incorporated in the clinical decision for adjuvant treatment.

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.