According to the present view, metastasis marks the end in a sequence of genomic changes underlying the progression of an epithelial cell to a lethal cancer. Here, we aimed to find out at what stage of tumor development transformed cells leave the primary tumor and whether a defined genotype corresponds to metastatic disease. To this end, we isolated single disseminated cancer cells from bone marrow of breast cancer patients and performed singlecell comparative genomic hybridization. We analyzed disseminated tumor cells from patients after curative resection of the primary tumor (stage M0), as presumptive progenitors of manifest metastasis, and from patients with manifest metastasis (stage M1). Their genomic data were compared with those from microdissected areas of matched primary tumors. Disseminated cells from M0-stage patients displayed significantly fewer chromosomal aberrations than primary tumors or cells from M1-stage patients (P < 0.008 and P < 0.0001, respectively), and their aberrations appeared to be randomly generated. In contrast, primary tumors and M1 cells harbored different and characteristic chromosomal imbalances. Moreover, applying machine-learning methods for the classification of the genotypes, we could correctly identify the presence or absence of metastatic disease in a patient on the basis of a single-cell genome. We suggest that in breast cancer, tumor cells may disseminate in a far less progressed genomic state than previously thought, and that they acquire genomic aberrations typical of metastatic cells thereafter. Thus, our data challenge the widely held view that the precursors of metastasis are derived from the most advanced clone within the primary tumor.T he prevailing paradigm of carcinogenesis suggests that epithelial cells sequentially accumulate multiple genetic and epigenetic changes underlying the disorganization of tissue morphology and uncontrolled growth (1). The model predicts that certain additional genomic events initiate invasiveness of the tumor and subsequently progression to metastasis. However, this hypothesis of an ''additional event'' initiating metastasis relatively late in tumorigenesis was recently challenged by another model based on global gene expression analysis of primary breast cancers in which groups of genes were identified that predicted the development of distant metastasis (2). Thus it was concluded that the proclivity to metastasize is acquired early during multistep tumorigenesis, although it manifests only much later after mutation of other genes (3).A closer analysis of the natural course of breast cancer reveals several inconsistencies with both models. Why, after curative resection of a primary tumor and its regional lymph nodes, does it often take years or decades until clinical metastases appear? It is difficult to understand how a cell that has been selected at the primary site for acquisition of self-sufficiency in growth signals, unlimited proliferative potential, sustained angiogenesis, and unresponsiveness to growth inhibitory signals...

Cytokeratin-positive cells in the bone marrow of prostate cancer patients are only prognostically relevant when detected before surgery. Because we could not identify significant genetic differences between pre- and postoperatively isolated tumor cells before manifestation of metastasis, we postulate the existence of perioperative stimuli that activate disseminated tumor cells. Patients with cytokeratin-positive cells in bone marrow before surgery may therefore benefit from adjuvant therapies.

To date, the clinical value of lymph node size in colon cancer has been investigated only in a few studies. Only in radiological diagnosis is lymph node size routinely recognized, and nodes Z10 mm in diameter are considered pathologic. However, the few studies regarding this topic suggest that lymph node size is not a reliable indicator of metastatic disease. Moreover, we hypothesized that increasing lymph node size is associated with favorable outcome. By performing a morphometric study, we investigated the clinical significance of lymph node size in colon cancer in terms of metastatic disease and prognosis. A cohort of 237 cases with excellent lymph node harvest (mean lymph node count: 33±17) was used. The size distribution in node-positive and -negative cases was almost identical. In all, 151 out of the 305 metastases detected (49.5%) were found in lymph nodes with diameters r5 mm. Only 25% of lymph nodes 410 mm showed metastases. Minute lymph nodes r1 mm were involved only very rarely (2 of 81 cases). In 67% of the cases, the largest positive lymph node was o10 mm. The prognostic relevance of lymph node size was investigated in a subset of 115 stage I/II cases. The occurrence of Z7 lymph nodes that were 45 mm in diameter was significantly associated with better overall survival. Our data show that lymph node size is not a suitable factor for preoperative lymph node staging. Minute lymph nodes have virtually no role in correct histopathological lymph node staging. Finally, large lymph nodes in stage I/II disease might indicate a favorable outcome.

Endoscopic mucosal resection (EMR) is commonly accepted as a standard treatment for early gastric cancer (EGC) with low risk of lymph node metastasis because it is minimally invasive and has a good safety profile [1,2]. However conventional EMR nearly always results in piecemeal resection when lesions are larger than 20 mm in diameter, and even in smaller lesions R0 en bloc resection is often missed. Endoscopic submucosal dissection (ESD) is a new promising technique which can overcome this difficulty. In contrast to EMR, ESD allows en bloc resection of lesions larger than 20 mm in diameter. Advantages of the en bloc resection are an improvement in histopathological assessment of R0 resection and the lower risk of recurrence [3,4]. The Japanese Gastric Cancer Association (JGCA) defined guideline criteria for conventional EMR in the treatment of EGCs. EMR was judged adequate in elevated EGCs of less than 20 mm in diameter and in depressed EGCs of up to 10 mm without ulceration. Further restrictions were histology of differentiated adenocarcinoma, absence of submucosal invasion, and absence of lymphatic or vascular invasion [5]. However Gotoda et al. showed that these criteria might be too strict and too many patients might be unnecessarily treated by surgery [6]. Therefore based on an analysis of the risk of lymph node involvement in more than 5000 EGCs the expanded criteria were defined, as the risk of lymph node metastases in this group of patients was similar to that in the JGCA guideline group [6]. The expanded criteria are now widely accepted in Japan, and recently published studies show that there is no difference in outcome between treatment based on the guideline criteria and that based on the expanded criteria [7]. Expanded resection criteria are deBackground and study aims: Endoscopic submucosal dissection (ESD) is a promising technique for the resection of early gastric neoplasia. There are only a few data from the Western world to date. Methods: Over a 7-year-period, 104 gastric lesions were treated with ESD in a European referral center, of which 91 were included in this study. A total of 66 lesions were early gastric cancer (EGC) and 25 were adenomas. Of the EGCs, 11 lesions (16.7 %) fulfilled the guideline criteria (EGC-GC) and 55 lesions (83.3 %) fulfilled the expanded resection criteria (EGC-EC) of the Japanese guidelines for the treatment of gastric cancer. Results: ESD was technically possible in 85 lesions (93.4 %). In six lesions ESD was not possible due to non-lifting. En bloc resection rates for all lesions, ECGs-GC, ECGs-EC, and adenomas were 87.1 %, 100 %, 88.2 %, and 79.2 %, respectively. R0 en bloc resection rates were 74.1 %, 90 %, 68.6 %, and 79.2 %, respectively. Complications were: one