PubMed · 10508598
The source did not provide an abstract. Follow the original record for more information.
Explore connections, maps & timelines
1999-09-09. At the double.. https://doi.org/10.1016/s0960-9822(99)80406-0
Cite the original work for its findings. Save a collection to share your selection of sources.
KEEP EXPLORING
BACKGROUND: Oncologic resection techniques affect outcome for colon cancer and rectal cancer, but standardized guidelines have not been adopted. The National Cancer Institute sponsored a panel of experts to systematically review current literature and to draft guidelines that provide uniform definitions, principles, and practices. METHODS: Methods were similar to those described by the American Society of Clinical Oncology in developing practice guidelines. Experts representing oncology and surgery met to review current literature on oncologic resection techniques for level of evidence (I-V, where I is the best evidence and V is the least compelling) and grade of recommendation (A-D, where A is based on the best evidence and D is based on the weakest evidence). Initial guidelines were drafted, reviewed, and accepted by consensus. RESULTS: For the following seven factors, the level of evidence was II, III, or IV, and the findings were generally consistent (grade B): anatomic definition of colon versus rectum, tumor-node-metastasis staging, radial margins, adjuvant R0 stage, inadvertent rectal perforation, distal and proximal rectal margins, and en bloc resection of adherent tumors. For another seven factors, the level of evidence was II, III, or IV, but findings were inconsistent (grade C): laparoscopic colectomy; colon lymphadenectomy; level of proximal vessel ligation, mesorectal excision, and extended lateral pelvic lymph node dissection (all three for rectal cancer); no-touch technique; and bowel washout. For the other four factors, there was little or no systematic empirical evidence (grade D): abdominal exploration, oophorectomy, extent of colon resection, and total length of rectum resected. CONCLUSIONS: The panel reports surgical guidelines and definitions based on the best available evidence. The availability of more standardized information in the future should allow for more grade A recommendations.
The 5' region for the endothelin receptor B (EDNRB) gene is a complex CpG island giving rise to four individual transcripts initiating within the island. Here, for the first time, we analyze the relationship between methylation and gene expression in a CpG island located in the 5' region of a gene with multiple transcription start sites. The CpG island was unmethylated in normal prostate and bladder tissue, whereas it became methylated in apparently normal colonic epithelium. Tumors derived from these tissues were frequently hypermethylated relative to the respective normal tissues. Analysis of 11 individual CpG sites located throughout the CpG island showed that specific sites with high methylation levels in several tumors were also methylated in normal tissues, suggesting that they might serve as foci for further de novo methylation. This region also had high levels of methylation in several cancer cell lines, and we found that a low methylation level in a small region within the 5' region correlated with expression of the 5'-most transcript. Interestingly, almost complete methylation 200-1000 bp downstream of the transcriptional start site did not block expression of this transcript. Finally, we show that treatment with 5-aza-2'-deoxycytidine can induce transcriptional activation of the four EDNRB transcripts. Our results show the existence of differential, tissue-dependent methylation at the EDNRB 5' region, suggest the existence of a spreading mechanism for de novo methylation, starting from methylation hotspots, and show that hypermethylation immediately 3' to a transcriptional start site does not prevent initiation.
Explore the source record for details and available documents.