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Query: UMLS:C0677930 (primary tumor)
 20,210 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

The fact that the national death rate from carcinoma of the colon and rectum has remained static over the past two decades is strong incentive for future investigation of measures to allow detection in its early and more favorable stage. Although no significant improvements in surgical techniques have afforded improvement in longevity, certain technical factors are known to inhibit tumor implantation during surgery. Data suggest that the extent of en bloc resection is the most crucial factor in avoiding recurrence. Extensive use of radiotherapy as the sole method of treatment or as preoperative or postoperative adjunctive therapy remains investigational, but it seems likely that this form of treatment will play an increasing role in the future. Preoperative radiotherapy seems to be useful in reducing the stage of the neoplasm and the incidence of extraserosal involvement; postoperative radiotherapy is beneficial for palliation. Chemotherapy, particularly with the fluorinated pyrimidines (5-FU and 5-FUDR), is being evaluated for its usefulness in lengthening survival time; response to 5-FU is occasionally dramatic. It remains for major investigational centers to clarify the role of combination chemotherapy in metastatic disease. Immunotherapy at present must be considered an unproven mode of treatment and of inconclusive benefit in any stage of colorectal carcinoma. Carcinoembryonic antigen assay is a useful prognostic and diagnostic tool in localizing primary tumor and in subsequent evaluation of response to treatment.
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PMID:Colorectal carcinoma: overview of management techniques. 15 80

The potential of seven tracers for the metabolic imaging of tumors by positron emission tomography was studied using five experimental tumor models. The tracers examined were 2-deoxy-2-[18F]fluoro-D-glucose ([18F]FDG), 2-deoxy-2-[18F]fluoro-D-galactose (2-[18F]FdGal) and 2-deoxy-2-[18F]fluoro-L-fucose (2-[18F]FdFuc) for investigating energy metabolism. L-[methyl-11C]Methionine ([11C]Met) and 6-[18F]fluoro-L-fucose (6-[18F]FFuc) were used for assessing protein and glycoprotein synthesis, while [3H]thymidine ([3H]Thd) and 2-deoxy-5'-[18F]fluorouridine ([18F]FdUrd) were used to investigate nucleic acid metabolism. The highest mean uptake by the five different tumors was found for [3H]Thd, followed in order by [18F]FDG, [11C]Met, 2-[18F]FdGal, [18F]FdUrd, 2-[18F]FdFuc and 6-[18F]FFuc. The tumor-to-tissue uptake ratios indicated that the nucleosides, [11C]Met and 6-[18F]FFuc were better tracers in the brain region. All the tracers except for the fucose analogs were suitable for the thoracic region, while [11C]Thd and [18F]FDG were superior in the abdominal region. In comparison with the primary tumor model of Lewis lung carcinoma (3LL), [3H]Thd uptake in the artificial metastatic 3LL model showed the maximum enhancement, followed by [18F]FDG, [11C]Met and the other tracers. The [18F]FDG uptake correlated with the [3H]Thd uptake. [18F]FdUrd, 6-[18F]FFuc and 2-[18F]FdGal could be used for distinguishing different types of tumors. The combined use of these radiotracers can possibly allow the assessment of tumor metabolism, and this indicates the viability of tumors.
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PMID:Tumor diagnosis by PET: potential of seven tracers examined in five experimental tumors including an artificial metastasis model. 138 72

Local recurrence occurs in 4-47% of breast cancer patients and is often associated with development of metastatic foci and resistant cell populations. Thus, recurrent breast cancer indicates a poor prognosis for the patient. Local tumor-derived 13762NF rat mammary adenocarcinoma cell clone MTF7(T20) was injected into the inguinal mammary fat pad and allowed to grow before surgical excision. Individual locally growing (primary) tumors were removed and established in short-term tissue culture. Corresponding local recurrences were excised after regrowth and established in short-term tissue culture. All sublines were tested for in vitro sensitivities to 5-fluoro-2'-deoxyuridine, Adriamycin, and ionizing X-irradiation. Using a clonogenic colony formation assay, responses of individual sublines ranged from 85 to 1500 ng/ml for Adriamycin and 65 to 10,000 nM for FdUrd. Some recurrences were significantly more resistant while others were more sensitive than the corresponding primary tumor lines. All recurrences had smaller 90% lethal dose values than the corresponding parent or primary tumor in response to Adriamycin; whereas, to 5-fluoro-2'-deoxyuridine, 90% lethal dose values revealed that most lines were quite resistant. Statistically significant differences in radiation survival were observed only for lines LR1a and LR5 (more sensitive). There was no apparent correlation between sensitivities to chemotherapy agents or X-irradiation and experimental metastatic potential in LR sublines. These dose-response data indicate that locally recurrent tumors are frequently, but not always, different from the original primary tumor in response to chemotherapy agents and ionizing X-irradiation. Although an exact mechanism is unknown, it is likely that "selective" pressures which eliminate large numbers of cells, in this case surgery, change tumor composition so that recurrent tumors may no longer be equivalent to the tumor mass that was originally excised. This suggests that treatment strategies should be planned accordingly.
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PMID:Development and characterization of a rat model for locally recurring mammary tumors: sensitivities to 5-fluoro-2'-deoxyuridine, adriamycin, and X-irradiation. 296 81