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Biomedical subjects

K Sikora

Publications and source records attributed to K Sikora.

At least 19 recordsLinked to original sources
PubMed1994

Combined choriocarcinoma and yolk sac tumor arising in Barrett's esophagus.

A patient with primary adenocarcinoma with yolk sac and trophoblastic differentiation occurring in Barrett's esophagus is reported. Yolk sac differentiation at this site has not been described previously. The diagnosis of germ cell differentiation initially was suggested by the finding of elevated serum tumor marker levels. The patient experienced disease remission after cytotoxic chemotherapy. Germ cell differentiation may be difficult to identify in small biopsy samples, which may not be representative of the tumor as a whole. The finding of germ cell differentiation defines therapy and predicates for a relatively good prognosis, which is contrast to adenocarcinoma. Because of the significance of germ cell differentiation in the selection of appropriate therapy, immunostaining for germ cell tumor markers is suggested in all patients with adenocarcinoma who are younger than 50 years.

Adenocarcinoma↗
PubMed1994

Gene therapy for cancer using tumour-specific prodrug activation.

Current treatments for metastatic malignant disease are often ineffective. One of the most promising of the selective genetic strategies against cancer is VDEPT (virally directed enzyme prodrug therapy). This uses a viral vector to carry a prodrug-activating enzyme gene into both tumour and normal cells. By linking the foreign gene downstream of tumour-specific transcription units, tumour-specific expression of the foreign enzyme gene can be achieved. We have developed a genetic therapy strategy using VDEPT against cancers that overexpress the oncogene ERBB2. This occurs in approximately one-third of breast and pancreatic tumours (and in a smaller proportion of other tumours) and involves transcriptional up-regulation of the ERBB2 gene with or without gene amplification. We have constructed a chimeric minigene consisting of the proximal ERBB2 promoter linked to the gene encoding cytosine deaminase, an enzyme that can deaminate the prodrug 5-fluorocytosine (5-FC) to form cytotoxic 5-fluorouracil (5-FU). We have constructed a double-copy recombinant retrovirus to deliver the enzyme gene under the control of the ERBB2 promoter into a panel of ERBB2 expression-positive (ERBB2+) and -negative (ERBB2-) pancreatic and breast cell lines. Cytosine deaminase activity was high in ERBB2+ transduced cells but was not detected in ERBB2- transduced cells. Significant cell death was observed in ERBB2+ transduced cells treated with 5-FC whereas ERBB2- cells were not affected. Hence we present a novel gene therapy strategy that is potentially tumour-specific and could be used against a range of tumour types that overexpress the ERBB2 oncogene.

Base Sequence↗
PubMed1992

Gene therapy for cancer.

The molecular basis of cancer is now understood to involve activation of dominant oncogenes and inactivation of tumour suppressor genes, and these genetic events may represent novel targets for cancer therapy. This review focuses on the potential use and ethical implications of gene transfer to alter the behaviour of somatic cells in cancer patients. Antisense nucleic acids and ribozymes represent informational drugs that may be used to modulate the expression of selected genes and suppress malignant behaviour in cancer cells. Genetic immunomodulation by introducing genes for cytokines into cancer cells or lymphocytes can stimulate a cytotoxic immune response against the tumour. Gene transfer techniques can be applied to target prodrug activation specifically to tumour cells and also to protect normal tissues against toxic chemotherapy. Gene replacement therapy could even be used to restore the function of defective tumour suppressor genes.

Animals↗
PubMed1992

Measurements of blood flow and exchanging water space in breast tumors using positron emission tomography: a rapid and noninvasive dynamic method.

A noninvasive dynamic method for the measurement of blood flow, using 15O-labeled water and positron emission tomography, has been developed and used to study 20 patients with breast carcinoma. The mean tumor flow was 29.8 +/- 17.0 (SE) ml/dl/min of tissue, while normal breast flow was 5.6 +/- 1.4 ml/dl/min of tissue. The exchanging water space of tissue known as the volume of distribution of the tracer (Vd) was also derived. This is defined as the volume of water in tissue that exchanges with a unit volume of water in arterial blood during the period of the study (7 min). The mean tumor Vd was 0.56 +/- 0.15 ml/ml while normal breast Vd was 0.14 +/- 0.05 ml/ml. The low value in normal breast is partly due to the high fat content of the tissue. The mean flow per unit of exchangeable volume was similar in tumor (52.8 +/- 22.0) and normal breast tissue (45.2 +/- 20.0). This suggests that the major discrepancy seen in measured values of flow between breast tumors and normal breast principally reflects the different composition of the two tissues. This method is rapid and suited for studying the reactivity of human tumor vasculature, so extending studies are being performed on animal tumors.

Adult↗
PubMed1992

Bladder cancer: inter-relationships between chemotherapy and radiotherapy.

There has been increasing interest in the role of chemotherapy as primary treatments for patients with urothelial cancer and because of the poor prognosis of locally advanced tumours with conventional treatment, trials have been initiated comparing radiotherapy with chemotherapy as primary therapies. In this context it is important to assess the relationship between the responses to chemotherapy and radiotherapy, and this we have examined in 64 patients treated with MVMJ (methotrexate, vinblastine, mitozantrone and carboplatin). Either a complete or a partial response was found in 29 of the 64 patients, 15 had stable disease and 13 had progression of disease. Seven patients died within the first treatment month. The survival of the responding patients ranged from 114 to 1184 days. Six of 15 patients who had had pelvic irradiation prior to chemotherapy responded to MVMJ, the maximum duration of response being more than 3 years. Twenty-two patients had radiotherapy following their chemotherapy. One of 13 patients not responding to MVMJ had a transient response to radical radiotherapy. Only 1 of 9 patients responding to chemotherapy and then relapsing responded to subsequent radical radiotherapy. Patients with metastatic disease or with recurrent disease after radiotherapy have a worthwhile chance of responding to chemotherapy and achieve durable remissions. In contrast, radiotherapy appears relatively ineffective in patients whose disease progresses or relapses after chemotherapy given as primary treatment with curative intent.

Adult↗
PubMed1991

Comparison of dexamethasone and ondansetron in the prophylaxis of emesis induced by moderately emetogenic chemotherapy.

A multicentre, randomised, double-blind, cross-over trial was done to compare the efficacy and safety of a serotonin receptor antagonist--ondansetron--and dexamethasone in the prophylaxis of acute and delayed emesis and nausea induced by moderately emetogenic non-platinum-containing chemotherapy regimens. Patients were treated as outpatients and received intravenous ondansetron 4 mg or dexamethasone 8 mg before chemotherapy and oral maintenance (ondansetron 4 mg every 6 h and dexamethasone reducing from 4 mg to 1 mg 6-hourly between days 1 and 5) for 5 days. 112 patients were treated (38 men, 73 women, 1 with no gender recorded; age range 30-73 years) and 100 were evaluable for cross-over analysis. Patients taking ondansetron or dexamethasone reported no significant difference in complete and major control of acute (83% vs 79%, p = 0.46) or delayed (82% vs 88%, p = 0.214) emesis (vomiting plus retches). Significantly more patients on dexamethasone (87%) than on ondansetron (72%) reported control of delayed nausea (days 2-5) (p = 0.003). Both drugs were well tolerated with no significant difference in the number of adverse events, and this is reflected by similar patient preference for ondansetron (40%) and dexamethasone (30%) (p = 0.244). Both drugs offer adequate out-patient control of chemotherapy-induced emesis; however, dexamethasone has an advantage in the control of delayed nausea, and also in terms of cost and resource allocation.

Acute Disease↗
PubMed1991

Immune modulation and cancer.

The concept that the immune system is involved in defence against cancer goes back nearly a hundred years. Despite increased sophistication in our analysis of the immune response it has proven difficult to demonstrate a powerful role of the immune system in either the prevention or treatment of cancer. Animal data has consistently and clearly shown that the immune system can identify and reject experimental tumours. In patients the data is more conflicting. The isolation of individual cytokines which stimulate specific components of the immune response and have a anti-cancer effect does suggest, however, that as we learn more about the interaction between immunity and cancer, novel methods for the diagnosis and therapy of cancer will be developed.

Antigens, Neoplasm↗
PubMed1991

New therapeutic modalities for cancer.

A review is given on new biological approaches to cancer therapy based on knowledge concerning interferons, interleukins. LAK-cells, tumour-infiltrating lymphocytes, tumour necrosis factor, colony-stimulating factors, monoclonal antibodies and oncogenes. There are many potential permutations for the application of biological therapy for cancer. One of the most important developments has been the increased understanding of the molecular mechanisms of malignancy through which biological manipulation can be tailored to an individual tumour. Although current clinical studies are not demonstrating high response rates they may well be analogous to the advances seen with chemotherapy in its early days. As yet only relatively small numbers of patients have had access to, or been suitable for, treatment. With further refinements in production, administration, and an increase in the specificity of treatment, the possibility of curing metastatic solid tumours may become a reality.

Antibodies, Monoclonal↗
PubMed1991

Preoperative radiotherapy combined with resection of squamous cell carcinoma of the mid-thoracic oesophagus. Does a histopathological malignancy grading system assess actual survival?

The aim of our study was to assess the reproducibility of the findings of Hambraeus et al. In their group of patients with squamous cell carcinoma of the oesophagus who underwent preoperative radiotherapy and resection, the histopathological malignancy grading score system was found to predict survival. We studied nine patients with squamous cell cancer of the mid-thoracic oesophagus, who had received radiotherapy followed by surgery and survived over 12 months. We did not confirm the prognostic value of the histopathological malignancy grading score system.

Aged↗