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Biomedical subjects

K Welvaart

Publications and source records attributed to K Welvaart.

At least 37 records · Page 2Linked to original sources
PubMed1994

Inactive urokinase and increased levels of its inhibitor type 1 in colorectal cancer liver metastasis.

BACKGROUND/AIMS: Human colorectal carcinogenesis was previously found to be associated with an increased urokinase-type plasminogen activator expression, both in antigen and activity, accompanied by simultaneously enhanced levels of plasminogen activator inhibitors type 1 and type 2. This increased proteolytic activity may contribute to invasive growth and metastasis of the tumors. METHODS: In the present study, homogenates of liver metastases, primary colorectal carcinomas, and adjacent normal tissues were evaluated regarding the level and composition of urokinase, tissue-type plasminogen activator, and plasminogen activator inhibitors. RESULTS: Concentrations of urokinase were significantly increased in primary carcinomas and liver metastases compared with normal tissues, whereas tissue-type plasminogen activator levels were significantly decreased. Liver metastases showed, in contrast to the carcinomas, hardly any activity of plasminogen activators, which could be attributed to the enhanced presence of the inactive proenzyme form of urokinase in combination with more complexes of plasminogen activators with inhibitors. Furthermore, liver metastases had an eightfold higher content of inhibitor type 1 compared with the primary carcinomas. The excess of inhibitors was confirmed by addition of plasminogen activators to metastasis homogenates, which resulted in increased complex formation. CONCLUSIONS: Colorectal cancer metastasis in the liver is associated with an inactivation of the enhanced urokinase cascade, which might allow tumor cells to settle in the liver.

Colorectal Neoplasms↗
PubMed1993

[Combination external and internal radiotherapy for esophageal carcinoma: a new prospect].

Thirty-five patients with an inoperable or non-resectable oesophageal carcinoma were treated with external radiotherapy to a maximum dose of 60 Gy followed by a booster irradiation by means of intraluminal brachytherapy at a low dose rate (40-112 cGy/h). For this extra irradiation, which lasted 20-36 h, a catheter with a thickness of 3 mm was introduced through the nose. This treatment could be carried out without sedation. The total radiation dose after the combination therapy amounted to 65-75 Gy. Of the 35 patients, 17 were pretreated with dilatation or laser therapy. The palliative effect after the external and internal irradiation was very good; only one patient still had minor dysphagia 6 weeks after the treatment. Transient irradiation oesophagitis occurred in 16 patients. In three patients, a secondary benign stenosis developed. The median duration of survival was 11 months, the 2-year survival rate was 10%. A comparison of these results with a historical control group treated only with external irradiation shows that the duration of survival of these patients appears to be increased during the first 45 weeks.

Adult↗
PubMed1993

Combined external beam and low dose rate intraluminal radiotherapy in oesophageal cancer.

Thirty-five patients with oesophageal cancer were treated with external beam irradiation (50-60 Gy) followed by a boost-dose of 15-20 Gy by means of low dose rate intraluminal brachytherapy. Of the 35 patients treated 17 (48%) were pretreated with laser therapy or dilation alone. Although the intraluminal application time was long (up to 36 h) the treatment was feasible with minor acute toxicity. The palliative effect of the combined treatment was excellent; a 6 weeks post-treatment 32 of the 35 patients were able to eat solid food. Late complications were seen in six patients (17%), of which only one was severe and probably treatment-related. The median survival was 11 months; the 1- and 2-year survival were 42% and 10% respectively. The survival was strongly dependent on local control. Distant metastases became evident in 23% of patients. The interval between external radiotherapy and brachytherapy seemed to be critical. The results were compared with 68 historical controls. A significantly better survival was observed at 6 months. It is concluded that low dose rate intraluminal brachytherapy is a useful and feasible technique to increase the total dose for obtaining a better local control. The shortcomings are discussed and ideas for further improvement are mentioned.

Aged↗
PubMed1992

Significance of local recurrence after mastectomy for breast cancer.

In a retrospective study 678 patients who underwent (modified) radical mastectomy between 1970 and 1986 were analysed. By comparing the groups of patients who experienced local recurrence, regional recurrence or distant metastasis during follow-up with patients who remained free of disease, we have tried to gain some insight into the significance of local recurrence. By looking at the prognostic factors and the disease-free period there is hardly any difference between the patients with either a local, regional or distant recurrence. Actuarial survival of patients with local recurrence is slightly better than the survival of patients with distant metastasis (P = 0.009). From our results and from the literature we conclude that an isolated local recurrence after mastectomy for breast cancer is, in most cases, a first manifestation of metastatic disease. Probably only a minority of the local recurrences is caused by tumour cells left behind in the operation field.

Adult↗
PubMed1992

Multiple primary melanomas in a patient with familial-type DNS during clomiphene-induced pregnancy.

A 35-year old woman developed six primary cutaneous melanomas during her third pregnancy. She had received clomiphene treatment for nearly 2 years previously. She developed two more primary melanomas 15 and 21 months after giving birth. All melanomas were histologically associated with preexisting dysplastic naevi. The patient showed the characteristic phenotype of the dysplastic naevus syndrome; a cousin and an aunt were treated for malignant melanoma and the patient's brother had histologically confirmed dysplastic naevi. The course of her first two pregnancies was not complicated by the development of melanomas. We suggest that clomiphene may have played a role in the activation or progression of these 'precursor lesions' into malignant melanoma.

Adult↗
PubMed1992

Operative bypass for incurable cancer of the head of the pancreas.

A series of 83 patients with incurable cancer of the pancreatic head were analysed. Obstructive jaundice required surgical intervention in all of them. Different biliary decompression operations, either single or with concomitant prophylactic gastro-enterostomy were constructed in different ways. From our study we conclude: a single bypass, using the gallbladder and anastomosed with the jejunum is preferred in those cases where life expectation is estimated to be less than 3 months. Delayed gastric emptying after gastro-enterostomy is a frequent complication. Double bypasses are recommended only in those cases where duration of life is estimated at more than 3 months.

Adult↗
PubMed1991

[Sexual dysfunction in men following surgical treatment for rectosigmoid carcinoma].

In a retrospective study we performed an analysis of the sexual (dys)function in 26 men operated in the University Hospital Leiden, the Netherlands, for rectosigmoid carcinoma. Nine patients (mean age 59.8 years (45-67)) underwent abdomino-perineal resection and 17 (mean age 59.5 years (43-75)) underwent (low) anterior resection. All men were sexually active before surgery. Following abdomino-perineal resection only 2 patients are sexually active, five are unable to achieve an erection and seven have no orgasms. Three patients only achieve an incomplete erection. One patient has a retrograde ejaculation. Following anterior resection 12 of 17 patients are sexually active, four are unable to achieve an erection or orgasm. Four patients only achieve an incomplete erection. Five patients have a retrograde ejaculation. It is concluded that sexual disorders occur frequently after surgery for rectosigmoid carcinoma, and following abdomino-perineal resection in practically all cases, while the nature of the disorder varies greatly. It is very important to inform the patient before surgery.

Aged↗
PubMed1991

The choice between surgical resection and radiation therapy for patients with cancer of the esophagus and cardia: a retrospective comparison between two treatments.

The choice of treatment for patients with cancer of the esophagus and cardia is controversial. Since overall survival is poor, the most important aim of treatment should be improvement of the main complaint: the inability to eat. In a retrospective analysis of 265 patients, referred to the University Hospital in Leiden, The Netherlands, comparisons were made between palliative effects of surgical resection (N = 92) and irradiation (N = 128). Several methods of comparing surgery with irradiation are possible: (1) all surgical patients vs. all irradiated patients; (2) only those surgical patients who survived the operation (N = 70) vs. all irradiated patients (N = 128); and (3) survivors after resection (N = 70) vs. only those irradiated patients treated with "curative" radiation (N = 62). Analysis of prognostic factors showed that in both surgical and irradiated patients, the only statistically significant factor was the (dis)ability to eat. Criteria to be considered to make individual recommendations for either treatment are presented.

Adult↗
PubMed1991

Screening for skin cancer in The Netherlands.

In the summer of 1989 a screening campaign for skin cancer was organized along part of the beach in the western region of The Netherlands, using a mobile trailer. On 4 consecutive Saturdays, 3,069 individuals were examined. A total of 65 individuals with a suspected lesion were found and referred to their general practitioner. The compliance with referral was 80%. Histological reports, obtained from 46 suspected lesions, showed: 6 melanomas (all with a thickness less than 1 mm), 2 squamous cell carcinomas, 23 basal cell carcinomas, 5 dysplastic naevi and 10 benign skin lesions. The positive predictive value of the visual examination appeared to be 83%. The campaign attracted much publicity. The effects of this publicity were measured by a questionnaire sent to all general practitioners and dermatologists in the region. It appeared that during the campaign and in the ensuing 2 months there had been an increase in the number of diagnoses of benign skin lesions and a moderate increase in the diagnoses of malignant lesions.

Adolescent↗
PubMed1991

Villous tumors of the duodenum. Presentation of five cases.

Five cases of villous tumors of the duodenum are reported. These tumors have a predilection for the periampullary region and tend to present with jaundice or obstruction of the duodenal lumen. In four of these patients, malignant transformation was seen. Endoscopy and biopsy play a major rôle in attempting to obtain an accurate preoperative diagnosis. Unfortunately, the diagnosis of malignant degeneration is frequently missed, even when multiple biopsies are taken. For this reason villous tumors should always be resected, and the strategy of treatment must depend on pre-, intra- and postoperative histological evaluation, location in the duodenum and intra-operative findings.

Adenocarcinoma↗