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The progression of cancer is largely dependent on neoangiogenesis. Circulating endothelial progenitor cells (EPC) have the ability to form complete vascular structures in vitroand play a crucial role in tumor vasculogenesis. Emerging evidence suggests that surgical injury may induce the mobilization of EPC in animal models, and this might have a negative effect on the prognosis of cancer patients. We studied 20 patients (10 men, 65±13 years) undergoing laparotomy for surgical treatment of various forms of abdominal cancer, and 20 age- and sex-matched healthy control subjects. The number of circulating EPC, defined as CD34+/KDR+ cells identified among mononuclear cells isolated from peripheral venous blood, was determined preoperatively and at days 1 and 2 after surgery. Surgery induced a significant increase in circulating EPC levels at day 1 (from 278/mL, interquartile range 171–334, to 558/mL, interquartile range 423–841, p<0.001) and day 2 (709/mL, interquartile range 355–834, p<0.001) compared with baseline values. EPC levels did not change in control subjects. Seven subjects who underwent laparotomic surgery for non-neoplastic disease also showed an increase in EPC levels after surgery (p=0.009 and p=0.028 at day 1 and day 2, respectively). We conclude that patients undergoing elective laparotomic surgery for cancer demonstrate an increase in EPC post-operatively. The potential adverse effects of surgical stress-induced EPC mobilization on tumor and metastasis growth in cancer patients need to be addressed in future studies.

Biliopancreatic diversion (BPD), a gastrectomy with a long ROUX en Y reconstruction, reduces intestinal absorption by delaying the mixing of food and biliopancreatic juices, and induces persistent weight loss in obese patients unresponsive to medical treatments. The levels of leptin (a plasma protein synthesised in human adipose tissue) are increased in obese subjects and significantly decrease after a major weight loss. A possible role of thyroid hormones in regulating adipose tissue metabolism in humans has been proposed, but it is not universally accepted and the relationship between thyroid function and leptin levels has not yet been clearly defined. We studied serum leptin, TSH, fT4 and fT3 levels in 38 obese patients (26 women and 12 men), before and 12 months after BPD. There was a significant post-surgical decrease in BMI and circulating leptin levels in all of the treated subjects, but thyroid function did not seem to be affected (TSH and fT4 levels were unchanged). However, fT3 levels significantly decreased after surgery. Our data suggest that BPD-induced malabsorption has no direct effect on thyroid function, but possibly reduces the peripheral conversion of thyroxine to T3. Further studies seem to be necessary to clarify the clinical relevance of these observations.

A phase III malaria vaccine trial in 13 villages in an endemic area, South Venezuela, compared incidence rates of Plasmodium falciparum and Plasmodium vivax infections in 1422 vaccinated and 938 nonvaccinated subjects over 18 months. The SPf66 vaccine was given in three doses, on days 0, 20, and 112. Vaccination was complete in 976 subjects (68.7%). Minor side effects requiring no treatment were reported by 123 (12.6%), with an apparent increase in frequency from the first to the third vaccine dose. No autoimmune evidence was observed in a sample of subjects. Antibodies against SPf66 were present at low titers in 24.7% of tested subjects before vaccination, increasing to 53.6% after the second dose and to 73.6% after the third dose; 26.4% of subjects initially seronegative never seroconverted. The SPf66 malaria vaccine showed a protective efficacy of 55% (95% confidence interval, 21%-75%) against Pi falciparum and of 41% (19%-57%) against P. vivax malaria.