[Role of obesity in colorectal carcinogenesis]

Body size and longitudinal body weight changes do not increase mortality in incident peritoneal dialysis patients of the Brazilian peritoneal dialysis multicenter study

OBJECTIVES

To determine the roles of body size and longitudinal body weight changes in the survival of incident peritoneal dialysis patients.

PATIENTS AND METHODS

Patients (n = 1911) older than 18 years of age recruited from 114 dialysis centers (Dec/ 2004-Oct/2007) and participating in the Brazilian Peritoneal Dialysis Multicenter Cohort Study were included. Clinical and laboratory data were collected monthly (except if the patient received a transplant, recovered renal function, was transferred to hemodialysis, or died).

RESULTS

Survival analyses were performed using Kaplan-Meier survival curves and Cox proportional hazards. Total follow-up was 34 months. The mean age was 59 years (54% female). The weight category percentages were as follows: underweight: 8%; normal: 51%; overweight: 29%; and obese 12%. The multivariate model showed a higher risk of death for a body mass index <18.5 kg/m², a neutral risk between 25 and 29.9 kg/m² and a protective effect for an index >30 kg/m². Patients were divided into five categories according to quintiles of body weight changes during the first year of dialysis: <-3.1%, -3.1 to+0.12%, +0.12 to <+3.1% (reference category), +3.1 to +7.1% and >+7.1%. Patients in the lowest quintile had significantly higher mortality, whereas no negative impact was observed in the other quintiles.

CONCLUSION

These findings suggest that overweight/obesity and a positive body weight variation during the first year of peritoneal dialysis therapy do not increase mortality in incident dialysis patients in Brazil.

Diabetes and risk of tumors: oncologic considerations

Type 2 diabetes mellitus and malignant tumors are frequent diseases worldwide. The incidence of these two diseases is growing continuously and causes serious health care problem. Population based epidemiologic studies show that the coexistence of type 2 diabetes and malignant tumors is more frequent than expected by the age-corrected incidence and prevalence of each disease. Epidemiologic studies and meta-analyses show that type 2 diabetes increases the risk and tumor specific mortality of certain cancers. The overlapping risk factors of the diseases suggest a relationship between type 2 diabetes and malignant tumors, with a significant role of obesity as a major risk factor. In the pathophysiology of type 2 diabetes there are several biological processes, which may explain the higher cancer risk in type 2 diabetes. In vitro experiments, and in vivo animal studies show that the mitotic effect of hyperinsulinemia plays an important role in the relationship of cancer and type 2 diabetes mellitus. Recent studies show that the different treatment modalities, antidiabetic drugs and their combinations used for the treatment of type 2 diabetes can modify cancer risk. The majority of the data show that metformin therapy decreases, while insulin secretagog drugs slightly increase the risk of certain types of cancers in type 2 diabetes. Metformin can decrease cell proliferation and induce apoptosis in certain cancer cell lines. Endogenous and exogenous (therapy induced) hyperinsulinemia may be mitogenic and may increase the risk of cancer in type 2 diabetes. Human studies showed that the analogue insulin glargin increases the risk of certain cancers. As a result of conceptual weaknesses in study design, data collection, and statistical methods the results of these studies are questionable. According to present knowledge, obtaining and maintaining optimal metabolic target values with the appropriate choice of treatment modality is the aim of treatment in type 2 diabetes. Presently, study results showing elevated mitogenic potential with some antidiabetic treatment modalities are not taken into account, when considering the choice of antidiabetic treatment in type 2 diabetic patients. In the care of patients with increased cancer risk, oncologic considerations should be taken into account. Well designed, prospective, clinical studies would be necessary to demonstrate the possible correlation between treatment modalities of type 2 diabetes and change of cancer risk in type 2 diabetes mellitus. Orv. Hetil., 2011, 152, 1144–1155.

Immunological, Hematological, and Glycemia Effects of Dietary Supplementation withAgaricus sylvaticuson Patients’ Colorectal Cancer

Objective: The aim of this study was to evaluate the effects of dietary supplementation with Agaricus sylvaticus fungus on hematological, immunological, and glycemia levels of postsurgical patients with colorectal cancer. Methods: A randomized, placebo-controlled, clinical trial was conducted at the General Hospital of Brazil for 6 months. Fifty-six patients with colorectal cancer (stages I, II, and III) were divided into 2 groups: A. sylvaticus (30 mg/kg/day) and placebo. Complete hemogram, serum iron, and fasting glycemia evaluations were carried out throughout the treatment course. Subjects were divided according to body mass index (BMI), sex, and stage of colorectal cancer. Data were analyzed using SPSS 14.0 programs, Student’s t test, and F statistical test, with P ≤ 0.05 considered significant. Results: After 6 months of supplementation, the group that received A. sylvaticus showed significant increases in hemoglobin ( P = 0.0001), hematocrit ( P = 0.0001), erythrocytes ( P = 0.01), mean cell volume ( P = 0.01), mean cell hemoglobin ( P = 0.0001), mean cell hemoglobin concentration ( P = 0.0001), and neutrophil levels ( P = 0.0001). The platelet count was significantly reduced ( P = 0.03), but remained within normal levels. No significant alterations were observed in the placebo group. The study group was composed of 32 women (57.1%) and 24 men (42.9%). Mean BMI was 24.65 kg/m2. Glycemia levels in the placebo group (average age 59.14 ± 12.95 years) were: initial, 94.36 ± 15.34 mg/dl; 3 months, 98.12 ± 15.54 mg/dl ( P = 0.03); and 6 months, 98.52 ± 9.03 mg/dl ( P = 0.01). Glycemia levels in the supplemented group (average age 56.34 ± 15.53 years) were: initial, 95.92 ± 11.64 mg/dl, 3 months, 94.88 ± 12.24 mg/dl ( P = 0.65); and 6 months, 92.86 ± 6.82 mg/dl ( P = 0.01). Conclusions: The results of this study suggest that supplementation with A. sylvaticus produces benefits in hematological and immunological parameters and can reduce glycemia levels in patients with colorectal cancer.

Type 2 diabetes and metabolic syndrome as conditions leading to malignant tumors

Az utóbbi években egyre több bizonyíték szólt a metabolikus szindróma és a 2-es típusú diabetes mellitus karcinogén hatásáról. A bizonyítékok között első helyen az epidemiológiai észlelések állnak. A különböző tumorfajták és a metabolikus szindróma, illetve a 2-es típusú diabetes mellitus között nemek, rasszok és földrajzi elterjedtség szerint eltérő mértékben mutatható ki kauzális összefüggés. A lehetséges közös patomechanizmusok az elhízáskor a zsírszövetben excesszíven termelődő adipokinek, a tartós és postprandialis hyperglykaemia, a hyperinsulinismus és az inzulinrezisztencia, egyéb növekedési faktorok, mint a proinzulin, inzulinszerű növekedési faktor-1, reaktív oxigén-szabadgyökök, angiogenezis, inflammáció és gyulladásos citokinek sejtproliferatív hatásai. Kiderült, hogy a peroxiszómaproliferátor aktiválta receptoroknak és az őket szabályozó ubiquitin proteaszómarendszernek is meghatározó szerepe van a sejtproliferáció befolyásolásában. Ezek a mechanizmusok metabolikus szindrómában mind atherosclerosis, mind karcinogenezis irányában kockázati tényezőként szerepelnek. Ez a felismerés új utat nyithat mindkét kórkép megelőzése és kezelése szempontjából.