The association of diabetes and obesity with prostate cancer aggressiveness among Black Americans and White Americans in a population-based study. Cancer Causes Control. 2016;27:1475-1485. [PMID: 27830399 DOI: 10.1007/s10552-016-0828-0]

Overall and central obesity and prostate cancer risk in African men

PURPOSE

African men are disproportionately affected by prostate cancer (PCa). Given the increasing prevalence of obesity in Africa, and its association with aggressive PCa in other populations, we examined the relationship of overall and central obesity with risks of total and aggressive PCa among African men.

METHODS

Between 2016 and 2020, we recruited 2,200 PCa cases and 1,985 age-matched controls into a multi-center, hospital-based case-control study in Senegal, Ghana, Nigeria, and South Africa. Participants completed an epidemiologic questionnaire, and anthropometric factors were measured at clinic visit. Multivariable logistic regression was used to examine associations of overall and central obesity with PCa risk, measured by body mass index (BMI), waist circumference (WC), waist-to-hip ratio (WHR), and waist-to-height ratio (WHtR), respectively.

RESULTS

Among controls 16.4% were obese (BMI ≥ 30 kg/m2), 26% and 90% had WC > 97 cm and WHR > 0.9, respectively. Cases with aggressive PCa had lower BMI/obesity in comparison to both controls and cases with less aggressive PCa, suggesting weight loss related to cancer. Overall obesity (odds ratio: OR = 1.38, 95% CI 0.99-1.93), and central obesity (WC > 97 cm: OR = 1.60, 95% CI 1.10-2.33; and WHtR > 0.59: OR = 1.68, 95% CI 1.24-2.29) were positively associated with D'Amico intermediate-risk PCa, but not with risks of total or high-risk PCa. Associations were more pronounced in West versus South Africa, but these differences were not statistically significant.

DISCUSSION

The high prevalence of overall and central obesity in African men and their association with intermediate-risk PCa represent an emerging public health concern in Africa. Large cohort studies are needed to better clarify the role of obesity and PCa in various African populations.

Diabetes and cancer: Epidemiological and biological links

The incidence of diabetes and cancer has increased significantly in recent years. Furthermore, there are many common risk factors for both diabetes and cancer, such as obesity, sedentary lifestyle, smoking, and ageing. A large body of epidemiological evidence has indicated that diabetes is considered as an independent risk factor for increased rates of heterogeneous types of cancer occurrence and death. The incidence and mortality of various types of cancer, such as pancreas, liver, colorectal, breast, endometrial, and bladder cancers, have a modest growth in diabetics. However, diabetes may work as a protective factor for prostate cancer. Although the underlying biological mechanisms have not been totally understood, studies have validated that insulin/insulin-like growth factor (IGF) axis (including insulin resistance, hyperinsulinemia, and IGF), hyperglycemia, inflammatory cytokines, and sex hormones provide good circumstances for cancer cell proliferation and metastasis. Insulin/IGF axis activates several metabolic and mitogenic signaling pathways; hyperglycemia provides energy for cancer cell growth; inflammatory cytokines influence cancer cell apoptosis. Thus, these three factors affect all types of cancer, while sex hormones only play important roles in breast cancer, endometrial cancer, and prostate cancer. This minireview consolidates and discusses the epidemiological and biological links between diabetes and various types of cancer.

Obesity, race, and long-term prostate cancer outcomes

BACKGROUND

The authors previously found that obesity was linked with prostate cancer (PC)-specific mortality (PCSM) among men who underwent radical prostatectomy (RP). Herein, in a larger RP cohort, the authors investigated whether the association between obesity and long-term PC outcomes, including PCSM, differed by race.

METHODS

Data from 5929 patients who underwent RP and were in the Shared Equal Access Regional Cancer Hospital (SEARCH) database were analyzed. Prior to RP, body mass index (BMI) was measured and recorded in the medical records. BMI was categorized as normal weight (<25 kg/m² ), overweight (25-29.9 kg/m² ), and obese (≥30 kg/m² ). The authors assessed the association between BMI and biochemical disease recurrence (BCR), castration-resistant prostate cancer (CRPC), metastasis, and PCSM, accounting for confounders.

RESULTS

Of the 5929 patients, 1983 (33%) were black, 1321 (22%) were of normal weight, 2605 (44%) were overweight, and 2003 (34%) were obese. Compared with white men, black men were younger; had higher prostate-specific antigen levels; and were more likely to have a BMI ≥30 kg/m² , seminal vesicle invasion, and positive surgical margins (all P ≤ .032). During a median follow-up of 7.4 years, a total of 1891 patients (32%) developed BCR, 181 patients (3%) developed CRPC, 259 patients (4%) had metastasis, and 135 patients (2%) had died of PC. On multivariable analysis, obesity was found to be associated with an increased risk of PCSM (hazard ratio, 1.78; 95% confidence interval, 1.04-3.04 [P = .035]). No interaction was found between BMI and race in predicting PCSM (P ≥ .88), BCR (P ≥ .81), CRPC (P ≥ .88), or metastasis (P ≥ .60). Neither overweight nor obesity was associated with risk of BCR, CRPC, or metastasis (all P ≥ .18).

CONCLUSIONS

Obese men undergoing RP at several Veterans Affairs hospitals were found to be at an increased risk of PCSM, regardless of race.

Metabolic Alterations, Aggressive Hormone-Naïve Prostate Cancer and Cardiovascular Disease: A Complex Relationship

Background: Epidemiological studies suggest a possible relationship between metabolic alterations, cardiovascular disease and aggressive prostate cancer, however, no clear consensus has been reached. Objective: The aim of the study was to analyze the recent literature and summarize our experience on the association between metabolic disorders, aggressive hormone-naïve prostate cancer and cardiovascular disease. Method: We identified relevant papers by searching in electronic databases such as Scopus, Life Science Journals, and Index Medicus/Medline. Moreover, we showed our experience on the reciprocal relationship between metabolic alterations and aggressive prostate cancer, without the influence of hormone therapy, as well the role of coronary and carotid vasculopathy in advanced prostate carcinoma. Results: Prostate cancer cells have an altered metabolic homeostatic control linked to an increased aggressivity and cancer mortality. The absence of discrimination of risk factors as obesity, systemic arterial hypertension, diabetes mellitus, dyslipidemia and inaccurate selection of vascular diseases as coronary and carotid damage at initial diagnosis of prostate cancer could explain the opposite results in the literature. Systemic inflammation and oxidative stress associated with metabolic alterations and cardiovascular disease can also contribute to prostate cancer progression and increased tumor aggressivity. Conclusions: Metabolic alterations and cardiovascular disease influence aggressive and metastatic prostate cancer. Therefore, a careful evaluation of obesity, diabetes mellitus, dyslipidemia, systemic arterial hypertension, together with a careful evaluation of cardiovascular status, in particular coronary and carotid vascular disease, should be carried out after an initial diagnosis of prostatic carcinoma.

The association of metformin use with prostate cancer aggressiveness among Black Americans and White Americans in a population-based study

PURPOSE

Metformin has been associated with a reduced incidence of prostate cancer and improved prostate cancer outcomes. However, whether race modifies the association between metformin use and prostate cancer aggressiveness remains uncertain. The association between metformin use and prostate cancer aggressiveness was examined separately in Black Americans (Blacks) and White Americans (Whites).

METHODS

The study population consisted of 305 Black and 195 White research participants with incident prostate cancer and self-reported diabetes from the North Carolina-Louisiana Prostate Cancer Project. High-aggressive prostate cancer was defined using a composite measure of Gleason sum, prostate-specific antigen, and clinical stage. Multivariable logistic regression was used to assess the association between metformin use and high-aggressive prostate cancer at diagnosis, separately among Whites and Blacks, with adjustment for age, screening history, site, education, insurance, and body mass index.

RESULTS

Metformin use was associated positively with high-aggressive prostate cancer in Blacks (OR 2.01; 95% CI 1.05, 3.83). By contrast, a weak inverse association between metformin use and high-aggressive prostate cancer was found in Whites (OR 0.80, 95% CI 0.34, 1.85).

CONCLUSIONS

The association between metformin use and prostate cancer aggressiveness may be modified by race.

Association of Anthropometric Measures with Prostate Cancer among African American Men in the NCI-Maryland Prostate Cancer Case-Control Study

Background: Obesity is a cancer risk factor. Although it does not increase the risk of localized prostate cancer, it raises the risk of the aggressive disease in men of European ancestry. Few studies investigated obesity as a prostate cancer risk factor in men of African ancestry. Findings from those studies were heterogeneous, but some reported an association of excess body fatness with aggressive disease.Methods: We examined the relationship of body mass index (BMI), waist circumference, and waist-hip ratio with prostate cancer in African American (AA) and European American (EA) men in the NCI-Maryland Prostate Cancer Case-Control Study consisting of 798 men with incident prostate cancer (402 AA and 496 EA) and 1,008 population-based controls (474 AA and 534 EA). BMI was self-reported. Waist circumference and waist-hip ratio were calculated from measurements at enrollment.Results: A high BMI either at enrollment or years prior to it was associated with a decreased risk of prostate cancer in AA men. In contrast, an elevated BMI tended to increase the disease risk in EA men. Waist circumference was inversely associated with prostate cancer in both AA and EA men, whereas a high waist-hip ratio did not associate with prostate cancer in AA men but tended to be associated with advanced/aggressive disease in EA men.Conclusions: Our findings reveal an obesity paradox among AA men in this study population, where a high BMI and waist circumference associated with a decreased disease risk.Impact: Our observations expand the knowledge of how obesity may affect prostate cancer risks in AAs. Cancer Epidemiol Biomarkers Prev; 27(8); 936-44. ©2018 AACR.

The Association of Diabetes and Obesity With Prostate Cancer Progression: HCaP-NC

BACKGROUND

The role of race in modifying the association among diabetes, obesity, and prostate cancer (CaP) progression is not well studied. We evaluated diabetes and obesity in association with time to CaP progression in White Americans (Whites) and Black Americans (Blacks).

METHODS

Our study sample consisted of 363 White and 284 Black research participants from the Health Care Access and CaP Treatment in North Carolina (HCaP-NC) cohort. The association between self-reported diabetes or obesity and CaP progression (mean follow-up time approximately 5 years) was assessed using Cox proportional hazards modeling, with adjustment for potential confounders. Stratum-specific hazard ratio (HR) estimates for Whites and Blacks were evaluated.

RESULTS

Self-reported diabetes was not associated with CaP progression in the cohort as a whole (HR: 0.86, 95%CI: 0.54, 1.35), or among racially defined groups (Whites, HR: 1.03, 95%CI: 0.50, 2.13 or Blacks, HR: 0.77, 95%CI: 0.43, 1.39). Obesity was positively associated with CaP progression among Whites, in models including (HR: 1.79, 95%CI: 1.08, 2.97), and excluding (HR: 1.80, 95%CI: 1.09, 2.96) diabetes as a covariate. No association was observed between obesity and CaP progression in Blacks or the cohort as whole.

CONCLUSIONS

Self-reported diabetes was not associated with CaP progression In HCaP-NC. Obesity was associated with CaP progression only among White research participants. Prostate 77:878-887, 2017. © 2017 Wiley Periodicals, Inc.