Prostate cancer: How can we improve the health of men who receive ADT?

The role of dietary fat throughout the prostate cancer trajectory

Prostate cancer is the second most common cancer diagnosed world-wide; however, patients demonstrate exceptionally high survival rates. Many lifestyle factors, including obesity and diet, are considered risk factors for advanced prostate cancer. Dietary fat is a fundamental contributor to obesity and may be specifically important for prostate cancer patients. Prostate cancer treatment can result in changes in body composition, affecting quality of life for survivors by increasing the risk of co-morbidities, like cardiovascular disease and diabetes. We aim to examine dietary fat throughout the prostate cancer treatment trajectory, including risk, cancer development and survivorship. Focusing on one specific nutrient throughout the prostate cancer trajectory provides a unique perspective of dietary fat in prostate cancer and the mechanisms that may exacerbate prostate cancer risk, progression and recurrence. Through this approach, we noted that high intake of dietary fat, especially, high intake of animal and saturated fats, may be associated with increased prostate cancer risk. In contrast, a low-fat diet, specifically low in saturated fat, may be beneficial for prostate cancer survivors by reducing tumor angiogenesis and cancer recurrence. The insulin-like growth factor (IGF)/Akt signaling pathway appears to be the key pathway moderating dietary fat intake and prostate cancer development and progression.

High-risk Prostate Cancer Treated With Dose-escalated RT: An Analysis of Hormonal Therapy Use and Duration, and Prognostic Implications of PSA Nadir ≤0.2 to Select Men for Short-term Hormonal Therapy

OBJECTIVES

To determine prognostic factors to select high-risk men receiving dose-escalated radiation therapy (RT) who will have favorable outcomes with short-term (ST) or no androgen deprivation therapy (ADT).

METHODS

Medical records of 458 men treated with definitive RT for high-risk, nonmetastatic prostate cancer at 3 academic referral centers from 1988 to 2009 were examined. Median dose was 76.4 Gy. Men received no ADT (n=105), STADT (<12 mo, n=194), or long-term ADT (LTADT: ≥12 mo, n=160). Univariate and multivariable analysis for freedom from distant metastases (FFDM) and cause-specific survival (CSS) were performed. Median follow-up was 71 months.

RESULTS

Seven-year FFDM was 83% and CSS was 91%. Multivariable analysis demonstrated that prostate-specific antigen (PSA) nadir ≤0.2 (HR=0.36; 95% CI, 0.20-0.64) and Gleason score (GS) were associated with FFDM and CSS (all P<0.05). ADT duration was not associated (P>0.05). Those with PSA nadir ≤0.2 ng/mL had improved outcomes. Men with GS 9 disease did poorly despite a PSA nadir ≤0.2 ng/mL and had improved CSS with LTADT (95% vs. 71%, P<0.05).

CONCLUSIONS

Select men with high-risk disease treated with dose-escalated RT may not require LTADT. In men treated with ADT, PSA nadir ≤0.2 is an independent prognostic factor associated with FFDM and CSS. Men without GS 9 may have acceptable outcomes with STADT if PSA nadir is ≤0.2 ng/mL. Further investigation is necessary to elucidate the role of PSA nadir in determining the optimal length of adjuvant ADT.

The low density lipoprotein receptor modulates the effects of hypogonadism on diet-induced obesity and related metabolic perturbations

Here, we investigated how LDL receptor deficiency (Ldlr(-/-)) modulates the effects of testosterone on obesity and related metabolic dysfunctions. Though sham-operated Ldlr(-/-) mice fed Western-type diet for 12 weeks became obese and showed disturbed plasma glucose metabolism and plasma cholesterol and TG profiles, castrated mice were resistant to diet-induced obesity and had improved glucose metabolism and reduced plasma TG levels, despite a further deterioration in their plasma cholesterol profile. The effect of hypogonadism on diet-induced weight gain of Ldlr(-/-) mice was independent of ApoE and Lrp1. Indirect calorimetry analysis indicated that hypogonadism in Ldlr(-/-) mice was associated with increased metabolic rate. Indeed, mitochondrial cytochrome c and uncoupling protein 1 expression were elevated, primarily in white adipose tissue, confirming increased mitochondrial metabolic activity due to thermogenesis. Testosterone replacement in castrated Ldlr(-/-) mice for a period of 8 weeks promoted diet-induced obesity, indicating a direct role of testosterone in the observed phenotype. Treatment of sham-operated Ldlr(-/-) mice with the aromatase inhibitor exemestane for 8 weeks showed that the obesity of castrated Ldlr(-/-) mice is independent of estrogens. Overall, our data reveal a novel role of Ldlr as functional modulator of metabolic alterations associated with hypogonadism.