Preoperative weight change and risk of adverse outcome following radical prostatectomy: results from the Shared Equal Access Regional Cancer Hospital database

White adipose tissue-derived factors and prostate cancer progression: mechanisms and targets for interventions

Obesity represents an important risk factor for prostate cancer, driving more aggressive disease, chemoresistance, and increased mortality. White adipose tissue (WAT) overgrowth in obesity is central to the mechanisms that lead to these clinical observations. Adipose stromal cells (ASCs), the progenitors to mature adipocytes and other cell types in WAT, play a vital role in driving PCa aggressiveness. ASCs produce numerous factors, especially chemokines, including the chemokine CXCL12, which is involved in driving EMT and chemoresistance in PCa. A greater understanding of the impact of WAT in obesity-induced progression of PCa and the underlying mechanisms has begun to provide opportunities for developing interventional strategies for preventing or offsetting these critical events. These include weight loss regimens, therapeutic targeting of ASCs, use of calorie restriction mimetic compounds, and combinations of compounds as well as specific receptor targeting strategies.

Obesity and biochemical recurrence in clinically localised prostate cancer: a systematic review and meta-analysis of 86,490 patients

BACKGROUND

The association of obesity with biochemical recurrence (BCR) after treatment of clinically localised prostate cancer (PC) shows inconsistent results. Our aim was to systematically review all evidence evaluating obesity as a prognostic factor for BCR.

METHODS

We searched PubMed, Web of Science and Scopus, from inception to June 1, 2021. Cohort studies reporting BCR among PC patients stratified by body mass index (BMI) were included. To assess the quality of the selected studies, we used the Newcastle-Ottawa scale (NOS). Risk of BCR among obese patients (BMI ≥ 30 kg/m²) was compared with normal weight (BMI < 25), pooling individual hazard ratios (HR) in random-effect meta-analysis. Associations for continuous BMI per 5 kg/m² were also calculated. Subgroup analyses were conducted to assess reasons for heterogeneity and causal criteria were formally evaluated.

RESULTS

We identified 46 cohort studies including 86,490 PC patients. A total of 14,719 (17.1%) patients developed BCR. There was no consistent definition of BCR. Obesity was associated with BCR (HR: 1.25, 95% CI: 1.11-1.39, I²: 70.3%), and there was a 10% increase (95% CI: 4-15%, I²: 66.3%) in BCR per 5 kg/m² increase in BMI. The heterogeneity was high but decreased in the subgroup of highest-quality NOS score and when the BMI was measured by the researchers (I²: 0.0%). The association was consistent in patients receiving radical prostatectomy but not in patients receiving other therapies.

CONCLUSIONS

Obesity showed a moderate, consistent relationship with biochemical recurrence after radical prostatectomy. Measurement of BMI and BCR was variable, highlighting the need for standardised clinical guidelines. Preventive weight control programs may have a role in reducing BCR for clinically localised PC patients.

Feasibility of a Weight Management Program Tailored for Overweight Men with Localized Prostate Cancer - A Pilot Study

BACKGROUND

Overweight men with prostate cancer are more likely to suffer from recurrence and death following prostatectomy compared with healthy weight men. This study tested the feasibility of delivering a comprehensive program to foster weight loss before and weight maintenance after surgery in overweight men with localized prostate cancer.

METHODS

Twenty overweight men scheduled for prostatectomy elected either the intervention (n = 15) or the nonintervention (n = 5). Anthropometrics, biomarkers, diet quality, nutrition literacy, quality of life, and long-term follow-up were assessed in both groups.

RESULTS

The intervention led to 5.55 kg of weight loss including 3.88 kg of fat loss from baseline to surgery (mean = 8.3 weeks). The intervention significantly increased fiber, protein, fruit, nut, and vegetable intake; and decreased trans fats intake during weight loss. The intervention significantly reduced insulin, C-peptide, systolic blood pressure, leptin:adiponectin ratio, and visceral adiposity compared to the nonintervention. Post-surgically, weight loss was maintained. Changes in lipid profiles, nutrition literacy, and follow-up were not statistically significant in either group.

CONCLUSION

Significant weight loss (≥5%) is feasible with a coaching intervention in overweight men preparing for prostatectomy and is associated with favorable cardiometabolic effects. This study is registered under NCT02252484 (www.clinicaltrials.gov).

Diet and Lifestyle in Prostate Cancer

A variety of diet and lifestyle factors have been studied with respect to prostate cancer risk in large, prospective cohort studies. In spite of this work, and in contrast to other common cancers, few modifiable risk factors have been firmly established as playing a role in prostate cancer. There are several possible explanations for the lack of well-established risk factors. First, prostate cancer has among the highest heritability of all common cancers; second, early life exposures may play an important role in risk, rather than mid- and later-life exposures assessed in most epidemiological studies. Finally, prostate-specific antigen (PSA) screening plays a critical role in prostate cancer detection and incidence rates, which has important implications for epidemiological studies.Among modifiable risk factors, smoking and obesity are consistently associated with higher risk specifically of advanced prostate cancer. There is also considerable evidence for a positive association between dairy intake and overall prostate cancer risk, and an inverse association between cooked tomato/lycopene intake and risk of advanced disease. Several other dietary factors consistently associated with risk in observational studies, including selenium and vitamin E, have been cast into doubt by results from clinical trials. Results for other well-studied dietary factors, including fat intake, red meat, fish, vitamin D, soy and phytoestrogens are mixed.In practical terms, men concerned with prostate cancer risk should be encouraged to stop smoking, be as physically active as possible, and achieve or maintain a healthy weight. These recommendations also have the advantage of having a positive impact on risk of type 2 diabetes, cardiovascular disease, and other chronic diseases. Reducing dairy intake while increasing consumption of fish and tomato products is also reasonable advice.

The association of weight change in young adulthood and smoking status with risk of prostate cancer recurrence

The decades before prostate cancer diagnosis represent an etiologically relevant time period for prostate cancer carcinogenesis. However, the association of weight gain in young adulthood with subsequent biochemical recurrence among men with prostate cancer is not well studied, particularly among smokers. We conducted a prospective cohort study of 1,082 men with prostate cancer and treated with either radical prostatectomy or radiation between 2003 and 2010. The association of weight at age 20, weight at age 50 and weight change from age 20 to age 50 with biochemical recurrence was assessed using Cox Proportional Hazards with adjustment for confounders. Stratum-specific hazard ratio (HR) estimates by smoking status were evaluated. In the overall cohort, weight at age 20 (HR per 30 kg: 1.56, 95% confidence interval (CI): 1.02, 2.38, p-trend: 0.039), weight at age 50 (HR per 30 kg: 1.80, 95% CI: 1.32, 2.47, p-trend: <0.001) and weight change from age 20 to age 50 (HR per 30 kg: 1.84, 95% CI: 1.24, 2.74, p-trend: 0.003) were associated with biochemical recurrence. In stratified analyses, weight change from age 20 to age 50 was significantly associated with biochemical recurrence only in former smokers (HR per 30 kg: 3.87, 95% CI: 1.88, 8.00, p-trend: <0.001) and ever smokers (HR per 30 kg: 2.38, 95% CI: 1.27, 4.45, p-trend: 0.007). No significant association was observed between weight gain in young adulthood and biochemical recurrence in never smokers. Our study adds further evidence that weight gain during early adult years conveys long-term risk for adverse cancer outcomes.

Weight change, obesity and risk of prostate cancer progression among men with clinically localized prostate cancer

Obesity is associated with an increased risk of fatal prostate cancer. We aimed to elucidate the importance and relevant timing of obesity and weight change for prostate cancer progression. We identified 5,158 men diagnosed with localized prostate cancer (clinical stage T1/T2) from 1986 to 2012 in the Health Professionals Follow-up Study. Men were followed for biochemical recurrence and lethal prostate cancer (development of distant metastasis or prostate cancer-specific mortality) until 2012. Cox regression estimated hazard ratios (HRs) for body mass index (BMI) at age 21, BMI at diagnosis, "long-term" weight change from age 21 to diagnosis and "short-term" weight change over spans of 4 and 8 years preceding diagnosis. Because weight, weight change and mortality are strongly associated with smoking, we repeated analyses among never smokers only (N = 2,559). Among all patients, neither weight change nor BMI (at age 21 or at diagnosis) was associated with lethal prostate cancer. Among never smokers, long-term weight gain was associated with an increased risk of lethal disease (HR for gaining >30 pounds vs. stable weight [±10 pounds] 1.59, 95% CI, 1.01-2.50, p-trend = 0.06). Associations between weight change, BMI and lethal prostate cancer were stronger for men with BMI ≥ 25 at age 21 compared to those with BMI < 25. Weight change and obesity were not associated with an increased risk of biochemical recurrence. Our findings among never smoker men diagnosed with localized prostate cancer suggest a positive association between long-term weight gain and risk of lethal prostate cancer. Metabolic changes associated with weight gain may promote prostate cancer progression.

Obesity and cancer: mechanistic insights from transdisciplinary studies

Obesity is associated with a range of health outcomes that are of clinical and public health significance, including cancer. Herein, we summarize epidemiologic and preclinical evidence for an association between obesity and increased risk of breast and prostate cancer incidence and mortality. Moreover, we describe data from observational studies of weight change in humans and from calorie-restriction studies in mouse models that support a potential role for weight loss in counteracting tumor-promoting properties of obesity in breast and prostate cancers. Given that weight loss is challenging to achieve and maintain, we also consider evidence linking treatments for obesity-associated co-morbidities, including metformin, statins and non-steroidal anti-inflammatory drugs, with reduced breast and prostate cancer incidence and mortality. Finally, we highlight several challenges that should be considered when conducting epidemiologic and preclinical research in the area of obesity and cancer, including the measurement of obesity in population-based studies, the timing of obesity and weight change in relation to tumor latency and cancer diagnosis, and the heterogeneous nature of obesity and its associated co-morbidities. Given that obesity is a complex trait, comprised of behavioral, epidemiologic and molecular/metabolic factors, we argue that a transdisciplinary approach is the key to understanding the mechanisms linking obesity and cancer. As such, this review highlights the critical need to integrate evidence from both epidemiologic and preclinical studies to gain insight into both biologic and non-biologic mechanisms contributing to the obesity-cancer link.

Cigarette smoking is associated with an increased risk of biochemical disease recurrence, metastasis, castration-resistant prostate cancer, and mortality after radical prostatectomy: results from the SEARCH database

BACKGROUND

The current study was conducted to analyze the association between cigarette smoking and metastasis (the primary outcome) as well as time to biochemical disease recurrence (BCR), metastasis, castration-resistant prostate cancer (CRPC), and prostate cancer-specific and overall mortality (secondary outcomes) after radical prostatectomy among men from the Shared Equal Access Regional Cancer Hospital cohort.

METHODS

A retrospective analysis was performed of 1450 subjects for whom smoking status was available from preoperative notes. Analysis of baseline characteristics by smoking status was performed using the chi-square and rank sum tests. The association between smoking status and time to the event was analyzed using Kaplan-Meier plots, the log-rank test, and Cox and competing risk models.

RESULTS

A total of 549 men (33%) men were active smokers and 1121 (67%) were nonsmokers at the time of surgery. Current smokers were younger and had a lower body mass index, higher prostate-specific antigen level, and more extracapsular extension and seminal vesicle invasion (all P<.05). A total of 509 patients, 26 patients, 30 patients, 18 patients, and 217 patients, respectively, experienced BCR, metastasis, CRPC, prostate cancer-related death, and any-cause death over a median follow-up of 62 months, 75 months, 61 months, 78 months, and 78 months, respectively. After adjusting for preoperative features, active smoking was found to be associated with an increased risk of BCR (hazards ratio [HR], 1.25; P=.024), metastasis (HR, 2.64; P=.026), CRPC (HR, 2.62; P=.021), and overall mortality (HR, 2.14; P<.001). Similar results were noted after further adjustment for postoperative features, with the exception of BCR (HR, 1.10; P=.335), metastasis (HR, 2.51; P=.044), CRPC (HR, 2.67; P=.015), and death (HR, 2.03; P<.001).

CONCLUSIONS

Among patients undergoing radical prostatectomy, cigarette smoking was associated with an increased risk of metastasis. In addition, smoking was associated with a higher risk of BCR, CRPC, and overall mortality. If confirmed, these data suggest that smoking is a modifiable risk factor in patients with aggressive prostate cancer.

Predicting bone scan positivity after biochemical recurrence following radical prostatectomy in both hormone-naive men and patients receiving androgen-deprivation therapy: results from the SEARCH database

BACKGROUND

To evaluate the factors associated with positive bone scans after biochemical recurrence (BCR) following radical prostatectomy in both hormone-naive subjects and subjects after androgen-deprivation therapy (ADT).

METHODS

Retrospective analysis of 380 bone scans of 301 hormone-naive subjects and 214 bone scans of 137 subjects after ADT following BCR from the Shared Equal Access Regional Cancer Hospital database. Generalized estimating equations and local regression plots were used to evaluate bone scan positivity by patients' demographics, pathological features, PSA levels and kinetics.

RESULTS

Among hormone-naive subjects and subjects on ADT, bone scan positivity was seen in 24 (6%) and 65 (30%) subjects, respectively. In hormone-naive subjects, the higher prescan PSA, higher PSA velocity (PSAV) and shorter PSA doubling time (PSADT) were significantly associated with positive scans (P=0.008, P<0.001 and P<0.001, respectively). In subjects after ADT, the prescan PSA, PSAV and PSADT were significantly associated with positive scans (P=0.011, P<0.001 and P=0.002, respectively). Regression plots showed increased scan positivity with increasing PSA levels and shortening PSADT (all P<0.001) for both hormone-naive subjects and subjects after ADT. For a given PSA level and PSADT, subjects on ADT had higher bone scan positivity.

CONCLUSIONS

In both hormone-naive subjects and subjects after ADT, more aggressive and advanced disease identified by higher PSA levels, higher PSAV and shorter PSADT were associated with higher bone scan positivity. For the same PSA level and PSADT, subjects after ADT had higher bone scan positivity than hormone-naive subjects. Therefore, PSA levels and kinetics may be used as selection criteria for bone scan in these patients.

Lifestyle and dietary factors in prostate cancer prevention

The etiology of prostate cancer (PCa) is still largely unknown and the only well-established risk factors are those that are non-modifiable (age, race, and family history). Therefore, the identification of lifestyle and dietary factors which might prevent PCa development and progression is of paramount importance from a public health point of view. Accumulating evidence indicates that obesity may have a dual effect on PCa: an increased risk of aggressive PCa and a decreased risk of localized PCa. Both occupational and leisure time physical activity have been observed to be associated with a reduced PCa risk. Different dietary factors including coffee have been examined in several epidemiological studies, but results have been mostly inconsistent. However, these inconsistencies can be, at least partly, explained by the fact that the majority of those studies examined total PCa risk only and, in addition, they did not take into account the different genetic characteristics within the study populations. Therefore, the future epidemiological studies should focus on the analysis of PCa subtypes separately in order to examine possible etiological heterogeneity of PCa in relation to some exposures. In addition, differences in the genetic characteristics of the study participants should be taken into account to explore the possibility of gene-environment interactions.

Metformin does not affect risk of biochemical recurrence following radical prostatectomy: results from the SEARCH database

Background

While epidemiologic studies suggest that metformin use among diabetics may decrease prostate cancer (PC) incidence, the effect of metformin use on PC outcome is unclear. We investigated the association between pre-operative metformin use, dose and duration of use and biochemical recurrence (BCR) in PC patients with diabetes who underwent radical prostatectomy (RP).

Methods

We conducted a retrospective cohort analysis within the Shared Equal Access Regional Cancer Hospital (SEARCH) database of 371 PC patients with diabetes who underwent RP. Time to BCR between metformin users and non-users, and by metformin dose and duration of use was assessed using multivariable Cox proportional analysis adjusted for demographic, clinical and/or pathologic features. Time to castrate-resistant PC (CPRC), metastases and PC-specific mortality were explored as secondary outcomes using unadjusted analyses.

Results

Of 371 diabetic men, 156 (42%) were using metformin prior to RP. Metformin use was associated with more recent year of surgery (p<0.0001) but no clinical or pathologic characteristics. After adjustment for year of surgery, clinical and pathologic features, there were no associations between metformin use (HR 0.93; 95%CI 0.61–1.41), high metformin dose (HR 0.96; 95%CI 0.57–1.61) or duration of use (HR 1.00; 95%CI 0.99–1.02) and time to BCR. A total of 14 patients (3.8%) developed CRPC, 10 (2.7%) distant metastases and 8 (2.2%) died from PC. Unadjusted analysis suggested high metformin dose versus non-use was associated with increased risk of CRPC (HR 5.1; 95%CI 1.6–16.5), metastases (HR 4.8; 95%CI 1.2–18.5) and PC-specific mortality (HR 5.0; 95%CI 1.1–22.5).

Conclusions

Metformin use, dose or duration of use was not associated with BCR in this cohort of diabetic PC patients treated with RP. The suggestion that higher metformin dose was associated with increased risk of CPRC, metastases and PC-specific mortality merits testing in large prospective studies with longer follow-up.

Fish oil slows prostate cancer xenograft growth relative to other dietary fats and is associated with decreased mitochondrial and insulin pathway gene expression

Background

Previous mouse studies suggest that decreasing dietary fat content can slow prostate cancer (PCa) growth. To our knowledge, no study has yet compared the effect of multiple different fats on PCa progression. We sought to systematically compare the effect of fish oil, olive oil, corn oil, and animal fat on PCa progression.

Methods

A total of 96 male SCID mice were injected with LAPC-4 human PCa cells. Two weeks following injection, mice were randomized to a fish oil, olive oil, corn oil, or animal fat-based Western diet (35% kcals from fat). Animals were euthanized when tumors reached 1,000mm³. Serum was collected at sacrifice and assayed for PSA, insulin, IGF-1, IGFBP-3, and PGE-2 levels. Tumors were also assayed for PGE-2 and COX-2 levels and global gene expression analyzed using Affymetrix microarrays.

Results

Mice weights and tumor volumes were equivalent across groups at randomization. Overall, fish oil consumption was associated with improved survival, relative to other dietary groups (p=0.014). On gene expression analyses, the fish oil group had decreased signal in pathways related to mitochondrial physiology and insulin synthesis/secretion.

Conclusions

In this xenograft model, we found that consuming a diet in which fish oil was the only fat source slowed tumor growth and improved survival, compared to mice consuming diets composed of olive oil, corn oil, or animal fat. While prior studies showed that the amount of fat is important for PCa growth, the current study suggests that type of dietary fat consumed may also be important.

Obesity and prostate cancer: weighing the evidence

CONTEXT

Obesity and prostate cancer (PCa) affect substantial proportions of Western society. Mounting evidence, both epidemiologic and mechanistic, for an association between the two is of public health interest. An improved understanding of the role of this modifiable risk factor in PCa etiology is imperative to optimize screening, treatment, and prevention.

OBJECTIVE

To consolidate and evaluate the evidence for an epidemiologic link between obesity and PCa, in addition to examining the proposed underlying molecular mechanisms.

EVIDENCE ACQUISITION

A PubMed search for relevant articles published between 1991 and July 2012 was performed by combining the following terms: obesity, BMI, body mass index and prostate cancer risk, prostate cancer incidence, prostate cancer mortality, radical prostatectomy, androgen-deprivation therapy, external-beam radiation, brachytherapy, prostate cancer and quality of life, prostate cancer and active surveillance, in addition to obesity, BMI, body mass index and prostate cancer and insulin, insulin-like growth factor, androgen, estradiol, leptin, adiponectin, and IL-6. Articles were selected based on content, date of publication, and relevancy, and their references were also searched for relevant articles.

EVIDENCE SYNTHESIS

Increasing evidence suggests obesity is associated with elevated incidence of aggressive PCa, increased risk of biochemical failure following radical prostatectomy and external-beam radiotherapy, higher frequency of complications following androgen-deprivation therapy, and increased PCa-specific mortality, although perhaps a lower overall PCa incidence. These results may in part relate to difficulties in detecting and treating obese men. However, multiple molecular mechanisms could explain these associations as well. Weight loss slows PCa in animal models but has yet to be fully tested in human trials.

CONCLUSIONS

Obesity appears to be linked with aggressive PCa. We suggest clinical tips to better diagnose and treat obese men with PCa. Whether reversing obesity slows PCa growth is currently unknown, although it is an active area of research.