Pathologic variables and recurrence rates as related to obesity and race in men with prostate cancer undergoing radical prostatectomy

Effects of dietary fat on spontaneous metastasis of Lewis lung carcinoma in mice

The present study assessed the effects of dietary fat on spontaneous metastasis of Lewis lung carcinoma in mice. Three-week old male C57BL/6 mice were fed the AIN-93G diet or a 45% fat diet (% kcal.) for 7 weeks before they were subcutaneously injected with 2.5 × 10⁵ viable carcinoma cells. The primary tumor was resected 2 weeks later, and mice were maintained on their respective diets for an additional 2 weeks. The high-fat diet significantly increased body weight and abdominal adipose weight compared to the AIN-93G diet. Feeding mice the 45% fat diet resulted in a two-fold increase in the number of lung metastases (P < 0.05), a 35% increase in tumor cross-sectional area, and a 50% increase in tumor volume compared to mice fed the AIN-93G diet. There were no differences in plasma concentrations of TIMP-1, IL-1β, VEGF and MCP-1 in non-tumor-bearing mice fed the AIN-93G diet or the high-fat diet, but significant increases in these cytokines in tumor-bearing mice fed the AIN-93G diet compared to the non-tumor-bearing mice fed the same diet (P < 0.05 for each comparison). Further significant increases in these cytokines in tumor-bearing mice fed the 45% fat diet compared to the same tumor-bearing mice fed the AIN-93G diet (P < 0.05 for each comparison). The high-fat diet significantly increased plasma leptin and significantly decreased plasma adiponectin compared to the AIN-93G diet in both non-tumor-bearing and tumor-bearing mice. Results of the present study demonstrated that the high-fat diet enhanced spontaneous metastasis of Lewis lung carcinoma in mice and that this aggressiveness was accompanied with significant increases in plasma concentrations of angiogenic cytokines, suggesting that dietary fat affects metastasis by promoting angiogenic processes.

Racial variation in the pattern and quality of care for prostate cancer in the USA: mind the gap

OBJECTIVE

To review the literature on racial variation in the pattern of care (PoC) and quality of care (QoC) for prostate cancer, as there are known racial disparities in the incidence and outcomes of prostate cancer. While there are some biological explanations for these differences, they do not completely explain the variation. Differences in the appropriateness and QoC delivered to men of different racial groups may contribute to disparities in outcome.

METHODS

We searched the USA National Library of Medicine PubMed system for articles pertaining to quality indicators in prostate cancer and racial disparities in QoC for prostate cancer.

RESULTS

While standards for appropriate treatment are not clearly defined, racial variation in the PoC has been reported in several studies, suggesting that African-American men may receive less aggressive treatment. There are validated QoC indicators in prostate cancer, and researchers have begun to evaluate racial variation in adherence to these quality indicators. Further quality comparisons, particularly in structural measures, may need to be performed to fully evaluate differences in QoC.

CONCLUSIONS

There is mounting evidence for racial variation in the PoC and QoC for prostate cancer, which may contribute to observed differences in outcome. While some of the sources of racial variation in quality and outcome have been identified through the development of evidence-based guidelines and validated quality indicators, opportunities exist to identify, study and attempt to resolve other components of the quality gap.

Copy number and gene expression differences between African American and Caucasian American prostate cancer

Background

The goal of our study was to investigate the molecular underpinnings associated with the relatively aggressive clinical behavior of prostate cancer (PCa) in African American (AA) compared to Caucasian American (CA) patients using a genome-wide approach.

Methods

AA and CA patients treated with radical prostatectomy (RP) were frequency matched for age at RP, Gleason grade, and tumor stage. Array-CGH (BAC SpectralChip2600) was used to identify genomic regions with significantly different DNA copy number between the groups. Gene expression profiling of the same set of tumors was also evaluated using Affymetrix HG-U133 Plus 2.0 arrays. Concordance between copy number alteration and gene expression was examined. A second aCGH analysis was performed in a larger validation cohort using an oligo-based platform (Agilent 244K).

Results

BAC-based array identified 27 chromosomal regions with significantly different copy number changes between the AA and CA tumors in the first cohort (Fisher's exact test, P < 0.05). Copy number alterations in these 27 regions were also significantly associated with gene expression changes. aCGH performed in a larger, independent cohort of AA and CA tumors validated 4 of the 27 (15%) most significantly altered regions from the initial analysis (3q26, 5p15-p14, 14q32, and 16p11). Functional annotation of overlapping genes within the 4 validated regions of AA/CA DNA copy number changes revealed significant enrichment of genes related to immune response.

Conclusions

Our data reveal molecular alterations at the level of gene expression and DNA copy number that are specific to African American and Caucasian prostate cancer and may be related to underlying differences in immune response.

Energetics in colorectal and prostate cancer

For decades, extensive research has explored the association between factors related to energy balance and the development of both colorectal cancer and prostate cancer. Physical inactivity, obesity, higher red meat consumption or Western pattern diet, insulin and insulin-like growth factors (IGFs) appear to increase the risk of colorectal cancer while obesity, high animal fat intake, insulin and IGFs have been associated with increasing prostate cancer risk and/or aggressiveness. Recently, there are growing observational data on the relationship between energetic host factors and progression of these cancers. While there are no large randomized trials in either colorectal cancer or prostate cancer assessing these factors on disease progression or disease-related mortality, the data supporting associations between some of these factors and colorectal or prostate cancer survivorship are getting more compelling. This article will evaluate the emerging data on energy balance in patients with colorectal or prostate cancer.

Biological mechanisms linking obesity and cancer risk: new perspectives

Body mass index, as an approximation of body adiposity, is associated with increased risk of several common and less common malignancies in a sex- and site-specific manner. These findings implicate sex- and cancer site-specific biological mechanisms underpinning these associations, and it is unlikely that there is a "one system fits all" mechanism. Three main candidate systems have been proposed-insulin and the insulin-like growth factor-I axis, sex steroids, and adipokines-but there are shortfalls to these hypotheses. In this review, three novel candidate mechanisms are proposed: obesity-induced hypoxia, shared genetic susceptibility, and migrating adipose stromal cells. While public health policies aimed at curbing the underlying causes of the obesity epidemic are being implemented, there is a parallel need to better understand the biological processes linking obesity and cancer as a prerequisite to the development of new approaches to prevention and treatment.

Evidence supports a faster growth rate and/or earlier transformation to clinically significant prostate cancer in black than in white American men, and influences racial progression and mortality disparity

PURPOSE

The incidence of prostate cancer is approximately 60% higher and the mortality rate is 2 to 3 times greater in black than in white American men. We propose that a more rapid prostate cancer growth rate and/or earlier transformation from latent to aggressive prostate cancer in black than in white men contribute to this disparity.

MATERIALS AND METHODS

We evaluated entirely embedded prostate glands on autopsy from 1,056 black and white men who died of causes other than prostate cancer. We also reviewed data from our radical prostatectomy database and from the Detroit Surveillance, Epidemiology and End Results database.

RESULTS

Autopsy data indicated that subclinical prostate cancer in black and white men starts at early age and clinical characteristics do not differ by race at early ages. Radical prostatectomy specimen data revealed that prostate cancer volume and Gleason grade were greater in black than in white men. Advanced or metastatic prostate cancer occurred at a 4:1 ratio in black and white men, respectively, in the Detroit Surveillance, Epidemiology and End Results registry database.

CONCLUSIONS

Results showed that age at prostate cancer initiation and clinical characteristics did not differ by race in our autopsy series, prostate cancer volume after radical prostatectomy was greater in black than in white men and disease became distant disease at a ratio of 4 black men to 1 white man in the Detroit Surveillance, Epidemiology and End Results population. These findings support the concept that prostate cancer grows more rapidly in black than in white men and/or earlier transformation from latent to aggressive prostate cancer occurs in black than in white men.

Diabetes and outcomes after radical prostatectomy: are results affected by obesity and race? Results from the shared equal-access regional cancer hospital database

BACKGROUND

Diabetes is associated with lower prostate cancer risk. The association of diabetes with prostate cancer outcomes is less clear. We examined the association between diabetes and outcomes after radical prostatectomy and tested whether associations varied by race and/or obesity.

MATERIALS AND METHODS

This study is a retrospective analysis of 1,262 men treated with radical prostatectomy between 1988 and 2008 within the Shared Equal-Access Regional Cancer Hospital database. We examined the multivariate association between diabetes at surgery and adverse pathology, biochemical recurrence (BCR), and prostate-specific antigen doubling time at recurrence using logistic, proportional hazards, and linear regression, respectively. Data were examined as a whole and stratified by race and obesity.

RESULTS

Diabetes was more prevalent among black (22% versus 15%, P < 0.001) and more obese men (P < 0.001). Diabetes was associated with higher tumor grade (odds ratio, 1.73; P = 0.002), seminal vesicle invasion (odds ratio, 1.73; P = 0.04), but not BCR (P = 0.67) or PSADT at recurrence (P = 0.12). In the secondary analysis, among white obese men, diabetes was associated with 2.5-fold increased BCR risk (P = 0.002) and a trend toward shorter PSADT, whereas among all other men (nonobese white men and black men), diabetes was associated with 23% lower recurrence risk (P = 0.09) and longer PSADT (P = 0.04).

CONCLUSION

In a radical prostatectomy cohort, diabetes was not associated with BCR. In the secondary analysis, diabetes was associated with more aggressive disease in obese white men and less aggressive disease for all other subsets. If externally validated, these findings suggest that among men with prostate cancer, the association between diabetes and prostate cancer aggressiveness may vary by race and obesity.

Obesity as a predictor of adverse outcome across black and white race: results from the Shared Equal Access Regional Cancer Hospital (SEARCH) Database

BACKGROUND

Across multiple studies, obesity has been associated with an increased risk of higher grade disease and prostate-specific antigen (PSA) recurrence after radical prostatectomy (RP). Whether these associations vary by race is unknown. In the current study, the authors examined the association between obesity and outcome after RP stratified by race.

METHODS

A retrospective analysis was performed on 1415 men in the Shared Equal Access Regional Cancer Hospital (SEARCH) database who underwent RP between 1989 and 2008. The association between increased body mass index (BMI) and adverse pathology and biochemical recurrence was examined using multivariate logistic regression and Cox models, respectively. Data were examined stratified by race.

RESULTS

After adjusting for preoperative clinical characteristics, higher BMI was associated with higher tumor grade (P = .008) and positive surgical margins (P < .001) in white men, and similar but statistically nonsignificant trends were observed in black men. No significant interaction was noted between race and BMI for associations with adverse pathology (P(interaction)> or =.12). After adjusting for preoperative clinical characteristics, higher BMI was associated with an increased risk of recurrence in both white men (P = .001) and black men (P = .03). After further adjusting for pathologic variables, higher BMI was associated with significantly increased risk of recurrence in white men (P = .002) and black men (P = .01). No significant interactions were observed between race and BMI for predicting biochemical progression adjusting either for preoperative factors (P(interaction) = .35) or for preoperative and pathologic features (P(interaction) = .47).

CONCLUSIONS

Obesity was associated with a greater risk of recurrence among both black men and white men. Obesity did not appear to be more or less influential in 1 race than another but, rather, was identified as a risk factor for aggressive cancer regardless of race.

Prostate cancer-specific mortality after radical prostatectomy for patients treated in the prostate-specific antigen era

PURPOSE

The long-term risk of prostate cancer-specific mortality (PCSM) after radical prostatectomy is poorly defined for patients treated in the era of widespread prostate-specific antigen (PSA) screening. Models that predict the risk of PCSM are needed for patient counseling and clinical trial design.

METHODS

A multi-institutional cohort of 12,677 patients treated with radical prostatectomy between 1987 and 2005 was analyzed for the risk of PCSM. Patient clinical information and treatment outcome was modeled using Fine and Gray competing risk regression analysis to predict PCSM.

RESULTS

Fifteen-year PCSM and all-cause mortality were 12% and 38%, respectively. The estimated PCSM ranged from 5% to 38% for patients in the lowest and highest quartiles of predicted risk of PSA-defined recurrence, based on a popular nomogram. Biopsy Gleason grade, PSA, and year of surgery were associated with PCSM. A nomogram predicting the 15-year risk of PCSM was developed, and the externally validated concordance index was 0.82. Neither preoperative PSA velocity nor body mass index improved the model's accuracy. Only 4% of contemporary patients had a predicted 15-year PCSM of greater than 5%.

CONCLUSION

Few patients will die from prostate cancer within 15 years of radical prostatectomy, despite the presence of adverse clinical features. This favorable prognosis may be related to the effectiveness of radical prostatectomy (with or without secondary therapy) or the low lethality of screen-detected cancers. Given the limited ability to identify contemporary patients at substantially elevated risk of PCSM on the basis of clinical features alone, the need for novel markers specifically associated with the biology of lethal prostate cancer is evident.

Obese men have higher-grade and larger tumors: an analysis of the duke prostate center database

Obesity is associated with increased risk of positive surgical margins and prostate specific antigen (PSA) recurrence among men undergoing radical prostatectomy. To what degree positive margins contribute to poorer outcome is unclear. Thus, we sought to examine the association between body mass index (BMI) and more objective measures of tumor aggressiveness, tumor grade and size. We carried out a retrospective analysis of 2302 patients treated with radical prostatectomy at the Duke Prostate Center from 1988-2007. Tumor volume was calculated by multiplying prostate weight by percent of specimen involved with cancer. Associations between BMI and tumor volume and high-grade disease (Gleason >or=4+3) independent of pre-operative clinical characteristics of age, race, PSA, clinical stage, biopsy Gleason sum, and year of surgery were assessed using linear and logistic regression, respectively. Mean and median BMI among all subjects was 28.1 and 27.6 kg m(-2), respectively. Increased BMI was significantly associated with younger age (P<0.001), black race (P<0.001), more recent year of surgery (P<0.001), and positive surgical margins (P<0.001). After adjusting for multiple clinical pre-operative characteristics, higher BMI was associated with a greater percent of the prostate involved with cancer (P=0.003), increased tumor volume (P<0.001), and high-grade disease (P=0.007). Men with a BMI >or=35 kg m(2) had nearly 40% larger mean tumor volumes than normal weight men (5.1 versus 3.7 cc), after adjustment for multiple clinical characteristics. In this study, obese men undergoing radical prostatectomy had higher-grade and larger tumors, providing further evidence that obese men undergoing radical prostatectomy have more aggressive prostate cancers.

Evaluation of the 8q24 prostate cancer risk locus and MYC expression

Polymorphisms at 8q24 are robustly associated with prostate cancer risk. The risk variants are located in nonprotein coding regions and their mechanism has not been fully elucidated. To further dissect the function of this locus, we tested two hypotheses: (a) unannotated microRNAs (miRNA) are transcribed in the region, and (b) this region is a cis-acting enhancer. Using next generation sequencing, 8q24 risk regions were interrogated for known and novel miRNAs in histologically normal radical prostatectomy tissue. We also evaluated the association between the risk variants and transcript levels of multiple genes, focusing on the proto-oncogene, MYC. RNA expression was measured in histologically normal and tumor tissue from 280 prostatectomy specimens (from 234 European American and 46 African American patients), and paired germline DNA from each individual was genotyped for six 8q24 risk single nucleotide polymorphisms. No evidence was found for significant miRNA transcription within 8q24 prostate cancer risk loci. Likewise, no convincing association between RNA expression and risk allele status was detected in either histologically normal or tumor tissue. To our knowledge, this is one of the first and largest studies to directly assess miRNA in this region and to systematically measure MYC expression levels in prostate tissue in relation to inherited risk variants. These data will help to direct the future study of this risk locus.

The effect of obesity and lower serum prostate-specific antigen levels on prostate-cancer screening results in American men

OBJECTIVE

To determine if lower serum total prostate specific antigen (PSA) levels in obese American men affect prostate-cancer screening results, as an increased body mass index (BMI) is inversely associated with PSA level, but the effect of this association on PSA screening results for prostate cancer is unknown.

SUBJECTS AND METHODS

We analysed the most recent National Health and Nutrition Examination Surveys (NHANES 2001-2002, 2003-2004, and 2005-2006), a nationally representative cross-sectional sample of non-institutionalized adults aged > or =20 years. Logistic regression was used to estimate the odds of an 'abnormal' PSA level (4.0 or 2.5 ng/mL) based on BMI categories of normal (18.5-24.9 kg/m(2)), overweight (25-29.9) and obese (30-39.9) in men who were eligible for prostate-cancer screening with serum total PSA tests (age 40-75 years, BMI 18.5-39.9 kg/m(2), PSA <20 ng/mL).

RESULTS

In all, 3152 participants with no known prostate cancer, representing 46 million American men, were eligible for prostate-cancer screening. After controlling for age and race, there was a statistically significant trend of a lower likelihood of having a serum total PSA level of > or =4.0 ng/mL with increased BMI. When men were stratified by race, this effect was apparent only in white non-Hispanic men, with obese men in this group having a 46% lower likelihood of having an 'abnormal' PSA level (odds ratio 0.54, 95% confidence interval 0.31-0.91; P = 0.024) than those with a normal BMI. There was no observable trend in either African-American or Hispanic men. In addition, there was no observable trend with a serum total PSA threshold of 2.5 ng/mL, regardless of race.

CONCLUSIONS

Obese white non-Hispanic men are about half as likely as those with a normal BMI to have a PSA level of > or =4.0 ng/mL. These results might affect prostate-cancer screening with serum total PSA. Further studies are needed to better define the association of BMI and PSA in racial minority subgroups.

Body mass index is not a prognostic marker for prostate-specific antigen failure and survival in Dutch men treated with brachytherapy

OBJECTIVE

To examine the relationship between body mass index (BMI) and biochemical recurrence (BCR), cancer-specific (CSS) and overall survival (OS) in men treated with permanent prostate brachytherapy (PPB), as there is limited information on the affect of obesity on treatment outcomes for prostate cancer.

PATIENTS AND METHODS

In all, 1530 patients with clinically localized prostate cancer who underwent PPB were studied. Clinical and pathological data were retrospectively obtained from medical records. The BMI was classified as normal (< 25 kg/m(2)), overweight (25-30 kg/m(2)) and obese (> or = 30 kg/m(2)). BCR was defined as a rise in PSA levels of > or = 2 ng/mL after the nadir had been reached. The cause of death was determined for each deceased patient. Patients with metastatic prostate cancer who died of any cause were classified as prostate cancer deaths. RESULTS In all, 617 (40%) patients were classified as having a normal weight, 754 (49%) overweight and 159 (10%) were obese. The Kaplan-Meier 8-year risk of BCR (95% confidence interval) was 33.3% (27.2-39.4), 29.2% (23.5-34.9) and 29.3% (12.4-46.2) for patients with a BMI of < 25 kg/m(2), 25-30 kg/m(2) and > or = 30 kg/m(2), respectively. The 8-year CSS was 88.2% (83.1-93.3), 88.6% (83.7-93.5) and 90.6% (79.9-101.4) and the 8-year OS was 70.1% (63.6-76.6), 72.9% (66.6-79.2) and 81.8% (69.3-94.3) for these three groups, respectively. Multivariate proportional hazard regression analyses of BMI and established prognostic factors for BCR confirmed the absence of any prognostic value of BMI on BCR, CSS and OS.

CONCLUSIONS

BMI did not appear to have any prognostic value for BCR, CCS or OS in patients with clinically localized prostate cancer treated with PPB.

Expression of androgen and estrogen related proteins in normal weight and obese prostate cancer patients

BACKGROUND

Obesity is associated with an aggressive form of prostate cancer and with alterations in androgen and estrogen metabolism. We hypothesized that changes in components of the sex steroid receptor axis may contribute to the clinical aggressiveness of prostate cancer in obese patients.

METHODS

A database was assembled containing clinical and pathological variables from 539 patients treated with radical prostatectomy at a single urban hospital between 1994 and 2002. Tissue microarrays were constructed from representative patients and expression of androgen receptor (AR), PSA, estrogen receptor alpha (ERalpha), estrogen receptor beta (ERbeta), and aromatase was examined.

RESULTS

Higher BMI correlated strongly with black race, the presence of extra-capsular extension, and higher pathologic stage. Expression of AR, PSA, ERbeta and aromatase in cancerous epithelial cells did not differ according to obesity status. However, decreased expression of ERalpha and aromatase was observed in the stromal compartment surrounding non-cancerous acini in obese patients.

CONCLUSION

We confirm the previously reported associations between obesity and aggressive clinical and pathologic features in our single-institution, urban teaching hospital. In comparing obese versus non-obese patients, there was no difference in expression of androgen or estrogen related proteins in cancerous epithelial cells. However, there was a down-regulation of ERalpha and aromatase in the stroma of obese patients. Our data suggest obesity may cause stromal changes in the sex steroid production and signaling pathways which may affect prostate cancer growth via intracrine/paracrine mechanisms.

Race and time from diagnosis to radical prostatectomy: does equal access mean equal timely access to the operating room?--Results from the SEARCH database

BACKGROUND

African American men with prostate cancer are at higher risk for cancer-specific death than Caucasian men. We determine whether significant delays in management contribute to this disparity. We hypothesize that in an equal-access health care system, time interval from diagnosis to treatment would not differ by race.

METHODS

We identified 1,532 African American and Caucasian men who underwent radical prostatectomy (RP) from 1988 to 2007 at one of four Veterans Affairs Medical Centers that comprise the Shared Equal-Access Regional Cancer Hospital (SEARCH) database with known biopsy date. We compared time from biopsy to RP between racial groups using linear regression adjusting for demographic and clinical variables. We analyzed risk of potential clinically relevant delays by determining odds of delays >90 and >180 days.

RESULTS

Median time interval from diagnosis to RP was 76 and 68 days for African Americans and Caucasian men, respectively (P = 0.004). After controlling for demographic and clinical variables, race was not associated with the time interval between diagnosis and RP (P = 0.09). Furthermore, race was not associated with increased risk of delays >90 (P = 0.45) or >180 days (P = 0.31).

CONCLUSIONS

In a cohort of men undergoing RP in an equal-access setting, there was no significant difference between racial groups with regard to time interval from diagnosis to RP. Thus, equal-access includes equal timely access to the operating room. Given our previous finding of poorer outcomes among African Americans, treatment delays do not seem to explain these observations. Our findings need to be confirmed in patients electing other treatment modalities and in other practice settings.

Body mass index as a prognostic marker for biochemical recurrence in Dutch men treated with radical prostatectomy

OBJECTIVE

To investigate whether body mass index (BMI) is a prognostic factor for biochemical recurrence (BCR) in Dutch men after radical prostatectomy (RP), as although epidemiological studies of obesity in relation to prostate cancer have provided conflicting results, recent studies from the USA suggest that a higher BMI is a risk factor for progression of prostate cancer.

PATIENTS AND METHODS

Of the 1417 patients with prostate cancer who had RP at two University hospitals, 1302 were included in the present study. BMI (kg/m(2)) classes were defined as normal (<25), overweight (25-30) and obese (> or =30). The median follow-up was 59 months and clinical data were obtained retrospectively from charts. BCR was defined as two consecutive prostate-specific antigen (PSA) levels of >0.1 ng/mL.

RESULTS

In all, 600 patients were classified as having normal weight (43.9%), 665 as overweight (48.6%) and 103 as obese (7.5%). Overall, 297 patients developed BCR after RP; the 10-year risk (95% confidence interval) of BCR was 31.9 (26.6-37.2)%, 30.5 (25.8-35.2)% and 23.9 (14.9-32.9)% for patients in the three categories, respectively (P = 0.836). Multivariable proportional hazard regression analyses of BMI and established prognostic factors for BCR did not change these results.

CONCLUSION

BMI appeared to have no prognostic value for BCR in Dutch patients with clinically localized prostate cancer and treated with RP.

Epidemiology, pathology, and genetics of prostate cancer among African Americans compared with other ethnicities

Prostate cancer is the most common cancer affecting men in the Western world. In the United States, it is the second leading cause of cancer related deaths after lung and bronchus carcinoma. No definitive causes of prostate cancer (PCa) have been identified to date but, increasing age, a positive family history, and sub-Saharan African ancestry are strongly linked to its development. African American men (AAM) have the highest reported incidence rates in the United States and their mortality from the disease is markedly higher than that of European American men (EAM). Conversely, Asian American men and Pacific Islanders (API), American Indian and Alaskan Native (AI/AN) men, and Hispanic men all have lower incidence and mortality rates as compared with EAM. The reasons for these differences are unclear. However, it is clear that AAM have more advanced PCa when diagnosed. Several other reasons have been suggested and these include differences in treatments and health seeking behavior among the ethnic groups, cultural beliefs, environmental/lifestyle factors, dietary and genetic factors. In conclusion, there are multiple factors that impact prostate cancer outcome and that may be responsible for ethnic disparity. These factors are discussed in this chapter.

Potential for higher treatment failure in obese patients: correlation of elevated body mass index and increased daily prostate deviations from the radiation beam isocenters in an analysis of 1,465 computed tomographic images

PURPOSE

Recent clinical outcome studies on prostate cancer have reported the influence of patient's obesity on the biochemical failure rates after various treatment modalities. In this study, we investigated the effect of patient's physical characteristics on prostate shift in external beam radiotherapy (EBRT) and hypothesized that there maybe a correlation between patient physique and tumor shift.

METHODS AND MATERIALS

A retrospective analysis was performed using data for 117 patients who received image-guided radiation therapy (IGRT) for prostate cancer between January 2005 and April 2007. A total of 1,465 CT scans were analyzed. The standard deviations (SDs) of prostate shifts for all patients, along with patient weight, body mass index (BMI), and subcutaneous adipose-tissue thickness (SAT), were determined. Spearman rank correlation analysis was performed.

RESULTS

Of the 117 patients, 26.5% were considered normal weight, 48.7% were overweight, 17.9% were mildly obese, and 6.9% were moderately to severely obese. Notably 1.3%, 1.5%, 2.0%, and 21.2% of the respective shifts were greater than 10 mm in the left-right (LR) direction for the four patient groups, whereas in the anterior-posterior direction the shifts are 18.2%, 12.6%, 6.7%, and 21.0%, respectively. Strong correlations were observed between SAT, BMI, patient weight, and SDs of daily shifts in the LR direction (p < 0.01).

CONCLUSIONS

The strong correlation between obesity and shift indicates that without image-guided radiation therapy, the target volume (prostate with or without seminal vesicles) may not receive the intended dose for patients who are moderate to severely obese. This may explain the higher recurrence rate with conventional external beam radiation therapy.

The effect of obesity on survival in patients with ovarian cancer

OBJECTIVE

Data has suggested obesity as an independent prognostic factor for lower survival in patients with epithelial ovarian cancer (EOC). We sought to determine if obesity portends a disadvantage to surgical outcomes at the time of initial surgery affecting survival.

METHODS

A retrospective chart review of patients diagnosed with EOC was performed. All patients underwent primary cytoreductive surgery followed by taxane/platinum-based chemotherapy. Patient demographics, surgicopathologic and survival data were evaluated. Patients were compared based on body mass index (BMI) (<30 vs. > or =30) and BMI strata (underweight, normal weight, overweight, obese and morbidly obese). Survival analyses were performed with the Kaplan Meier method and compared using the log rank test, chi(2) test, and Fischer's exact test.

RESULTS

304 patients were identified. 71 patients (23%) were obese (BMI>30). The groups were similar in regard to stage, grade, histology, and chemotherapy administered. In regard to surgical outcomes, no difference was seen in estimated blood loss (EBL), operating room (OR) time, or operative complications excluding wound complications. Optimal debulking rates were similar in obese and non-obese patients (52% vs. 51% respectively, p=0.88). There was no statistical difference in progression free survival (17 vs. 11 months) or overall survival (48 vs. 40 months) between the two groups or across BMI strata.

CONCLUSION

Although obesity has been reported as an independent prognostic factor for survival, this data demonstrates that survival rates are similar between obese and non-obese patients when optimal debulking statuses are the same. Therefore, maximal effort should be directed towards optimal debulking obese patients with EOC.

Obesity is a significant risk factor for prostate cancer at the time of biopsy

OBJECTIVES

Studies suggest obesity is associated with decreased prostate cancer risk. We hypothesized obesity is biologically associated with increased risk, although this is obscured owing to hemodilution of prostate-specific antigen (PSA) and larger prostate size.

METHODS

We retrospectively studied 441 consecutive men undergoing prostate biopsy between 1999 and 2003 at two equal access centers within the Veterans Affairs Greater Los Angeles Healthcare System. We estimated the association between obesity (body mass index >or= 30 kg/m(2)) and positive biopsy and Gleason >or=4+3 using logistic regression analysis adjusting for multiple clinical characteristics.

RESULTS

A total of 123 men (28%) were obese and 149 men (34%) had cancer. Median PSA and age were 5.7 ng/mL and 63.9 years, respectively. Obese men had significantly lower PSA concentrations (P = .02) and larger prostate volumes (P = .04). Obesity was not significantly related to age (P = .19) or race (P = .37). On univariate analysis, obesity was not associated with prostate cancer risk (odds ratio [OR] 1.13, 95% confidence interval [CI] 0.73-1.75, P = .58). However, after adjusting for multiple clinical characteristics, obesity was associated with significantly increased prostate cancer risk (OR 1.98, 95% CI 1.17-3.32, P = .01). After multivariable adjustment, there was no significant association between obesity and high-grade disease (P = .18).

CONCLUSIONS

Without adjustment for clinical characteristics, obesity was not significantly associated with prostate cancer risk in this equal-access, clinic-based population. However, after adjusting for the lower PSA levels and the larger prostate size, obesity was associated with a 98% increased prostate cancer risk. These findings support the fact that current prostate cancer screening practices may be biased against obese men.

Prediagnostic body-mass index, plasma C-peptide concentration, and prostate cancer-specific mortality in men with prostate cancer: a long-term survival analysis

BACKGROUND

Excess body-mass index (BMI) has been associated with adverse outcomes in prostate cancer, and hyperinsulinaemia is a candidate mediator, but prospective data are sparse. We assessed the effect of prediagnostic BMI and plasma C-peptide concentration (reflecting insulin secretion) on prostate cancer-specific mortality after diagnosis.

METHODS

This study involved men diagnosed with prostate cancer during the 24 years of follow-up in the Physicians' Health Study. BMI measurements were available at baseline in 1982 and eight years later in 1990 for 2546 men who developed prostate cancer. Baseline C-peptide concentration was available in 827 men. We used Cox proportional hazards regression models controlling for age, smoking, time between BMI measurement and prostate cancer diagnosis, and competing causes of death to assess the risk of prostate cancer-specific mortality according to BMI and C-peptide concentration.

FINDINGS

Of the 2546 men diagnosed with prostate cancer during the follow-up period, 989 (38.8%) were overweight (BMI 25.0-29.9 kg/m(2)) and 87 (3.4%) were obese (BMI >/=30 kg/m(2)). 281 men (11%) died from prostate cancer during this follow-up period. Compared with men of a healthy weight (BMI <25 kg/m(2)) at baseline, overweight men and obese men had a significantly higher risk of prostate cancer mortality (proportional hazard ratio [HR] 1.47 [95% CI 1.16-1.88] for overweight men and 2.66 [1.62-4.39] for obese men; p(trend)<0.0001). The trend remained significant after controlling for clinical stage and Gleason grade and was stronger for prostate cancer diagnosed during the PSA screening era (1991-2007) compared with during the pre-PSA screening era (1982-1990) or when using BMI measurements obtained in 1990 compared with those obtained in 1982. Of the 827 men with data available for baseline C-peptide concentration, 117 (14%) died from prostate cancer. Men with C-peptide concentrations in the highest quartile (high) versus the lowest quartile (low) had a higher risk of prostate cancer mortality (HR 2.38 [95% CI 1.31-4.30]; p(trend)=0.008). Compared with men with a BMI less than 25 kg/m(2) and low C-peptide concentrations, those with a BMI of 25 kg/m(2) or more and high C-peptide concentrations had a four-times higher risk of mortality (4.12 [1.97-8.61]; p(interaction)=0.001) independent of clinical predictors.

INTERPRETATION

Excess bodyweight and a high plasma concentration of C-peptide both predispose men with a subsequent diagnosis of prostate cancer to an increased likelihood of dying of their disease. Patients with both factors have the worst outcome. Further studies are now needed to confirm these findings.

Impact of obesity on clinicopathologic outcomes after robot-assisted laparoscopic prostatectomy

PURPOSE

To investigate the impact of body mass index (BMI) on pathologic and functional outcomes after robot-assisted laparoscopic prostatectomy (RALP).

PATIENTS AND METHODS

We evaluated 400 consecutive patients who underwent RALP at the Mayo Clinic between 2002 and 2006. Patients were categorized as normal weight (BMI <25 kg/ m(2), n = 94), overweight (BMI 25-29.9 kg/m(2), n = 187), and obese (BMI >or=30 kg/m(2), n = 119). Clinicopathologic features of the groups were compared, and logistical regression analysis was used to assess the associations of BMI with pathologic and functional outcomes after RALP.

RESULTS

Overweight and obese patients were more likely to have pT(3/4) disease (P = 0.0024) and pathologic Gleason 7 to 10 cancers (P < 0.0001). Overall, 9/94 (9.6%) normal-weight patients had a positive surgical margin (SM), compared with 25/187 (13.4%) overweight patients and 21/119 (17.6%) obese men (P = 0.087). On multivariate analysis, however, increasing BMI was not significantly associated with an increased risk of positive SM (odds ratio 1.12, 95% confidence interval 0.72-1.76, P = 0.61). In addition, although obese men had longer operative times (P = 0.049) and greater intraoperative blood loss (P = 0.04), we found no association between BMI and transfusion requirement (P = 0.34), length of hospital stay (P = 0.54), or the rates of early (P = 0.37) or late (P = 0.86) complications. Moreover, in those patients with follow-up available at 1 year after RALP, obesity did not impact the return of continence (P = 0.62) or potency (P = 0.13).

CONCLUSION

BMI was not an independent predictor of positive SM, complications, incontinence, or erectile dysfunction after RALP. These data suggest that RALP may offer equivalent margin rates and functional outcomes for patients across BMI.

Robotic radical prostatectomy in overweight and obese patients: oncological and validated-functional outcomes

OBJECTIVES

To determine the impact of body mass index (BMI) on perioperative functional and oncological outcomes in patients undergoing robotic laparoscopic radical prostatectomy (RLRP) when stratified by BMI.

METHODS

Data were collected prospectively for 945 consecutive patients undergoing RLRP. Patients were evaluated with the UCLA-PCI-SF36v2 validated-quality-of-life questionnaire preoperatively and postoperatively to 24 months. Patients were stratified by BMI as normal weight (BMI < 25 kg/m(2)), overweight (BMI = 25 to < 30 kg/m(2)) and obese (BMI > or = 30 kg/m(2)) for outcomes analysis.

RESULTS

Preoperatively, obese men had a significantly greater percentage of medical comorbidities (P < .01) as well as a baseline erectile dysfunction (lower mean baseline Sexual Health Inventory for Men score [P = .01] and UCLA-PCI-SF36v2 sexual function domain scores [P = .01]). Mean operative time was significantly longer in obese patients when compared with normal and overweight men (234 minutes vs 217 minutes vs 214 minutes; P = .0003). Although overall complication rates were comparable between groups, a greater incidence of case abortion caused by pneumoperitoneal pressure with excessive airway pressures was noted in obese men. Urinary continence and potency outcomes were significantly lower for obese men at both 12 and 24 months (all P < .05).

CONCLUSIONS

In this series, obese men experienced a longer operative time, particularly during the initial robotic experience. As such, surgeons early in their RLRP learning curve should proceed cautiously with surgery in these technically more difficult patients or reserve such cases until the learning curve has been surmounted. These details, including inferior urinary and sexual outcomes, should be discussed with obese patients during preoperative counseling.

Is the body mass index a predictor of adverse outcome in prostate cancer after radical prostatectomy in a mid-European study population?

OBJECTIVES

To evaluate the effect of body mass index (BMI) on the histopathological and clinical outcome in prostate cancer.

PATIENTS AND METHODS

In a prospective urological cancer database, 620 patients with prostate cancer had a radical prostatectomy (RP) as a curative treatment. The patients were categorized into three groups of BMI (kg/m(2)); <or=25.0 (190, 'normal weight'), >25.0-30.0 (343, 'overweight') and >30.0 (87, 'obese'). We evaluated the histopathological features and the clinical follow-up after RP. The median (range) age of the men was 64.4 (41.1-80.1) years and the median follow-up 5.5 (0.1-15.1) years. The preoperative median prostate-specific antigen (PSA) levels for normal, overweight and obese patients were 9.0 (0.3-133.0), 8.9 (0.4-230.0) and 9.2 (0.5-194.0) ng/mL, respectively.

RESULTS

Serum PSA levels were no different among the three groups (P = 0.92). The normal, overweight and obese patients had organ-confined prostate cancer in 53.7%, 57.1% and 58.6%, respectively (P = 0.34) and had lymph node metastases in 7.9%, 7.6% and 4.6% (P = 0.58). Tumour grading was no different for the three groups (P = 0.25). The PSA recurrence-free, prostate cancer-specific and overall survival for the three BMI groups did not differ significantly (each P > 0.05).

CONCLUSION

The BMI cannot be shown to be a predictor of adverse prognosis either for histopathological features or for the clinical outcome, e.g. PSA-free, prostate cancer-specific and overall survival, in a mid-European study population after RP.

Relationship between serum adiponectin and prostate cancer grade

BACKGROUND

Obesity is associated with prostate cancer (PCA) grade, but the mechanism behind this relationship is not understood. Adiponectin is an adipokine that has been linked with the development of hormonally sensitive carcinomas, including prostate cancer. We evaluated the relationship between serum adiponectin and Gleason score (GS) in a prospective series of patients seen in a single institution.

METHODS

Localized PCA patients evaluated at Dana-Farber Cancer Institute between 2001 and 2005 who enrolled in a prospective serum banking protocol were eligible for this study. Patients with prior hormonal therapy and/or metastatic disease were excluded. High-grade disease was defined as biopsy or radical prostatectomy (RP) GS of 7 or higher. Logistic regression models were used to assess the relationship between high-grade disease and adiponectin levels while adjusting for other potential prognostic variables.

RESULTS

There were 539 patients included in this study, of whom 199 had undergone RP. Median age was 60 years. Median PSA was 5.1 ng/dl. Biopsy GS of 7 or higher was seen in 46.9% of patients. For biopsy GS, higher PSA, older age, and higher BMI were significantly associated with increased odds of GS 7 or higher, but adiponectin was not. In men undergoing RP, there was a significant inverse relationship between pathologic GS and adiponectin dichotomized at the median, due to a significantly higher rate of upgrading in patients with lower adiponectin (P = 0.014).

CONCLUSIONS

Although there was no association between biopsy GS and adiponectin, in patients who had undergone RP, lower adiponectin was independently associated with high-grade prostate cancer.

Diabetes and mortality in men with locally advanced prostate cancer: RTOG 92-02

PURPOSE

Diabetes is associated with lower risk of prostate cancer. Most men with diabetes are obese, and obesity is associated with greater prostate cancer mortality. Whether diabetes influences outcomes after prostate cancer diagnosis is unknown.

PATIENTS AND METHODS

We assessed the relationship between prevalent diabetes and mortality using data from Radiation Therapy Oncology Group Protocol 92-02, a large randomized trial of men (N = 1,554) treated with radiation therapy and short-term versus long-term adjuvant goserelin for locally advanced prostate cancer. Regression and proportional hazard models were performed to evaluate relationships between prevalent diabetes and all-cause mortality, prostate cancer mortality, and non-prostate cancer mortality. Covariates included age, race, tumor stage, Gleason score, prostate-specific antigen, weight, and treatment arm.

RESULTS

There were a total of 765 deaths; 210 (27%) were attributed to prostate cancer. In univariate analyses, prevalent diabetes was associated with greater all-cause mortality and non-prostate cancer mortality but not prostate cancer mortality. After controlling for other covariates, prevalent diabetes remained significantly associated with greater all-cause mortality and non-prostate cancer mortality (hazard ratio [HR] = 2.12; 95% CI, 1.69 to 2.66; P < .0001) but not prostate cancer mortality (HR = 0.80; 95% CI, 0.51 to 1.25; P = .34). In contrast, weight was associated with greater prostate cancer mortality (HR = 1.77; 95% CI, 1.22 to 2.55; P = .002) but not all-cause or non-prostate cancer mortality.

CONCLUSION

Weight but not prevalent diabetes is associated with greater prostate cancer mortality in men receiving combined modality treatment for locally advanced disease. These observations suggest that the association between obesity and greater prostate cancer mortality is mediated by mechanism(s) other than the characteristic metabolic alterations of diabetes.

The SEARCH Database Study Group, Jayachandran J, Aronson WJ, Terris MK, Presti JC, Amling CL, Kane CJ, Freedland SJ. Obesity and positive surgical margins by anatomic location after radical prostatectomy: results from the Shared Equal Access Regional Cancer Hospital database

OBJECTIVES

To determine if there is predilection for any specific anatomical location of positive surgical margins (PSMs) after radical prostatectomy (RP) for prostate cancer in obese men, as previous studies found that obesity was associated with an increased risk of PSMs.

PATIENTS AND METHODS

We analysed retrospectively 1434 men treated with RP between 1989 and 2007 within the Shared Equal Access Regional Cancer Hospital database. The association between increased body mass index (BMI) and overall and site-specific PSMs was assessed using multivariate logistic regression.

RESULTS

After adjusting for several preoperative clinical and pathological characteristics, a higher BMI was associated with an increased risk of PSMs both overall and at all specific anatomical locations (all P or=35 kg/m2, there was more variation, with the highest excess risk of PSMs at the bladder neck and apex.

CONCLUSIONS

Obesity was associated with an increased risk of overall PSMs and at all anatomical locations. Although the excess risk of PSMs was similar across all anatomical locations, there was a suggestion of a higher risk of apical margins among the most obese men, which if validated, further supports the importance of the apical dissection in all men and suggests added difficulty in obese patients.

Impact of socioeconomic factors on prostate cancer outcomes in black patients treated with surgery

OBJECTIVES

The role of socioeconomic factors in the worse outcome of black men with prostate cancer remains unclear. To determine whether socioeconomic factors affect prostate cancer outcomes, we studied a cohort of only black patients to minimize known confounding factors.

METHODS

We studied black men treated with radical prostatectomy at New York Veterans Administration Medical Center and Memorial Sloan-Kettering Cancer Center between 1990 and 2005. A centralized pathology review process determined the Gleason score of all cases. Prostate-specific antigen (PSA) recurrence at both sites was defined as PSA of 0.2 or greater with a confirmatory rise. By matching patients' home zip codes to the U.S. Census Bureau database, we obtained corresponding socioeconomic data regarding median household income (income) and percentage of population with a high school (degree). We analyzed income, education, and clinical and pathological parameters for the whole cohort.

RESULTS

We studied 430 black patients. They resided in neighborhoods where median household income was $41,498.10 and mean percentage of high school graduates was 73.4%. A total of 88 patients (20.9%) had PSA recurrence. Median follow-up for survivors was 37 months. Neither income nor education evaluated as continuous or categorical variables were predictors of PSA recurrence. When evaluated as composite categorical variable, the combination of greater income and education did not predict disease-free survival.

CONCLUSIONS

Data suggest that socioeconomic factors have limited impact on PSA recurrence in black men treated with radical prostatectomy. Thus, biologic factors might have a role in the poor outcomes in this population.

Biological mediators of effect of diet and stress reduction on prostate cancer

BACKGROUND

A 6-month pilot intervention trial was conducted to determine whether adoption of a plant-based diet, reinforced by stress reduction, could reduce the rate of prostate-specific antigen (PSA) increase, a marker of disease progression, in asymptomatic, hormonally untreated patients experiencing consistently increasing PSA levels after surgery or radiation.

METHODS

A pre-post design was used to examine (1) the effect of intervention on potential mediators of disease progression, including body composition and weight-related biomarkers (sex steroid hormones and cytokines), and (2) whether changes in these variables were associated with change in rate of PSA increase. The baseline rate of PSA increase (from the time of posttreatment recurrence to the start of intervention) was ascertained from medical records. Body composition and biomarkers were assessed at baseline (prior to intervention), during the intervention (3 months), and at the end of the intervention (6 months). Changes in body composition and biomarkers were determined and compared with rates of PSA increase over the corresponding time intervals.

RESULTS

There was a significant reduction in waist-to-hip ratio (P=.03) and increase in circulating sex hormone binding globulin (P=.04). The rate of PSA increase decreased from the preintervention period (PSA slope=0.059) to the period from 0 to 3 months (PSA slope=0.002, P<.01) and increased slightly, although not significantly, from 0 to 3 months to the period from 3 to 6 months (0.029, P=.43).

CONCLUSIONS

Adoption of a plant-based diet and stress reduction may reduce central adiposity and improve the hormonal milieu in patients with recurrent PC. Changes in the rate of increase in PSA were in the same direction as changes in waist-to-hip ratio and opposite those of sex hormone binding globulin, raising the possibility that the effect of the intervention may have been mediated, in part, by these variables.

Interrelationships between dietary restriction, the IGF-I axis, and expression of vascular endothelial growth factor by prostate adenocarcinoma in rats

Human studies suggest that excessive energy intake and obesity may influence prostate cancer progression. Rodent experiments demonstrate that diet restriction attenuates tumor growth in parallel with reduced vascular density. The present study examines changes in the insulin-like growth factor I (IGF-I) axis caused by dietary restriction and their association with the expression of vascular endothelial growth factor (VEGF) in prostate cancer. Weanling male Copenhagen rats were randomized into control or 40% dietary restricted groups (n = 5). After 8 wk, rats were implanted with rat AT6.3 prostate adenocarcinoma cells. Two weeks later, the animals were sacrificed and serum, normal prostate, liver, and prostate tumor samples were collected for analyses. Dietary restriction reduced serum concentrations of IGF-I by 35% (P < 0.05) and increased IGF-binding protein-3 (IGFBP3) by sevenfold (P < 0.0001). Lower circulating IGF-I concentrations were correlated with reduced IGF-I mRNA expression in the liver, the primary source of circulating IGF-I. Dietary restriction also lowered mRNA expression of IGF-I (45%, P = 0.0242) and its receptor IGFIR (40%, P = 0.0083) in prostate tumors. Similarly, reduced VEGF mRNA (30%, P = 0.0176) and secreted VEGF protein (33%, P = 0.0003) were observed in prostate cancer of restricted rats. An in vitro study employing AT6.3 prostate cancer cells demonstrated dose- and time-dependent stimulation of VEGF expression by IGF-I. These results suggest that dietary restriction reduces endocrine and prostate tumor autocrine/paracrine IGF-I expression, which contributes to reduced VEGF expression and signaling, to inhibit tumor angiogenesis associated with prostate tumorigenesis.

Obesity and risk of biochemical failure for patients receiving salvage radiotherapy after prostatectomy

PURPOSE

Obesity has been proposed as an independent risk factor for patients undergoing surgery or radiotherapy (RT) for prostate cancer. Using body mass index (BMI) as a measure of obesity, we tested its role as a risk factor for patients receiving salvage RT after prostatectomy.

METHODS AND MATERIALS

Rates of subsequent biochemical relapse were examined in 90 patients who underwent salvage RT between 1984 and 2004 for biochemical failure after radical prostatectomy. Median follow-up was 3.7 years. The BMI was tested as a continuous and categorical variable (stratified as <25, 25-<30, and >or=30 kg/m(2)). Univariate and multivariate proportional hazards regression analyses were performed for clinical, pathologic, and treatment factors associated with time to relapse after salvage RT.

RESULTS

There were 40 biochemical failures after salvage RT with a median time to failure of 1.2 years. The BMI was not associated with adverse clinical, pathologic, or treatment factors. On multivariate analysis, obesity was independently significant (hazard ratio [HR], 1.2; p = 0.01), along with RT dose (HR, 0.7; p = 0.003) and pre-RT prostate-specific antigen level (HR, 1.2; p = 0.0003).

CONCLUSIONS

This study is weakly suggestive that obesity may be a risk factor for salvage RT patients. Whether this results from greater biologic aggressiveness or technical inadequacies cannot be answered by this study. Given the very high failure rate observed for severely obese patients, we propose that technical difficulties with RT are at play. This hypothesis is supported by the RT literature and could be prospectively investigated. Techniques that optimize targeting, especially in obese patients, perhaps seem warranted at this time.

Obesity and oncological outcome after radical prostatectomy: impact of prostate-specific antigen-based prostate cancer screening: results from the Shared Equal Access Regional Cancer Hospital and Duke Prostate Center databases

OBJECTIVE

To indirectly test the hypothesis that prostate-specific antigen (PSA)-based screening is biased against obese men due to haemodilution of PSA, and thus results in delayed diagnosis and poorer outcome beyond the biological link between obesity and aggressive prostate cancer.

PATIENTS AND METHODS

We sought to examine the association between body mass index (BMI) and the outcome of radical prostatectomy (RP) separately for men with PSA-detected cancers (cT1c) or with abnormal digital rectal examination (DRE) findings (cT2/T3), and stratified by year of treatment, using two large databases. We conducted a retrospective cohort study of 1375 and 2014 men treated by RP between 1988 and 2007 using the Shared Equal Access Regional Cancer Hospital (SEARCH) and Duke Prostate Center (DPC) databases. We evaluated the association between BMI and adverse pathological features and biochemical progression, using logistic regression and Cox proportional hazards models, adjusting for several clinical characteristics, respectively. Data were examined as a whole and as stratified by clinical stage (cT1c vs cT2/T3) and year of surgery (>or=2000 vs <2000).

RESULTS

In both cohorts a higher BMI was associated with high-grade disease (P <or= 0.02) and positive surgical margins (P < 0.001) and these results did not vary by clinical stage. A higher BMI was significantly associated with biochemical progression (P <or= 0.03) in both cohorts. When stratified by clinical stage, obesity was significantly related to progression in both cohorts among men with T1c cancers (P <or= 0.004) but not in men with cT2/T3 cancers (P > 0.3). Among men with T1c disease, the association between BMI and biochemical progression was limited to men treated in 2000 or later (P <or= 0.002) and was not apparent in men treated before 2000 (P > 0.4).

CONCLUSIONS

Obese men with PSA-detected cancers and treated with RP since 2000 were at significantly greater risk of biochemical progression, while obese men treated before 2000 or diagnosed with an abnormal DRE were not at significantly greater risk of progression. These findings support the hypothesis that current PSA-based screening is less effective at finding cancers in obese men, leading to more aggressive tumours at diagnosis. Lowering the PSA threshold for biopsy among obese men might help to improve outcomes among this high-risk group.