Influence of body mass index on prostate‐specific antigen failure after androgen suppression and radiation therapy for localized prostate cancer

Abstract

BACKGROUND Increasing body mass index (BMI) is associated with shorter time to prostate‐specific antigen (PSA) failure after radical prostatectomy. Whether BMI is associated with time to PSA failure was investigated in men treated with androgen suppression therapy (AST) and radiation therapy (RT) for clinically localized prostate cancer. METHODS The observational prospective cohort study consisted of 102 men with clinically localized prostate cancer who received 70 Gy RT with 6 months of AST on a single arm of a randomized trial between December 1995 and April 2001. Height and weight data were available at baseline for 99 (97%) of the men, from which BMI was calculated. Adjusting for age (continuous) and known prognostic factors including PSA level (continuous), Gleason score, and T‐category, Cox regression analyses were performed to analyze whether BMI (continuous) was associated with time to PSA failure (PSA >1.0 ng/mL and increasing >0.2 ng/mL on 2 consecutive visits). RESULTS Median age and median BMI (interquartile range [IQR]) at baseline was 72 (69.1–74.7) years and 27.4 (24.8–30.7) kg/m,2 respectively. In addition to an increasing PSA level (P = .006) and Gleason 8–10 cancer (P = .024), after a median follow‐up (IQR) of 6.9 (5.6–8.5) years, an increasing BMI was also significantly associated with a shorter time to PSA failure (adjusted hazard ratio [HR]: 1.10; 95% confidence interval [CI]: 1.01–1.19; P = .026) after RT and AST. CONCLUSIONS After adjusting for known prognostic factors, baseline BMI is significantly associated with time to PSA failure after RT and AST for men with clinically localized prostate cancer. Further study is warranted to assess the impact of an increasing BMI after AST administration on PSA failure, prostate cancer‐specific, and all‐cause mortality. Cancer 2007. © 2007 American Cancer Society.

Prognostic impact of abdominal adiposity, waist circumference and body mass index in patients with intermediate-risk prostate cancer treated with radiotherapy

“…[6][7][8][9] In the current study, using more sophisticated anthropometric measures of abdominal obesity than previous EBRT studies and treating patients with IGRT techniques, we were unable to show that obesity or a specific fat distribution predisposes towards a higher risk of biochemical failure. This was true at least in patients with intermediate-risk disease, despite the fact that ultrasonographic prostate localization could be limited by its poor image quality in obese patients 31 and its accuracy compared with implanted fiducial markers is questioned.…”

“…1, [3][4][5] Similarly, several studies of conventional external beam radiotherapy (EBRT), with or without androgen deprivation therapy (ADT) for patients with localized prostate cancer, have suggested that a high BMI is a strong predictor of biochemical relapse. [6][7][8][9] Conversely, a similar association has not been found in other surgical series 10,11 or in patients treated with permanent seed brachytherapy (BT).…”

“…8,13,28 Radiotherapy series examining the relationship between obesity and risk of biochemical failure in patients with prostate cancer have reported conflicting results. Obesity has been identified as an independent risk factor for increased biochemical relapse after EBRT [6][7][8][9] but not after permanent low-dose-rate BT. [12][13][14] This might be because accurate dose delivery can be compromised in obese patients by spatial shifts in prostate position and setup errors greater than 10 mm 29,30 whereas similar problems are not present in BT.…”

Obesity-related systemic factors promote an invasive phenotype in prostate cancer cells

“…5,6 Similar to obese men, obese mice fed a high fat diet also results in increased adiposity, circulating growth factors and inflammation when compared with control mice and may contribute to prostate cancer progression. [7][8][9][10] Studies suggest that cancer cells undergo an epithelialmesenchymal-transition (EMT) program at the initiation of invasion, which is a critical process for metastasis. 11,12 Hallmarks of EMT include loss or decreased protein expression of e-cadherin, increased vimentin and deregulation of b-catenin.…”

Obesity and mortality in men with locally advanced prostate cancer

“…11,[14][15][16] The data following radiation therapy (RT) is limited. Two recent retrospective analyses suggested that BMI is a predictor of PSA failure among patients treated with external beam RT with or without androgen deprivation therapy (ADT), 17,18 while another report suggested that this may not be the case following brachytherapy. 19 Biochemical failure, however, only weakly correlates with risk of cancer-specific mortality.…”