Investigating the prostate specific antigen, body mass index and age relationship: is an age-BMI-adjusted PSA model clinically useful?
OBJECTIVE
Previous studies indicate a possible inverse relationship between prostate-specific antigen (PSA) and body mass index (BMI), and a positive relationship between PSA and age. We investigated the associations between age, BMI, PSA, and screen-detected prostate cancer to determine whether an age-BMI-adjusted PSA model would be clinically useful for detecting prostate cancer.


METHODS
Cross-sectional analysis nested within the UK ProtecT trial of treatments for localized cancer. Of 18,238 men aged 50-69 years, 9,457 men without screen-detected prostate cancer (controls) and 1,836 men with prostate cancer (cases) met inclusion criteria: no history of prostate cancer or diabetes; PSA < 10 ng/ml; BMI between 15 and 50 kg/m2. Multivariable linear regression models were used to investigate the relationship between log-PSA, age, and BMI in all men, controlling for prostate cancer status.


RESULTS
In the 11,293 included men, the median PSA was 1.2 ng/ml (IQR: 0.7-2.6); mean age 61.7 years (SD 4.9); and mean BMI 26.8 kg/m2(SD 3.7). There were a 5.1% decrease in PSA per 5 kg/m2increase in BMI (95% CI 3.4-6.8) and a 13.6% increase in PSA per 5-year increase in age (95% CI 12.0-15.1). Interaction tests showed no evidence for different associations between age, BMI, and PSA in men above and below 3.0 ng/ml (all p for interaction >0.2). The age-BMI-adjusted PSA model performed as well as an age-adjusted model based on National Institute for Health and Care Excellence (NICE) guidelines at detecting prostate cancer.


CONCLUSIONS
Age and BMI were associated with small changes in PSA. An age-BMI-adjusted PSA model is no more clinically useful for detecting prostate cancer than current NICE guidelines. Future studies looking at the effect of different variables on PSA, independent of their effect on prostate cancer, may improve the discrimination of PSA for prostate cancer.
School of Social and Community Medicine, University of Bristol, Canynge Hall, 39 Whatley Road, Bristol, BS8 2PS, UK. sean.harrison@bristol.ac.uk.
Sean
http://orcid.org/0000-0002-7966-0700
S
Harrison
School of Social and Community Medicine, University of Bristol, Canynge Hall, 39 Whatley Road, Bristol, BS8 2PS, UK.
Kate
K
Tilling
School of Social and Community Medicine, University of Bristol, Canynge Hall, 39 Whatley Road, Bristol, BS8 2PS, UK.
Emma L
EL
Turner
School of Social and Community Medicine, University of Bristol, Canynge Hall, 39 Whatley Road, Bristol, BS8 2PS, UK.
J Athene
JA
Lane
School of Social and Community Medicine, University of Bristol, Canynge Hall, 39 Whatley Road, Bristol, BS8 2PS, UK.
Andrew
A
Simpkin
School of Social and Community Medicine, University of Bristol, Canynge Hall, 39 Whatley Road, Bristol, BS8 2PS, UK.
Michael
M
Davis
School of Social and Community Medicine, University of Bristol, Canynge Hall, 39 Whatley Road, Bristol, BS8 2PS, UK.
Jenny
J
Donovan
Nuffield Department of Surgery, John Radcliffe Hospital, University of Oxford, Oxford, OX3 9DU, UK.
Freddie C
FC
Hamdy
University Department of Oncology, Addenbrooke's Hospital, Hills Road, Cambridge, CB2 0QQ, UK.
David E
DE
Neal
School of Social and Community Medicine, University of Bristol, Canynge Hall, 39 Whatley Road, Bristol, BS8 2PS, UK.
Richard M
RM
Martin
D000367:Age Factors; D000368:Aged; D015992:Body Mass Index; D016022:Case-Control Studies; D003430:Cross-Sectional Studies; D055088:Early Detection of Cancer; D006801:Humans; D007610:Kallikreins / Q000032:analysis*; D008297:Male; D008875:Middle Aged; D009765:Obesity / Q000453:epidemiology; D017430:Prostate-Specific Antigen / Q000032:analysis*; D011471:Prostatic Neoplasms / Q000175:diagnosis / Q000453:epidemiology*; D016032:Randomized Controlled Trials as Topic; D006113:United Kingdom / Q000453:epidemiology
C549870:KLK3 protein, human; D007610:Kallikreins; D017430:Prostate-Specific Antigen
Age; BMI; PSA; PSA–BMI equation; Prostate cancer; Prostate cancer screening