Subcutaneous adipose tissue characteristics and the risk of biochemical recurrence in men with high-risk prostate cancer

Andrew M McDonald; John B Fiveash; Robert S Kirkland; Rex A Cardan; Rojymon Jacob; Robert Y Kim; Michael C Dobelbower; Eddy S Yang

doi:10.1016/j.urolonc.2017.07.012

Subcutaneous adipose tissue characteristics and the risk of biochemical recurrence in men with high-risk prostate cancer

Urol Oncol. 2017 Nov;35(11):663.e15-663.e21. doi: 10.1016/j.urolonc.2017.07.012. Epub 2017 Aug 7.

Authors

Andrew M McDonald¹, John B Fiveash², Robert S Kirkland², Rex A Cardan², Rojymon Jacob², Robert Y Kim², Michael C Dobelbower², Eddy S Yang²

Affiliations

¹ Department of Radiation Oncology, University of Alabama at Birmingham, Hazelrig-Salter Radiation Oncology Center, Birmingham, AL. Electronic address: ammcdonald@uabmc.edu.
² Department of Radiation Oncology, University of Alabama at Birmingham, Hazelrig-Salter Radiation Oncology Center, Birmingham, AL.

PMID: 28797587
DOI: 10.1016/j.urolonc.2017.07.012

Abstract

Purpose/objective(s): To assess subcutaneous adipose tissue characteristics by computed tomography (CT) as potential imaging biomarkers predictive of biochemical recurrence in men with high-risk prostate cancer receiving radiotherapy (RT).

Materials and methods: This retrospective study included men with high-risk prostate cancer (PSA>20ng/ml, Gleason score ≥8, or clinical extraprostatic extension) treated between 2001 and 2012. All patients received definitive, dose-escalated external beam RT along with a course of neoadjuvant, concurrent, and adjuvant androgen deprivation therapy (ADT). Each patient also had a treatment planning CT that included the L4-L5 vertebral interface and prostate specific antigen (PSA) measurements for at least 2 years following RT. The subcutaneous adipose tissue was contoured on a single axial CT slice at the level of L4-L5. The average CT attenuation, in Hounsfield units (HU), of the structure was calculated and defined as SAT_HU. SAT_AREA was defined as the cross-sectional area of the structure (in cm²) that was then normalized by the square of patient height. Biochemical failure (BF) was defined as a PSA rise of 2ng/ml from the nadir. Freedom from BF (FFBF) was calculated from start time of ADT using the Kaplan-Meier method. Estimates of FFBF were stratified by SAT_HU and SAT_AREA quartiles.

Results: A total of 171 men met the inclusion criteria with a median follow-up of 5.6 years. The mean SAT_HU (±standard deviation) was -99.2HU (±6.1HU), and the mean SAT_AREA was 93.2cm²/m² (±39.4cm²/m²). The 5- and 8-year rates of FFBF across all patients were 81.5% and 73.5%, respectively. Patients in the lowest quartile of SAT_HU experienced significantly higher FFBF compared to the other quartiles (Q4 vs. Q1, P = 0.017; Q4 vs. Q2, P = 0.045; Q4 vs. Q3, P = 0.044). No other differences in FFBF were observed between quartiles of SAT_AREA or other quartiles of SAT_HU.

Conclusion: Lower subcutaneous adipose tissue density was associated with a lower rate of BF following RT with ADT for men with high-risk prostate cancer. Further research is needed to elucidate the biological underpinnings of this clinical finding and the role adipose tissue plays in modulating oncologic behavior and outcomes.

Keywords: Adipose tissue density; Body composition; Computed tomography; Imaging biomarker; Prostate cancer.

MeSH terms

Aged
Androgen Antagonists / therapeutic use
Combined Modality Therapy
Dose-Response Relationship, Radiation
Humans
Kaplan-Meier Estimate
Male
Middle Aged
Neoplasm Recurrence, Local
Prostate / drug effects*
Prostate / pathology
Prostate / radiation effects*
Prostate-Specific Antigen / analysis
Prostatic Neoplasms / diagnosis
Prostatic Neoplasms / therapy*
Radiotherapy / methods
Retrospective Studies
Risk Factors
Subcutaneous Fat / diagnostic imaging
Subcutaneous Fat / metabolism*
Tomography, X-Ray Computed

Substances

Androgen Antagonists
Prostate-Specific Antigen