PURPOSE: Determine whether fat distribution, body mass index, or clinical and dosimetric factors are associated with prostate specific antigen (PSA) bounce (PSAb) of ≥1.6 ng/mL in patients treated with permanent seed 125I prostate brachytherapy (PB).
METHODS AND MATERIALS: We identified 23 patients with a PSAb of ≥1.6 ng/mL. For each patient with a bounce, at least one control with similar age (age ± 2 years, n=31) was identified. Control patients had to have no bounce (≤ 0.2 ng/mL) and a most recent PSA of < 1 ng/mL. CT at Day 30 after PB was used to determine the volume of subcutaneous adipose tissue, visceral adipose tissue, and peri-prostatic fat. Univariate and multivariate logistic models were used to assess the association between PSAb and adipose tissue distribution and clinical and dosimetric factors.
RESULTS: Mean patient age was 62.3 ± 5.3 years. Mean PSAb height was 2.7 ± 0.8 ng/mL, and mean time to bounce was 9.6 ± 4 months. More than 90% of the patients reached a PSA nadir before PSAb within 12 months post-PB. Patients showing PSAb were more likely to have a T1c disease vs. T2a (odds ratio = 18.87; 95% confidence interval: 2.32-454.55; p=0.019) and a lower seed activity per cc of prostate volume (odds ratio=0.02; 95% confidence interval=0.42-2.22; p=0.026). Neither fat distribution nor body mass index was associated with PSAb (p=0.11-0.597).
CONCLUSIONS: Clinical and dosimetric factors play a role in PSAb of ≥1.6 ng/mL. Fat distribution is not associated with a PSAb. There is presently no satisfactory theory to explain the etiology of PSAb.
Written by:
Chira C, Taussky D, Gruszczynski N, Meissner A, Larrivée S, Carrier JF, Donath D, Delouya G. Are you the author?
Departement of Radiation Oncology, Centre hospitalier de l'Université de Montréal (CHUM), Hôpital Notre-Dame Hospital, Montreal, Québec, Canada; CRCHUM-Centre de recherché du Centre Hospitalier de l'Université de Montréal, Montreal, Québec, Canada.
Reference: Brachytherapy. 2013 Jul 24. pii: S1538-4721(13)00281-X.
doi: 10.1016/j.brachy.2013.05.005
PubMed Abstract
PMID: 23891340
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