The impact of androgen deprivation therapy on setup errors during external beam radiation therapy for prostate cancer

• Published in: Strahlentherapie und Onkologie Vol. 193; no. 6; pp. 472 - 482
• Main Authors: Onal, Cem, Dolek, Yemliha, Ozdemir, Yurday
• Format: Journal Article
• Language: English
• Published: Berlin/Heidelberg Springer Berlin Heidelberg 01-06-2017; Springer Nature B.V
• Subjects: Aged; Aged, 80 and over; Androgen Antagonists - therapeutic use; Androgens; Anilides - therapeutic use; Cancer therapies; Chemoradiotherapy; Combined Modality Therapy; Computed tomography; Cone-Beam Computed Tomography; Correlation analysis; Correlation coefficients; Deprivation; Errors; Fiducial Markers; Gonadotropin-Releasing Hormone - agonists; Humans; Male; Medicine; Medicine & Public Health; Middle Aged; Neoadjuvant Therapy; Nitriles - therapeutic use; Oncology; Organ Size; Original Article; Patient Positioning; Patients; Prostate - radiation effects; Prostate cancer; Prostatic Neoplasms - diagnostic imaging; Prostatic Neoplasms - drug therapy; Prostatic Neoplasms - radiotherapy; Radiation therapy; Radiotherapy; Retrospective Studies; Systematic errors; Tosyl Compounds - therapeutic use; Risikoorgane; Toxizität; Referenzmarker; Prostate-specific antigen; Toxicity; Fiducial markers; Organs at risk; Radiotherapy, image-guided; Prostataspezifisches Antigen; Radiotherapie, bildgesteuerte
• ISSN: 0179-7158; 1439-099X
• DOI: 10.1007/s00066-017-1131-z

Purpose
To determine whether setup errors during external beam radiation therapy (RT) for prostate cancer are influenced by the combination of androgen deprivation treatment (ADT) and RT.
Materials and methods
Data from 175 patients treated for prostate cancer were retrospectively analyzed. Treatment was as follows: concurrent ADT plus RT, 33 patients (19%); neoadjuvant and concurrent ADT plus RT, 91 patients (52%); RT only, 51 patients (29%). Required couch shifts without rotations were recorded for each megavoltage (MV) cone beam computed tomography (CBCT) scan, and corresponding alignment shifts were recorded as left–right (x), superior–inferior (y), and anterior–posterior (z). The nonparametric Mann–Whitney test was used to compare shifts by group. Pearson’s correlation coefficient was used to measure the correlation of couch shifts between groups. Mean prostate shifts and standard deviations (SD) were calculated and pooled to obtain mean or group systematic error (M), SD of systematic error (Σ), and SD of random error (σ).
Results
No significant differences were observed in prostate shifts in any direction between the groups. Shifts on CBCT were all less than setup margins. A significant positive correlation was observed between prostate volume and the z‑direction prostate shift (
r
 = 0.19,
p
 = 0.04), regardless of ADT group, but not between volume and x‑ or y‑direction shifts (
r
 = 0.04,
p
 = 0.7;
r
 = 0.03,
p
 = 0.7). Random and systematic errors for all patient cohorts and ADT groups were similar.
Conclusion
Hormone therapy given concurrently with RT was not found to significantly impact setup errors. Prostate volume was significantly correlated with shifts in the anterior–posterior direction only.