Whole-pelvis, "mini-pelvis," or prostate-only external beam radiotherapy after neoadjuvant and concurrent hormonal therapy in patients treated in the Radiation Therapy Oncology Group 9413 trial.
OBJECTIVE
The Radiation Therapy Oncology Group (RTOG) 9413 trial demonstrated a better progression-free survival (PFS) with whole-pelvis (WP) radiotherapy (RT) compared with prostate-only (PO) RT. This secondary analysis was undertaken to determine whether "mini-pelvis" (MP; defined as > or = 10 x 11 cm but < 11 x 11 cm) RT resulted in progression-free survival (PFS) comparable to that of WP RT. To avoid a timing bias, this analysis was limited to patients receiving neoadjuvant and concurrent hormonal therapy (N&CHT) in Arms 1 and 2 of the study.


METHODS
Eligible patients had a risk of lymph node (LN) involvement > 15%. Neoadjuvant and concurrent hormonal therapy (N&CHT) was administered 2 months before and during RT for 4 months. From April 1, 1995, to June 1, 1999, a group of 325 patients were randomized to WP RT + N&CHT and another group of 324 patients were randomized to receive PO RT + N&CHT. Patients randomized to PO RT were dichotomized by median field size (10 x 11 cm), with the larger field considered an "MP" field and the smaller a PO field.


RESULTS
The median PFS was 5.2, 3.7, and 2.9 years for WP, MP, and PO fields, respectively (p = 0.02). The 7-year PFS was 40%, 35%, and 27% for patients treated to WP, MP, and PO fields, respectively. There was no association between field size and late Grade 3+ genitourinary toxicity but late Grade 3+ gastrointestinal RT complications correlated with increasing field size.


CONCLUSIONS
This subset analysis demonstrates that RT field size has a major impact on PFS, and the findings support comprehensive nodal treatment in patients with a risk of LN involvement of > 15%.
Roach
Mack
M
University of California San Francisco, San Francisco, CA 94143-1708, USA. roach@radonc17.ucsf.edu
DeSilvio
Michelle
M
Valicenti
Richard
R
Grignon
David
D
Asbell
Sucha O
SO
Lawton
Colleen
C
Thomas
Charles R
CR
Shipley
William U
WU
D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D000726:Androgen Antagonists / Q000627:therapeutic use*; D016009:Chi-Square Distribution; D018572:Disease-Free Survival; D017619:Hemibody Irradiation / Q000379:methods*; D006801:Humans; D008297:Male; D008875:Middle Aged; D020360:Neoadjuvant Therapy / Q000379:methods*; D010388:Pelvis; D017430:Prostate-Specific Antigen / Q000097:blood; D011471:Prostatic Neoplasms / Q000188:drug therapy* / Q000401:mortality / Q000532:radiotherapy*; D018709:Statistics, Nonparametric
D000726:Androgen Antagonists; D017430:Prostate-Specific Antigen