Inclusion Criteria:

Patients eligible for enrolment in the study must meet all of the following criteria:

- Males <85 years of age

- No clinically relevant abnormal findings on the screening ECG

- Patients with asymptomatic PSA failure following radical therapy with curative intent
for clinically localised prostate cancer. PSA failure is defined as:

- After primary radiotherapy:

- 3 rises in PSA levels from nadir PSA, with each determination at least 4 weeks apart
and a final PSA level ≥2 ng/mL above nadir PSA

- Time from radiotherapy should be at least 1 year from termination of radiotherapy
treatment

- After radical prostatectomy with or without salvage radiotherapy:

- 3 rises in PSA level from nadir PSA, with each determination at least 4 weeks apart
and each PSA level ≥0.2 ng/mL and a final PSA level ≥0.4 ng/mL (nadir PSA is defined
as the lowest PSA value achieved after therapy)

- Serum PSA levels:

- ≥2 ng/mL and ≤20ng/mL for primary radiotherapy patients

- ≥0.4 ng/ml and ≤10ng/ml for radical prostatectomy with or without salvage
radiotherapy patients

- PSADT >3 months and ≤24 months

- Clinical stage T1-T3a N0 M0

- Non-metastatic prostate cancer, as confirmed on a negative bone scan performed within
6 months prior to randomisation (Visit 2)3.

- No evidence of local recurrence in radical prostatectomy or salvage radiotherapy
patients

- Expected survival ≥2 years

- Eastern Cooperative Oncology Group (ECOG) performance status 0, 1 or 2 (see Appendix
1)

Miscellaneous:

- Able to swallow and retain oral medication

- Able and willing to participate in the full 2 years of the study

- Able to read and write (the MAX-PC questionnaire is self-administered), understand
instructions related to study procedures and give written informed consent

- In France, a patient will be eligible for inclusion in this study only if either
affiliated to or a beneficiary of a social security category.

Exclusion Criteria:

- Any unstable serious co-existing medical condition(s) including but not limited to
myocardial infarction, coronary bypass surgery, unstable angina, cardiac arrhythmias,
clinically evident congestive heart failure or cerebrovascular accident within 6
months prior to Visit 1, or uncontrolled diabetes or peptic ulcer disease which is
uncontrolled by medical management

- Abnormal liver function tests (greater than 2 times the upper limit of normal [ULN]
for alanine aminotransferase [ALT], aspartate aminotransferase [AST] or alkaline
phosphatase [ALP] or >1.5 x ULN for bilirubin).

- Serum creatinine >1.5 x ULN

- History of another malignancy within 5 years that could affect the diagnosis of
prostate cancer

- History or current evidence of drug or alcohol abuse within 12 months prior to Visit
1

- History of any illness (including psychiatric) that, in the opinion of the
investigator, might confound the results of the study or pose additional risk to the
patient

- Known hypersensitivity to any 5-AR inhibitor or to any drug chemically related to
dutasteride

Disease characteristics:

- Serum PSA levels

- >20 ng/mL in primary radiotherapy patients

- >10 ng/mL in radical prostatectomy with or without salvage radiotherapy patients

- PSADT ≤3 months or >24 months

- Biochemical failures in post brachytherapy patients

- Clinical stage N+ or M+

- Patient has previously been treated for prostate cancer with any of the following:

- Chemotherapy

- Oestrogens (e.g. megestrol, medroxyprogesterone, cyproterone, Diethylstilbestrol
[DES])

- Drugs with anti-androgenic properties (e.g. spironolactone if >50mg/day, flutamide,
bicalutamide, ketoconazole, progestational agents), (except when used for adjuvancy
or neoadjuvancy in the context of a primary radical treatment in which case their use
should have been for no more than 6 months and should have completed at least 1 year
before Visit 1 [Note: the use of topical ketoconazole is permitted prior to and
during the study and the use of cimetidine is permitted prior to study entry]

- GnRH analogues (e.g., leuprolide, goserelin) except when used for adjuvancy or
neoadjuvancy in the context of a primary radical treatment (in this case use should
have been for no more than 6 months and should have finalised at least 1 year before
Visit 1)

- Orchiectomy

Concomitant medications:

- Glucocorticoids, except inhaled or topical, are not permitted within 3 months prior
to Visit 1 or during the study

- Current and/or previous use of finasteride (Proscar, Propecia) or dutasteride
(GI198745, AVODART™) exposure within 6 months prior to Visit 1

- Anabolic steroids within 6 months prior to Visit 1

- Participation in any other investigational or marketed drug trial within the 30 days
prior to Visit 1 or any time during the study period