HAROW: the first comprehensive prospective observational study comparing treatment options in localized prostate cancer.

Purpose: To collect data on primary treatment decision and follow-up in patients with diagnosed, histologically confirmed localized (T1a-T2c/N0/M0) prostate cancer (PCa) for up to 5 years in a prospective observational non-interventional study.

Methods: Patients were non-randomly allocated to one of the five treatment strategies: hormone therapy, active surveillance, radiation, operation, or watchful waiting.

Results: A total of 3169 patients were included by 259 participating sites; 2957 patients had at least one follow-up visit. 54.8 % of tumors at baseline were staged as T1c, 38 % as T2a-T2c, and 7.1 % as T1a or T1b (missing: 0.2 %). 38.9, 32.6 and 26.6 % of patients were classified as low risk, intermediate risk, and high risk according to d'Amico, respectively (missing: 1.8 %). 56.6 % of patients underwent prostatectomy as primary therapy, 16.4 % received radiation, 6.9 % HT, 15.8 and 4.3 % decided for AS or WW. Mean follow-up was 28.4 months. Progression rates were between 8.6 % (RT) and 33.1 % (AS).

Conclusion: Whereas RP remains the main treatment option of localized PCa, active surveillance appears to become an accepted and selectively employed treatment option. Careful selection of patients is documented by the highest proportion of patients with low risk (82.5 %), PSA density <0.2 ng/ml/ml (77.5 %), T1 staging (83.6 %), Gleason score ≤6 (92.5 %), ≤2 positive biopsies (79.4 %), and lowest mean PSA (5.8 ng/ml) in the AS group. The relatively high progression rate in the AS group has to be considered in the context of treatment changes; 71/155 patients had a documented change of treatment and 62 of them with a follow-up period of >3 months.