Long-Term Follow-up of Untreated Stage T1a Prostate Cancer

Stage T1a prostate cancer is defined as incidental adenocarcinoma detected at the time of the transurethral resection of the prostate (TURP), involving 5% or less of the resected prostatic tissue (1). It is estimated that 6.5% of men undergoing TURP will have stage T1a adenocarcinoma of the prostate (2). The biologic potential of stage T1a adenocarcinoma is uncertain (2). Some studies (3,4) have suggested that a significant proportion of patients (16%–26%) with stage T1a carcinoma will have clinically aggressive disease. However, our knowledge is limited with regard to the long-term outcome for untreated patients with stage T1a cancer. A recent study (5) indicated that 8% of men with untreated, clinically occult, and incidental cancer have metastatic progression with up to 15 years follow-up. In this study, we sought to determine the natural history of untreated stage T1a prostate cancer after long-term follow- up. The study group consisted of 102 consecutive case subjects who were diagnosed with stage T1a prostate cancer at Mayo Clinic during the period from 1960 through 1970. None of these men were treated until there was evidence of disease progression. The ages of the case subjects at diagnosis ranged from 48 to 91 years (mean, 69 years). All histologic slides were reviewed by two pathologists (L. Cheng and D. G. Bostwick) and fulfilled the American Joint Committee on Cancer criteria for stage T1a cancer (1). The weight of resected prostatic tissue ranged from 3g to 115g (mean, 24 g). Cancer volume, determined by the grid method, ranged from 0.01 cm3 to 0.22 cm3 (mean, 0.06 cm3). The mean Gleason score was 5 (range, 2–7), and the mean number of cancer foci was 1.6 (range, 1–5). The mean follow-up after initial diagnosis was 9.5 years (range, 0.3–31 years). One case subject was alive without evidence of disease. Fifty five case subjects died of intercurrent diseases, four case subjects died of prostate cancer, and 14 died of unknown causes. Twenty-eight subjects were lost to follow-up. During the follow-up of 9.5 years, 14 men (14%) developed clinical progression (Table 1). The interval from diagnosis to clinical progression ranged from 1.0 to 23 years (mean, 7.3 years). Five case subjects had systemic progression, including four who died of prostate cancer. Six case subjects developed palpable prostatic nodules with subsequent biopsyproven prostate cancer. Gleason grade was higher in recurrent cancer than in initial TURP specimens in all cases (Table 1), suggesting the possibility of dedifferentiation during cancer progression. Of the 54 men who were followed for more than 8 years, eight (15%) developed clinical progression of disease. In summary, men with untreated stage T1a prostate cancer are at risk of clinical progression of cancer.