Some patients with a histopathological diagnosis of prostate cancer have a
tumour that behaves benignly during long-term follow-up. The proportion of
patients with such a tumour is unknown, as is the fraction who die of prost
ate cancer between 10 and 20 y of follow-up. All men aged 45-84y obtaining
a diagnosis of prostate cancer between 1965 and 1993 and being reported to
the Finnish Cancer Registry were observed. Death was recorded as caused by
prostate cancer or not. We identified 11,500 men with localized prostate ca
ncer and in this group the disease-specific survival rare reached a plateau
at approximately 30% after 23 y of follow-up. In the same cohort, 5% of th
e patients died of prostate cancer during years 11-20 of follow-up. During
the observation period, somewhat less than half of the patients with locali
zed prostate cancer who died, died of the disease. This proportion decrease
d with duration of followup. In conclusion, early aggressive therapy for lo
calized prostate cancer is unnecessary, in terms of survival, for those wit
h a benignly behaving tumour (about 30% in this series) or who die of inter
current disease (about 50% in this series). Such therapy may, however, prol
ong life for the patients and may cure the patients that die of prostate ca
ncer after more than 10 y follow-up.