Assessment of tumor control following definitive radiotherapy in carcinoma of the prostate--a continuing dilemma
Pilepich, M.V.
Progress in Clinical and Biological Research 239: 681-689
1987
ISSN/ISBN: 0361-7742 PMID: 3658989 Document Number: 299440
Following completion of radiotherapy, clinically detectable (palpable) and histologically identifiable prostate carcinoma may persist for an extended period before it undergoes complete resolution. Although in most patients treated with adequate radiotherapy tumor resolution by both clinical and histological criteria occurs in the first 2 years, in a proportion of patients complete resolution may occur during the third year or even later. Since the proportion of patients with late resolution appears to be quite small, it seems reasonable to use the histologically identifiable tumor in the biopsy specimen beyond the second postirradiation year as a criterion for the diagnosis of treatment failure. The available data are insufficient to establish, by histological evaluation, the true pattern of tumor resolution. To achieve such a goal one would need to assess a substantial population of patients, adequately irradiated in a standardized manner, by systemic periodic biopsies over several years. To avoid selection biases, all patients, regardless of the clinical findings, would need to undergo biopsies. To avoid sampling errors, particularly in patients without palpable abnormalities, multiple specimens would need to be obtained from several quadrants of the prostate. The studied population should not receive hormonal management in conjunction with radiotherapy. Only completion of this ideal, hypothetical study and correlation of the biopsy results with long-term follow-up data on local failure, the incidence of distant metastases, and survival would make possible meaningful interpretation of the biopsy results in the future. Only then would it become possible to assign a statistical probability of local and/or distal failure as a function of the biopsy status at a certain point in time.