Re: Influence of blood prostate specific antigen levels at age 60 on benefits and harms of prostate cancer screening: population based cohort study
Definition of metastasis
At risk of being labelled as a pedantic, I have to disagree, with the use of the word 'metastasis' outside the context of its clinical definition.
Oxford dictionary defines metastasis as 'The development of secondary malignant growths at a distance from a primary site of cancer' (1) .
In clinical practice, the use of the word ’metastasis’ conforms to the Oxford dictionary definition. But in this paper, patients with high PSA (>100) seems to have been termed as having metastatic disease in the absence of any clinical or radiological evidence of metastasis.
Moreover, patients with ultra high PSA but without radiological evidence of metastasis can treated radically with good clinical outcome. For instance, Saskatchewan cancer registry reports that in patients with PSA of ≥ 100 ng/ml, Radiotherapy was associated with an excellent 5- and 10-year cause-specific survival of 80% and 54% (2). Patients with PSA >100 had a median time to biochemical progression of 88 months following radiotherapy in our limited case series (3). These excellent survival rates are certainly not comparable to the poor prognosis of patients with radiologically evident metastasis.
Could the authors clarify the number of patients labelled as having metastatic disease purely because of high PSA but without any clinical evidence of metastasis? A PSA >100 at diagnosis in the unscreened group is not necessarily an indicator of poor prognosis if there is no clinical or radiological evidence of metastasis. (4).
Overall the authors are to be congratulated for proposing and evaluating a novel strategy to minimise the risk of over diagnosis as well as increase the effectiveness of the PSA screening in prostate cancer. External validation of their strategy in an independent group would make an important difference to the de facto PSA screening programme.
1. Definition of metastasis in English: Oxford Dictionaries. [Internet]. [cited 2014 Mar 31]. Available from: http://www.oxforddictionaries.com/definition/english/metastasis
2. Rodrigues G, Bae K, Roach M, Lawton C, Donnelly B, Grignon D, et al. Impact of ultrahigh baseline PSA levels on biochemical and clinical outcomes in two Radiation Therapy Oncology Group prostate clinical trials. Int J Radiat Oncol Biol Phys. 2011 Jun 1;80(2):445–52.
3. Walker GA, Perry CJ, Sundar S. Radical prostate radiotherapy to M0 patients with a presenting PSA of more than 100. ESTRO 31. European Society for Radiotherapy & Oncology Annual meeting. Barcelona: Radiotherapy and Oncology 2012.; p. S431.
4. Carlsson S, Assel M, Sjoberg D, Ulmert D, Hugosson J, Lilja H, et al. Influence of blood prostate specific antigen levels at age 60 on benefits and harms of prostate cancer screening: population based cohort study. BMJ. 2014 Mar 28;348(mar28 1):g2296–g2296.
Competing interests: No competing interests