Two large randomised trials with 12 years follow-up.  One shows reduction in prostate cancer deaths, the other produced a null result. But science cannot prove a null, and point estimates were favourable in both trials. Moreover, there were many differences in implementation of screening across the two large trials. So the authors of a recent study  amalgamated the individual research from each individual study and analysed the consolidated dataset to adjust for differences in screening intensity using a measure of the average time by which diagnosis is advanced by screening compared to not screening. This was calculated in different ways, but the results do suggest a screening effect on prostate cancer deaths of about 8%. Whether this translates into all-cause mortality is uncertain, as per a previous News Blog on this issue. I was attracted to this paper, not only because prostate screening is a controversial and important public health issue, but also because it deals with a common scenario in contemporary clinical research – apparently contradictory trial results where one trial provides a null result and the other provides a positive result.
— Richard Lilford, CLAHRC WM Director
- Schröder FH, Hugosson J, Roobol MJ, et al. Screening and prostate cancer mortality: results of the European Randomised Study of Screening for Prostate Cancer (ERSPC) at 13 years of follow-up. Lancet. 2014; 384: 2027-35.
- Pinsky PF, Prorok PC, Yu K, et al. Extended mortality results for prostate cancer screening in the PLCO trial with median follow-up of 15 years. Cancer. 2017; 123: 592-9.
- Tsodikov A, Gulati R, Heijnsdijk AEM, et al. Reconciling the Effects of Screening on Prostate Cancer Mortality in the ERSPC and PLCO Trials. Ann Intern Med. 2017; 164: 449-55.
- Lilford RJ. Thyroid Cancer: Another Indolent Tumour Prone to Massive Over Diagnosis. NIHR CLAHRC West Midlands News Blog. 24 March 2017.