From Andrew Sanderson, Spennymoor, County Durham, UK
Your leader on screening is clear and accurate (7 April, p 5). When I was a general medical practitioner, I was often unsure what to do with a marginally raised level of prostate specific antigen (PSA), which may indicate prostate cancer.
The problem is that the gland's enlargement in benign prostatic hypertrophy also leads to more PSA due to increasing numbers of cells. In prostate cancers, the gland has a few more cells, but the key difference is that they leak more PSA into the blood. That's what my urologist told me before extracting my cancerous prostate.
Mostly, I arranged repeated tests for my patients, often over many years. I was then faced with the problem of how to deal with slowly rising levels of PSA. This was solved by one patient who had undergone years of testing. He had plotted his PSA levels against time and he came to see me when the PSA rise accelerated. This indicated that the leakiness or the number of cells was shooting up. He underwent successful treatment for his cancer.
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