PSA (prostate-specific antigen) is a protein produced by the prostate gland in men, a small gland in the pelvis between the penis and bladder. A raised PSA level may indicate infection or inflammation of the prostate (prostatitis), or prostate cancer. PSA is often used to monitor prostate cancer.
It is thought that significant amounts of vigorous physical activity, including cycling, may cause a rise in PSA for up to 48 hours afterwards. The level can also be increased by sexual activity. It is therefore advisable that all of these should be avoided in the couple of days before a PSA blood test is taken. In addition, digital rectal examination (performed by doctors to examine the prostate gland) should not be carried out in the week before a PSA test. If an unexpectedly high reading is identified, it usually makes sense to repeat the test. So in your case if you cycled in the 48 hours before the PSA test, then it is possible that cycling has affected the reading. This result should be confirmed by repeating the test, as above.
The use of PSA as a diagnostic screening test for prostate cancer in people without any symptoms is controversial as the test cannot always reliably detect cases of prostate cancer. False positive and false negative results mean that some people without clinically significant prostate cancer will have a raised PSA requiring further investigation (e.g. biopsies) and sometimes treatment. These may be invasive and will cause harm in some people, for example through complications. Meanwhile, others who have the condition will have a normal PSA and may be incorrectly reassured. Finally, in those found to have ‘early’ prostate cancer, we don’t always know which cancers need to be treated aggressively and which can be safely monitored.
Dr Matt Brooks
This was first published in the April / May 2015 edition of Cycling UK's Cycle magazine.