PSA levels – what is normal and when is it investigated?

A raised PSA level does not have to mean that you have prostate cancer. Most men with a moderately high level, up to 10 micrograms per litre, do not have cancer but a completely benign prostate enlargement.

Infection in the prostate also raises the level. What the test measures and who should take it is described in more detail here PSA test.

Source: Prostatacancerförbundet (prostatacancer.se).

The larger the prostate is, the higher the PSA level becomes. A normal prostate is around 15 to 30 cubic centimetres. Most men with benign prostate enlargement have a prostate of 30 to 90 cubic centimetres.

As a simple rule of thumb, the PSA level can be up to one tenth of the prostate size without there being reason to suspect cancer. A man with a prostate of 60 cubic centimetres can therefore have a level of up to 6 micrograms per litre without investigation being needed – provided that there is no hardening in the prostate.

Source: Prostatacancerförbundet (prostatacancer.se).

The relationship between the PSA level and the prostate size is called PSA density, and is calculated by dividing the level by the size. A level of 6 micrograms per litre and a prostate of 60 cubic centimetres gives a PSA density of 0.1.

PSA density says more about the risk of a prostate cancer requiring treatment than the PSA level alone: the lower the density, the lower the risk.

Men with a PSA density below 0.1 and a prostate that feels benign on examination have such a low risk that they do not need to undergo a tissue sample. Conversely, a tissue sample is usually warranted where the PSA density is above 0.2, even if the MRI examination does not show any suspected tumour.

Source: Prostatacancerförbundet (prostatacancer.se).

For men with newly detected prostate cancer there is a relationship between the PSA level and how extensive the cancer is. The higher the level, the higher the risk that the cancer has grown outside the prostate.

Spread of an untreated prostate cancer is rare as long as the level is below 20 micrograms per litre, while most men with levels above 100 have spread to the lymph nodes or the skeleton. Prostate cancer with Gleason grade 5 can, however, be spread even at low levels.

Source: Prostatacancerförbundet (prostatacancer.se).

After treatment the level has a different meaning. After curative surgery or radiotherapy the PSA level should be very low, and after surgery an increase of just a few tenths means that there are remaining cancer cells.

Source: Prostatacancerförbundet (prostatacancer.se).

The PSA level is an important piece of the puzzle in the investigation, but it does not say how aggressive any cancer is. That assessment is made on the tissue sample, by a pathologist who grades the cancer according to the Gleason system Limitations of the Gleason method.

It is that grading which determines whether treatment is recommended or whether active surveillance is sufficient Surveillance vs. surgery. Because the assessment is based on human review of tissue, it can vary between pathologists – and it is precisely there that an independent analysis can give a more secure basis for the decision What is a second opinion?.