Early diagnosis is the diagnosis of a cancer before it begins to produce symptoms. This diagnosis can be carried out by an individual or form part of so-called regional screening or early diagnosis. These campaigns call on groups at risk of developing a particular type of cancer.
In order to carry out an early diagnosis, one needs a reliable screening method (a mammogram for instance) or analysis (PSA for prostate cancer, Fecatest or occult blood analysis in faeces for intestinal cancer).
The test tool used on high risk groups must help reduce mortality rates resulting from the cancer which predominates in this group.
The perhaps best known case is breast cancer. Through so-called screening campaigns and mammograms performed on women who do not present apparent symptoms of breast cancer, it is possible to detect breast cancer from its very early, hence curable, stages. Used in this manner, mammography allows a decrease in mortality rates of 30% in women aged between 50 and 65.
Is there anything similar in place for prostate cancer?
This is a controversial topic. On the one hand, there is in fact a method which enables the early diagnosis of prostate cancer, called PSA (see further) but on the other hand, campaigns which make use of PSA and early diagnosis of prostate cancer have so far not been proven to reduce mortality rates for this type of cancer.
This is why there is no worldwide consensus in terms of advising all men at risk of developing prostate cancer to periodically submit to a PSA.
Let’s talk about PSA
PSA (as it is known due to the acronym of its denomination in English, or prostate specific antigen) represents a genuine revolution in the early diagnosis of this type of cancer.
PSA is exclusively produced by on type of tissue, namely the epithelium of the prostate, which is what makes it so specific.
How is this assessed?
By a simple blood test.
How is it measured?
Analysts provide the test results in nanograms per millilitre (ng/ml).
As a general rule, the PSA value is considered normal when under 4 ml/ng, suspicious between 4 and 10 and possibly indicative of prostate cancer when the value exceeds 10.
These numbers are used for guidance purposes only and prostate cancer can be diagnosed even when the value is below 10.
The higher the PSA level, the greater the risk; PSA alone is however never considered definitive evidence but rather a significant warning sign.
Is it possible for PSA to increase in the absence of prostate cancer?
Yes, it is. This is why it is unadvisable to carry out a PSA under any of the following circumstances:
a)Ejaculation may temporarily raise PSA level, meaning that one should refrain from sexual activity two days prior to the analysis.
b)This can also arise as a result of prostate inflammation, infection, benign hyperplasia (increase in size) and rectal examination.
c) Some drugs such as finasteride which are used in the treatment of benign hyperplasia may also increase its levels.
What is free PSA?
This is the PSA which circulates in the bloodstream without being protein bound like the hence forth described PSA.
What is the use of free PSA?
Especially in non definite cases (PSA between 4 and 10 ng/ml), a low percentage of free PSA over the total PSA suggests the likelihood of cancer.
Conversely, high levels of free PSA likely point towards a benign case.
It is therefore not sufficient to determine total PSS levels; free PSA must also be measured.
What is the contribution of PSA in terms of prostate cancer?
Ever since its introduction in the nineties the presentation model of prostate cancer has changed dramatically.
Indeed prior to the introduction of this test, most men readily displayed skeletal symptoms at the time of their initial cancer diagnosis, with the characteristic pain in the bones confirmed by x-rays. Those cases were thus already incurable.
This model has turned things around. Nowadays, most prostate cancer sufferers are diagnosed while the cancer is still confined to the prostate and thus curable.
As a matter of fact, prostate cancer-related mortality has gone down in recent years.
This evolution may not be solely due to PSA. There is however a very direct correlation between its introduction and the reduction in mortality.
Does PSA have any other fields of application?
PSA is very useful in helping to monitor patients after their treatment. As long as PSA levels fall within normal ranges, the illness is considered absent.
Conversely, if periodic checks show an increase in PSA, further tests should be carried out to see if the disease has progressed.
The implication is that a person who ahs undergone treatment for prostate cancer must submit to periodical PSA analyses.