Prostate Cancer & PSA Testing
Recently, more men in Australia are being diagnosed with prostate cancer, said to be the primary cause of cancers. Reportedly, it was the reason for about 30% of tumours in 2006. This is likely the result of prostate specific antigen (PSA) testing in asymptomatic men. Normal and abnormal tissues produce PSA that increases with the growth of prostate in older men, in benign conditions like Benign Prostatic Hypertropy or in prostate cancer.
There are pros and cons in PSA testing hence the controversy behind its purposes. Understanding them could help you understand the risks and the treatments involved in prostate cancer.
In every 100 men with prostate cancer who undergo radical prostatectomy, 1 dies after the operation. A big percentage suffers from erectile dysfunctions while about 20% may encounter urinary incontinence.
- PSA testing can detect early prostate cancer that has no symptoms.
- Early detection could stop the progress of cancer and treatment is likely to be potentially curative.
- Treatment side-effects and risks are unlikely as significant as that of advanced cancer stage.
- Slow growing prostate cancers may not immediately threaten life but treatments may affect quality of life.
- PSA test can have an abnormal result even when there is no cancer or be normal even with the presence of cancer.
- Clinical evidence of lives saved or lives prolonged by PSA testing & monitoring is yet to be established.
The statistics in 1000 men:
For a man in his 40s – 1 in 1000
For a man in his 50s – 12 in 1000
For a man in his 60s – 45 in 1000
For a man in his 70s – 80 in 1000
While the value of PSA is being established, understanding what it is and its terminologies is important.
Single PSA Level – this is the assessment of the possible progress of prostate cancer based on a single PSA test. According to the Baltimore Longitudinal Study of Ageing, an over 75 year-old man is likely to succumb to prostate cancer while 25% of men with a PSA of 3-4 are with prostate cancer.
Free to Total PSA Ratio (FTTR) – this differentiates high PSA caused by malignant reasons from non-malignant reasons. Cancer-derived PSA affects plasma proteins hence a low FTTR may indicate that the PSA was caused by cancer.
PSA velocity (PSA-V) – with a PSA that is lower than 10, it is better to group it in 3 based on increase rate.
PSA <10 and PSA-V <0.3 ng/mL/yr - Unlikely a significant prostate cancer
PSA<10 and PSA –v>0.75ng/mL/yr - Possible malignancy; for further investigation
PSA<10 and PSA-V>1.0ng/mL/yr - Prostate biopsy recommended
PSA Doubling Time (PSA-DT) – this increase may indicate possible metastasis of the disease applicable before or after a radical surgical treatment. Its reliability is still questioned but the results are used as reference.
PSA-DT >1 year - Tumour (if present) is likely to be confined to prostate
PSA-DT <9 months - Suggests metastatic disease
PSA <3 in men aged <75 years - Patient unlikely to die from prostate cancer
PSA 3-4 - 25% may have prostate cancer
Source: Prostate Cancer Foundation of Australia