Cancer of the prostate is typically a slow growing tumour that affects older men. Prostate cancer has a
long latent period and the potential to be cured is also high. Screening of
prostate cancer is done by digital rectal examination and PSA testing. PSA
stands for Prostate Specific Antigen. It is a glycoprotein (an enzyme) produced
exclusively by the prostate. Only small amounts of PSA escape into the
circulation under normal circumstances. With distortion in its architecture or
an enlargement the serum PSA levels increase. PSA is a widely used screening
tool for prostate cancer because of the benefits like early detection and
diagnosis that it provides. However, controversies exist over its ability to
PSA screening cannot
predict if a prostate cancer is aggressive or not. The cancer may be lethal or
nonlethal. An early detection and screening is definitely useful for a man with
a lethal prostate cancer, but this is not the case with one having a nonlethal
form of the cancer. Men with nonlethal prostate cancer gain no benefits at all.
These men get 'over diagnosed' and 'over treated'. 'Over diagnosis' adds up the
burden of carrying a cancer diagnosis while 'over treatment' leads to purely
unwanted side effects that they never deserved.
The success of a
screening test depends on its capacity to find the disease that requires cure,
and on its power to meliorate disease-specific mortality. PSA screening may
provide no benefits at all for men with low baseline values.
The cut-off for PSA
levels vary with age. A study was done by a team lead by Pim van Leeuwen, MD,
of the Erasmus University Medical Centre in Rotterdam, the Netherlands. They attempted to make out if the baseline PSA can predict
which men have most benefit from screening.
The study has indicated
that a man's PSA level before diagnoses is indeed a good predictor for his
dying from prostate cancer, but the benefit of such a screening is limited for
men aged 55 to 74 years with low baseline PSA values. Instead, over treatment
and increased costs walk in. A developing country like India cannot afford this. Further studies are recommended.
"Balancing the harms and benefits of early detection of prostate cancer." Pim
J. van Leeuwen, David Connolly, Teuvo L.J. Tammela, Anssi Auvinen, Ries Kranse,
Monique J. Roobol, Fritz H. Schröder, and Anna Gavin. CANCER; Published Online:
September 13, 2010 (DOI:
CANCER, a peer-reviewed publication of the American Cancer Society