Scientists
in Ireland have developed a technique they hoped would be a more
reliable and accurate method to detect prostate cancer, in findings
recently published by the peer-reviewed open access scientific journal Advances in Modern Oncology Research (AMOR).
Prostate
cancer, afflicting mostly males over age 60, is the second most
commonly diagnosed cancer in men (after skin cancer) and is among the
leading cause of cancer-related deaths in men, according to World Health
Organization.
Common screening routines for prostate cancer are
blood test to detect elevated level of a protein produced by the
prostate called prostate-specific antigen (PSA), and/or a digital rectal
exam (DRE) in which a doctor feels the prostate through the rectum to
search for lumps known as nodules.
If PSA or DRE test results are
abnormal, there are several tests which can be administered to help
confirm a diagnosis of prostate cancer, according to the American
Society of Clinical Oncology’s recommendation. A magnetic resonance
imaging (MRI), for instance, uses magnetic fields to produce detailed
images of the body and measure the tumor’s size.
A transrectal
ultrasound (TRUS) test, meanwhile, is a procedure in which a doctor
inserts a probe into the rectum to capture images of the prostate using
sound waves. TRUS is usually done at the same time as another test: core
needle biopsy, in which a thin, hollow needle pierces through the
rectum wall to remove a small core prostate tissue for microscopic
examination.
While other tests may suggest that cancer is present,
only a biopsy can usually make a definite diagnosis. However, the
Trinity College Dublin scientists led by Dr Diarmaid C Moran and Dr
Laure Marignol noted that only 25%-30% of men with moderately elevated
PSA eventually have prostate cancer confirmed at biopsy, and therefore
many biopsies may ultimately prove unnecessary.
Despite PSA still
being recommended after a confirmed diagnosis of prostate cancer, new
clinical screening tools and strategies are clearly required to decrease
the unnecessary biopsy rate. Hence, “there is a growing demand for
individualized treatment plans, which necessitates the accurate
characterization of the location, extent and aggressiveness of the
tumor,” Moran and Marignol’s team stated.
According to the
scientists, “There has been great interest in determining the presence
or absence of tumor non-invasively with combined anatomical and
functional MRI.” Their findings proposed combining high resolution
images and functional techniques using MRI upon diagnosis based on
TRUS-guided biopsy performed.
“MRI is well-validated for local
staging of prostate cancer using qualitative assessment, including
high-resolution T2W images once the diagnosis has been established by
TRUS biopsy,” they noted.
The study sought to determine the
accuracy of three Apparent Diffusion Coefficient (ADC) threshold values
in detecting prostate cancer prior to prostate biopsy in patients
undergoing endorectal diffusion weighted (DW)-MRI.
Variations in
cellular structure between benign and malignant tissue would manifest as
differences in water diffusion. These differences can be exploited to
improve prostate cancer detection qualitatively but also quantitatively
by measuring changes in the ADC to potentially measure the
aggressiveness of the tumor, according to the scientists.
The
Dublin team studied 60 men with a clinical suspicion of prostate cancer
who underwent endorectal DW-MRI at 3.0 Tesla. Three ADC threshold values
(tADC: 1.0, 1.2 and 1.4x10-3mm2/s) were sequentially applied to ADC
maps for the detection of malignant lesions in the prostatic peripheral
zone.
The results, specifically at tADC 1.0x10-3mm2/s, proved
“considerably more accurate than PSA alone and offers promise as a tool
for not only screening of peripheral zone prostate cancer but
potentially also for characterizing its aggressiveness,” their findings
noted. This concept is particularly important in the context of
over-diagnosis and over-treatment of clinically insignificant cancers.
The
study duly acknowledged that more large-scale, adequately powered,
randomized and standardized studies are needed to determine whether
Gleason-score-specific (the most common grading system for prostate
cancer’s prognosis) ADC values can be established.
“If this could
be achieved, incorporation of ADC values into a diagnostic algorithm in
combination with other clinical parameters such as PSA and DRE might
ultimately allow low-risk patients to forego biopsy,” the scientists
said.
Additionally, for patients undergoing a policy of active
surveillance, decrease in the ADC values over baseline during serial
follow-up might signal an imperative for change to active treatment,
they concluded.
Reference:
Threshold-based
parametric analysis of diffusion-weighted magnetic resonance imaging at
3.0 Tesla to identify men with prostate cancer , Diarmaid C
Moran, Laure Marignol, Andrew J Fagan, Ruth Dunne, Antoinette S Perry,
Dearbhail O'Driscoll, Eoin Gaffney, Thomas H Lynch, James F M Meaney,
Donal H Hollywood, Advances in Modern Oncology Research, doi:
10.18282/amor.v1.i2.37, published December 2015.
Source: Piscomed Publishing
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