ATLANTA, Oct. 10 /PRNewswire/ -- A new study completed by Atlanta
radiation oncologists and just released in the September issue of The Journal
of Urology substantiates the effectiveness of simultaneous radiation for men
with early stage prostate cancer. The study, conducted by Atlanta-based
Radiotherapy Clinics of Georgia (RCOG), documented that all men with early
stage prostate cancer who were treated with modern, simultaneous radiation
(transperineal implantation followed by external beam radiation) demonstrated
an overall 88% five- and seven-year disease-free survival(1). Of equal
importance, the cure rates were calculated with an undetectable PSA (prostate
specific antigen) of 0.2 ng/ml. According to Dr. Frank Critz, Medical
Director of RCOG, how cure rates are calculated is just as important as the
results because there is no standard definition of PSA cure of prostate
To illustrate this point, Dr. Critz notes Dr. Frank Vicini's medical
research paper published in The Journal of Urology(2) as an excellent example
of manipulating cure rates. Dr. Vicini treated a large number of men with
linear accelerator irradiation alone. He then calculated five-year cure rates
in this same group of men but used different post-treatment PSA nadir levels
to define freedom from prostate cancer. (PSA nadir means the lowest PSA
measured after treatment.) The men had pre-treatment PSAs ranging from
4.1-10.0 ng/ml. The five-year cure rate was 74% when calculated with PSA nadir
of 4.0 ng/ml. It dropped to 54% when calculations were made with PSA nadir
1.5 ng/ml, and dropped even further to 45% when calculated with PSA nadir
"Had Dr. Vicini used PSA nadir 0.2 ng/ml, the cure rate would have been
significantly lower," explains Dr. Critz. "In other words, if an investigator
of radiation wants to make his cure rate better, all he has to do is calculate
his results with a high PSA nadir number. We found that unless men achieved
at least PSA nadir 0.2 ng/ml after irradiation, they would not be cured of
Dr. Critz' demand that PSA 0.2 ng/ml be the standard definition for
disease freedom from prostate cancer, whether treated by surgery or
irradiation, has created a national controversy in the radiation community.
Virtually all radiation oncologists calculate cure rates with the ASTRO
Committee definition of disease freedom. The ASTRO Committee definition is
based on a rising PSA after treatment and not on PSA nadir. Dr. Critz and the
doctors from RCOG argue against this definition because it produces
inaccurate, inflated cure rates.
"Defining disease freedom as PSA nadir 0.2 ng/ml for radiation treatment
is the same definition used after radical prostatectomy," states Dr. Critz.
"What upsets the radiological community is that PSA cutpoint 0.2 ng/ml
produces significantly lower cure rates from the ASTRO Committee definition of
disease freedom commonly used by radiation investigators."
The study referenced in the recently published article, conducted from
August 1992 through November 1996, followed 689 men ranging from 45 to
88 years of age (median age of 66) with clinical stage T1-T2, N0, Nx prostate
cancer. These patients were treated with modern, ultrasound guided
transperineal 125-I iodine seed implantation followed by three-weeks of
external beam irradiation. Treatment failure was defined as PSA nadir greater
than 0.2 ng/ml or a subsequent PSA increase above this level. Follow-up was
performed every six months starting from the date of implantation. Median
follow-up was four years.
Compared with other published cure rates after irradiation, simultaneous
irradiation has the highest documented cure rate for radiotherapy of prostate
cancer in the United States. With disease freedom calculated using PSA nadir
0.2 ng/ml, the overall cure rate of 88% is superior to the next highest
published cure rate of 55%.
"The physicians at RCOG strongly suggest a universal, standard PSA
definition of disease freedom for prostate cancer be used for all clinical
research, surgery or irradiation, and recommend this definition be PSA
cutpoint 0.2 ng/ml," says Dr. Critz. "We challenge all radiation oncology
investigators to calculate their results with PSA cutpoint 0.2 ng/ml. Only by
calculating with the same definition can treatment results be compared fairly.
This will allow patients to equitably compare prostate cancer treatments
across all modalities and choose the option -- and the physician -- that is
right for them."
RCOG prioritizes extensive physician training as opposed to two-day seed
implant courses; and its research findings have been published extensively in
scientific, peer-reviewed medical journals.
(1) Results of pretreatment PSA groups 4.0 ng/ml or less were 94%; 4.1 to
10.0 were 93%; 10.1 to 20.0 were 75%; and greater than 20.0 were 69%.
(2) The Journal of Urology 158:319-325,1997
SOURCE Radiotherapy Clinics of Georgia