Applying population dynamics modeling to patients with lymph node positive prostate cancer.
OBJECTIVE
We previously reported the applications of population dynamics modeling on cancer populations. Cancer death populations show a reproducible progression from an essentially linear phase, in which cure is likely, through a Gompertzian phase of advancing disease to an exponential phase of incurable disease. The latter 2 phases meet at an inflection, at which the disease process becomes incurable. Patients with prostate cancer and positive lymph nodes are often considered to be doomed to distant failure. We applied these models to that population to examine whether those data support this presumption.


METHODS
The public use Surveillance, Epidemiology and End Results Registry was queried for observed survival data on the population of men with nonmetastatic prostate cancer and positive lymph nodes presenting between 1988 and 1993. Lymph node data were first collated in 1988. The closing date was selected to allow a minimum 10-year followup since Surveillance, Epidemiology and End Results data are complete through 2003. These data were modeled using Gompertzian and exponential models to determine whether an inflection point exists.


RESULTS
Gompertzian modeling best described the observed survival of the 2,265 patients retrieved from the Surveillance, Epidemiology and End Results Registry. Analysis of the data revealed an inflection 4 years after diagnosis. We interpreted this to indicate that there is a 4-year window during which curative therapy may be initiated in this population of patients.


CONCLUSIONS
Patients with lymph node positive prostate cancer need not be considered to represent a doomed population, although new therapies are crucial in that case. We theorize that a 4-year window exists during which potentially curable therapies may be performed.
Johnstone
Peter A S
PA
Department of Radiation Oncology, Emory University School of Medicine, Atlanta, Georgia 30322, USA. peter@radonc.emory.org
Riffenburgh
Robert H
RH
Rossi
Peter J
PJ
Assikis
Vasily
V
Master
Viraj A
VA
Jani
Ashesh B
AB
D005500:Follow-Up Studies; D006801:Humans; D008207:Lymphatic Metastasis; D008297:Male; D015233:Models, Statistical; D011157:Population Dynamics; D011471:Prostatic Neoplasms / Q000453:epidemiology* / Q000556:secondary; D012189:Retrospective Studies; D018426:SEER Program / Q000706:statistics & numerical data*; D015996:Survival Rate / Q000639:trends; D013997:Time Factors; D014481:United States / Q000453:epidemiology