Michael W. Kattan,
Front
Oncol. 2016; 6: 123.
This
common analogy for describing newly diagnosed prostate cancer patients appears
to be attributable to Hinman,* who borrowed from Crile when applied to breast
cancer.
·
Turtles are patients with very slow
growing disease. Their disease grows so slowly that they need not be diagnosed,
for the disease will never spread to the point of causing problems within the
patient’s lifetime. A turtle will die of another cause, not prostate cancer.
·
The bird has been diagnosed too late
to have impact on the disease. It has already spread and cannot be meaningfully
slowed down, to the point where the patient is likely to die of his prostate
cancer. The bird is similarly not helped much by a diagnosis of prostate cancer
since it is already too late to stop the disease.
·
The rabbit sits in the sweet spot. The
rabbit is the man with prostate cancer who needs to be diagnosed (his disease
spreads faster than that of the turtle and indeed poses a threat to his life),
yet the disease is still curable (unlike the disease borne of the bird).
This
model holds for many other cancers, perhaps most. It can be helpful when
patients or physicians think about screening and treatment.
*The value of screening for prostatic carcinoma: a
commentary.
Hinman F Jr. Urol
Int. 1991;46(3):275-8.
Abstract
Can routine digital rectal examinations, transrectal
ultrasound studies, and prostate-specific antigen determinations reduce deaths
from prostatic carcinoma? The evidence is that the benefits of early diagnosis
and treatment are at least neutralized by the limited reliability and high
monetary and human costs of the test and by the lack of proof that treatment is
effective for those tumors detected. One must conclude that universal screening
is not now warranted and will await demonstration of effectiveness by
controlled studies.
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