With Focal Therapy, Some Prostate Cancer May Be Left Behind
Do you have friends who are considering focal cryotherapy — or even paying $25,000 in cash to go to the Dominican Republic for HIFU (High Intensity Focal Ultrasound)?
Jonathan Epstein, M.D., the Reinhard Professor of Urologic Pathology, has been concerned about a new trend in treatment designed to minimize side effects by just removing the part of the prostate that has cancer. It's called focal therapy, and it's based on the assumption that the biopsy is infallible.
Think of dandelion seeds on a
windy day, and imagine that
your job is to catch and account
for each one. Each core from a
needle biopsy shows only one thousandth
of the prostate.
So even if a biopsy shows that
cancer is just found on one side
of the prostate, that might not
be the case at all.
One reason prostate cancer can become such a formidable enemy is that it's like dandelions in the field, sprouting up in multiple area of the prostate all at once. Even worse, think of dandelion seeds on a windy day, and imagine that your job is to catch and account for each one. Each core from a needle biopsy shows only one-thousandth of the prostate. This means that even if a biopsy shows that cancer is just found on one side of the prostate, that might not be the case at all. A needle biopsy has been compared to looking with a needle in a haystack, because it takes such tiny cores of tissue. Even if it takes a lot of them — more than a dozen — that doesn't mean that cancer is not in the remaining tissue. And it doesn't mean that this cancer can't be significant.
"Definitive therapy for prostate cancer, whether by surgery or radiation therapy, intends to treat the entire prostate," says Epstein. "The greatest concern with focal therapy is that it will leave significant cancer behind on the side not treated." Until now, no one had ever tried to answer this question. In work recently published in the Journal of Urology, Epstein and colleagues investigated 100 consecutive radical prostatectomy specimens in which the needle biopsy showed that cancer was restricted to one side of the prostate. When they looked at the entire gland, would the other side turn out to be cancer-free? Would it have been safe to leave this prostate tissue behind? "Each prostate had, on average, about three separate tumors," says Epstein, and in general, most of the tumor on the opposite side from the positive biopsy site was very small. But one out of five men turned out to have potentially significant cancer — cancer that was larger, of higher grade, or cancer that had even extended out of the prostate — on the other side of the prostate. "Had these men undergone focal therapy, this would not have been treated." An unanswered question, he adds, is, "how many more men who had small tumors on the side opposite to the biopsy may have progressed with adverse outcomes over time, if they had selected focal therapy? Patients should be told the risks of leaving cancer behind before undergoing this experimental therapy."