PIN, or Prostatic Intra epithelial Neoplasia, is a pre-cancerous condition of the prostate. PIN does not cause PSA elevation. It is typically discovered as an incidental finding on a prostate biopsy performed for an unrelated condition such as benign prostatic hypertrophy.
Nine percent, or 115,000 of the 1.3-million prostatic biopsies performed annually, return with a diagnosis of high-grade PIN.
It is estimated that 9.4-million men between the ages of 40 and 69 harbor PIN without symptoms and/or knowledge of the fact that they have it.
Based upon retrospective studies, untreated high-grade PIN bears a risk of 39 percent probability of transforming into full blown cancer in one year, a 60 percent chance in two years and a 75 percent chance in three to five years.
Because PIN does not alter PSA levels, there is no good way of monitoring these patients except by repeated prostatic biopsies every three to six months until invasive prostatic cancer is diagnosed. Then a more aggressive treatment such as radical surgery, radiation or a combination of the two is employed.
Dr. Mitchell S. Steiner, the founder and chief executive officer of GTX, a Memphis study group, presented the results of a multi-institution, randomized, double-blind, placebo-controlled study involving 514 men with PIN treated with varying doses of Toremifene at the annual meeting of the American Association for Cancer Research (AACR).
Like Tamoxifen, Toremifene is a selective estrogen receptor blocker. It is well known that both estrogen and testosterone participate in prostate carcinogenesis. Steiner's study found a 22 percent reduction in prostate cancer at the end of six months of treatment of PIN with 20mg of Toremifene, and a 48 percent reduction by 12 months of treatment.
In a previously reported prostate cancer prevention study, Proscar reduced the incidence of prostate cancer but caused an excess of high grade cancers. Unlike Proscar, Toremifene did not cause any excess of high grade cancers.
Compared to the placebo group, Steiner said, there was no difference in the rate of erectile dysfunction, libido or gynecomastia. Additionally, there was no incidence of deep vein thrombosis in patients while taking Toremifene.
Toremifene treatment of patients with PIN appears to decrease the incidence of prostate cancer in a statistically and clinically significant manner.
Currently there is no approved treatment for PIN. If the phase III trials that began this month validate the efficacy of Toremifene, millions of men that harbor PIN will be potential beneficiaries.
Dr. V. Upender Rao, FACP, practices at the Cancer and Blood Disease Center in Lecanto.