New plastic devices target prostate cancer

October 12, 2011


Testing and treatment of prostate cancer is triggering both a huge public debate in the United States and an outpouring of interesting new technology using plastics devices. At the heart of both issues is the extent of the problem.

Prostate cancer is second behind lung cancer as the type of cancer that causes the most fatalities among men in the U.S., according to Cancer Facts & Figures 2011 published by the American Cancer Society. One in six men is likely to have prostate cancer at some time of their life, making it the most common cancer among men.

Insert-molded prostate biopsy device.
Two steel tubes are insert molded in ABS in a new device aimed at improving the effectiveness of prostate biopsies.

A search of the U.S. patent database turns up more than 40 mentions of the words "prostate" and "plastic" in the past two years. Many of the inventions deal with one of the controversies surrounding prostate treatment, the unintended damage to sensitive surrounding tissue that can result from treatment. 

Medi-Physics Inc. (Princeton, NJ) was awarded a patent Oct. 11 for an implantable device molded from bioresorbable material that provides radiation treatment close to a cancerous tumor. This type of emerging treatment, called brachytherapy, can avoid damage to the urethra, which is adjacent at one point to the prostate gland. Damage to the urethra can cause incontinence or impotence. The radioisotope that may be placed in the Medi-Physics invention is identified as iridium-192. One of the technology advances described in the patent is an improvement in molding of the polymer to boost its rigidity.

Envisioneering Medical Technologies (St. Louis, MO) was awarded a patent last year for a device that targets biopsy tissue in the prostate gland. This invention deals with another problem- the damage done by biopsies.

If prostate cancer is suspected from either a physical examination or due to a Prostate Specific Antigens (PSA) test, a biopsy is usually recommended by a primary care physician to collect tissue samples from the prostate for evaluation by a pathologist. Typically, nine to 18 tissue samples are taken from different areas of the prostate.

According to the patent filing: "Existing biopsy methods suffer from a number of disadvantages...it's difficult for physicians to precisely target biopsy sample locations, often causing the need for additional samples to be taken. Further, if a sample seems to confirm cancer, it is difficult for the physician to accurately know where in the prostate the sample was taken from."

The Envisioneering invention consists of a software-driven biopsy needle guide that works with a transrectal ultrasound probe and a bendable needle set. A newly developed dual-channel needle guide is composed of two 13-gauge stainless steel tubes that are insert molded with acrylonitrile-butadiene-styrene (ABS) by Plas-Tech Engineering  (Lake Geneva, WI). Michael Belgeri, director of operations for Envisioneering Medical Technologies, says:  "The part has a complex geometry which requires tight sealing at four locations, with a smooth flash-free finish for patient comfort." Plas-Tech is molding the part on a 120-ton JSW electric press. The tool, designed and built by Plas-Tech, has a spring-loaded design feature to retain tubes during molding.

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