Scientists at Weill Cornell Medical College in New York have attached a chemical tag (the isotope lutetium-177) that emits small amounts of radiation onto a monoclonal antibody (J591) that targets prostate cancer cells in bone, soft tissues and circulating blood that carry the protein antigen, prostate-specific membrane antigen (PSMA). Treatment with 177Lu-J591 may be optimally suited to patients with micro-metastatic disease. The developers of this therapy postulate that such treatment in men who have small volume disease not seen on bone scans could even result in a cure for some patients. They specifically refer to men who have had surgery and/or radiation at their primary prostate tumor site who are then experiencing rising PSA levels (biochemical failure) but their bone and CT scans remain negative for metastatic cancer. Results of a Phase II clinical trial of 177Lu-J591 in men who had failed hormonal therapy are summarized in a Jan. 31st, 2014 article from the Prostate Cancer Foundation (PCF). A subsequent Phase II clinical trial at Weill Cornell Medical College and twelve other centers is underway to determine if 177Lu-J591 can delay or prevent overt metastatic disease in men with rising PSA levels after primary treatment and early hormonal therapy but in whom bone and CT scans remain negative. The PSMA antigen is also expressed in other tumors such as liver, breast and kidney; hence this targeted radiotherapy could possibly be used in tumors other than prostate cancer. For further details, see the linked PCF article.
As we have come to expect, the Johns Hopkins Medicine Health Alerts always contain useful information for prostate cancer patients. For example, the January 19th, 2014 issue contained a primer describing the basic concepts and rationale of hormonal therapy. The February 9th edition reported three published studies which link coffee drinking and caffeine to a risk reduction for several types of cancer including aggressive prostate cancer, and its recurrence and progression. Thirdly, the February 16th issue described a study that concluded that PSA velocity (the rate of PSA change over time) “accurately predicted which men would develop prostate cancer and was significantly more accurate than a single PSA measurement in predicting which men would develop aggressive disease.”
I recently heard an interesting talk given by my local urologist in which he traced the history of prostate biopsies to detect cancers. I’d like to share a couple of insights that I learned. When my own cancer was first detected in 1995, the surgeons collected six samples via the trans-rectal route. I assume that at that time, this was the standard protocol. Currently, I understand twelve samples is the norm. However, my urologist stated that the trans-rectal route can easily miss cancers located in the anterior tissues of the prostate gland. Therefore, he recommended that the best route for biopsies is trans-perineal, i.e., the genital area between the scrotum and anus. This route provides better access to the anterior prostate. He also mentioned that a value called PSA-density, i.e. the amount of PSA produced per volume of gland, continues to be a useful indicator of possible malignancy. PSA density values have been used since the 1990’s. In fact, without realizing it personally, I had used it in my own case in 1995. An ultrasound had revealed that my prostate was not especially enlarged yet my PSA was consistently somewhat high in the 4.o ng/ml range. Naively, I reasoned that if a smaller gland was producing a higher than normal amount of PSA, something might be wrong. I was correct. Numerical guidelines for PSA densities are available though I don’t have that information at hand. My urologist also discussed the increasing use of magnetic resonance imaging (MRI) in guiding biopsies and delineating the prostate and surrounding tissues. An excellent overview of prostate MRI was written by UCLA Radiologist Dr. Daniel Margolis and published in the November, 2010 issue of the Prostate Cancer Research Institute (PCRI) Insights. An on-going clinical trial at the National Cancer Institute using MRI-guided focal therapy to treat low-risk, localized prostate cancer was also posted on this website on July 11th, 2012.