Precision treatment for prostate cancer
The world of cancer treatment is complex and as varied as every person diagnosed with the disease that occurs when abnormal cells divide in an uncontrolled way. As a radiation oncologist, I use radiation therapy to provide carefully targeted and regulated doses of high-energy radiation to kill cancer cells and shrink tumors.
Recently, a new era of treatment has been approved by the U.S. Food and Drug Administration (FDA) that we are now offering in the Cancer Center at Bothwell Regional Health Center. I first heard of this new treatment by attending scientific conferences. Following Nuclear Regulatory Commission (NRC) guidelines, Bothwell has been approved to offer a new theragnostic to treat metastatic prostate cancer in men who are PSMA positive.
PSMA means “prostate specific membrane antigen,” which is a molecule found on prostate cells and prostate cancer cells. About 1 in 8 men will be diagnosed with prostate cancer during their lifetime, and greater than 80% of men with prostate cancer are PSMA positive.
Theragnostics is a combination of the terms “therapeutics” and “diagnostics” and is a one-two punch that finds PSMA molecules on the prostate or anywhere in the body and delivers targeted medicine to kill the cancer cells. Because of its precision, theragnostics reduce the risk of harming nearby healthy tissues.
The principles for this treatment have been used for decades with other cancers, particularly thyroid cancers, yet therapies targeted at prostate cancer haven’t been available until now.
A typical patient would have metastatic prostate cancer and probably would have been treated with multiple regimes over the course of several years. They would have already received hormonal therapy and chemotherapy and have PSMA-positive prostate cancer, which can be identified using “positron emission tomography” or PET scan.
A PET scan is an imaging test that uses radioactive material to diagnose a variety of diseases. We use it to find tumors, diagnose heart disease, brain disorders and other conditions. The most common use of PET is cancer detection and cancer treatment evaluation. The amount of radiation during a PET scan is equal to about one or two chest X-rays.
Bothwell’s PET scanner is a mobile system that has been coming to the hospital every Monday morning and Wednesday afternoon for the last 15 years. Beginning about one year ago, Bothwell began to use a PSMA-labeled imaging tracer that allows us to detect prostate cancer cells anywhere in the body.
Patients receive the tracer injection at the hospital in our Nuclear Medicine department, wait an hour and then the scan is performed, which takes about 20 minutes. Our Nuclear Medicine chief technologist prepares the scan for radiologist review. If PSMA cancer cells are identified and the patient has met other criteria, they qualify for the new therapy.
The NRC has approved Bothwell to administer PLUVICTO® manufactured by Novartis. Pluvicto is composed of lutetium 177, a radioactive isotope, and PSMA-617, which binds to PSMA.
The patient returns to the hospital to receive Pluvicto, which is administered through an IV into the bloodstream and finds the PSMA positive cancer cells in a matter of two to three minutes. When Pluvicto is administered, it binds to PSMA-positive prostate cancer cells and then delivers radiation directly to the prostate cancer cells. Maximal penetration of the therapeutic radiation is about 2 millimeters.
Patients can return home with some radiation precautions regarding bathroom use, sleeping alone and getting plenty of water. They should also limit close contact with the general public for three days and with children and pregnant women for seven days. The treatment is repeated at six-week intervals for a total of six doses.
Pluvicto has been shown to improve the overall survival of men with metastatic prostate cancer. Side effects include decreased blood cell counts, fatigue and bladder infection. Its benefits are that there are no other treatments available that identify cancer cells and precisely kills them. Right now, the studies for the FDA-approved drug indicate the ideal timeline for receiving it; however, new studies are underway that may determine if the treatment can be moved up earlier in a patient’s treatment plan.
At Bothwell, I work closely with our medical oncologists, surgeons and other physicians to coordinate the most appropriate care for people with cancer in our communities. Our team continually works to provide the most available care that helps keep our patients close to home.
Dr. William Decker has worked for Bothwell Regional Health Center for 20 years and is the radiation oncologist at the Susan O’Brien Fischer Cancer Center. He is board-certified with the American Board of Radiology. Dr. Decker’s hobbies include playing musical instruments, snow skiing, theater and participating in an adult soccer league. He is an active member of the Sedalia community and participates in the Sedalia Symphony, Concert Band, Jazz ensembles and his church choir.