What is the prostate gland and how does it become cancerous?
The prostate gland produces part of the seminal fluid that protects sperm. It is located in front of the rectum and under the bladder, and surrounds the urethra, the tube through which urine flows from the bladder to and out of the penis.
Prostate cancer occurs when the cells of the prostate gland mutate and form a cancer. Male hormones (androgens), primarily the hormone testosterone, stimulate prostate cancer growth.
Most prostate cancer are adenocarcinomas, but there are other, less common types of prostate cancer, including sarcomas, small cell carincomas and transitional cell carcinomas.
What is the difference between prostate cancer adenocarcinomas, sarcomas, small cell carcinomas and transitional cell carcinomas? Do they require different types of therapy?
Prostate cancer adenocarcinomas comprise the vast majority (more than 95%) of cancers in the prostate. The growth of adenocarcinoma is primarily androgen driven and hence the main initial treatment for advanced disease is hormonal therapies to lower androgen levels.
The rarer forms are not androgen driven and are not treated with hormonal therapy. Small cell carcinoma, sarcoma and transitional cell carcinoma are primarily treated with chemotherapy aimed at that particular type of cancer.
What are the main treatments for prostate cancer and are these effective on advanced stages of the disease?
There are a number of different treatment options available for prostate cancer. The stage of the disease, age and health of the patient, and if the diagnosis is new or if the disease is recurring help clinicians determine which treatment or combination of treatment to prescribe.
Many prostate cancer treatments have side effects. It is important for patients and physicians to discuss what they may be and how they can be managed.
Some common treatments for localized prostate cancer include:
- Active surveillance (watchful waiting): Regular PSA tests and DRE to monitor disease progression; proactive treatment is initiated if the cancer causes symptoms or shows signs of growing.
- Surgery (radical prostatectomy): Surgical removal of the prostate and surrounding tissues.
- Radiation therapy: Using high-energy X-rays (radiation) to destroy cancer cells within the prostate. Brachytherapy is a type of radiation in which radioactive seeds or pellets are surgically placed into or near the cancer to destroy the cancer cells.
- Hormone therapy: Removing or blocking male sex hormones from working through surgery (i.e., surgical castration) or therapeutic methods (i.e., hormonal treatment) to prevent cancer cells from growing.
For patients with more advanced prostate cancer, options are growing and include:
- Immunotherapy/Vaccine Treatment
- Hormone Therapy
Certain oncology specialties such as breast cancer use a multidisciplinary approach (MDA). How important is this in prostate cancer treatments?
The growing prostate cancer treatment arsenal involves several clinical disciplines, making thoughtful treatment sequencing and coordination between specialists ever more vital. Against this backdrop, experts are increasingly recommending a multidisciplinary approach (MDA) as a best-practice standard for the care of patients with prostate cancer.
In the treatment of prostate cancer, the MDA team is usually comprised of a medical oncologist, radiation oncologist and urologist, as well as providers of several supportive services according to a patient’s needs. These other providers may include nurses, pathologists, psychologists, diagnostic imaging specialists, social workers, nutritionists, genetic counselors and pain management specialists.
By using an integrated and coordinated approach, the MDA team is able to provide patients with optimal care from the most appropriate specialists at a given time and more quickly identify patients who may benefit from combined treatments (such as radiation with hormonal therapy) or a change of course in treatment.
To determine the value of the MDA approach, in 2010, the Kimmel Cancer Center (KCC) of Thomas Jefferson University (TJU) reported on 15 years of experience with prostate cancer patients at its multidisciplinary clinic for genitourinary cancers, determining that the approach was successful in terms of both patients satisfaction and institutional data, which suggests improved outcomes in many men with locally advanced high-risk disease.
How has the therapeutic landscape for prostate cancer changed over recent years?
Until recently, treatment options for men with prostate cancer were very limited; however, since 2010, there has seen an increase in the number of treatments for advanced prostate cancer and its symptoms. These include a taxane chemotherapy – cabazitaxel (Jevtana), an immunotherapy – sipuleucel-T (Provenge), hormone therapies – abiraterone (Zytiga) and enzalutamide (Xtandi), and drugs to prevent skeletal complications of the disease – denosumab (Xgeva) and radium-223 (Xofigo). There are potentially even more new therapies on the way.
After years of the status quo, the availability of these novel options for advanced prostate cancer is transforming the way the disease is being treated.
What therapeutic approaches are experts studying at the moment to help patients with the disease live longer?
With more therapies available, researchers are now evaluating new treatment strategies including the appropriate sequence and combination of therapies to maximize outcomes. For example, physicians are considering earlier initiation of chemotherapy in hormone therapy patients whose disease is progressing, which has the potential to improve outcomes.
Having an expanded treatment arsenal also means that physicians must make other new decisions about which therapy is right for which patient. Historically, patient age has played a significant role in prostate cancer treatment decisions. However, research shows that age is not an independent predictor of prostate cancer–specific survival and that, in fact, less aggressive treatment in older men may be in part responsible for higher cancer-specific mortality rates observed with increasing age. Experts have asserted that optimal prostate cancer treatment should be based primarily on disease risk and other clinical factors rather than chronologic age.
What excites you most about the current research into prostate cancer treatments?
For years the only therapy that was effective for advanced prostate cancer was hormonal therapy. As we have advanced our knowledge of the pathophysiology of prostate cancer, many new therapies have recently emerged. We now can attack the cancer by blocking or inhibiting androgens, bolstering the immune system, killing dividing cancer cells with drugs that get around resistance, and effectively target cancer cells that have spread to bone.
I am most excited about how these strategies are prolonging the lives of men with prostate cancer. These therapies are a springboard for the development of even more effective, next generation drugs and combinations of therapies that will further improve the lives of these men.
What do you think the future holds for prostate cancer therapies?
New medicines, new combinations of medicines and new chemotherapy delivery systems hope to further improve the ability to cure or control cancer and improve quality of life. With the ever expanding number of active chemotherapy agents and other newer therapies, it is expected that the number of cancers effectively treated and cured using combined treatment modalities will continue to increase.
Where can readers find more information?
Readers can find comprehensive information about prostate cancer at:
About Dr. Nancy Dawson
Internationally-recognized genito-urinary cancer expert Nancy Dawson, MD, joined the Lombardi Comprehensive Cancer Center in 2007 as director of clinical research and attending oncologist at the Prostate Cancer Research and Treatment Center. When she began treating prostate cancer patients in the early 1980s, Dr. Dawson was one of the first oncologists—as opposed to urologists—to specialize in the disease. At Georgetown, she will continue developing novel approaches to the treatment of prostate, bladder and kidney cancers.
A 1979 graduate of the Georgetown University School of Medicine, and a military physician for 20 years, Dr. Dawson was recruited from the University of Maryland Greenebaum Cancer Center, where she was a professor of medicine and director of the genito-urinary medical oncology program. Board-certified in internal medicine, hematology, and oncology, Dr. Dawson retired as a colonel in the United States Army in June 1999. She began as a teaching fellow in the Department of Medicine at the Uniformed Services University of the Health Sciences in 1979 and held numerous positions at Walter Reed over the next 20 years, including Director of Clinical Research, Chief of Hematology-Oncology Service and Consultant to the Surgeon General of the Army. She has also served as a senior investigator position in the signal Transduction and Oncogenesis Section of the Medical Branch of the National Center Institute.