Types of Prostate Cancer
Prostate cancer is the most common cancer among men in the Unites States after skin cancer. But prostate cancer can affect men differently. It can be very slow to grow or it can be aggressive prostate cancer, spreading quickly to other parts of the body. Your oncologist needs to know what type of prostate cancer you have and how advanced it is. This information helps determine how the cancer cells might respond to treatment.
For early prostate cancer, some doctors and patients take a watch-and-wait approach, while advanced prostate cancer or cancer that has spread (metastatic prostate cancer) requires more aggressive treatment.
Diagnostic tests that help your doctor determine the type and stage of the prostate cancer include an ultrasound of your prostate, a biopsy to test prostate tissue samples, and MRI (magnetic resonance imaging). After the biopsy, the cancer is assigned a Gleason score, which is one indicator of the prognosis, or possible outcome. Lower Gleason scores (2 to 4) are usually less aggressive cancers, while higher scores (7 to 10) are more aggressive.
For you or your loved ones to understand a prostate cancer diagnosis, it’s helpful to have background information on the different types of prostate cancer.
The most common type of prostate cancers are adenocarcinomas, also called glandular prostate cancers. These make up about 99% of all prostate cancers. They develop from glandular cells that make the prostate fluid. There are subtypes of prostate adenocarcinomas:
Acinar adenocarcinoma is the most common prostate cancer and is often called conventional adenocarcinoma. As many as 95% of adenocarcinomas are this type. The cancer cells start growing in the periphery, or the outer part of the prostate. This is the type of cancer your doctor may feel during a digital rectal exam.
- Ductal adenocarcinoma of the prostate is much less common and when it does occur, it is often in conjunction with acinar adenocarcinoma. The cancer cells are more centralized in the prostate, although the cells can still affect the periphery. It is a more aggressive prostate cancer than acinar adenocarcinoma and is usually given a Gleason score of at least 4.
There are even rarer forms of adenocarcinoma, including mucinous (colloid) carcinoma, cribriform carcinoma, squamous cell cancer, sarcomatoid carcinoma, carcinosarcoma, and prostate duct adenocarcinoma, or PDA. These affect a very small percentage of men diagnosed with prostate cancer.
Also called urothelial cancer, transitional cell carcinoma represents about 1 to 4% of prostate cancers. This cancer begins in the urethra and spreads to the prostate. It can begin in the prostate itself, but this is even rarer. It is usually diagnosed only after symptoms appear, such as difficulty urinating.
A neuroendocrine tumor in the prostate is a type of cancer that doesn’t produce prostate-specific antigen, so these tumors are not detected by the PSA blood test. Although neuroendocrine prostate cancers are rare, the most common is an aggressive type called small cell prostate cancer. Even rarer is large cell prostate cancer.
This type is not well understood by doctors. Because it is so rare, there is not enough data for doctors to tell for sure if it is an aggressive or slow-growing type of prostate cancer. Some studies show it may be more aggressive than adenocarcinomas of the prostate gland.
These tumors are cancers that develop in the smooth muscle of the prostate, not within the prostate glands as other prostate cancers do.
Men whose prostate cancer that does not respond to treatment or whose cancer returns after certain types of hormone therapy or removal of the testes (orchiectomy) has castration-resistant prostate cancer. Prostate cancer that does not respond to any type of hormone therapy is hormone-refractory prostate cancer.
Treatments for prostate cancer depend on how advanced the cancer is, and if it is a first-time diagnosis or recurrent cancer (cancer that returns after an initial course of treatment). Treatment options include radiation therapy, hormone therapy, chemotherapy, targeted therapy, and prostatectomy. Treatment for advanced metastatic prostate cancer (stage 5, or V) is generally designed to relieve symptoms and slow the cancer’s growth as much as possible. Palliative cancer care is a type of treatment for all stages of cancer, but is especially important for advanced prostate cancer (stages 4 and 5).
When prostate cancer is detected early in the disease, you and your oncologist may choose an ‘active surveillance’ approach. This recommendation is generally for men who have a low-staged cancer that is not expected to progress rapidly and isn’t causing symptoms. If you decide on this approach, you will have blood tests every 3 to 6 months and a biopsy within 6 to 12 months after initial diagnosis. The biopsy can be repeated within 2 to 5 years, or sooner if the cancer is progressing.
Men who are older or who have other life-threatening illnesses may be candidates for ‘watchful waiting.’ With watchful waiting, you do not undergo frequent, invasive testing. One of the reasons for watchful waiting is a slow-growing prostate tumor can behave more like a chronic disease rather than a fatal condition. Watchful waiting is an acceptable option for any man (regardless of age) with a low-grade prostate tumor. Your oncologist will only recommend treatment if the tumor causes bothersome symptoms, such as difficulty urinating.
Although treatment is similar for the different types of prostate cancer listed above, knowing what type and stage of prostate cancer you have is important for treatment success. It helps you understand the treatment plan your doctor designs for you, and may help identify if you are eligible for a clinical trial. Trials look at new and better ways to treat prostate cancer. Many trials are specific for a particular stage, such as early stage prostate cancer or advanced prostate cancer. The trial may also consider the type of prostate cancer, such as neuroendocrine prostate cancer.