Types of prostate cancer: Common and rare forms

The type of prostate cancer that you have is an important piece of information that your healthcare team uses to decide on treatment and determine your prognosis. Different types of prostate cancer act in different ways and may need different treatments.

To find out the cancer type, healthcare professionals in the lab look at the cancer cells with a microscope. The way the cells look and how they react to various tests give clues about the kind of cells that are involved in the cancer. The results often are given in a pathology report.

Most prostate cancers, also called malignant neoplasms of the prostate, are carcinomas. Carcinoma is a general term for cancer that starts in epithelial tissue. Epithelial tissue forms a lining in many places in the body, such as the outer lining of the skin and the inside lining of many organs. In the prostate, epithelial tissue lines the glands and ducts.

Types of prostate carcinoma include adenocarcinoma, squamous cell carcinoma, small cell carcinoma, neuroendocrine carcinoma and others. A pathology report uses terms like these to describe the cancer cells. The report often is written for healthcare professionals, so it can be hard to understand.

Here’s a look at the terms used to describe the different types of prostate cancer. Use this information to get ready to talk with your healthcare professional about your cancer type and what it means for your prognosis.

There are many types of prostate cancer.

Acinar adenocarcinoma is the most common type of prostate cancer. It starts in gland cells in the prostate.

Adenocarcinoma is a general term for cancer that starts in gland cells. Acinar adenocarcinoma starts in a specific part of a gland called the acini. In the prostate, the acini are round, pouch-shaped parts of the glands that help make the fluid part of semen.

When the cancer cells look like typical acinar adenocarcinoma cells, healthcare professionals may say they are conventional. Sometimes the cells look a little bit different, so they might be considered subtypes of acinar adenocarcinoma. There are several subtypes:

• Pleomorphic giant cell adenocarcinoma is made up of large cells that look very different from one another.
• Prostatic intraepithelial neoplasia-like carcinoma also is called PIN-like carcinoma. The cancer cells look similar to a prostate growth that is not cancer called high-grade prostatic intraepithelial neoplasia (HGPIN).
• Sarcomatoid carcinoma has cells that look similar to sarcoma cells. Sarcomas are cancers that start in the bones and connective tissues.
• Signet ring cell-like carcinoma has cells that look like signet rings. A signet ring is worn on a finger and has a flat surface on the top.

Ductal adenocarcinoma also starts in gland cells inside the prostate, similar to acinar adenocarcinoma. But this rare type starts in the tubelike parts of the glands, called ducts. The ducts carry fluid from the acini to the urethra, which is a tube that carries urine and semen out of the body.

Some prostate cancers have both acinar and ductal cells. If most of the cancer cells are ductal, then the cancer is considered a ductal adenocarcinoma. In most cancers with both types of cells, the cancer is made up mostly of acinar cells, so the cancer is considered acinar adenocarcinoma. Sometimes a cancer with both types of cells is described as an adenocarcinoma with ductal features.

Squamous cell carcinoma is made up of cells that look like squamous cells. Squamous cells are thin, flat cells found in the skin and the inside lining of many organs. Squamous cells aren’t common in the prostate, so it’s not clear how or why this type develops there. This type is rare.

Adenosquamous carcinoma is made up of adenocarcinoma cells and squamous cell carcinoma cells. This type is rare.

Adenoid cystic carcinoma also is called basal cell carcinoma. Adenoid cystic carcinoma starts in the basal cells of the prostate, which help shape and support the acini and ducts. Under a microscope, the cancer looks very similar to adenoid cystic carcinoma of the salivary glands. That similarity is where the name comes from. This is a rare type of prostate cancer.

Neuroendocrine carcinoma, also called neuroendocrine tumor, is a cancer that starts in neuroendocrine cells. Neuroendocrine cells have traits similar to nerve cells, which send and receive signals from the brain, and endocrine cells, which make hormones that regulate various body functions. Neuroendocrine carcinomas can happen anywhere in the body. It’s rare to have neuroendocrine prostate cancer (NEPC) when first diagnosed with prostate cancer. More often, it’s found after treatment for prostate adenocarcinoma.

Types of neuroendocrine prostate cancer include:

• Large cell carcinoma of the prostate has cells that look large when viewed with a microscope.
• Small cell carcinoma of the prostate is the most common type of neuroendocrine prostate cancer. This type is made up of cells that look small.
• Well-differentiated neuroendocrine tumor used to be called carcinoid tumor. Well differentiated means that the cells look similar to healthy cells.

Sometimes prostate cancer can start as an adenocarcinoma and turn into a neuroendocrine carcinoma after hormone therapy treatment. This type of prostate cancer is called treatment-related neuroendocrine carcinoma of the prostate or aggressive variant prostate cancer. When this change happens, the cancer no longer responds to hormone therapy.

It’s common for acinar adenocarcinoma to have some neuroendocrine cells mixed in. Healthcare professionals sometimes call this adenocarcinoma with neuroendocrine differentiation.

Sarcoma is a cancer that happens in the bones and connective tissues. It most often starts in the arms, legs and belly. Prostate sarcoma is rare.

Types of sarcoma that can happen in the prostate include:

• Leiomyosarcoma starts in muscle tissue. It’s the most common type of prostate sarcoma in adults.
• Rhabdomyosarcoma also starts in muscle tissue. It’s the most common type of prostate sarcoma in children.
• Prostate stromal sarcoma starts in connective tissue in the prostate. While other types of sarcoma can happen in many places in the body, this type only happens in the prostate.

Lymphoma is a cancer of the lymphatic system, which is part of the immune system. Lymphoma most often affects germ-fighting cells in the lymph nodes. Sometimes it affects other areas of the body. It’s rare for lymphoma to start in the prostate.

Most prostate lymphomas are types of non-Hodgkin lymphoma, such as diffuse large B-cell lymphoma and other B-cell lymphomas.

Other cancers can affect the prostate, even though they aren’t considered prostate cancers:

• Urothelial carcinoma starts in the cells that line the urinary tract. It used to be called transitional cell carcinoma. When it’s found in the prostate, it usually has spread there from the bladder or urethra. Urothelial cancer also can start in the part of the urethra that passes through the prostate.
• Metastatic cancer is cancer that spreads from where it started to other parts of the body. Examples of cancers that can spread to the prostate include lung cancer, skin cancer and pancreatic cancer.

Acinar adenocarcinoma is the only common type of prostate cancer. All other types are considered rare. Out of every 100 people diagnosed with prostate cancer, more than 95 have adenocarcinoma. Most of those have the acinar type.

Aggressive types of prostate cancer tend to grow more quickly and have a greater risk of spreading. They typically have a poorer prognosis.

Types of prostate cancer that are typically less aggressive include:

• Prostatic intraepithelial neoplasia-like carcinoma.
• Well-differentiated neuroendocrine tumor.

Aggressive types of prostate cancer may include:

• Adenoid cystic carcinoma.
• Ductal adenocarcinoma.
• Large cell carcinoma.
• Pleomorphic giant cell adenocarcinoma.
• Prostate lymphoma.
• Prostate stromal sarcoma.
• Sarcomatoid carcinoma.
• Signet ring cell-like adenocarcinoma.
• Small cell carcinoma.
• Squamous cell carcinoma.
• Treatment-related neuroendocrine carcinoma, also called aggressive variant prostate cancer.

Healthcare professionals often use the cancer’s grade to decide how aggressive it is. They may consider other factors as well. To decide on the cancer’s grade, a healthcare professional looks at the cancer cells under the microscope and compares the cancer cells to healthy cells.

• Low-grade prostate cancers have cells that look similar to healthy cells. This means the cancer is less likely to be aggressive.
• High-grade prostate cancers have cells that look very different from healthy cells. This means the cancer is more likely to be aggressive.

It’s possible for a prostate cancer to start as a less aggressive cancer and change to become an aggressive one, though this isn’t common. Sometimes the cancer is found to be more aggressive when it returns or if it spreads, called metastatic prostate cancer. For most low-grade adenocarcinomas that only affect the prostate, the risk of becoming more aggressive is very small.

Most types of prostate cancer cause similar symptoms. The most common symptoms are needing to urinate more often and having trouble getting started when urinating.

Some types can cause other symptoms. For example:

• Neuroendocrine carcinomas may make hormones that might cause symptoms such as weight gain in the torso, wide stretch marks on the skin and a round face.
• Sarcoma often grows quickly and gets quite large. It may block the flow of urine or make it harder to pass bowel movements.
• Lymphoma may cause fever, chills, night sweats and weight loss.

Healthcare professionals aren’t sure what causes most prostate cancers. Many of the types of prostate cancer are very rare. It’s hard to say what might cause these very rare types because there isn’t enough information about them.

Some types of prostate cancer have different risk factors. For example:

• Younger age is common in some types. Rhabdomyosarcoma mostly affects children. Lymphoma in the prostate can happen at any age, including in children. Prostate stromal sarcoma usually happens in adults younger than 65.
• Older age is common in most types, including acinar adenocarcinoma. Sarcomatoid carcinoma tends to happen at an older age than most other types.
• Previous prostate cancer treatment is a risk factor for certain types. Hormone therapy and radiation therapy may raise the risk of squamous cell carcinoma and treatment-related neuroendocrine carcinoma of the prostate.

All types of prostate cancer are diagnosed using similar tests and procedures. These typically include a physical exam, blood tests, imaging tests and a procedure to remove a sample of tissue for testing, called a biopsy. Prostate biopsy results tell the healthcare team about the type of prostate cancer.

There are some differences between the types of prostate cancer when it comes to diagnosis.

PSA testing doesn’t detect all types of prostate cancer. PSA test stands for prostate-specific antigen test. A high level of PSA in the blood usually is the first sign of prostate cancer. Acinar adenocarcinoma and ductal adenocarcinoma often cause elevated PSA levels. Other prostate cancer types are less likely to raise PSA levels, including:

• Adenoid cystic carcinoma.
• Lymphoma.
• Neuroendocrine tumor.
• Sarcoma.
• Sarcomatoid carcinoma.
• Squamous cell carcinoma.

Gleason score isn’t used for every type of prostate cancer. The Gleason score describes the grade of a prostate cancer. It helps the healthcare team decide whether the cancer is likely to be aggressive. Gleason scores are used only for prostate adenocarcinomas.

When the cancer is in the prostate only, treatment often is similar across the types. Options typically include surgery to remove the prostate, called prostatectomy, and radiation therapy. These can be used with or without other treatments.

Treatment may differ when it comes to medicines. Not all types of prostate cancer respond to the same medicines

• Hormone therapy uses medicines to block the hormones cancer cells need to survive. Hormone therapy for prostate cancer doesn’t work for certain types, including lymphoma, sarcoma, sarcomatoid carcinoma, small cell carcinoma and squamous cell carcinoma.
• 化学療法 medicines work by stopping fast-growing cells. There are many different chemotherapy medicines. Healthcare professionals consider the type of cells involved in the cancer when deciding which medicines might work best. For example, prostate lymphomas are treated with the same chemotherapy medicines used for other lymphomas but not the medicines used for prostate adenocarcinoma.

Talk with your healthcare team about your prostate cancer type. Ask about how the type might affect your treatment options and your prognosis. Many factors go into deciding your prognosis. The prostate cancer type is just one. Others include your overall health and whether the cancer has spread beyond the prostate.