In the United States bladder cancer is the fourth most common cancer in men. It is estimated that around 84,000 new cases and 17,200 deaths due to bladder cancer will occur across US men and women during 2021.1
Bladder cancer occurs when cells that make up the bladder begin to grow in an abnormal and uncontrolled way. Bladder cancers are assigned to different types according to the cell type they arise from, as determined by microscopic examination of urine samples and tissue biopsies. There are several types of bladder cancer, and each is associated with different risk factors and outlooks.
In this article we discuss the different types of bladder cancer and explain some of the terms that are often used to describe them.
What is the most common type of bladder cancer?
Urothelial carcinoma, also called transitional cell carcinoma, is the most common type of bladder cancer, accounting for approximately 9 out of every 10 cases.2 This type of cancer starts in the urothelial cells lining the inner surface of the bladder wall. Cancerous urothelial cells form a tumor that can grow into the deeper layers of the bladder wall and spread to nearby lymph nodes and organs. In some instances, cancer cells may break away from the bladder tumor(s) and form new tumors in distant parts of the body. This is called metastatic bladder cancer.
Urothelial carcinoma bladder tumors may be classified as ‘non-muscle invasive’ or ‘muscle invasive’ and assigned to a specific ‘T’ category according to the nature and extent of their growth.
Non-muscle invasive urothelial carcinoma
Urothelial carcinoma is classified as non-muscle invasive if it has not spread beyond the urothelium or underlying connective tissue into the muscular layer of the bladder wall. Most patients (around 80%3) are diagnosed with this type of the disease.
Non-muscle invasive urothelial carcinoma tumors may be:
- Papillary or ‘Ta’ tumors. These finger-like tumors are based in the urothelium and grow outwards into the hollow center of the bladder.
- Flat or ‘Tis’ tumors. These are flat tumors that can appear as a reddened, velvet-like area on the bladder lining. Also commonly referred to as ‘carcinoma in situ’, they have a greater tendency than papillary tumors to spread into the deeper layers of the bladder wall.
- T1’ tumors. This tumor type extends beyond the urothelium into the underlying connective tissue of the bladder wall.
Muscle invasive urothelial carcinoma
Muscle invasive urothelial carcinoma tumors have spread into or through the muscle layer of the bladder wall.
- ‘T2’ tumors have spread into the muscle layer of the bladder wall.
- ‘T3’ tumors have spread through the muscle layer and into the fatty tissue surrounding the bladder.
- ‘T4’ tumors have spread to nearby pelvic organs, the pelvic wall, or the abdominal wall.
As well as assigning a ‘T’ category, the commonly used ‘TNM’ clinical staging system also assigns urothelial carcinoma to an ‘N’ category (describes spread to nearby lymph nodes) and an ‘M’ category (describes spread to distant lymph nodes or organs). For further information regarding bladder cancer classification, see Bladder Cancer Stages.
Metastatic urothelial carcinoma
If urothelial carcinoma of the bladder spreads to distant organs or lymph nodes outside the pelvis it is called metastatic urothelial carcinoma. It is more common for muscle invasive tumors than non-muscle invasive tumors to spread in this way. Urothelial carcinoma can metastasize to almost any organ, but the most common sites are lymph nodes, bones, lung, and liver.
What other types of bladder cancer are there?
Several less common types of bladder cancer make up the remaining approximately 10% of bladder cancers. Some examples of the uncommon types include:
- Squamous cell carcinoma: Squamous cells develop in the lining of the bladder as a result of irritation or inflammation. These cells may eventually become cancerous. Although squamous cell carcinoma is uncommon, making up around 4% of all bladder cancers,2 it has a high likelihood of progression.
- Adenocarcinoma: This type of bladder cancer consists of glandular-type cells and is usually invasive. Overall, around 2% of bladder cancers are adenocarcinomas.2
- Small cell carcinoma: Small cell carcinomas of the bladder start in nerve-like cells. This bladder cancer type is rare, accounting for less than 1% of bladder cancers,4 but can grow rapidly and spread to other parts of the body.
- Sarcoma: A sarcoma is a type of cancer that begins in the body’s supporting tissues, such as bone, muscle, fibrous tissues, and fat. Very rarely, sarcomas may arise from the muscle or fat layers of the bladder.
Although the treatment for most bladder cancer types (other than sarcoma) is similar for early-stage tumors, different drugs may be used if chemotherapy is undertaken.
Other terms often used to describe bladder cancer
Although bladder cancer types are assigned based on the cells that the cancer originates from, several other terms may be used to describe the disease.
- Advanced bladder cancer is another term that may be used to describe metastatic bladder cancer. It means that the cancer has spread to distant parts of the body such as the lungs, bones, liver, or lymph nodes outside the pelvis.
- Locally advanced bladder cancer refers to cancer that has grown through the bladder wall, and possibly into nearby lymph nodes or organs, but has not spread to distant sites in the body.
- Bladder cancer stage describes where the cancer is located within the bladder and any sites of spread. As described above, the ‘TNM’ staging system assigns a patient’s bladder cancer to a tumor (T), lymph node (N) and metastasis (M) category. These categories may also be combined to give an overall stage number: an overall stage of 0 or 1 describes early disease, while stage 4 is the most advanced. For further information regarding staging, see Bladder Cancer Stages.
- Bladder cancer grade is based on the microscopic appearance of cancer cells and suggests how fast a cancer might grow. Low-grade cancer cells appear similar to normal cells and usually grow slowly, whereas high-grade cancer cells have a very abnormal appearance and tend to grow quickly. High-grade cancers are more likely than low-grade cancers to spread.
What is the most aggressive form of bladder cancer?
In general, bladder cancers that are muscle invasive and/or have high-grade cells are the most serious and aggressive. The less common types of bladder cancer such as squamous cell carcinoma, adenocarcinoma, and small cell carcinoma have a greater tendency to be muscle invasive compared to urothelial carcinoma. However, if left untreated, initially low-grade, non-muscle invasive urothelial carcinoma can progress into the bladder wall and spread to other parts of the body.
The prognosis for bladder cancer is very favorable when the disease is detected early, so it is important to see your doctor if you are experiencing symptoms that could be due to bladder cancer. The most common early sign of bladder cancer is the presence of blood in the urine (‘hematuria’). Other symptoms that may be experienced include urinary irritation (e.g., pain or a burning sensation during urination) and changes in bladder habits. For further information regarding the signs and symptoms of bladder cancer, see Bladder Cancer Symptoms.
How is bladder cancer detected?
Several tests and procedures, including non-invasive genomic urine tests like Cxbladder, are available to determine whether an individual has bladder cancer or to establish an alternative diagnosis. Some of these clarify the presence of symptoms (such as haematuria) and others identify alternative causes of these symptoms (such as an infection). Importantly, these tests and procedures are used in combination to determine an overall diagnosis.
Learn more about bladder cancer detection
Last Updated: 10 Nov 2021 12:24 pm
- American Cancer Society. Key Statistics for Bladder Cancer. Accessed August 9, 2021.
- American Society of Clinical Oncology (ASCO). Bladder Cancer: Introduction. Accessed August 10, 2021.
- Afonso JP, Freitas R, António Morais FL, et al. Urothelial bladder cancer progression: lessons learned from the bench. J Cancer Metastasis Treat 2015;1:57-66.
- American Urological Association. Small Cell Carcinoma. Accessed August 16, 2021.
- Abufaraj M, Gust K, Moschini M, et al. Management of muscle invasive, locally advanced and metastatic urothelial carcinoma of the bladder: a literature review with emphasis on the role of surgery. Transl Androl Urol. 2016;5:735-744.
- American Cancer Society. Bladder Cancer Signs and Symptoms. Accessed August 14, 2021.
- American Cancer Society. Survival Rates for Bladder Cancer. Accessed August 8, 2021.
- American Cancer Society. What is Bladder Cancer? Accessed August 10, 2021.
- American Society of Clinical Oncology (ASCO). Bladder Cancer: Stages and Grades. Accessed August 9, 2021.
- American Society of Clinical Oncology (ASCO). Sarcomas, Soft Tissue: Introduction. Accessed August 10, 2021.
- American Urological Association. Non-muscle Invasive Bladder Cancer. Accessed August 8, 2021.
- Anastasiadis A, de Reijke TM. Best practice in the treatment of nonmuscle invasive bladder cancer. Ther Adv Urol. 2012;4:13-32.
- Cancer Council. Understanding Bladder Cancer. Accessed July 19, 2021.
- Holyoake A, O'Sullivan P, Pollock R, et al. Development of a multiplex RNA urine test for the detection and stratification of transitional cell carcinoma of the bladder. Clin Cancer Res. 2008;14:742-9.
- Kavalieris L, O'Sullivan PJ, Suttie JM, et al. A segregation index combining phenotypic (clinical characteristics) and genotypic (gene expression) biomarkers from a urine sample to triage out patients presenting with hematuria who have a low probability of urothelial carcinoma. BMC Urol. 2015;15:23.
- Shinagare AB, Ramaiya NH, Jagannathan JP, et al. Metastatic pattern of bladder cancer: correlation with the characteristics of the primary tumor. AJR Am J Roentgenol. 2011;196:117-22.
- Teyssonneau D, Daste A, Dousset V, et al. Metastatic non-muscle invasive bladder cancer with meningeal carcinomatosis: case report of an unexpected response. BMC Cancer. 2017;17:323.
- Uhlman MA, Bevill MD, Goodheart MJ, et al. Bladder cancer will grow anywhere: report of a urothelial carcinoma drop metastasis to the vagina and literature review. Can J Urol. 2016;23:8379-81.
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