Staging and grading cancer allows medical professionals to understand the different types, locations, and severity of bladder cancer. The “TNM” bladder staging system provides a framework and categorization for a disease (bladder cancer) that requires different strategies of treatment as per its current state of progress. Depending on how malignant cells look under a microscope, staging describes the cancer site and whether it has spread (metastasized) to the surrounding tissues, organs or beyond. With this information, the doctor may determine the optimal treatment strategy and its possible outcome.
“Cancer of the urinary bladder is the fourth most prevalent non-skin cancer in males in the USA, and ranks ninth in frequency among women. An estimated 61 420 new cases of bladder cancer were diagnosed in the USA in 2006. Tobacco smoking has been implicated in epidemiological studies as the cause of approximately 50% of bladder cancer cases in men and 30% in women. Various chemical and industrial exposures account for another 25% of these tumors in men and 11 % in women”1
Describing Bladder Cancer and Staging
“Bladder cancer starts when cells that make up the urinary bladder start to grow out of control. As more cancer cells develop, they can form a tumor and, with time, spread to other parts of the body. The bladder is a hollow organ in the lower pelvis. It has flexible, muscular walls that can stretch to hold urine and squeeze to send it out of the body. The bladder’s main job is to store urine. Urine is liquid waste made by the 2 kidneys and then carried to the bladder through 2 tubes called ureters. When you urinate, the muscles in the bladder contract, and urine is forced out of the bladder through a tube called the urethra.”2
Specialists perform Bladder Cancer staging after removing and examining a biopsy through the urethra, in a procedure called Trans-Urethral Resection of Bladder Tumor or TURBT. Additionally, the patient requires further examination to detect if cancer has metastasized.
“A thorough understanding of the epidemiology of bladder cancer can assist in the prevention and early detection of the disease. In addition, staging, grading, and risk stratification are essential for determining the most appropriate management strategies for non–muscle invasive bladder cancer (NMIBC) based on risk of recurrence and progression.”3
TNM bladder staging system
“A staging system is a standard way for the cancer care team to describe how far cancer has spread. The staging system most often used for bladder cancer is the American Joint Committee on Cancer (AJCC) TNM system”4
Doctors use various tests and radiological scans to find a comprehensive TNM staging to answer the following questions:
- (T) Tumor: what is the site of the primary tumor and how big is it?
- (N) Node: which and how many lymph nodes are affected (if any)?
- (M) Metastasis: to which parts of the body has cancer spread to (if any) and to what extent?
The answers to these questions are considered together to discover an individual’s staging results. There are five stages of bladder cancer:
- Stage 0
- Stages 1 to 4
“Numbers or letters after T, N, and M provide more details about each of these factors. Higher numbers mean the cancer is more advanced. Once a person’s T, N, and M categories have been determined, usually, after surgery, this information is combined in a process called stage grouping to assign an overall stage. The earliest stage cancers are called stage 0 (or carcinoma in situ), and then range from stages I (1) through IV (4).”5
“While the TNM staging of bladder cancer guides both treatment and prognosis, there remains substantial heterogeneity among similarly staged patients, with respect to treatment response and overall outcomes. Therefore, there is a critical need for the identification of biomarkers to diagnose bladder cancer at an early stage, monitor recurrence, refine prognostic estimates, and predict response to treatment in patients with bladder cancer. Further, identification of such biomarkers is critical to refining our understanding of the pathogenesis of the disease, the biological basis for outcome disparities, and to informing more efficient treatment and surveillance strategies.”7
WHO Grading of Urothelial Papilloma
“Traditionally, bladder carcinomas have been graded according to the World Health Organization (WHO) 1973 grading of urothelial papilloma: well-differentiated (G1), moderately differentiated (G2), or poorly differentiated (G3). In 2004, the WHO and the International Society of Urological Pathology (ISUP) published a new grading system that employs specific cytologic and architectural criteria. The new WHO/ISUP classification differentiates between papillary urothelial neoplasms of low malignant potential (PUNLMP) and low-grade and high-grade urothelial carcinomas.”8
Grouping of Cancer Stages
It occurs during the beginning of cancer, affecting the surface of the bladder’s inner lining. The cancer has not affected the underlying connective tissues and the muscles. Other name for this stage of bladder cancer is non-invasive papillary urothelial carcinoma. On the TNM staging system, it is Ta, N0, M0.
Medically, this stage of bladder cancer is called flat/carcinoma in situ. The cancer grows in the inner lining of the bladder without affecting bladder muscles, tissues or its hollow part. On the TNM staging system, it is Tis, N0, M0.
The bladder cancer has spread beyond the bladder lining into the lamina propria mucosae. The bladder wall muscles, lymph nodes or surrounding organs are unaffected. The corresponding TNM staging system is T1, N0, M0.
Bladder cancer has invaded the bladder wall muscles. This stage is also called invasive cancer or muscle-invasive cancer. The tumor, however, has not spread to the surrounding fat, lymph nodes or organs. The TNM staging system is T2, N0, M0.
Bladder cancer at this stage has metastasized beyond the bladder wall muscle to the fat layer and surrounding organs, such as the prostate, the uterus or the vagina. The lymph nodes are unaffected. The TNM staging system for this is T4a, N0, M0
A specialist may identify this stage observing any of the following tumor states:
- The tumor metastases have reached the pelvic or abdominal wall without invading the lymph nodes or other organs. This is T4b, N0, M0.
- The tumor metastases have reached local lymph nodes only. This is T, N1-3, M0
- The bladder cancer may or may not have metastasized to the lymph nodes but metastases have already reached various other organs. This is T, any N, M1.
“If cancer cells are found in the tissue sample from the bladder, a pathologist studies the sample under a microscope to learn the grade of the tumor. Tumors with higher grades tend to grow faster than those with lower grades. They are also more likely to spread. Your doctor uses this grade along with other factors to decide your treatment options.”10
“Grading describes how aggressive the cancer cells are:
- Low grade – The cancer cells look fairly normal and behave similarly to healthy cells. The cells tend to grow slowly. Most bladder tumors are low grade.
- High grade – The cancer cells look very abnormal and grow disorderly. These cells tend to grow very quickly.
Bladder cancer can also be graded on a scale of 1–3. Grade 1 cancers are the slowest growing and grade 3 cancers are the most aggressive.”11
The staging and grading method categorizes and defines the different types of bladder cancers that appear in various stages. The ability to identify different cancers prepares physicians to plan treatment and attack the condition adequately.
“Historically, most of the data on the distribution of grade and stage of bladder cancer have been derived from retrospective studies on selected, often hospital- or clinic-based, patient populations. Such studies are likely to include a disproportionate number of patients with more aggressive or advanced-stage tumors.”12
The complexity of bladder cancer staging may cause confusion among patients. Ask your doctor to explain any questions about your stage in a way you can understand.
(1, 12) Histological classification and stage of newly diagnosed bladder cancer in a population-based study from the Northeastern United States. Schned, A., Andrew, A., Marsit, C., Kelsey, K., Zens, M., & Karagas, M. Scandinavian Journal of Urology and Nephrology. 2008. https://www.tandfonline.com/doi/abs/10.1080/00365590801948166?journalCode=isju19
(2) About Bladder Cancer. The American Cancer Society medical. American Cancer Society. 2019. https://www.cancer.org/content/dam/CRC/PDF/Public/8557.00.pdf
(3, 10) Bladder Cancer Handbook. Cole, B., & Derossett, J. University of Michigan Rogel Cancer Center. 2014. http://www.med.umich.edu/cancer/files/bladder-cancer-handbook.pdf
(4, 5) Bladder Cancer Stages. The American Cancer Society medical. American Cancer Society. 2019. https://www.cancer.org/cancer/bladder-cancer/detection-diagnosis-staging/staging.html
(6, 9) Guidelines on Non-muscle-invasive Bladder Cancer (Ta, T1 and CIS). Babjuk, M., Böhle, A., Burger, M., Compérat, E., Kaasinen, E., Palou, J., Rouprêt, M., Van, Rhijn, B., Shariat, S., Sylvester, R., & Zigeuner, R. European Association of Urology. 2015. https://uroweb.org/wp-content/uploads/EAU-Guidelines-Non-muscle-invasive-Bladder-Cancer-2015-v1.pdf
(7) Biomarkers for bladder cancer management: present and future.Ye, F., Wang, L., Castillo- Martin, M., McBride, R., Galsky, M., Zhu, J., Boffetta, P., Zhang, D., & Cordon- Cardo, C. American Journal of Clinical and Experimental Urology. 2014. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4219291/
(8) Epidemiology, Staging, Grading, and Risk Stratification of Bladder Cancer. Colombel, M., Soloway, M., Akaza, H., Böhle, A., Palou, J., Buckley, R., Lamm, D., Brausi, M., Witjes, A., & Persad, R. European Association Urology. 2008. http://citeseerx.ist.psu.edu/viewdoc/download?doi=10.1.1.500.5369&rep=rep1&type=pdf
(11) Staging and prognosis of bladder cancer. Cancer Council. 2012. https://www.cancersa.org.au/information/a-z-index/staging-and-prognosis-of-bladder-cancer