Bladder cancer

Bladder cancer is the most common malignancy involving the urinary system. In 2020 it was the 10th most common cancer with 573,278 new cases worldwide (440,864 men and 132,414 women) [1].

Several risk factors are associated with the development of bladder cancer [2-4]. There is strong evidence linking bladder cancer to exposure to carcinogens, in particular the use of tobacco, especially cigarettes.  It is estimated that up to half of all bladder cancers are caused by cigarette smoking and that smoking increases a person’s risk of bladder cancer two to four times above baseline risk [3]. In addition, occupational exposure to chemicals in processed paint, dye, metal, and petroleum products are associated with the development of bladder cancer [2-4]. Occurrence of genetic mutations in some chromosomal genes that play an important role in the regulation of cell division, lead to tumours in the urinary bladder [5].

Blood in urine, often referred to as hematuria, is the most common first symptom or sign of bladder cancer [2].  When bladder cancer is suspected, the most useful diagnostic test is cystoscopy which can be performed in a urology clinic. If cancer is suspected on cystoscopy, the patient is typically scheduled for a bimanual examination under anaesthesia and a repeat cystoscopy in an operating room so that transurethral resection of bladder tumour(s) (TURBT) and/or biopsies can be performed. Urothelial carcinomas are often multifocal – the entire urothelium needs to be evaluated if a tumour is found. If a high-grade cancer (including carcinoma in situ) or invasive cancer is detected, the patient is at high risk for extra-bladder tumour dissemination [6-10].

The disease staging is performed in accordance with the American Joint Committee on Cancer/ Union for International Cancer Control (AJCC/UICC) TNM classification of malignant tumours (TNM) system, where T represents the size or direct extent of the primary tumour,  N, the degree of spread to regional lymph nodes, and M, distant metastasis. In brief, the term superficial or Non-Muscle-Invasive Bladder Cancer (NMIBC) refers to tumours not extending into the muscle layer of the bladder and no spread to outside the bladder. NMIBC comprises in situ cancer (carcinoma in situ (CIS) or tumour in situ (Tis), small papillary bladder cancers extending into the lumen of the bladder (Ta tumours), and T1 tumours which are superficial bladder cancers that have spread from the bladder lining (urothelium) into the layer of connective tissue underneath (the lamina propria) [11].

Tumours can be graded based on their histological appearance, as ‘low-grade’ (LG) if they appear similar to normal cells, and ‘high-grade’ (HG) if they appear poorly differentiated [10, 11].

Approximately 70% to 80% of patients with newly diagnosed bladder cancer will present with NMIBC, mostly Ta (70% of NMIBC), T1 (20%), and CIS (10%). Of the patients diagnosed with NMIBC, 50-70% will recur, and roughly 10–20% will progress to muscle invasive disease, without treatment [12, 13]. In patients with low-grade Ta disease, the 15-year progression-free survival is 95% with no cancer-specific mortality [14]. Intravesical BCG is recommended as a first-line treatment for intermediate and high risk NMIBC after TURBT in European and US Guidelines to reduce the risk of recurrence and progression and improve patient outcomes [16, 17]. The relapse rate following BCG-intravesical immunotherapy is approximately 40% [15]. In some cases, repeat BCG course can be considered [18].

For more details, please see the International Agency for Research on Cancer on Bladder Cancer and Saginala et al., Epidemiology of Bladder Cancer, Med Sci (Basel). 2020 Mar; 8(1):15.

 

References:

1. Global cancer statistics 2020 Accessed Feb 15 2021 2. Burger et al. Eur Urol. 2013; 63(2):234-41. 3. Brennan et al. Cancer Causes Control. 2001;12(5):411-7. 4. Letasiova et al. 2012;11 Suppl 1:S11. 5. Zhang, X., Zhang, Y.. Cell Biochem Biophys 73, 65–69 (2015). 6. Monteiro et al. World J Urol. 2019 Jan;37(1):51-60 7. Woldu et al. BJU Int. 2017;119(3):371-380. 8. Spiess et al. J Natl Compr Canc Netw. 2017;15(10):1240-1267. 9. Kamat et al. J Immunother Cancer. 2017;5(1):68. 10. Babjuk et al. Eur Urol. 2017;71(3): 447-461. 11.Comperat et al. Eur Urol Focus. 2018. 12. Sylvester et al. Eur Urol. 2006;49:466–5. discussion 75-7 13. Fernandez-Gomez et al. J Urol. 2009;182:2195–203. 14. Herr J Urol. 2000;163:60–2 15. Cambier et al. Eur Urol. 2016;69(1):60-9. 16. Babjuk et al. Eur. Urol. 2017 Mar; 71 (3):447-61. 17. Chang et al. J Urol. 2016; 196: 1021. 18. European Association of Urology Accessed Mar 21, 2021.