Bladder cancer refers to any of several types of malignant growths of the urinary bladder. It is a disease in which abnormal cells multiply without control in the bladder. The bladder is a hollow, muscular organ that stores urine; it is located in the pelvis. The most common type of bladder cancer begins in cells lining the inside of the bladder and is called urothelial carcinoma or transitional cell carcinoma (TCC).
Bladder tumors are either non-muscle invasive or muscle invasive. Non-muscle invasive bladder tumors are found only in the inner lining of the bladder. Muscle invasive bladder tumors grow into the deeper layers of the bladder wall. The stage and grade of the tumor determine what will happen if it is not removed.
What Happens if a Non-Muscle Invasive Bladder Tumor is Not Removed?
Non-muscle invasive bladder cancers are limited to the inner lining of the bladder wall. There are two main types of non-muscle invasive bladder cancer:
Ta Tumors
Ta tumors are flat, non-invasive lesions. The cancerous cells are only found in the urothelium, which is the innermost layer of the bladder wall. Ta tumors do not extend into the deeper muscular layers of the bladder.
If left untreated, around 50-70% of Ta tumors will recur (come back after treatment). Of those that recur, 10-20% will progress to a higher grade or stage. Higher grade tumors are more likely to recur and progress than low grade tumors.
Recurrence means the cancer comes back after treatment. It may come back in the same site as the original tumor or elsewhere in the bladder.
Progression refers to the cancer growing into deeper layers of the bladder wall or spreading to other organs. As a Ta tumor progresses, it can become a T1 tumor (invading the subepithelial connective tissue) or a muscle-invasive tumor.
T1 Tumors
T1 tumors invade into the subepithelial connective tissue beneath the bladder lining. However, they do not extend into the muscle layer of the bladder wall.
If not removed, 50-70% of T1 tumors will recur. Of these recurrences, 30-50% will progress to muscle-invasive disease. T1 high-grade tumors are more likely to progress than low-grade tumors.
Outcomes if Left Untreated
The main risk if non-muscle invasive bladder tumors are left untreated is that they will continue to recur and eventually progress to muscle-invasive disease. Muscle-invasive bladder cancer has much worse outcomes.
Recurrences will require repeat treatments with bladder resection. This can lead to significant bother with frequent office visits for detection and treatment.
In a small proportion of cases, an untreated Ta or T1 tumor may progress to life-threatening muscle-invasive or metastatic bladder cancer. However, with routine surveillance, recurrences can usually be detected and treated before this occurs.
What Happens if a Muscle Invasive Bladder Tumor is Not Removed?
Muscle invasive bladder cancer invades into the muscular layer of the bladder wall. There are two main types:
T2 Tumors
T2 tumors extend into the muscularis propria, which is the thick muscular layer of the bladder wall.
T3 Tumors
T3 tumors invade through the muscularis propria into the perivesical fat layer that surrounds the outer bladder wall.
T4 Tumors
T4 tumors invade through the perivesical fat and into adjacent organs, such as the uterus, vagina, prostate, rectum, or pelvic wall.
If left untreated, most muscle invasive bladder cancers will continue to grow, spreading into other pelvic organs and bones. From there, they can metastasize (spread) to distant sites like the lungs, liver, and lymph nodes.
Outcomes if Left Untreated
Muscle invasive bladder cancer is very dangerous if left untreated. Outcomes get progressively worse with higher stage disease:
– T2 tumors: 5-year survival is 15-60%, depending on grade. Median survival is 1-3 years.
– T3 tumors: 5-year survival is around 35%. Median survival is 11-18 months.
– T4 tumors: 5-year survival is 15-25%. Median survival is 9 months.
Metastatic bladder cancer has an even worse prognosis, with 5-year survival rates of 5-15%.
Most patients diagnosed with muscle invasive bladder cancer require aggressive treatment with radical cystectomy (bladder removal) to have a chance at long-term survival. Chemotherapy may also be recommended, either before or after surgery.
Without treatment, most patients will succumb to their disease within 1-3 years. Complications can include kidney failure, metabolic disorders, infections, bleeding, pain, and bowel obstruction. Ultimately, the growing cancer will cause organ failure and death.
Conclusions
– Non-muscle invasive bladder tumors have a high risk of recurrence if not removed, but a relatively low risk of progression to muscle-invasive disease. With surveillance, progression can usually be detected early.
– Muscle invasive bladder cancer is very dangerous if not treated aggressively. Without cystectomy and possibly chemotherapy, most patients will die of their disease within a few years.
– Any bladder tumors that recur or grow into deeper layers over time should be completely resected. Regular cystoscopy follow-up is important to detect recurrences.
– Leaving any bladder tumor untreated risks progression to more advanced disease. Seek medical advice to determine the appropriate treatment options based on the tumor type, grade, and stage.
References
| 1. | Babjuk M, et al. European Association of Urology Guidelines on Non-muscle-invasive Bladder Cancer (TaT1 and Carcinoma In Situ) – 2019 Update. Eur Urol. 2019. |
| 2. | Alfred Witjes J, Lebret T, Compérat EM, Cowan NC, De Santis M, Bruins HM, et al. Updated 2016 EAU Guidelines on Muscle-invasive and Metastatic Bladder Cancer. Eur Urol. 2017. |
| 3. | Pasin E, Josephson DY, Mitra AP, Cote RJ, Stein JP. Superficial bladder cancer: an update on etiology, molecular development, classification, and natural history. Rev Urol. 2008. |
| 4. | Sylvester RJ, van der Meijden AP, Oosterlinck W, Witjes JA, Bouffioux C, Denis L, et al. Predicting recurrence and progression in individual patients with stage Ta T1 bladder cancer using EORTC risk tables: a combined analysis of 2596 patients from seven EORTC trials. Eur Urol. 2006. |
| 5. | Gandaglia G, Popa I, Abdollah F, Schiffmann J, Trudeau V, Shariat SF, et al. Progression-free and cancer-specific survival in patients undergoing radical cystectomy for bladder cancer: a competing risks analysis. J Urol. 2014. |