Small cell bladder cancer is a rare type of bladder cancer. It’s more aggressive than other types of bladder cancer and those with it have a poorer outlook. Treatment can involve surgery, chemotherapy, or radiation therapy.

The American Cancer Society estimates that 82,290 people will receive a diagnosis of bladder cancer in the United States in 2023. Most of these will be urothelial carcinoma, which makes up more than 90% of bladder cancer diagnoses.

There are also several rarer types of bladder cancer as well. One of these is small cell bladder cancer. Researchers estimate that it makes up only 0.5% to 0.7% of all bladder cancers.

In this article, we take a closer look at small cell bladder cancer, including the outlook for people with this type of cancer and how it’s diagnosed and treated.

Small cell bladder cancer is a rare type of bladder cancer. It forms in neuroendocrine cells, which are nerve-like cells that release hormones in response to signaling from your nervous system.

Compared with other types of bladder cancers, small cell bladder cancer is very aggressive. That means that it typically grows and spreads more quickly.

A 2021 case study notes that more than 60% of small cell bladder cancers have spread to distant tissues at the time of diagnosis. This is called metastatic cancer. The most common metastatic sites are your:

Other bladder cancers

There are also other types of bladder cancer:

  • Urothelial carcinoma: Urothelial carcinoma accounts for more than 90% of bladder cancers. It starts in urothelial cells, which line your bladder and other parts of your urinary tract (kidneys, ureter, bladder, urethra).
  • Squamous cell carcinoma: Squamous cell carcinoma makes up 1% to 2% of bladder cancers and starts in the cells in your bladder lining. It often happens in response to bladder irritation or inflammation.
  • Adenocarcinoma: Adenocarcinoma makes up about 1% of bladder cancers and starts in mucus-producing cells.
  • Sarcoma: Sarcoma begins in your bladder muscle cells and is very rare.

The main symptom of small cell bladder cancer is blood in your urine. Other potential symptoms include:

These symptoms can all be caused by more common conditions, such as a urinary tract infection (UTI). But it’s still important to see a doctor or healthcare professional for them, especially if they’re lasting or happen frequently.

Symptoms of small cell bladder cancer having spread outside of your bladder can be:

Cancer starts due to DNA changes that cause cells to grow and divide out of control. These can be changes that are inherited from your parents or changes that happen during your life due to lifestyle and environmental factors.

What exactly causes small cell bladder cancer is unknown. But this type of bladder cancer has been associated with older age and smoking.

Like other types of bladder cancer, small cell bladder cancer is more common in people assigned male at birth and in white individuals. The reasons for this are currently unknown.

  • a family history of bladder cancer
  • certain genetic changes associated with bladder cancer
  • exposure to arsenic in drinking water
  • workplace exposures to certain chemicals
  • use of the herbal supplement Aristolochia fangchi
  • conditions that cause chronic bladder irritation, such as UTIs, kidney stones, and urinary catheters
  • previous radiation therapy or chemotherapy with cyclophosphamide

The diagnostic process starts with a doctor taking your medical history and doing a physical exam. If they suspect that you may have bladder cancer, they’ll order additional tests, such as:

If you receive a diagnosis of small cell bladder cancer, a doctor will also do additional tests to see if the cancer has metastasized. These involve imaging and can include:

Cystectomy, or surgical removal of your bladder, is the mainstay treatment for small cell bladder cancer. When this is done, urinary diversion is also needed to create a new way for urine to leave your body.

Chemotherapy regimens for small cell bladder cancer often involve platinum-based chemotherapy drugs (cisplatin, carboplatin) as well as etoposide. It can be used before surgery or after surgery:

Not everyone with small cell bladder cancer may be eligible for surgery. These individuals may receive chemotherapy, radiation, or both. It’s possible that an immunotherapy drug, such as atezolizumab (Tecentriq) may be used as well.

Small cell bladder cancer is an aggressive type of bladder cancer. In many people, the cancer has already metastasized when they receive a diagnosis. As such, the outlook for people with this type of bladder cancer is generally poorer than it is for those with other types of bladder cancer.

A 2017 study involving 38 individuals who had received a diagnosis of small cell bladder cancer found that the median survival was 11.8 months and the overall 5-year survival was 14%.

Researchers looked at how factors like age, cancer stage, and tumor grade affected survival. They found that the only significant indicator for improved survival was the absence of spread to people’s lymph nodes or metastasis.

A 2019 study compared early-stage with late-stage small cell bladder cancer. The outlook for people with late-stage cancers remained poor, with a median survival of 9 months. The outlook for people with early-stage cancers was improved for those who received a diagnosis early and got it treated aggressively.

Small cell bladder cancer is a very rare but aggressive type of bladder cancer. Its symptoms are similar to other types of bladder cancer and can include blood in your urine, frequent urination, and painful urination.

Small cell bladder cancer grows and spreads quickly, meaning the outlook for people with it is poor. But your outlook can be improved when your receive a diagnosis of this cancer early and get it treated aggressively.

The symptoms of small cell bladder cancer can be similar to more common conditions like UTIs. Always see a doctor if you have concerning urinary symptoms that are lasting or happen frequently.