A drug used to treat breast cancer may also help bladder cancer patients, research suggests.
Herceptin is used to treat breast cancer
Scientists found elevated levels of a protein called HER2 - targeted by the drug - in more than half of patients with advanced bladder cancer.
These patients were given herceptin and traditional chemotherapy - and in 70% of cases their tumours shrank.
The study, by the University of Michigan, was presented at an American Society of Clinical Oncology meeting.
Herceptin, given along with chemotherapy, has been shown to cut the risk of a recurrence of disease by a half in women with HER2-positive breast cancer.
The drug is associated with fewer side effects than standard chemotherapy drugs.
This is because it seeks out specific molecules known to play a role in cancer development, and leaves normal cells unharmed.
Researcher Professor Maha Hussain said: "While we are still in the beginning, I think this trial provides an approach for metastatic (spreading) bladder cancer that has not been previously explored."
Aggressive form of disease
The Michigan team examined 113 people with bladder cancer that had spread to other organs.
They found 52% had high levels of HER2.
The HER2-positive patients appeared to have more aggressive tumours.
They were more likely to have cancer in their liver, bones and lungs than those with HER2-negative tumours.
Only 7% of patients given a combination of herceptin and standard chemotherapy saw their cancer continue to progress.
On average the herceptin patients lived for 15 months, comparable to overall survival rates for advanced bladder cancer.
But, Professor Hussain points out, the patients participating in the study had a more aggressive disease.
"We were quite encouraged to see in this study good responses to treatment," he said.
Professor Margaret Knowles, of the Cancer Research UK's Clinical Centre in Leeds, described the findings as "exciting" but said further larger studies were needed to back them up.
"For patients with advanced metastatic disease, novel forms of therapy are much needed.
"Current treatment for such patients is chemotherapy and/or radiotherapy but less than half of patients get a significant benefit.
"Targeted therapies such as Herceptin allow the identification of the patients most likely to respond, based on the molecular profile of their tumour."
Bladder cancer affects twice as many men as women in the UK. It is the fourth most common cancer in men and the tenth most common in women.
There are over 10,700 new cases each year, and approximately 4,900 people die from the disease.
It is most common in people over 50.
The disease affects the inner lining of the bladder and develops slowly.