Bladder cancer more often fatal for women
Women are diagnosed at a more advanced stage of the disease, when the cancer is more likely to have spread, according to a Norwegian study.
Your chances of surviving cancer can depend on your gender. In most cancers, survival favours women but the opposite is true for bladder cancer. Men make up three quarters of those diagnosed with the disease.
As of 2016, figures from the Cancer Registry of Norway show that nearly eight out of ten men survive bladder cancer after five years, as compared to only seven out of ten women who survive for the same length of time.
Researcher Bettina Kulle Andreassen at the Cancer Registry wanted to investigate this difference more closely and found thought-provoking results. The study was recently published in the European Journal of Cancer.
Men’s advantage only lasts first two years
Andreassen and her colleagues based their research on patients who were diagnosed with bladder cancer over a 15-year period starting in 1997. Information on more than 15,000 patients from the Cancer Registry of Norway was included in the study.
Then she checked how the patients fared, from their diagnosis and until they eventually died.
According to Andreassen, risk rates for women with bladder cancer are significantly higher than for men, but the researcher found that this only applies to the first two years after diagnosis.
After this, women have a slightly better prognosis than men.
"This is because most of the women with the most advanced bladder cancer have died and only those in an earlier stage of the disease have survived," says Andreassen.
This study is the first to show that the risk profile between men and women changes over time.
Metastasis more likely in women
The researchers found that women were more often diagnosed at a later stage of cancer. In other words, the cancer had had a chance to metastasize (spread) more by the time bladder cancer was detected in women.
"This obviously lowers the chances of survival," says Andreassen.
This study enabled the researchers to more accurately determine how much a later diagnosis actually contributes to the difference in survival rates.
Andreassen and her colleagues have calculated that later diagnosis accounts for half of the explanation for why women have a worse prognosis than men for the first two years after diagnosis.
Why women are diagnosed at a later stage isn’t clear, but the researchers have some theories.
Women are typically quicker than men to visit their doctor when they notice unusual symptoms. So why is bladder cancer detected later in women than in men?
Masked by bladder infection
Blood in the urine is a typical symptom of bladder cancer. The average age for detecting bladder cancer is 73 for men, and somewhat higher for women.
Menstruation is clearly long past at this age. However, women are more often prone than men to bladder or urinary tract infections (UTIs). It isn’t that uncommon for women to find blood in the urine.
"Some studies have shown that doctors are more likely to prescribe antibiotics for bladder infection when women come in with pain in the bladder and blood in the urine," Andreassen said.
A Swedish study has shown that it takes longer before women are referred to a specialist for bladder problems than men.
"Women’s warning signs aren’t picked up in the same way," says Andreassen.
Blood in the urine is more unusual among men, and so the symptoms are more of a red flag for doctors.
Doctors should be on the alert
Detecting bladder cancer early is crucial for a good outcome.
"The next step after urine testing is to examine the bladder through the urethra, which is quite an invasive procedure," says Andreassen.
She thinks that sending women to urologists immediately is therefore a bit too hasty.
Instead, women’s GPs need to ensure that UTIs are documented and to be on the alert if symptoms don’t resolve after treatment.
This recommendation has been included in the new version of the treatment programme to be published this summer.
Smoking increases risk
Age is a risk factor, and smoking increases the risk.
"Doctors may be quicker to consider the possibility of bladder cancer when symptoms occur in older women who smoke or have smoked," Andreassen says.
Ideally, we should have a reliable test based on a blood test, or preferably a urine test, that is a gentle method to detect bladder cancer early in the process, says the researcher. But that test doesn’t exist yet.
Bladder cancer on the rise
Bladder cancer is far more prevalent among men than women. In Norway 1271 men were diagnosed in 2016, compared to only 488 women.
But this type of cancer is on the rise, especially among women in Norway.
The researchers believe this may be due in part to the fact that women’s smoking habits now resemble those of men, and at the same time occupational risk differences have evened out over time.
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Read the Norwegian version of this article at forskning.no.
