Patients with prostate, bladder or kidney cancers are five times more likely to commit suicide, a survey led by an Indian-origin scientists has found.
The analysis also showed that cancer patients are about three times more likely to commit suicide than the general population.
The proportion of attempted suicides which result in a completed or successful suicide was higher in cancer patients, with a higher proportion still in patients with urological cancers.
Severe psychological stress is one of the main side-effects of both a diagnosis of cancer and cancer treatment, with depression affecting between 5 and 25 per cent of cancer patients: many are also affected by Post-Traumatic Stress Disorder (PTSD).
Previous research has shown that the vast majority of cancer patients who have symptoms of depression often go untreated.
The study shows a substantial increase in suicide attempts and successful suicides in cancer patients.
It is the largest UK study looking at suicide in cancer patients. The research team led by Prashant Patel at the University of Birmingham in the UK examined the records from the England and Wales Hospital Episode Statistics database, from the period 2001 to 2011.
They linked this with cause of death statistics.
This is also the first time that a major study has examined suicidal intent in cancer patients - which they defined as the ratio of successful suicides to the rate of attempted suicides.
They found that this rate was far higher (1 to 7) in patients with prostate cancer than in the general population (1 to 25), which may show a greater determination to commit suicide in cancer patients.
"This is important as we know that people who attempt suicide are at higher risk of subsequently being successful in completing a suicide," said Mehran Afshar from St George's Hospital in London, UK.
"We have shown this 'intent' to commit to be far higher in our cancer population, thus confirming a real need to address psychological issues early on in the management of these patients," said Afshar.
Previous research has shown that a vast majority of cancer patients who have symptoms of depression go untreated.
The study also showed significant differences between the time to a successful suicide, which means that some cancer patients are more vulnerable in certain periods.
The researchers identified a total of 980,761 (493,234 males and 487,094 female) cancer patients which meant that 13.4 million-person years were included in the final data analysis. The team identified 162 suicides and 1,222 suicide attempts.
In the general population, the suicide rate is 10 per 100,000 people. The team found that the all-cancer suicide rate was 30 per 100,000 people.
In the urological cancers the figures are 36 per 100,000 people in kidney cancer, 48 suicides per 100,000 in bladder cancer, and 52 per 100,000 people in prostate cancer.
In the general population, there is an average of 25 suicide attempts for each successful suicide. In kidney cancer this ratio is 1 suicide for every 10 attempts.
In bladder and prostate cancer, this ratio drops to one suicide for every 7 attempts.
The time taken to commit suicide also varies substantially. Median time to suicide is 175 days from diagnosis for kidney cancer, 846 days for prostate cancer, and 1037 days for bladder cancer.