A Canadian oncologist has urged doctors and other healthcare professionals to be more aware of the potential risk of suicide among cancer patients and to offer extra support to the most vulnerable and their families.
In a study published on line (Thursday 19 October) in Annals of Oncology the author said that while suicide is comparatively rare, his analysis of 1.3 million cancer cases in the United States revealed that 19 out of every 1,000 male cancer patients and four out of every 1,000 female cancer patients took their own lives – a total of 1,307 men and 265 women.
At around 24 suicides per 100,000 among cancer patients per year, the rate was between two and two and a half times that of the general American population (10.6 per 100,000 per year, which also includes the cancer population).
The nearly five-fold preponderance of males to female cancer suicides reflects the male-female ratio for suicide in the general population.
The risk of suicide varied according to a number of different factors, including gender, prognosis, the stage of disease, the type of cancer, ethnicity and family situation, according to the study's author Dr Wayne Kendal, a radiation oncologist at the Ottawa Hospital Regional Cancer Centre.
"If we were to draw a composite picture of the patient most at risk, this would be a widowed white male, with a new diagnosis of possibly head and neck cancer or multiple myeloma, with widespread and perhaps high-grade disease or maybe a history of other cancers. By contrast, a patient with decreased risk of suicide would be a woman of African-American heritage, with perhaps colorectal or cervical cancer, and living with her spouse," said Dr Kendal.
Looked at overall, i.e. men and women combined, the cancers involving the highest suicide rates were those of the lung and bronchus, bladder, head and neck, oesophagus and myeloma, with lower rates for those of the breast and liver. However, when it was split according to sex, the results were different.
The suicide rates for most cancer sites in females were similar to each other, except for colorectal and cervical cancer, which were lower. Among males, the highest rates were for head and neck cancer, liver cancer and myeloma. Rates among bladder, oesphagus and lung and bronchus cancer were no higher than for other male cancers. Leukaemia, prostate and brain cancers had a lower suicide risk than other male cancers.
Both sexes were more likely to commit suicide if their cancer had already spread from its primary site to distant organs by the time it was diagnosed, with a higher suicide rate being detectable for men with intermediate stages.
Another difference between the sexes was that the highest suicide rate among men was immediately after diagnosis, whereas among women it appeared more or less constant over time.
Both sexes had an increased risk if they were divorced, but the risk for men was more than halved if they were married. For women it was about a third lower.
African-Americans had a lower risk, consistent with the lower risk for African-Americans amongst the general population, possibly due to religious beliefs, family support and a cultural rejection of suicide: the rate among African-American males with cancer was in fact more in line with that of female cancer patients.
"Many of the extremes of risk seen within the male cancer cohort were not as apparent among the females," said Dr Kendal. "Particularly with sites involving greatest risk for males, such as head and neck cancer and myeloma, it looks as if issues around quality of life, coping, symptom control and psychological distress were important. The almost five-fold fewer recorded female suicides could mean that lower statistical power might account for the lack of a similar findings, or it could be that female cancer patients did experience similar problems but were less inclined to react through self-directed violence – much as we see in the general female population."
One apparent anomaly was that, although poor prognosis was associated with higher risk, pancreatic cancer, which has generally a very poor outlook, did not carry any higher suicide risk than that of other cancers. Refusal by the patient of either surgical or radiotherapy treatment did not heighten risk: however there was a statistically significant higher risk of suicide when surgery was deemed contraindicated – indicative of advanced cancer or additional health problems.
"Clearly, any conclusions about risk factors can only be speculative," said Dr Kendal. "It could be that in cancers where surgery or radiotherapy were not deemed appropriate, patients felt a sense of hopelessness. In cancers, such as those of the head and neck, particularly oropharyngeal cancer, where pain and difficulty feeding are factors, or in myeloma where we see a lot of chronic pain, weakened bones and fractures, quality of life issues might play a role."
He said that, within this particular study, it was not possible to differentiate from the data between suicides associated with affective illnesses or substance abuse versus those motivated by desire for relief from terminal illness or the avoidance of being a burden to others.
"However, the data did confirm that married status lowered the risk of suicide and, overall, it seems plausible to conclude that depression played a likely role in many of the suicides."
Dr Kendal concluded: "We must get the message out to physicians, nurses and social workers that they should be aware of the potential for suicide in their cancer patients and that maybe, by giving people in need, and their families, more support and providing better symptom control we might be able to foster the desire to continue living."
 Suicide & cancer: a gender comparative study. Annals of Oncology. doi:10.1093/annonc/mdl385.
 Data source: Surveillance, Epidemiology, and End Results (SEER) 9 Public-Use population-based registry. April 2004 release of November 2003 submission.
A PDF of the research paper is available immediately on request from Margaret Willson or from 09.00 hrs Wednesday 18 October on: http://www.oxfordjournals.org/our_journals/annonc/press_releases/freepdf/mdl385
Please acknowledge Annals of Oncology as a source in any reports.
Annals of Oncology is the monthly journal of the European Society for Medical Oncology.
Annals of Oncology website: http://annonc.oxfordjournals.org/
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