A cancer diagnosis can strain any relationship. But when a woman gets news of a life-threatening illness, her husband is six times more likely to leave her than if the tables were turned and the man got the bad news, according to new research.

The study included diagnoses of both cancer and multiple sclerosis and found an overall divorce rate of nearly 12 percent, which is similar to that found in the normal population.

But when the researchers looked at gender differences, they found the rate was nearly 21 percent when women were the patients compared with about 3 percent when men got the life-threatening diagnosis.

The researchers suggest men are less able to commit, on the spot, to being caregivers to a sick partner, while women are better at assuming such home and family responsibilities.

"Part of it is a sense of self-preservation," said study researcher Dr. Marc Chamberlain, director of the neuro-oncology program at the Seattle Cancer Care Alliance (SCCA). "In men that seems to operate very highly and they don't feel this codependence, this requirement to nurture their significant other who has this life-threatening illness, but rather decide what's best for me is to find an alternative mate and abandon my fatally flawed spouse."

Chamberlain is also a professor of neurology and neurosurgery at the University of Washington School of Medicine.

Life-threatening illness

The findings, announced today, come from a study of 515 patients who had enrolled in 2001 and 2002 at the SCCA, Huntsman and Stanford University School of Medicine. The researchers followed the participants until February 2006.

The men and women in the study (about evenly split) were divided into groups by diagnosis, with 214 having a malignant primary brain tumor, 193 with a solid tumor not related to the central nervous system, and 108 patients with multiple sclerosis.

Similar results were found for all diagnosis types, in which divorce was much more likely if the woman was the patient.

Cancer strain

Chamberlain realizes the enormity of a cancer diagnosis. "We find ourselves as a caregiver with someone with cancer, and that cancer isn't just affecting that patient but it affects profoundly that entire family," Chamberlain told LiveScience.

For instance, the patient may have been the sole provider or income or the person who maintained the home. In addition, with brain tumors and multiple sclerosis, Chamberlain says, a patient's personality can change. "That's not easy for caregivers."

Even so, sticking together could be what's best for the patient, the researchers found.

"We found patients who were divorced or separated had a much higher rate of hospitalization during their illness, which I think reflects lack of social support," Chamberlain said, adding such patients also were much less likely to participate in clinical trials, to seek alternative treatments or to even complete treatment regimens. They were also more likely than those who stayed in marriages to die at home.

The results will be detailed in the Nov. 15 issue of the journal Cancer.