Women of lower socioeconomic status (SES) are less likely to survive after a cancer diagnosis largely due to unhealthy lifestyle factors, such as smoking, that are more common among less educated, poorer individuals, Norwegian researchers report.

“According to our study, we see that low SES is not a risk factor itself, it is the underlying lifestyle or behaviour that matters,” Dr. Tonje Braaten of the University of Tromso told Reuters Health.

While cancer survival is known to be worse for people of lower socioeconomic status, it hasn’t been clear exactly why, Braaten and her team note in the journal BMC Public Health.

To investigate, they analyzed data on 91,814 women from the Norwegian Women and Cancer Study who answered a questionnaire between 1996 and 1998. By the end of 2004, 3,899 of the women had been diagnosed with cancer and 919 had died from the disease.

As the cancer patients’ socioeconomic status as measured by years of education or household income rose, their risk of dying from the disease decreased, Braaten and her colleagues found. Education appeared to play the strongest role, and was closely linked to whether or not a woman smoked.

Some researchers have suggested that cancer is less likely to be diagnosed early, when it is most treatable, among poorer, less educated people, while worse quality of cancer care has also been proposed as a factor explaining the mortality-socioeconomic status link.

The current findings didn’t consistently support these hypotheses, the researchers say, but instead provide evidence that lifestyle factors drive the relationship. They point out that smoking accounted for half of the increased risk of dying seen among the least educated women compared to the most educated.

“We know that lifestyle factors strongly affect the risk of getting cancer,” Braaten noted, “but now we find that lifestyle prior to cancer diagnosis also may affect your likelihood of surviving from cancer.”

SOURCE: BMC Public Health, online June 8, 2009.