TUESDAY, Feb. 26 (HealthDay News) -- In the first year after being diagnosed with breast cancer, working women lose an average of 27 percent of their income, a new study finds.

Researchers from Laval University in Quebec interviewed 829 women at one, six and 12 months after their breast cancer diagnosis. The women were asked a number of work-related questions, such as their working status before their diagnosis, the amount of time absent from work due to the disease, and types of compensation received during their work absences.

The women were also asked about their perceptions of their financial status, and whether it had changed for the worse at one year after breast cancer diagnosis.

Of the 800 women who completed all three interviews, 459 had paying jobs at the time of their diagnosis and 403 of those women had work absences or reduced work hours after their diagnosis. On average, these women lost 27 percent of the wages they would normally have earned if they hadn't been ill, even after all forms of compensation were taken into account. Ten percent of the women lost more than two-thirds of their income.

The study found wide variation in the percentage of lost wages. Those most likely to suffer a large loss of income were: less educated; lived farther from the hospital where they had their cancer treatment; had more serious disease; required chemotherapy; or were self-employed, worked part time, or recently hired at their job.

"These findings should sensitize clinicians to the real extent to which wage losses resulting from breast cancer can substantially and negatively affect the financial situation of working women and their families," the study authors wrote.

The study was published in the Feb. 26 online issue of the Journal of the National Cancer Institute.