Teachers in California appear to be at higher risk of developing breast and endometrial cancers but have lower rates of lung and cervical cancer, according to California researchers.

The study of 133,479 female teachers in California began in 1995 and found that the women had a 51 percent higher rate of breast cancer than other California women. They also had a 72 percent greater risk of endometrial cancer.

"Clearly, teachers face a higher risk of many cancers. These women most likely have in common certain risk factors that contribute to their increased risk. As we gather more information on our study participants over the next few years, we should gain insight into the causes of these cancers," said Leslie Bernstein, PhD, professor of preventive medicine and lead author of the study.

The study, reported in the journal Cancer Causes and Control, is the first to look examine the incidence of cancer in schoolteachers.

Approximately 87 percent of the participants are non-Hispanic white. However, substantial numbers of African Americans, Hispanics, Asians and Pacific Islanders were included in the study.

Researchers found the following for teachers:

• 28 percent greater risk of ovarian cancer;
• 59 percent greater risk of melanoma;
• 47 percent greater risk of lymphoma;
• 28 percent greater risk of leukemia;
• 34 percent lower risk of lung cancer;
• 47 percent lower risk of cervical cancer.

"What surprised me about these results was the magnitude of the excess risk, particularly for breast cancer," said Dr. Ronald K. Ross, professor at the Keck School of Medicine at the University of Southern California. "There are some serious issues here that need to be understood and addressed. This high risk is particularly alarming given the large number of active and retired female teachers residing in California."

Researchers speculate that teachers share certain lifestyle and environmental factors that could contribute to the teachers' increased or decreased risk of cancer.

Investigators plan to send out additional questionnaires and look closely at factors such as family history, diet and environment. "We expect to see many more initiatives coming out of this study," said Bernstein.

Other sources: University of Southern California