Abdominal pain and swelling can be early symptoms of ovarian cancer, but they are often attributed to other causes, potentially delaying an earlier diagnosis of the disease, according to a new study.

After reviewing the medical records of nearly 20,000 women, researchers found that as early as 12 months before diagnosis, women with ovarian cancer were twice as likely as women without the disease to report these symptoms to their doctors. But they were initially treated for stomach problems rather than given tests for the cancer.

"This study lends support to the idea that some women are having symptoms before diagnosis [of ovarian cancer] and could possibly have an earlier diagnosis if appropriate tests were offered earlier," said study author Dr. Lloyd H. Smith, chairman of the department of obstetrics and gynecology at the University of California, Davis.

"Having these symptoms is very unlikely to mean ovarian cancer but if the symptoms can't at first be attributed to another cause, it would be wise for a doctor to recommend that a woman be administered pelvic imaging and a serum test, called CA125, that can indicate ovarian cancer", he said.

The study results appear in the journal Cancer.

"This study is very important because it tells us that ovarian cancer patients have a much higher incidence of these symptoms than do women without the disease," said Dr. Robert Morgan Jr., staff physician with the division of medical oncology and therapeutics research at the City of Hope Cancer Center, in Duarte, Calif.

For the study, the researchers used data from diagnosis codes for nearly 20,000 women aged 68 or older -- 1,985 of whom had ovarian cancer, 6,024 of whom had breast cancer, and an age-matched group of 10,941 women without cancer, according to Forbes.com.

The group of women with breast cancer served as an extra control since they share some epidemiologic similarities with ovarian cancer patients.

The researchers found that women with ovarian cancer were twice as likely as women without the disease to report symptoms of stomach discomfort, both a year and nine months before diagnosis.