(CBS) -- New research suggested that women who are overweight may need to be screened for breast cancer more frequently than slimmer women.
Data was gathered from a study that included over 2,000 Swedish women, aged 55 to 74, diagnosed with invasive breast cancer between 2001 and 2008. The average BMI was 25.6. BMI is a rough estimate of body fat based on height and weight measurements.
A normal BMI is considered to be between 18.5 and 24.9, 25 to 25.9 is overweight and any BMI over 30 is considered obese.
According to the research, heavier women were at a greater risk of having cancer detected after the tumor has grown large--over two centimeters--than slimmer women. The data also showed the women have a worse prognosis when their breast cancers are detected between regular cancer screenings.
"It seems overweight women would need shorter time intervals between screenings than other women, but our study was not designed to quantify how much," explained Dr. Fredrik Strand, a radiologist at the Karolinska University Hospital.
Women with a BMI higher than 25 with interval cancers had a worse prognosis than thinner women. A worse prognosis was defined as the cancer coming back, the cancer spreading or death from cancer, according to Strand.
Strand also reported that the study findings might be stronger if done in a U.S. population because people in the U.S. tend to be heavier than in Sweden.
Dr. Laurie Margolies, chief of breast imaging at Mount Sinai Health System in New York City, said the study adds "another piece of evidence that might end the confusion about when to get a mammogram. Women should be screened every year."