THURSDAY, May 8 (HealthDay News) -- While the rate at which
breast cancer tumors grow varies among patients, that growth tends
to be faster among younger women, Norwegian researchers report.
These findings may help in planning and evaluating screening
programs, clinical trials and other studies, the researchers
say.
Using a new mathematical model, the scientists were also able to
estimate the numbers of breast cancers detectable by mammography.
This is a new approach to estimating the growth rate of tumors and
the ability of mammograms to find them.
"There are enormous implications for the sensitivity of breast
cancer screening programs," lead researcher Harald Weedon-Fekjr, of
the Department of Etiological Research, Cancer Registry of Norway,
said in a statement.
"We found that mammography screen test sensitivity increases
sharply with increased tumor size, as one might expect. Detection
rates are just 26 percent for a 5 millimeter tumor but increase to
91 percent once a tumor is 10 millimeter in size," he added.
The report was published in the May 8 issue of the online
journal
Breast Cancer Research.
In the study, Weedon-Fekjr, and colleagues tested their model
using mammography results from 395,188 women aged 50 to 69.
The researchers found that the growth rate of tumors varied
significantly between patients. About one in 20 tumors doubled in
size, from 10 to 20 millimeters in just over a month. However, a
similar number of tumors took more than six years to double in
size.
Based on this finding, Weedon-Fekjr's team estimated that it
takes an average of 1.7 years for tumors to double in size.
Moreover, tumor growth appeared to be faster among younger women
and slowed as women aged, the researchers noted.
"Tumor growth and test sensitivity estimates can be directly
linked to tumor size in a full population study, resulting in very
useful growth estimates directly connected to a biologically
relevant measure," the researchers wrote.
"Tumor growth seems to vary greatly between tumors, with higher
growth rates among younger women. Most tumors become visible at
screening when they reach a diameter of 5 millimeters to 10
millimeters," they concluded.
One expert thinks this study again confirms the need for women
to have a mammogram every year.
"This study continues to prove why we need to screen women every
year, starting at age 40," said Debbie Saslow, director of breast
and gynecologic cancer at the American Cancer Society.
This is another study that shows that tumors grow faster in
younger women, Saslow said. "It just doesn't make sense to have
guidelines that say younger women should be screened every one to
two years and every year as they get older," she said.
More information
For more on breast cancer, visit the
U.S. National Cancer Institute.
