A new approach to estimate tumour growth, developed by scientists at the Department of Etiological Research, Cancer Registry of Norway, has indicated that the growth of breast cancer tumours is faster in younger women as compared to older women.
This new model, developed by Harald Weedon-Fekjær of the Department of Etiological Research, Cancer Registry of Norway and colleagues, can also determine the proportion of breast cancers which are detected at screening (screen test sensitivity).
In addition, it also provides a new approach to simultaneously estimating the growth rate of breast cancer and the ability of mammography screening to detect tumours.
The results of the study have demonstrated that tumour growth rates vary considerably among patients, with generally slower growth rates with increasing age at diagnosis.
While earlier studies of tumour growth rates in people have were based mainly on small and selected samples, the new approach deals with a very large population of breast cancer patients included in the Norwegian Breast Cancer Screening Program.
The new model was applied to cancer incidence and tumour measurement data from 395,188 women aged between 50 and 69 years old.
It was found that tumour growth varies considerably between subjects. About one in twenty tumours double in size in just over a month from 10 to 20mm, while similar numbers took more than six years to grow to this size. They estimated the mean time for a tumour to double in size from 10 to 20 mm in diameter is 1.7 years.
"There are enormous implications for the sensitivity of breast cancer screening programs. We found that mammography screen test sensitivity (STS) increases sharply with increased tumour size, as one might expect. Detection rates are just 26 percent for a 5 mm tumour but increase to 91 percent once a tumour is 10 mm in size" explained Weedon-Fekjær.
The details of the study are published in BioMed Central's open access journal, Breast Cancer Research.