Mortality risk is higher in women who develop breast cancer when pregnant. Those so diagnosed in the 12 months after pregnancy are 48 per cent more likely to die than other young women with breast cancer, according to research led by The University of Western Australia.
However, in a study of almost 3,000 breast cancer patients aged less than 45, it was found that if the cancer was diagnosed during pregnancy their risk of dying was only three per cent higher than for non-pregnant women diagnosed with cancer.
Research Assistant Professor Angela Ives in UWA's Cancer and Palliative Care Research and Evaluation Unit said very little was known about gestational breast cancer (cancer diagnosed during pregnancy or up to a year later).
"We decided to find out more so that women could make informed choices about their cancer management and pregnancy outcome," she said.
With her colleagues, Asst/Professor Ives analysed statistics from the Western Australian Data Linkage System - one of a handful of such systems in the world.
"The comprehensive system brings together population-based hospital morbidity data, birth and death records, cancer registrations and midwives' notifications linked back to 1980. In this case we have been able to identify all cases of gestational breast cancer diagnosed in WA and all other cases of breast cancer in similar aged women to identify what is different about them.
"We know that pregnancy and breast-feeding reduce the long-term risk of a woman developing breast cancer but we also know that, in the short-term, having been pregnant may increase the risk of developing breast cancer. There needs to be further research into what might be happening at cell level with the way tumours grow and the role played by the body's immune response."
The researchers, who presented their findings at the European Breast Cancer Conference in Barcelona recently, are also studying the cumulative effect on survival of pregnancy and breast-feeding time from conception to the date of cancer diagnosis.