Associations Between Pregnancy, Breastfeeding, Breast Cancer and Survival Detailed

However, the study of 2,752 breast cancer patients by Australian researchers found that if the breast cancer was diagnosed while the women were pregnant, their risk of dying was nearly the same as other, non-pregnant women diagnosed with breast cancer - only three percent higher.

Assistant Professor Angela Ives, a research fellow at The University of Western Australia, will tell the conference that the findings suggest that the cumulative effect of pregnancy may play a role in breast cancer prognosis and this, along with whether a woman breast feeds, needs further investigation.

However, she said: "It is important to stress that our findings should not discourage women from breast feeding as we know that this is beneficial to both mother and baby in a number of ways. While most breast symptoms or abnormalities identified in young women are benign, it is important that when a woman is pregnant or breast feeding any symptoms or abnormalities are not assumed to be due to the pregnancy or breast feeding, particularly if the symptoms persist. It is important that both health professionals and young women are breast aware, even during pregnancy and breast-feeding, and promptly have symptoms investigated to allow early diagnosis.

"For women who are diagnosed with breast cancer after pregnancy, they and their clinicians may wish to consider different forms of treatment to improve survival."

Prof Ives said that because very little is known about gestational breast cancer (breast cancer that is diagnosed while a woman is pregnant or up to 12 months after completion of a pregnancy, including terminations or miscarriages) she and her colleagues decided to find out more so that women could make informed choices about their breast cancer management and pregnancy outcome.

Using the Western Australia Data Linkage System, they identified a group of 2,752 women, aged less than 45, diagnosed with breast cancer in Western Australia between January 1982 and December 2003. They followed them to December 2007 or to their date of death, if earlier.

"The WA Data Linkage System is one of only five comprehensive record linkage systems in the world. It brings together population-based hospital morbidity data, birth and death records, mental health services data, 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," she said.

The researchers took account of additional factors such as age at diagnosis, histological tumour grade, stage of disease and whether the cancer had spread to the lymph nodes. From the total number of women, 182 were diagnosed with gestational breast cancer, 55 while they were pregnant and 127 after the end of the pregnancy. Prof Ives found that, as might be expected, histological tumour grade, disease stage and lymph node involvement were all associated with a worse survival for all the women. The finding of the increased risk of death if breast cancer was diagnosed after pregnancy remained after adjusting for lymph node status, disease stage at diagnosis, histological tumour grade and age.