SAN ANTONIO – Pregnancy-associated breast cancer carries a relatively poor prognosis regardless of whether the malignancy is diagnosed during pregnancy or post partum, a meta-analysis has shown.
The meta-analysis included 29 matched case-control studies totaling 3,529 women with pregnancy-associated breast cancer – defined as breast cancer diagnosed during pregnancy or within 1 year afterward – and 36,914 controls whose breast cancer was unrelated to pregnancy.
This is believed to be the largest-ever meta-analysis addressing the prognosis of pregnancy-associated breast cancer, a relatively rare disease, Dr. Hatem A. Azim Jr. reported at the annual San Antonio Breast Cancer Symposium. In addition to the published reports, Dr. Azim and coauthors contacted the various study investigators to obtain unpublished data.
Women with pregnancy-associated breast cancer had a significantly greater risk of death than did controls, Dr. Azim and colleagues found: In a multivariate analysis, pregnancy increased the overall mortality rate by 46%. This held true even after adjustment for differences in tumor size, nodal status, and systemic therapy, according to Dr. Azim of the Jules Bordet Institute at the Free University of Brussels.
The secondary outcome measure in the meta-analysis was disease-free survival. Patients with pregnancy-associated breast cancer had a 59% increased risk of relapse compared with women with nonpregnancy-related breast cancer.
Roughly 6% of breast cancers are diagnosed in women before the age of 40, and of those only about 10% are diagnosed during pregnancy or within a year after. The relative rarity of this condition precludes conducting definitive large prospective clinical trials addressing patient prognosis.
Despite the rarity of pregnancy-associated breast cancer, however, it’s an important condition for a couple of reasons: The incidence of pregnancy-associated breast cancer is increasing because of the popular trend for delay of childbirth until later in life, and the condition poses a thorny therapeutic challenge because of the poor prognosis.
Dr. Azim reported no relevant financial disclosures.