P1-08-17: Pregnancy-Associated Breast Cancer Does Not Have a Worse Outcome in the 4912 Women with Breast Cancer of the AMAZONA Project.
Authors: Liedke PER , Szymonifka J , Simon SD , Barrios CH , Bines J , Finkelstein D , Goss PE 
Published: June 2012

Introduction: Pregnancy traditionally is considered a protective factor for breast cancer. Recent data suggests that pregnancy-associated breast cancer (PABC), a distinct biologic variant possibly related to breast involution, can occur up to 10 years post-partum and may carry a worse prognosis than that of age matched sporadic or nulliparous breast cancer. The Amazona project is a retrospective cohort of 4,912 Brazilian women with breast cancer that has previously reported on worse outcomes of patients according to type of institution where treatment was received (San Antonio 2009 abstr. 3082). We have assessed the outcomes of PABC in the Amazona cohort.

Objectives: 1- To identify whether women who were diagnosed with breast cancer up to 10 years after their first pregnancy had worse disease free survival (DFS) and overall survival (OS) than nulliparous women (NW); 2- to assess if age at first pregnancy is related to age of breast cancer diagnosis and worse DFS or OS; 3- to assess whether number of pregnancies is associated with worse DFS or OS; 4- to assess whether time from first pregnancy to diagnosis or age of first pregnancy are associated with histological grade, clinical stage or tumor expression of ER, PR, and HER2.

Methods: We analyzed 4836 women for whom parous history was available, in respect to DFS, OS, tumor clinical stage, histological grade, expression of ER, PR and HER2, according to age of first pregnancy, diagnosis up to 5 and 10 years after first pregnancy, and number of pregnancies, using NW as controls. Analysis of DFS and OS was done by Cox regression modeling adjusted for institution type, stage, ER, PR, HER2 and grade.

Results: Our cohort had 1996 nulliparous women and 2840 parous women. The median follow up was 28 months and there were 318 deaths and 735 recurrences. We did not find any correlation between PABC with DFS (5 year interval HR 1.15, 95%CI 0.43−3.07; 10 year interval HR 1.01, 95%CI 0.57−1.81) or OS (5 year interval HR 1.88, 95%CI 0.6−5.94; 10 year interval HR 0.5, 95%CI 0.73−3.09), nor was there a correlation between age at first pregnancy with age of breast cancer diagnosis. We also did not see any difference between age of first pregnancy and DFS or OS.

Women with 3 or more pregnancies had worse OS (HR 0.71, 95%CI 0.54−0.93) but not worse DFS (HR 0.93, 95%CI 0.76−1.13).Tumors diagnosed within 5 or 10 years from first pregnancy did not differ by grade, ER, PR, HER2, and clinical stage from those of NW. Women who had their first pregnancy after age 20 tended to have more ER positive (OR 1.99, 95%CI 1.49−2.65), PR positive (OR 1.40, 95%CI 1.06−1.87), and HER2 positive (OR 1.85, 95%CI 1.22−2.79) tumors than NW.

Conclusions: In this large cohort of breast cancer patients from the diverse geographic and socioeconomic spectrum of Brazil we did not find any association between PABC or age of first pregnancy to DFS or OS. The association with worse OS but not DFS for women with 3 or more pregnancies might be due to confounding factors. PABC was not associated with worse clinical prognostic factors. Women who had their first pregnancy after age 20 were more likely to have ER+, PR+ and HER2 + tumors than nulliparous patients.

Citation Information: Cancer Res 2011;71(24 Suppl):Abstract nr P1-08-17.