Prognosis of triple-negative breast cancer associated with pregnancy: A propensity score-matched analysis from the French CALG (Cancer Associé à la Grossesse) network

INTRODUCTION: Triple-negative (TN) breast cancer represents one third of pregnancy-associated breast cancers (PABC). The aims of the current study were to describe oncological and obstetrical outcomes of patients with TN-PABC and to compare their prognosis with TN-non-PABC patients using a propensity score. MATERIALS AND METHODS: Between January 2005 and December 2020, data of patients with histologically proven TN-PABC were collected and compared with data of TN-non-PABC patients under the age of 46 years diagnosed during the same period using a propensity score (PS). RESULTS: After PS matching (tumor size and lymph node involvement),there were 59 patients in each group. The median follow-up was 14 months (IQR 4.8–40.1) for the TN-PABC group and 60 months (IQR 30.7–101.4) for the TN-non-PABC group. Eight recurrences occurred in the TN-PABC group and 10 in the TN-non-PABC group (adjusted OR (AOR) = 0.60 (0.21–1.60), HR (Cox adjusted model- AHR) = 1.25 (0.53–2.94)). Two patients died in the TN-PABC group, and six in the TN-non-PABC group with an AOR = 0.23 (0.03–1.01) and an AHR = 0.58 (0.12–2.69). All the patients diagnosed during the second (n = 17) and third trimesters (n = 28) continued their pregnancies, with a median term at delivery of 38 WG (IQR 36–39). All patients gave birth to healthy newborns. CONCLUSION: Although the TN subtype is associated with poor prognosis in pregnant patients due to advanced stage at diagnosis and high lymph node involvement, our PS-matched case-control study showed that pregnancy per se does not worsen the prognosis in terms of recurrence-free and overall survival.