Abstract P3-18-08: Feasibility and safety of breast-conserving surgery in early-stage breast cancers during the first trimester of pregnancy

Abstract

Abstract Background: Breast cancer is the most common malignancy occurring during gestation and should be managed with the same protocols as for young non-pregnant women. In early-stage breast cancer during pregnancy (PrBC), breast-conserving surgery (BCS) with delayed radiation therapy (RT) is a reasonable alternative to radical mastectomy. Regrettably, no specific and widely adopted guidelines on the surgical management of these patients are available. In this study, we investigated the feasibility and safety of BCS during the first trimester of pregnancy in women with early-stage PrBC. Method: The first trimester was defined as 12 weeks and 6 days after the first day of the last menstruation. As for internal protocols, the surgical strategy for PrBC followed the same conservative-oriented schemes applied for nonpregnant patients. Only women with early-stage PrBC treated with BCS during pregnancy followed by planned RT to the whole breast after delivery were included. Exclusion criteria were i) clinical diagnosis or suspicion of inflammatory breast cancer; ii) multicentric disease; iii) diffuse malignant microcalcifications on mammography; iv) previous; v) connective tissue disease, and vi) syndromic breast cancers. All cases underwent central pathological review at the Pathology Department of the European Institute of Oncology. The primary outcome was the isolated local recurrence (ILR). Results: Among 168 PrBC patients, 67 (39.9%) were diagnosed during the first trimester of gestation. Of these, 30 patients (age range, 23-43 years; median=36 years; gestational age, 2-12 weeks; median=7 weeks; median follow-up time=6.5 years) met the inclusion criteria. None of the patients included in this study experienced perioperative surgical complications. No ILR was observed within three months (n=30), 1 year (n=27), and 5 years (n=18) after surgery. The 5-year overall survival rate for all patients was 97% (n=29/30). Four patients experienced ILR or new carcinomas after 6-13 years. These patients are still alive and disease-free after 14-17 years of follow-up. Discussion: In our study, both adjuvant endocrine therapy and anti-HER2 treatment were postponed after delivery. Local recurrences/second primary tumors were observed in 4 out of 30 patients treated with BCS. Given that patient #4 did not receive postoperative RT, but an after-delivery mastectomy for preoperative diagnostic underestimation during pregnancy, this case does not represent a post-BCS recurrence. On the other hand, cases #1-3 could be considered real relapses. Two of these tumors occurred in patients that underwent CT during pregnancy, in which the interval between the end of systemic therapies and the onset of RT was not influenced by the pregnancy. In a single patient (not eligible for systemic treatment in pregnancy), the RT was performed with a longer interval than the usual one of the non-pregnant patients. Survival was not affected by local relapse, underlining the efficacy of salvage treatment.Conclusion: The findings of this study suggest that BCS in the first trimester of pregnancy can be considered reasonably safe for both mother and the child. Mammography should be mandatory in all patients for whom conservative surgery is recommended. Given that the availability of data concerning PrBC and its treatment is scarce and heterogeneous, multicentric studies are warranted. Citation Format: Nicola Fusco, Concetta Blundo, Massimo Giroda, Elham Sajjadi, Konstantinos Venetis, M. Cristina Leonardi, Elisa Vicini, Luca Despini, Claudia F. Rossi, Letterio Runza, Eugenia Di Loreto, Giovanna Scarfone, Elena Guerini-Rocco, Giuseppe Viale, Paolo Veronesi, Barbara Buonomo, Fedro A. Peccatori, Viviana E. Galimberti. Feasibility and safety of breast-conserving surgery in early-stage breast cancers during the first trimester of pregnancy [abstract]. In: Proceedings of the 2021 San Antonio Breast Cancer Symposium; 2021 Dec 7-10; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2022;82(4 Suppl):Abstract nr P3-18-08.