Chemosensitivity, tumor infiltrating lymphocytes (TILs), and survival of postpartum PABC patients treated by neoadjuvant chemotherapy

Abstract

Background: Pregnancy-associated breast cancer (PABC) refers to breast cancers (BC) diagnosed during pregnancy or shortly after birth. Although the inflammatory environment of post-partum PABC cases (designed as PP-PABC) may be deleterious, so far PP-PABC have scarcely been distinguished from breast cancers diagnosed during pregnancy. Furthermore, whether PP-PABC cases have an enhanced immune infiltration remains unknown. We investigated chemosensitivity, immune infiltration and survival of PP-PABC patients treated by neoadjuvant chemotherapy (NAC) compared to non-PABC matched BC patients.

Materials and methods: We identified PP-PABC cases among a cohort of 1199 invasive BC treated with NAC between 2002 and 2012. Each PP-PABC case was matched with 3 non-PABC controls, according to age and pathological breast cancer subtype. Microbiopsy specimens and paired surgical samples were evaluated for stromal lymphocyte infiltration. Association of clinical and pathological factors with pathological complete response (pCR) and disease-free survival (DFS) was assessed by univariate and multivariate analyses.

Results: Our final population study was composed of 116 patients (29 PP-PABC and 87 non-PABC). Median follow-up was of 49.0 and 29.3 months, respectively. After NAC, pCR rates (p = 0.64), post-NAC immune infiltration (stromal TILs: p = 0.67; intratumoral TILs: p = 0.14), and DFS rates (p = 0.17) were comparable between PP-PABC and non-PABC patients in global population. Similar results were found after stratification by pathological subtype.

Conclusion: We observed similar patterns between postpartum PABC and control tumors in terms of chemosensitivity, immune infiltration, and prognostic. Our results enhance the idea that PP-PABC should receive the same standard of care treatment as other patients, including neoadjuvant chemotherapy.

Keywords: Chemosensitivity; PABC; Post-partum breast cancer; Pregnancy associated breast cancer; Prognosis; TILs; Tumor infiltrating lymphocytes.