Does treatment sequence affect outcomes in patients with metaplastic breast cancer?

Promising Response to Neoadjuvant Chemotherapy Plus Immunotherapy in Metaplastic Breast Carcinoma

Purpose

Metaplastic breast carcinoma (MpBC) is a rare and aggressive subtype of breast cancer that often shows poor response to conventional neoadjuvant chemotherapy (NAC). This study aimed to evaluate the efficacy of combining NAC with immune checkpoint inhibitors (ICIs) in MpBC patients.

Methods

We conducted a retrospective analysis of MpBC patients treated with NAC, with or without the addition of immunotherapy, at Sun Yat-sen university Cancer center between 2017 and 2024. We assessed clinical and pathological response to NAC in MpBC patients.

Results

40 MpBC patients treated with NAC were identified, 33 patients treated with NAC alone, 7 patients treated with NAC and immunotherapy, 4 (10%) patients achieved pCR. Among the 33 patients treated with NAC alone, only 2 (6%) achieved pCR. In contrast, 7 patients received additional immunotherapy, and 3 started immunotherapy at the initiation of NAC, with 2 of these (67%) achieving pCR. Patients who received immunotherapy after disease progression on NAC showed varying degrees of tumor response, from stable disease (SD) to partial response (PR).

Conclusion

We observed a promising response on addition of immunotherapy to NAC among patients with MpBC, suggesting that immunotherapy may have great potential in the treatment of metaplastic breast carcinoma.

Chemotherapy is of prognostic significance to metaplastic breast cancer

This study aimed to evaluate the significance of chemotherapy (CT) among metaplastic breast cancer (MpBC), and to compare the survival outcomes between triple negative MpBC (MpBC-TNBC) and triple negative invasive ductal carcinoma (IDC-TNBC). SEER database was indexed to identify female unilateral primary MpBC diagnosed from 2010 to 2017. Patients were classified into neoadjuvant chemotherapy (NAC) with response (NAC-response), NAC-no response, adjuvant chemotherapy, and no CT. Breast cancer-specific survival (BCSS) and overall survival (OS) was estimated using the Kaplan-Meier method and compared by log-rank test. Cox regression was used to evaluate the independent prognostic factors. A 1:4 propensity score matching method was adopted to balance baseline differences. Altogether 1186 MpBC patients were enrolled, among them 181 received NAC, 647 received adjuvant CT and 358 did not receive any CT. Chemotherapy was an independent favorable prognostic factor. NAC-response and adjuvant CT had a significant or an obvious trend of survival improvement compared with NAC-no response or no CT. MpBC-TNBC was an independent unfavorable prognostic factor compared with IDC-TNBC. Among them, there was significant or trend of survival improvement among all TNBCs receiving NAC or adjuvant CT compared with no CT. Chemotherapy was of important significance to MpBC prognosis and should be integrated in comprehensive treatment for MpBC.