The spectrum of pathological changes in breast cancer following neoadjuvant chemotherapy

Breast cancer with advanced stage is common in Bangladeshi women. For the treatment of this deadly disease neoadjuvant chemotherapy (NAT) is the recent standard of care. NAT is useful for down-staging and to prevent micro-metastasis of tumour, on the other hand it causes variable clinical and pathological responses. This observational study was aimed to evaluate the morphological changes in neoplastic, nonneoplastic breast tissue and in the lymph nodes after NAT. To identify the clinical response and post operative histologic changes, this study prospectively selected 35 patients with locally advanced breast cancer treated with NAT. In these patients clinical response was assessed based on tumour size. Mastectomy specimens were collected and samplings were done in specific method. Majority (68%) of patients presented with breast lump measuring over 5cm with enlarged lymph nodes. After NAT the lump size reduced to <5cm and lymph nodes became nonpalpable in most (60%) of the patient. Complete clinical response (cCR) was observed in five patients. For histopathological evaluation, the tumour cellularity was semi quantitatively measured. Seventeen percent (17%) patient presented with 50% tumour cellularity in tumour bed. Most striking cytologic atypia was nuclear changes. The characteristic patterns of stomal changes were observed. Only 8 patients showed nonneoplastic breast tissue changes. In lymph nodes hyaline stromal scar was most commonly (23%) seen. This study observed that 2 patients had pathological complete response out of 5 clinically complete response patients. This study concluded that the knowledge of morphologic spectrum of treatment-induced breast tissue change is important for the pathologist to avoid misdiagnosis. This will help the clinician to take rational decision for management of the locally advanced breast cancer.