The association between methods of biopsy and survival following breast cancer: A hospital registry based cohort study.

Percutaneous biopsy in breast cancer has been associated with an increased risk of malignant cell seeding. However, the importance of these observations remains obscure due to lack of corroborating evidence from clinical studies. We determined whether method of biopsy is associated with breast cancer survival. This hospital registry-based cohort study included 3416 non-metastatic breast cancer patients diagnosed from 1993 to 2011 in a tertiary setting. Factors associated with biopsy methods were assessed. Multivariable Cox regression analysis was used to determine the independent prognostic impact of method of biopsy. Overall, 990 patients were diagnosed by core needle biopsy (CNB), 1364 by fine needle aspiration cytology (FNAC), and 1062 by excision biopsy. Excision biopsy was significantly associated with more favorable tumor characteristics. Radiotherapy modified the prognostic impact of biopsy method (Pinteraction < .001). Following multivariable analysis, excision biopsy was consistently associated with lower risk of mortality compared to FNAC in women receiving adjuvant radiotherapy (adjusted hazard ratio: 0.81, 95%CI: 0.66-0.99), but not in those who did not receive adjuvant radiotherapy (adjusted hazard ratio: 0.87, 95%CI: 0.65-1.17). While the risk of mortality was not different between patients undergoing FNAC and CNB when radiotherapy is administered, in the absence of radiotherapy, CNB was associated with higher risk of mortality than FNAC (adjusted hazard ratio: 1.57, 95%CI: 1.16-2.12). Given that our results contradict with findings of previous clinical studies assessing the prognostic impact of method of biopsy in women with breast cancer, further studies are warranted.