Abstract P3-02-05: Does MRI influence surgical planning more than clinical outcome? A cohort study of breast cancer patients receiving neoadjuvant therapy
Authors: McDermott M , Wilson C , Xu J , Illmann C , Simmons C 
Published: March 2017

Background: While magnetic resonance imaging (MRI) is a powerful diagnostic tool, there is currently no consensus on its role for breast cancer patients prior to the initiation of neoadjuvant therapy (NAT). In the adjuvant setting, there is evidence that the use of MRI is correlated with an increase the rate of mastectomies performed. There is currently no data describing how MRI is influencing treatment decisions or surgical management in the neoadjuvant setting. This study aimed to determine the impact of MRI on patients' surgical plan, and to understand the demographic differences in patients who had an MRI compared to those that did not in the neoadjuvant setting.

Methods: A secure database containing all potential NAT patients seen by medical oncologists at the BC Cancer Agency Vancouver Centre since 2012 was searched. Breast cancer patients who were treated with NAT and had undergone breast surgery before March 30, 2016 were identified. Tumour characteristics, surgical plan and surgical outcome were assessed retrospectively and compared between patients who had an MRI and patients who did not have an MRI.

Results: 270 patients were identified who met the inclusion criteria. Of those, 107 patients had a breast MRI and 163 patients did not. The two groups showed no significant pre-treatment differences with regards to type of breast cancer, receptor status, or clinical stage. The median age was 10 years younger in the MRI group (47 years) compared to the non-MRI group (57 years), p &lt; 0.0001. Patients who had an MRI had a non-significant higher rate of pathological complete response (pCR) than those who did not (30.8% and 21.5%, respectively, p=0.08). The surgical treatment did differ between these two groups; those who had MRI were more likely to have bilateral mastectomy (36.4% vs 23.3%, p=0.019) and less likely to have breast conserving surgery (BCS) (19.6% vs 31.9%, p=0.026). In the cohort that had an MRI, there was no significant difference in percentage of patients whose surgical plan was changed compared to the patients who did not have an MRI (33.6% and 28.8%, respectively). A change in surgical plan from a mastectomy to a BCS was more common in patients who did not have an MRI than those that did (31.9% and 13.9%, respectively). 45% of the surgeons who dictated a follow-up surgery consultation stated that the MRI was used to inform the surgical plan.

Discussions/Conclusions: In this real-world cohort, patients who had an MRI were more likely to undergo a bilateral mastectomy and less likely to have a BCS than the patients who did not have an MRI, despite having a higher rate of pCR. Age was the only baseline demographic difference between the two groups. These findings suggest that the role of MRI in the neoadjuvant setting needs to be refined further in order to avoid over-treatment.Background: While magnetic resonance imaging (MRI) is a powerful diagnostic tool, there is currently no consensus on its role for breast cancer patients prior to the initiation of neoadjuvant therapy (NAT). In the adjuvant setting, there is evidence that the use of MRI is correlated with an increase the rate of mastectomies performed. There is currently no data describing how MRI is influencing treatment decisions or surgical management in the neoadjuvant setting. This study aimed to determine the impact of MRI on patients' surgical plan, and to understand the demographic differences in patients who had an MRI compared to those that did not in the neoadjuvant setting.

Methods: A secure database containing all potential NAT patients seen by medical oncologists at the BC Cancer Agency Vancouver Centre since 2012 was searched. Breast cancer patients who were treated with NAT and had undergone breast surgery before March 30, 2016 were identified. Tumour characteristics, surgical plan and surgical outcome were assessed retrospectively and compared between patients who had an MRI and patients who did not have an MRI.

Results: 270 patients were identified who met the inclusion criteria. Of those, 107 patients had a breast MRI and 163 patients did not. The two groups showed no significant pre-treatment differences with regards to type of breast cancer, receptor status, or clinical stage. The median age was 10 years younger in the MRI group (47 years) compared to the non-MRI group (57 years), p &lt; 0.0001. Patients who had an MRI had a non-significant higher rate of pathological complete response (pCR) than those who did not (30.8% and 21.5%, respectively, p=0.08). The surgical treatment did differ between these two groups; those who had MRI were more likely to have bilateral mastectomy (36.4% vs 23.3%, p=0.019) and less likely to have breast conserving surgery (BCS) (19.6% vs 31.9%, p=0.026). In the cohort that had an MRI, there was no significant difference in percentage of patients whose surgical plan was changed compared to the patients who did not have an MRI (33.6% and 28.8%, respectively). A change in surgical plan from a mastectomy to a BCS was more common in patients who did not have an MRI than those that did (31.9% and 13.9%, respectively). 45% of the surgeons who dictated a follow-up surgery consultation stated that the MRI was used to inform the surgical plan.

Discussions/Conclusions: In this real-world cohort, patients who had an MRI were more likely to undergo a bilateral mastectomy and less likely to have a BCS than the patients who did not have an MRI, despite having a higher rate of pCR. Age was the only baseline demographic difference between the two groups. These findings suggest that the role of MRI in the neoadjuvant setting needs to be refined further in order to avoid over-treatment.

Citation Format: McDermott M, Wilson C, Xu J, Illmann C, Simmons C. Does MRI influence surgical planning more than clinical outcome? A cohort study of breast cancer patients receiving neoadjuvant therapy [abstract]. In: Proceedings of the 2016 San Antonio Breast Cancer Symposium; 2016 Dec 6-10; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2017;77(4 Suppl):Abstract nr P3-02-05.