MRI prediction of neoadjuvant chemotherapy response is equivalent in patients with or without mammographic calcifications: a step towards adapting surgical approach?

Abstract

Objectives: Current surgical policy recommends comprehensive excision of tumorous calcifications in breast cancer patients following neoadjuvant chemotherapy (NAC) regardless of MRI outcomes, despite MRI defining tumor response superior to mammography. The current study examines MRI prediction of response in tumors with vs without calcifications, using post-NAC surgical pathology as the standard of reference.

Methods: Retrospective analysis of 114 NAC patients between 2011 and 2018 including demographics, mammography, 3 T-MRI, and pathology compared two sub-groups: without (n = 62) or with (n = 52) mammographic calcifications. In the calcification cohort, the mammographic extent of calcifications and MRI enhancement overlapped. MRI prediction of response to NAC was correlated with pathology. Two-tailed paired T and Fisher's exact tests and Cohen's kappa coefficient were applied for analysis.

Results: There was no significant difference between the two sub-groups regarding demographics. Tumors demonstrated equivalent features regarding size, lymph node involvement, and DCIS component. ER-negative/HER2-positive tumors more commonly exhibited calcifications (33% n = 17 calcified vs 13% n = 8 non-calcified; p < 0.05); triple negative pathology rarely calcified (6% n = 3 calcified vs 33% n = 20 non-calcified; p < 0.05). NME was more common with calcifications (62% n = 32 calcified vs 29% n = 18 non-calcified; p < 0.05) and mass enhancement without (90% n = 56 non-calcified vs 81% n = 42 calcified; p < 0.05). Both groups responded similarly to NAC (pCR = 37% non-calcified vs 38% calcified); response on MRI equally correlated with pathology (69% both subgroups; p = 0.988).

Conclusion: We propose utilizing post-NAC MRI findings rather than mammography in planning surgery, as MRI prediction is independent of the presence or absence of calcifications. Prospective studies to evaluate this approach are warranted.

Key points: • No difference was found in demographic, clinical, pathology, or imaging characteristics between patients with or without tumoral calcifications on mammography prior to neoadjuvant chemotherapy. • Residual mammographic calcifications are inadequate predictors of residual invasive disease. MRI accurately recognized complete response and correctly correlated with post-treatment surgical pathology in 69% of patients, regardless of the presence or absence of mammographic calcifications. • We propose utilizing post-NAC MRI findings rather than mammography in planning post-NAC surgery, as MRI prediction of response is independent of the presence or absence of calcifications.

Keywords: Breast cancer; Magnetic resonance imaging; Mammography; Neoadjuvant therapy.