RESUMEN
The majority of breast cancers have a solid tumor growth pattern and are seen on mammography as dense masses with defined borders. Cancers detected as asymmetry are rare, and little has been published about their pathologic features. These cancers do not form discrete masses, and a border is not evident. This retrospective case series was undertaken to identify malignancies presenting as asymmetry, to describe their histologic and biologic features and to correlate these features with the mammographic appearance. During the 7.5 years of the study, 18,419 core needle biopsies (CNBs) were performed and 42 cases of malignancy presenting as asymmetry were diagnosed (0.2%). The majority were invasive carcinomas (30 or 71%), followed by ductal carcinoma in situ (9 or 21%) and lymphoma (3 or 7%). The invasive carcinomas could be divided into 3 groups: very small unifocal (T1a) carcinomas, larger unifocal carcinomas, and cases with multiple foci of invasion. The latter group had a higher rate of lymph node metastases and more stage III cancers. The invasive carcinomas were predominantly of special histologic types and associated with a minimal stromal response. In contrast, the cases of DCIS tended to be of higher grade and elicited periductal fibrosis, which likely contributed to the increased density seen on mammography. Although most of the invasive carcinomas were of favorable biologic type (97%) and were stage I (67%), triple negative carcinomas, as well as stage III carcinomas, were also detected. When evaluating core needle biopsies performed for asymmetry, pathologists should be aware that these cancers can have a subtle infiltrative appearance with little or no desmoplastic response, mirroring their appearance by imaging.
RESUMEN
PURPOSE: The relative biologic effectiveness (RBE) rises with increasing linear energy transfer toward the end of proton tracks. Presently, there is no consensus on how RBE heterogeneity should be accounted for in breast cancer proton therapy treatment planning. Our purpose was to determine the dosimetric consequences of incorporating a brachial plexus (BP) biologic dose constraint and to describe other clinical implications of biologic planning. METHODS AND MATERIALS: We instituted a biologic dose constraint for the BP in the context of MC1631, a randomized trial of conventional versus hypofractionated postmastectomy intensity modulated proton therapy (IMPT). IMPT plans of 13 patients treated before the implementation of the biologic dose constraint (cohort A) were compared with IMPT plans of 38 patients treated on MC1631 after its implementation (cohort B) using (1) a commercially available Eclipse treatment planning system (RBE = 1.1); (2) an in-house graphic processor unit-based Monte Carlo physical dose simulation (RBE = 1.1); and (3) an in-house Monte Carlo biologic dose (MCBD) simulation that assumes a linear relationship between RBE and dose-averaged linear energy transfer (product of RBE and physical dose = biologic dose). RESULTS: Before implementation of a BP biologic dose constraint, the Eclipse mean BP D0.01 cm3 was 107%, and the MCBD estimate was 128% (ie, 64 Gy [RBE = biologic dose] in 25 fractions for a 50-Gy [RBE = 1.1] prescription), compared with 100.0% and 116.0%, respectively, after the implementation of the constraint. Implementation of the BP biologic dose constraint did not significantly affect clinical target volume coverage. MCBD plans predicted greater internal mammary node coverage and higher heart dose than Eclipse plans. CONCLUSIONS: Institution of a BP biologic dose constraint may reduce brachial plexopathy risk without compromising target coverage. MCBD plan evaluation provides valuable information to physicians that may assist in making clinical judgments regarding relative priority of target coverage versus normal tissue sparing.