Scintimammographic detection of usual ductal breast hyperplasia with increased proliferation rate at risk for malignancy

Abstract

To estimate whether breast uptake of (99m)Tc-(V)DMSA and (99m)Tc-sestamibi in usual ductal epithelial breast hyperplasia (UDH) and apocrine metaplasia is related to cell proliferation rate (Ki-67) and oestrogen receptor (ER) expression, both of which are associated with the potential risk of evolving to malignancy. Among patients referred for suspicious breast findings on palpation and/or mammography and evaluated preoperatively with both radiopharmaceuticals, we retrospectively studied 17 (10 with UDH: group I; and seven with apocrine metaplasia: group II). Lesion-to-background (L/B) ratios in early and late acquisitions were calculated for both radiotracers in both groups, as well as their retention ratios. Ki-67 and oestrogen receptor expression were determined immunohistochemically. The late L/B ratios between the two tracers were compared, as were the late ratios for each tracer between Ki-67 < or = 3% and > 3%, and between ER < or = 15% and > 15%. Linear regression analysis was also performed between L/B and retention ratios and Ki-67 expression. There was a significant increase of the (99m)Tc-(V)DMSA L/B ratio in late images as compared to the early images in group I (P<0.05), while in group II it was not significantly increased (P=0.084). (99m)Tc-sestamibi ratios did not demonstrate variability over time in either group (P=0.156 and 0.274, respectively). Significant coefficient correlation was found between the (99m)Tc-(V)DMSA L/B(late) ratios and retention ratios and Ki-67 levels only for group I (r=0.889, P<0.001 and r=0.802, P<0.01, respectively). The (99m)Tc-(V)DMSA L/B(late) ratios in group I were significantly higher when Ki-67 > 3% than when Ki-67 < or = 3% (P=0.016) but did not differ considerably between ER > 15% and < or = 15% (P=0.732). (99m)Tc-(V)DMSA uptake in UDH correlates with Ki-67 expression. This could prove useful in identifying women with benign but high-risk breast pathologies who might benefit from chemoprophylaxis.