Assessment of proliferating cell nuclear antigen activity using digital image analysis in breast carcinoma following magnetic resonance-guided interstitial laser photocoagulation

This study examines proliferative activity in tumor cells of patients with histologically documented invasive breast carcinoma treated with magnetic resonance-guided interstitial laser photocoagulation (MR-GILP). Immunohistochemical marker for proliferating cell nuclear antigen (PCNA), a nuclear protein abundant in actively proliferating cells, is used. The study demonstrates the effectiveness of MR-GILP in ablating tumor cells of infiltrating breast cancer. The diagnosis of infiltrating breast carcinoma was confirmed by core needle biopsies. Using a specially designed magnetic resonance imaging (MRI) device, rotating delivery of excitation off-resonance (RODEO), tumors were measured ranging from 1.8 to 4.0 cm in greatest dimension. Seven formalin-fixed, paraffin-embedded archival tissues from seven patients with infiltrating carcinoma, status post-MR-GILP, were analyzed. Using PCNA immunoperoxidase (Biomeda Corp.), the proliferative capability of the remaining tumor cells around the focus of laser photocoagulation was determined. The lesions were digitally acquired using a Nikon Eclipse E800 microscope with an automated stage. Images were analyzed using Cool SNAP image editing software (version 1.0). Appropriate thresholds were set for positive staining and limited concentric radial measurements of equal area between all samples were compared at radial millimeter intervals from the center of laser ablation. The integrated area occupied by PCNA-positive cells per radial millimeter from the charcoal site (the center of the laser) increased as the distance from this site increased (a mean average at each radial measurement revealed: at the 1 mm radius the positive integrated area was 0.0024 mm²; at 2 mm, 0.0145 mm²; at 3 mm, 0.0351 mm²; at 4 mm, 0.0696 mm²; at 5 mm, 0.1025 mm²; and at 6 mm, 0.1263 mm²). MR-GILP is an effective mean of ablating breast carcinoma. This treatment option may represent an alternative to lumpectomy for a single lesion≤1 cm, or make patients with two separate lesions eligible for lumpectomy.