Background: Interstitial laser therapy (ILT) is a technique of destroying t
umor cells via thermal energy. Prior studies have shown that the procedure
is safe and efficacious in laboratory animals and that complete cell death,
as assessed by tetrazollium staining, is achieved in the laser treated are
a.
Design: Forty women with localized, mammographically detectable, Tl breast
cancers consented to be treated with ILT and then have the treated area sub
sequently excised. The delay period ranged from 5 to 42 days. Prior to ILT,
the diagnosis of breast carcinoma was established by stereotactic needle c
ore biopsy.
Results: All 40 cases showed a characteristic gross appearance, which consi
sted of a series of concentric rings surrounding a cavity corresponding to
the laser needle tip. The tissue immediately adjacent to the cavity appeare
d coagulated and showed the same "wind-swept" nuclei seen with cautery arti
fact. Surrounding this was a white-tan ring that histologically showed reco
gnizable tumor. No necrosis, increased apoptosis or inflammatory infiltrate
was noted in this area on hematoxylin-eosin sections. Immunostains for cyt
okeratin were negative in the recognizable tumor cells despite intense stai
ning in the epithelial cells outside the laser treated area. A ring of red
tan tissue which histologic ally consisted of necrotic tumor was seen next
and this, in turn, was surrounded by a rim of vascular proliferation and fa
t necrosis. The breast tissue outside the zone of fat necrosis appeared to
be unaffected by the laser therapy.
Conclusions: ILT appears to be an effective way to treat small localized br
east cancer. It is important for the pathologist to recognize the chances s
een after ILT, especially the zone containing pseudoviable tumor. Cytokerat
in may be a marker to identify these likely non-viable but recognizable tum
or cells. The extent of the laser affected area is defined by vascular prol
iferation and fat necrosis. (C) 2001 Excerpta Medica, Inc. All rights reser
ved.