Intraoperative fluorescence imaging with aminolevulinic acid detects grossly occult breast cancer: a phase II randomized controlled trial

Abstract

Background Re-excision due to positive margins following breast-conserving surgery (BCS) negatively affects patient outcomes and healthcare costs. The inability to visualize margin involvement is a significant challenge in BCS. 5-Aminolevulinic acid hydrochloride (5-ALA HCl), a non-fluorescent oral prodrug, causes intracellular accumulation of fluorescent porphyrins in cancer cells. This single-center Phase II randomized controlled trial evaluated the safety, feasibility, and diagnostic accuracy of a prototype handheld fluorescence imaging device plus 5-ALA for intraoperative visualization of invasive breast carcinomas during BCS. Methods Fifty-four patients were enrolled and randomized to receive no 5-ALA or oral 5-ALA HCl (15 or 30 mg/kg). Forty-five patients (n = 15/group) were included in the analysis. Fluorescence imaging of the excised surgical specimen was performed, and biopsies were collected from within and outside the clinically demarcated tumor border of the gross specimen for blinded histopathology. Results In the absence of 5-ALA, tissue autofluorescence imaging lacked tumor-specific fluorescent contrast. Both 5-ALA doses caused bright red tumor fluorescence, with improved visualization of tumor contrasted against normal tissue autofluorescence. In the 15 mg/kg 5-ALA group, the positive predictive value (PPV) for detecting breast cancer inside and outside the grossly demarcated tumor border was 100.0% and 55.6%, respectively. In the 30 mg/kg 5-ALA group, the PPV was 100.0% and 50.0% inside and outside the demarcated tumor border, respectively. No adverse events were observed, and clinical feasibility of this imaging device-5-ALA combination approach was confirmed. Conclusions This is the first known clinical report of visualization of 5-ALA-induced fluorescence in invasive breast carcinoma using a real-time handheld intraoperative fluorescence imaging device. Trial registration Clinicaltrials.gov identifier NCT01837225. Registered 23 April 2013.

Optical spectroscopy and imaging in surgical management of cancer patients

“…One potential caveat is that ALA‐PpIX fluorescence is susceptible to false positives due to inflammation, and it also remains to be seen if ALA‐PpIX can reliably detect DCIS. A recent Phase II randomized control trial [87] using 15 mg/kg oral ALA demonstrated positive predictive values of 100 and 55.6% inside and outside the gross tumor margin, respectively, the latter suggesting a potential impact on reducing re‐excision rates if confirmed in Phase III trials that are in progress. As in other applications, the use of an exogenous fluorescent agent adds cost and regulatory and operational complexities.…”

“…Ex vivo lumpectomy guidance techniques under development for rapid margin assessment: (A) large‐area OCT showing a commercial prototype system, top view of a lumpectomy specimen held by vacuum bag on the scanner platform, and example image of DCIS (arrow) with corresponding H&E stained histology section (courtesy Dr A. Berkeley, Perimeter Medical) [84]; (B) ALA‐PpIX fluorescence imaging using a hand‐held device (Courtesy Dr R. DaCosta, Princess Margaret Cancer Centre) with a “butterflied” lumpectomy specimen showing a region of DCIS with positive red ALA‐PpIX fluorescence and corresponding histology section indicating close (adapted from Ottolino‐Perry et al [87], with permission); (C) low‐frequency photoacoustic tomography showing a prototype scanner with water‐bath for acoustic coupling to the sample (held in a vacuum plastic bag) and arc‐scanning fiberoptic probe and close‐up of a 930 nm photoacoustic image of a lumpectomy specimen (arrow: positive margin) together with corresponding radiographs and ultrasound images (Courtesy Dr I. Kosik, Western University)…”

“…A recent initial trial in ex vivo surgical specimens of diffuse reflectance spectroscopy (400‐1700 nm) yielded 90% sensitivity and 88% specificity for tumor detection, including DCIS using fiberoptic instrumentation suitable also for in vivo use [74]. Intra‐operative ALA‐PpIX fluorescence imaging is currently undergoing clinical trials, extending prior work in ex vivo tissues [87]. NIR fluorescence imaging using antibody‐fluorophore conjugates has demonstrated delineation of breast cancer subtypes and sentinel lymph node identification [142].…”

Multimodal imaging needle combining optical coherence tomography and fluorescence for imaging of live breast cancer cells labeled with a fluorescent analog of tamoxifen

“…15 Conversely, fluorescent cellular marking of malignant breast tissue has been demonstrated through pre-operative administration of 5-aminolevulinic acid hydrochloride, but non-malignant proliferative cellular changes in tissue, including hyperplasia, columnar cell change, and atypical ductal hyperplasia, were also shown to give rise to a false-positive fluorescence signal. 16 The combination of multiple modalities provides a potential mitigation to the limitations of each individual imaging technique. In particular, the combination of OCT + fluorescence offers the OCT imaging resolution for visualizing microarchitectural changes associated with many forms of malignancy, 17 detection of critical structures such as blood vessels, 9 and highly specific fluorescence detection of certain forms of cancer.…”

“…In particular, the combination of OCT + fluorescence offers the OCT imaging resolution for visualizing microarchitectural changes associated with many forms of malignancy, 17 detection of critical structures such as blood vessels, 9 and highly specific fluorescence detection of certain forms of cancer. 16 Miniaturized fiber-optic probes that can augment OCT with fluorescence to perform multimodal imaging have been demonstrated in both intravascular [18][19][20] and endoscopic 21 applications. Recent work established the feasibility of inserting a multimodal fiber-optic probe through a guide needle, using both imaging modalities to improve yield in lung biopsies.…”