Breast cancer is the most widely diagnosed form of invasive cancer in women in the United States, Europe, and Australia. One of the most prominent challenges in the diagnosis and treatment of the disease is the localisation of the tumour. Identification of suspicious lesions forms the basis of screening programs, and accurately pinpointing the location of the lesion is important for guiding biopsy and obtaining an accurate diagnosis. At the stage of surgical removal of the tumour, its precise localisation, is again, imperative to ensure that all the cancerous tissue is removed.
Many projects in OBEL focus on developing optical tools to accurately detect the location and extent of the tumour at the time of surgery. The status of the tumour margin, the distance between the tumour and the boundary of the excised tissue, is a key predictor for local recurrence. A negative tumour margin, illustrated in Fig. 1(a), is the desired result, in which no cancerous tissue is found at the boundary of the excised lesion, suggesting that the cancerous tissue is totally enclosed within the excised tissue. Fig. 1(b) illustrates the case of a positive margin in which cancerous tissue is found at the boundary of the excised tissue, indicating that residual disease remains in the patient, and a second surgery may be required. It has been shown that tumour margins of <5 mm carry an increased risk of local recurrence. Currently, approximately 23% of women who undergo breast-conserving surgery must return for additional surgery due to insufficient margins. Improved guidance of tumour excision and intraoperative assessment of tumour margins have the potential to reduce the need for re-excision.
Several studies have shown potential for OCT in imaging breast cancer . OCT and its extensions, including elastography and polarization-sensitive OCT, may be suitable for intraoperative tumour assessment compared to other optical techniques due to the combination of depth-sectioning capability with micro-scale resolution and the ability to be implemented in compact, fibre-based probes. To perform OCT deep within solid tissues, we have developed OCT needle probes . Our group has shown the potential for needle OCT imaging of tumour margins in freshly excised breast tissues, with promising initial results . An example of an OCT image of a tumour margin in a human mastectomy sample, obtained using a 640-μm-diameter OCT needle probe, is shown in Fig. 2, along with corresponding histology. The tumour boundary is clearly delineated in the OCT image. Other features, including a blood vessel, connective tissue (stroma), and the characteristic honeycomb structure of adipose tissue, are also visualised in the OCT image.
Whilst OCT has shown potential for differentiating tumour from healthy tissue in breast cancer, contrast between tissue types is not always apparent based on OCT intensity. For example, carcinoma in situ and normal breast lobules both appear as highly optically scattering regions in OCT, possibly because both tissues have high cellular density. To address the need for additional contrast in OCT imaging of cancer, we have developed extensions of OCT to enhance tissue contrast, including optical coherence micro-elastography to visualise the mechanical contrast in breast cancer tissues , and parametric imaging of optical properties to quantitatively differentiate tissue types . The images below show results in breast cancer tissues using optical coherence micro-elastography and parametric imaging of optical properties, respectively.
Section 1. Breast cancer: quick links
1) Key techniques
2) Key researchers
- Prof. Robert McLaughlin
- Prof. Brendan Kennedy
- Kelsey Kennedy
- Andrea Curatolo
3) Key Publications
- L. Scolaro, R. A. McLaughlin, B. F. Kennedy, C. M. Saunders, and D. D. Sampson, “A review of optical coherence tomography in breast cancer,” Photonics & Lasers in Medicine.
- R. A. McLaughlin, B. C. Quirk, A. Curatolo, R. W. Kirk, L. Scolaro, D. Lorenser, P. Robbins, B. Wood, C. Saunders, and D. Sampson, “Imaging of Breast Cancer with Optical Coherence Tomography Needle Probes: Feasibility and Initial Results,” Selected Topics in Quantum Electronics, IEEE Journal of, 1-1 (2011).
- B. F. Kennedy, R. A. McLaughlin, K. M. Kennedy, L. Chin, P. Wijesinghe, A. Curatolo, A. Tien, M. Ronald, B. Latham, C. M. Saunders, and D. D. Sampson, “Evaluation of human breast tissue using optical coherence micro-elastography: potential for identifying cancer,” submitted to Cancer Research.
- R. A. McLaughlin, L. Scolaro, P. Robbins, C. Saunders, S. L. Jacques, and D. D. Sampson, “Parametric imaging of cancer with optical coherence tomography,” Journal of Biomedical Optics 15, 046029 (2010).