Photoacoustic microscopy for identifying sentinel lymph nodes of breast cancer

September 22, 2020

Accurate detection and characterization of SLNs are crucial in cancer staging and making therapeutic decisions. At present, the clinical gold standard used to detect SLNs is to label them with blue dye or a radioactive nanocolloid and then perform SLN biopsy. But these methods have drawbacks, radioscintigraphy has relatively poor spatial resolution, and blue dye will quickly label downstream LNs, leading to difficulties recognized SLN from other nodes. In addition, the removal of the SLN may cause some side effects, such as lymphedema, shoulder dysfunction, and arm numbness. Therefore, the ideal method for detecting SLN needs to have the following characteristics: 1) The probe can quickly enter the lymphatic system and retain in the SLN for a while. 2) The probe should contain a specific ligand for the selective targeting of breast cancer cells. 3) Imaging technique requires sufficient sensitivity and spatial resolution to detect the distribution of tumor cells in the entire SLN.

LN enlargement can occur during both tumour cell invasion and under inflammatory conditions. Therefore, the accurately identify the status of the SLN intraoperatively will help surgeons choose appropriate treatment regimen and minimize the complications caused by unnecessary LN removal. Although various nanoprobes based on passively targeting macrophages in SLN combined with imaging techniques have been developed to predict the metastatic status of SLNs, few can distinguish metastatic SLNs from inflamed LNs in vivo.

In a new paper published in Light Science & Application, a team of scientists, led by Professor Zhihong Zhang and Professor Qingming Luo from Wuhan National Laboratory for Optoelectronics-Huazhong University of Science and Technology, Wuhan, Hubei, China, and School of Biomedical Engineering, Hainan University, Haikou, Hainan, China, and co-workers have developed a CD44 and SR-B1 dual-targeting hyaluronic acid nanoparticle (5K-HA-HPPS) loaded with the near-infrared fluorescent/photoacoustic dye DiR-BOA for imaging SLNs in breast cancer. Due to the small size, negative charge, and target ligand, 5K-HA-HPPS can rapidly (<10 min) migrated to popliteal lns (pln) and showed prolonged retention time (>12 h) in pLN. More interestingly, they found that photoacoustic signals from 5K-HA-HPPS showed a significantly distinct spatial distribution among LNs of different statuses, which the signals were mainly distributed within tumour metastatic SLNs but at the peripheries of normal and inflamed LNs. The ratio of PA intensity (R) at the centre of the LNs compared with that at the periphery in the 5K-HA-HPPS group was 5.93 ± 0.75 for T-MLNs, which was much higher than that for the Inf-LNs (R = 0.2 ± 0.07) and N-LNs (R = 0.45 ± 0.09). The reported method and technique provide a new strategy for accurately identifying the status of SLNs during breast cancer surgery and facilitate the implementation of appropriate tumour treatment strategies.

Fluorescence imaging showed that 5K-HA-HPPS enhanced in both T-MLNs and Inf-LNs, indicating that T-MLNs and Inf-LNs cannot be distinguished according to their fluorescence intensities. Here wide-field fluorescence imaging is two-dimensional imaging, which possesses the advantage of sensitivity, convenience, and non-invasiveness for long-term monitoring, but it cannot distinguish whether the fluorescent signal is located inside the LN or at the periphery of the LN. By providing deep penetration and a high spatial resolution, photoacoustic microscopy has a great potential for the 3D visualization of photoacoustic signal distribution in intact LNs.

Both tumour cell infiltration and inflammation result in the enlargement of SLNs. Therefore, whether SLN enlargement is caused by the metastasis of tumour cells or inflammation should be determined before SLN resection. The presented technique possess the ability to distinguish metastatic SLNs from inflamed LNs, thus will expected to provide an in vivo detection method for quickly identifying whether the SLN has tumor metastasis and will reduce the complications caused by unnecessary LN removal during breast cancer surgery, which has potential clinical application value.

Light Publishing Center, Changchun Institute of Optics, Fine Mechanics And Physics, Chinese Academy

Related Breast Cancer Articles from Brightsurf:

Oncotarget: IGF2 expression in breast cancer tumors and in breast cancer cells
The Oncotarget authors propose that methylation of DVDMR represents a novel epigenetic biomarker that determines the levels of IGF2 protein expression in breast cancer.

Breast cancer: AI predicts which pre-malignant breast lesions will progress to advanced cancer
New research at Case Western Reserve University in Cleveland, Ohio, could help better determine which patients diagnosed with the pre-malignant breast cancer commonly as stage 0 are likely to progress to invasive breast cancer and therefore might benefit from additional therapy over and above surgery alone.

Partial breast irradiation effective treatment option for low-risk breast cancer
Partial breast irradiation produces similar long-term survival rates and risk for recurrence compared with whole breast irradiation for many women with low-risk, early stage breast cancer, according to new clinical data from a national clinical trial involving researchers from The Ohio State University Comprehensive Cancer Center - Arthur G.

Breast screening linked to 60 per cent lower risk of breast cancer death in first 10 years
Women who take part in breast screening have a significantly greater benefit from treatments than those who are not screened, according to a study of more than 50,000 women.

More clues revealed in link between normal breast changes and invasive breast cancer
A research team, led by investigators from Georgetown Lombardi Comprehensive Cancer Center, details how a natural and dramatic process -- changes in mammary glands to accommodate breastfeeding -- uses a molecular process believed to contribute to survival of pre-malignant breast cells.

Breast tissue tumor suppressor PTEN: A potential Achilles heel for breast cancer cells
A highly collaborative team of researchers at the Medical University of South Carolina and Ohio State University report in Nature Communications that they have identified a novel pathway for connective tissue PTEN in breast cancer cell response to radiotherapy.

Computers equal radiologists in assessing breast density and associated breast cancer risk
Automated breast-density evaluation was just as accurate in predicting women's risk of breast cancer, found and not found by mammography, as subjective evaluation done by radiologists, in a study led by researchers at UC San Francisco and Mayo Clinic.

Blood test can effectively rule out breast cancer, regardless of breast density
A new study published in PLOS ONE demonstrates that Videssa® Breast, a multi-protein biomarker blood test for breast cancer, is unaffected by breast density and can reliably rule out breast cancer in women with both dense and non-dense breast tissue.

Study shows influence of surgeons on likelihood of removal of healthy breast after breast cancer dia
Attending surgeons can have a strong influence on whether a patient undergoes contralateral prophylactic mastectomy after a diagnosis of breast cancer, according to a study published by JAMA Surgery.

Young breast cancer patients undergoing breast conserving surgery see improved prognosis
A new analysis indicates that breast cancer prognoses have improved over time in young women treated with breast conserving surgery.

Read More: Breast Cancer News and Breast Cancer Current Events is a participant in the Amazon Services LLC Associates Program, an affiliate advertising program designed to provide a means for sites to earn advertising fees by advertising and linking to