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Womens Health

Women's Health - Poster Session D

Poster CC3 - Electrical impedance spectroscopy to non-invasively screen for breast cancer

Friday, October 25, 2024
3:30 PM – 4:30 PM EST
Location: Exhibit Hall E, F & G

Introduction:  Interval breast cancer (IBC) is defined as any breast cancer that is detected between yearly breast mammogram screenings [1]. Given the rapid growth of IBCs, they are often more aggressive types of breast cancer that commonly manifest in individuals with genetic predispositions to cancer. These cancers have a 3.5 times higher mortality rate [2].

Historically, breast self-exams (BSEs) have been the recommended tool for IBC screening. Patients were advised to visually inspect their breasts for "changes in size, shape or symmetry," in addition to palpating the tissue for lumps [3]. While some BSEs are successful in detecting growths, most patients are unable to accurately detect abnormalities. If these atypical tissue growths are deep within the breast tissue, abnormalities are even harder to detect. BSEs, in the median case, are only able to detect tumors once they have grown to Stage II or later sizes [4]. At this point, the cancer may have spread to the lymph nodes and thus tends to have a higher mortality rate [5]. For this reason, BSEs have not been shown to reduce breast cancer mortality and are no longer recommended by breast health professionals [6].

We have identified no current market-ready alternatives for IBC screening at home. We filled this gap by developing a method of at-home screening that identifies possible irregularities in the breast tissue early in their development, empowering patients to make more informed decisions about their current clinical state with the potential to increase the survival rate for IBCs.

Materials and

Methods:  Electrical impedance spectroscopy (EIS) is a technique that stimulates a material with a known electrical signal and measures the resulting waveform’s amplitude and phase change to determine the electrical impedance of the material [7]. Previous research indicates that cancerous breast tissue has a different impedance than normal tissue [7], so our device seeks to detect changes in impedance using EIS between mammogram screenings.

The device consists of two components: the measuring cup, which holds the electrodes that interface with the skin, and the 3D-printed enclosure, which houses electronic components. The cup combines five carbon electrodes with a 3D-printed flexible frame of polyurethane filament in a hemispheric shape. Our device stimulates the tissue with a 100 Hz sinusoidal waveform, at a max leakage current output of 150 mA, which is applied to the tissue via the active electrode. The remaining four electrodes perform bipolar measurements across the tissue. The electrical circuitry of the board, a Nordic nrf52833 development kit board and battery, is encased in the enclosure.

Our device was tested on two sets of breast tissue phantoms, termed “dry” and “wet” phantoms. Dry phantoms are composed of a protoboard of resistors and capacitors embedded in silicon to mimic the electrical properties of a benign breast, a breast with a stage I tumor, and a breast with a stage II tumor [8]. The experiments were repeated on gelatin-based models, called “wet” phantoms, of benign and malignant breast tissue [8] to account for electrode-tissue interface effects on our EIS measurements.

Results, Conclusions, and Discussions: Dry phantoms were created to electrically simulate benign breast tissue, breast tissue with a Stage I tumor, and breast tissue with a Stage II tumor. A 3 Vpp sinusoidal wave was input into the phantom through the active carbon electrodes whilst the resulting amplitude of the sinusoidal wave was measured through the four receiving carbon electrodes for each of the three experimental cases. The device sampled the resulting sinusoidal wave and calculated the root mean square voltage, which was compared across experimental cases. Two-way ANOVA suggested a statistically significant difference in impedance values across the dry phantoms (p < 0.0001), suggesting that the device can accurately detect tumors at Stage I. The experiment was repeated with the wet phantoms. Calculated RMS voltage values were again statistically different as per t-tests (p < 0.001). In a blinded experiment, the device was found to have a 100% precision for detecting Stage I and Stage II tumors and a 96% and 100% accuracy for detecting Stage I and Stage II tumors, respectively.

There is a need for a method of at-home self-identification of breast abnormalities that does not rely on BSEs. Our device, which uses EIS, is a potential solution to fit this need, as it is highly accurate in testing. It is worth noting that our experiments were conducted on electrical models of the breast, which are not a substitute for clinical testing with patient breast tissue. Future clinical testing on participants with diverse breast sizes and tissue densities is necessary.

Our device is promising in its size, customizability, and low manufacturing costs. The use of 3D printed materials makes the device customizable to different breast shapes and sizes while keeping costs low. For the prototype, the cost to manufacture was estimated to be $71.78, making it affordable. Design refinement and manufacturing at scale could also significantly lower costs. We present a novel device that utilizes EIS to aid in the at-home detection of irregular breast tissue. While our results are still preliminary, the device shows promise as an at-home method of breast cancer screening that can detect cancers in early stages.

Acknowledgements (Optional):  References
[1] S. Niraula, N. Biswanger, P. Hu, P. Lambert, and K. Decker, “Incidence, Characteristics, and Outcomes of Interval Breast Cancers Compared With Screening-Detected Breast Cancers,” JAMA Netw Open, vol. 3, no. 9, p. e2018179, Sep. 2020, doi: 10.1001/jamanetworkopen.2020.18179.
[2] J. de Mello Ramirez Medina et al., “Advanced Clinical Stage at Diagnosis of Breast Cancer Is Associated with Poorer Health-Related Quality of Life: A Cross-Sectional Study,” Eur J Breast Health, vol. 15, no. 1, pp. 26–31, Jan. 2019, doi: 10.5152/ejbh.2018.4297.
[3] A. Woo, “What Is Breast Self-Awareness and Why Is It Important?,” NewYork-Presbyterian. Accessed: Jul. 24, 2024. [Online]. Available: https://healthmatters.nyp.org/what-is-breast-self-awareness-and-why-is-it-important/
[4] K. Rezak, “Stakeholder Interview,” Oct. 2023.
[5] “Tumor size and detection in breast cancer: Self-examination and clinical breast examination are at their limit - ClinicalKey.” Accessed: Feb. 06, 2024. [Online]. Available: https://www.clinicalkey.com/#!/content/playContent/1-s2.0-S0361090X08000615?returnurl=https:%2F%2Flinkinghub.elsevier.com%2Fretrieve%2Fpii%2FS0361090X08000615%3Fshowall%3Dtrue&referrer=
[6] J. Baker, “Stakeholder Interveiw with Radiologist Jay Baker,” Oct. 2023.
[7] H. J. Pandya et al., “Towards an automated MEMS-based characterization of benign and cancerous breast tissue using bioimpedance measurements,” Sensors and Actuators B: Chemical, vol. 199, pp. 259–268, Aug. 2014, doi: 10.1016/j.snb.2014.03.065.
[8] V. G. Sirtoli, K. Morcelles, and P. Bertemes-Filho, “Electrical properties of phantoms for mimicking breast tissue,” in 2017 39th Annual International Conference of the IEEE Engineering in Medicine and Biology Society (EMBC), Seogwipo: IEEE, Jul. 2017, pp. 157–160. doi: 10.1109/EMBC.2017.8036786.