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Indian J Nucl Med
Indian J Nucl Med
IJNM
Indian J Nucl Med
Indian Journal of Nuclear Medicine : IJNM : The Official Journal of the Society of Nuclear Medicine, India
0972-3919
0974-0244
Wolters Kluwer - Medknow India

IJNM-39-239
10.4103/ijnm.ijnm_33_24
Letter to the Editor
Molecular Imaging for Breast Cancer Phenotyping: Tc-99m sestamibi Scintigraphy cannot be Missed
Filippi Luca
Pisani Antonio Rosario 1
Rubini Giuseppe 1
Department of Oncohaematology, Nuclear Medicine Unit, Fondazione PTV Policlinico Tor Vergata University Hospital, Rome
1 Interdisciplinary Department of Medicine, Nuclear Medicine Unit, University of Bari Aldo Moro, Bari, Italy
Address for correspondence: Dr. Luca Filippi, Department of Oncohaematology, Nuclear Medicine Unit, Fondazione PTV Policlinico Tor Vergata University Hospital, Viale Oxford 81, Rome 00133, Italy. E-mail: lucfil@hotmail.com
May-Jun 2024
17 8 2024
39 3 239240
11 3 2024
14 4 2024
Copyright: © 2024 Indian Journal of Nuclear Medicine
2024
https://creativecommons.org/licenses/by-nc-sa/4.0/ This is an open access journal, and articles are distributed under the terms of the Creative Commons Attribution-NonCommercial-ShareAlike 4.0 License, which allows others to remix, tweak, and build upon the work non-commercially, as long as appropriate credit is given and the new creations are licensed under the identical terms.
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pmcSir,

We read with great interest the paper titled “Role of 99mTc-sestamibi scintimammography in predicting response to neoadjuvant chemotherapy (NACT) in locally advanced breast cancer (LABC): A prospective study” by Moulika et al.[1] in the Indian Journal of Nuclear Medicine. The study involved 34 patients with LABC who underwent scintigraphy with 99mTc-sestamibi before NACT. Parameters such as wash-out-rate (WOR) and tumor-to-normal breast ratio (T/B) were calculated based on early and late images, serving as surrogate biomarkers for P-glycoprotein (PgP) expression, which is associated with chemoresistance. The study found a negative correlation between WOR and the percentage decrease in tumor size, indicating higher PgP expression may lead to reduced response to chemotherapy. Conversely, a positive correlation was found between T/B buildup and the percentage decrease in tumor size, suggesting potential predictive value for this parameter in assessing response to NACT.

We praise the authors for their intriguing research, warranting further discussion. Over the past two decades, personalized medicine has emerged, recognizing that not all medications work equally for all patients. Instead, each person should be seen as a unique entity with distinct genetic, molecular, and environmental traits. Treatment strategies should be tailored to meet each patient’s specific needs. Molecular imaging, especially using nuclear medicine techniques such as positron emission tomography/computed tomography (PET/CT), provides valuable insights into tumor biology. PET/CT offers a wide range of radiopharmaceuticals, including 18F-fludeoxyglucose (FDG), which can preliminarily assess breast cancer characteristics. Studies show that less aggressive phenotypes have lower 18F-FDG uptake compared to more aggressive tumors. In addition, 18F-Fluoro-17β-Estradiol has recently been endorsed by the National Comprehensive Cancer Network as an in vivo imaging modality for identifying and quantifying estrogen receptor (ER), predicting response to ER-targeted therapy, and monitoring ER status to promptly detect acquired resistance.[2] Ultimately, a radiolabeled affibody, specifically 68Ga-ABY-025, has been synthesized and effectively utilized for detecting human epidermal growth factor receptor 2 (HER2) status in breast cancer patients. This approach has yielded promising preliminary results, offering the potential for prognostic stratification before initiating HER2-targeted therapy.[3]

In this scenario, none of the aforementioned PET-based radiopharmaceuticals can provide equivalent information to that obtained with 99mTc-sestamibi, which is indispensable for characterizing PgP-status in breast cancer before NACT. Indeed, it must be emphasized that PET/CT stands out in comparison to scintigraphy due to its superior spatial resolution and ability to provide accurate quantitative parameters. In this regard, in the paper by Moulika et al., the authors did not perform single-photon emission CT (SPECT/CT), which has been shown to significantly improve diagnostic accuracy compared to planar images alone.[4] This topic should be the focus of future investigations. However, SPECT still remains the most affordable and widespread nuclear medicine modality worldwide, with its own intrinsic value. From this perspective, further studies are needed to better define the role of various molecular imaging probes in the workup for the in vivo phenotyping of breast cancer, without overlooking the potential of each technological approach [Figure 1].

Figure 1 Schematic representation of the main positron emission tomography and gamma-camera/single-photon emission computed tomography tracers employed for breast cancer phenotyping. PET: Positron emission tomography, SPECT: Single-photon emission computed tomography, ER: Estrogen receptor

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Conflicts of interest

There are no conflicts of interest.
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1 Moulika JS Kalawat T Manthri RG Hulikal N Kadiyala S Bhargavi D Role of (99m) Tc-sestamibi scintimammography in predicting response to neoadjuvant chemotherapy in locally advanced breast cancer: A prospective study Indian J Nucl Med 2023 38 354 61 38390549
2 Mankoff D Balogová S Dunnwald L Dehdashti F DeVries E Evangelista L Summary: SNMMI procedure standard/EANM practice guideline for estrogen receptor imaging of patients with breast cancer using 16α-[(18) F] fluoro-17β-estradiol PET J Nucl Med 2024 65 221 3 38071554
3 Velikyan I Schweighöfer P Feldwisch J Seemann J Frejd FY Lindman H Diagnostic HER2-binding radiopharmaceutical, [(68) Ga] Ga-ABY-025, for routine clinical use in breast cancer patients Am J Nucl Med Mol Imaging 2019 9 12 23 30911434
4 Schillaci O Danieli R Filippi L Romano P Cossu E Manni C Scintimammography with a hybrid SPECT/CT imaging system Anticancer Res 2007 27 557 62 17348441
