Let’s talk about mammography

What is a mammogram?

A mammogram is nothing more than an X-ray of the mammary gland. Yes, just like when a person hurts their ankle and goes to the emergency room and they ask for an X-ray of the ankle … only, in this case, of the mammary gland. To be more exact, the Royal Spanish Academy defines it as “a fine-grained film breast X-ray, capable of obtaining images of soft tissues with great precision” (1). In the central region and a part of the south of our country, Mexico, they usually call it mammography, which etymologically derives from the Greek μαστός (mastós) that means “breast” (2) and γραφία (graphía) that means description, treatise, writing or representation graph (3). Well, regardless of the name you want to use (since both are correct and are used interchangeably), if by age it is already your turn to have your mammogram or a specialist doctor has requested it, this post will explain the generalities that you should Learn about this study, which I am going to tell you about is the only breast imaging study that has been shown to reduce mortality from breast cancer by 21% (4).

How is a mammogram performed?

The day you go to have your mammogram, you will be asked to come after a good shower at home, but without having applied deodorant, antiperspirant or powder in the breasts or armpits area. This is very important, because these products can give unnecessary artifacts or images in the result of your mammogram. If you have already had previous breast imaging studies, they will also ask you to bring them with you. This, so that the radiologist can compare previous studies with current ones, retrospectively. When you arrive at the radiology department, you will be transferred to a private, isolated place with a specialist mammography technician (who is usually female) who will guide you through the technical procedure. The study is done with one breast at a time. The mammary gland to be studied is placed on a flat support plate, where it rests and is gently compressed with a parallel plate called a paddle. The device then emits a small dose of X-rays, which passes through the breast to a detector located on the opposite side. This detector, be it a photographic film or in the form of electronic signals, will create the image of the breast, and these images will be the mammograms that, finally, we will be able to interpret (5).

What types of mammograms are there?

If we talk about the acquisition techniques of mammography, we can divide them into two: conventional acquisition and digital acquisition:

1.- Conventional acquisition mammograms use an analogous mastgraph and the acquisition of the images is carried out by a screen-film system and a developing equipment. This type of technique is the one referred to in the dictionary definition of the Royal Spanish Academy.

2.- Digital acquisition mammograms use digital mastgraphs where they acquire the images by detectors integrated into the mastgraph itself (digital) or external detectors (digitized) and the study is printed with a high-resolution equipment (4).

A brief history about mammography

The first mammograms in the world were acquired in a conventional way with analogous matographers, around 1960 in the United States; between the decades of the 70s and 90s they were the ones that predominated in that country. However, around the year 2000, digital mammograms began to develop (6). In 2005, a study entitled “Diagnostic Performance of Digital versus Film Mammography for Breast-Cancer Screening” was published in The New England Journal of Medicine by the DMIST (Digital Mammographic Imaging Screening Trial) group of researchers. In this study, they would study whether the use of digital mammography, compared to analog mammography, increased the diagnostic sensitivity of malignant tumors in radiographically dense breasts. They studied more than 49,000 asymptomatic American and Canadian women, and found that the diagnostic accuracy between the two studies was similar. However, in women younger than 50 years, or with radiographically dense breasts, or premenopausal and / or peri-menopausal, the diagnostic accuracy was higher with digital mammography (7). This is of utmost importance for Mexican women, because the average age of presentation of breast cancer is 52 years, unlike Canadian and American women, whose average age of presentation is 62 (4). At that time, in the United States only 7% of mastgraphers were digital, but as of the publication of this study, the migration to digital technology was rapid and well received, and in 2012 almost 90% of mastgraphers in the country they were already digital (6).

Benefits of digital mammography

At present, digital mammography (beware, not the digitized one that some X-ray cabinets sometimes promote as “digital” and, obviously, at a lower price) represents several advantages compared to the analog system. This is due to the fact that the acquisition, processing and visualization of the image of the breast are handled independently and through software, the number of repetitions of the study is reduced, the dose of ionizing radiation is lower, it allows to use systems computer-assisted detection system, allows the transmission of digital files to other experts for remote interpretation, and, ultimately, increases the timely detection of malignant tumors, especially in women with dense breasts as already mentioned (4, 5, 7).

What is a three-dimensional (3D) mammogram

Also, within this group of digital mammograms, there is three-dimensional (3D) mammography or tomosynthesis (4, 8). A limitation that conventional mammography has, or also called 2D, is that normal breast tissue can overlap the breast tumor and in this way, hide it and give us a falsely negative result. What tomosynthesis does is take multiple millimeter images of each other. These images are then digitally converted into 3D images, removing the effect of overlap (8). Tomosynthesis improves breast cancer detection by up to 27% (4) and the American Society of Breast Surgeons recently issued an official statement where it positions 3D mammography or tomosynthesis as the “preferred modality ”In all patients who undergo mammograms (9).

Now, if we talk about the different types of breast cancer screening studies, we also have two (10):

1. Screening study that consists of performing a mammogram in the manner of 2 traditional projections (cranio-caudal and medio-lateral-oblique) to each breast and used in patients without any breast symptoms (and preferably 3D mammography), and ;
   Diagnostic study consisting of the 2 traditional projections to each breast and the use of additional projections such as compression or magnification cones, lateral, rolled, cleavage, etc. Also consider the use of other diagnostic tools such as breast ultrasound and / or breast MRI. This type of study is performed in symptomatic patients (palpable breast mass, nipple discharge, mastalgia, or a radiological abnormality seen in the screening study) and is requested by the treating breast surgeon or breast radiologist. This is the importance of going to the right specialists.

What is the result of a mammogram?

Whenever a screening or diagnostic mammogram is performed, the radiologist, who must be a specialist in radiology and imaging and be certified by the Mexican board of radiology (and preferably have an added qualification in “Image of the Breast”) must report your study according to the BI-RADS classification system (11). BI-RADS is the acronym in English for “Breast Imaging-Reporting and Data System” and we use the acronym equally in English for our reports in Spanish. This was created in 1993 with the aim that all specialists in breast diseases and radiologists speak the same language in breast imaging studies and thus, with the results of the study, to be able to regulate the behavior to be followed (12). If your breast imaging study does not mention the BIRADS category in its conclusion, it is a study that fails to comply with the Official Mexican Standard 041 (11) and categorically, it is a deficient study. The BI-RADS classification ranges from 0 to 6 (4, 10, 11):

Hey! But I have heard that radiation from mammography is harmful, is it true?

Well, it is true that mammography produces radiation and it is also true that radiation causes damage to our body (any type of radiation does). However, when we compare the risk / benefit that we obtain when performing mammography, the benefit is clearly greater, since we can detect small and non-palpable breast cancers, which translates into early detection and a greater probability of cure. Now, next-generation and digital mastgraphs emit less radiation than first-generation analogs or digitals. And the truth is that radiation is received daily at all hours by different elements present in the world. On average, the total radiation dose a woman receives from a comprehensive breast screening study is approximately 0.4 millisieverts (mSv, which is a measure of radiation dose). To put it in perspective, the average radiation that all of us obtain naturally from the environment (known as background radiation), is 3 mSv in a year and this comes from cosmic radiation, the natural radioactivity of terrestrial materials or created by man and the radioactivity of elements that we consume daily (13, 14). When analog mammography predominated in the 1970s, the risk of having a screening mammogram was equated with smoking 3/8 of a cigarette, traveling 400 km by plane, or 700 km by car, or climbing a mountain for 20 seconds (6). Currently, performing a digital screening mammogram is equivalent to the radioactive exposure we naturally have to the environment for 7 weeks (13). The United States Environmental Protection Agency establishes regulatory limits and activates safety protocols at exposures of 100 mSv to protect its population (15). So, as you can see, the radiation dose that a state-of-the-art mammogram currently emits is minimal.

Hey! But I’ve been told that radiation from mammography also hurts the thyroid, so?

Actually, the effective dose (which is defined as the amount of radiation absorbed by the human body, adjusted to the type of radiation received and its effect on the particular organ) (16) of radiation is 0.13 mSv for a digital mammogram and 0.17 mSv for an analog mammogram. And to put it in perspective, this equates to 30 minutes of exposure to the environment (6), so the radiation dose to the thyroid is minimal. Sure, if you’re feeling more confident, you can always ask to have a thyroid lead protector fitted when you get your mammogram.

Well … and then, what mammogram should I have? Or did I get the right one?

As you can see, mammography has many key issues and concepts that the health professional must know perfectly to request it and above all be able to interpret it. For this reason, mammography should always be indicated by a doctor, preferably an expert in the diagnosis and treatment of breast tumors. It is common for you to hear in the consultation that the patient, by her own decision and also for practicality, goes to the nearest radiology office and asks for her mammogram or breast ultrasound herself. This, without any guidance or indication by the expert and, derived from this, results in a poorly indicated study, deficient in its technique or interpretation. Sometimes, it simply does not provide any benefit and needs to be repeated, but in the worst cases, I have witnessed poorly performed or misinterpreted studies, with “normal” results and the patient arriving later with a malignant tumor, mentioning in retrospect that The study that had been carried out had been “normal” [sic] for a long time. So, whenever a mammogram is requested or performed, be sure to go to the expert for its correct indication and to the expert for its correct subsequent review. Remember that we do not review studies … we review patients!

I hope this post has dispelled all the doubts you have about this study that is so important for you and for your health. If you have any doubts, questions or comments, contact me. I am at your command!

References:

1.- Asociación de Academias de la Lengua Española. (2017). Mamografía [Def. 1]. In Diccionario de la Lengua Española (23.1 ed.). Retrieved July 19, 2019, from https://dle.rae.es/?id=O6UsYRW

2.- Asociación de Academias de la Lengua Española. (2017). Masto- [Def. 1]. In Diccionario de la Lengua Española (23.1 ed.). Retrieved July 19, 2019, from https://dle.rae.es/?id=OZBwZS4

3.- Asociación de Academias de la Lengua Española. (2017). -grafía [Def. 1]. In Diccionario de la Lengua Española (23.1 ed.). Retrieved July 19, 2019, from https://dle.rae.es/?id=JPSoRik

4.- Cárdenas Sánchez, J., Erazo Valle-Solís, A. A., Arce Salinas, C., Bargallo Rocha, J. E., Bautista Piña, V., Cervantes Sánchez, G., . . . Valero Castillo, V. (2019). Consenso Mexicano sobre el diagnóstico y tratamiento del cáncer mamario (8va ed.) [8va]. Retrieved July 19, 2019, from http://www.consensocancermamario.com/documentos/FOLLETO_CONSENSO_DE_CANCER_DE_MAMA_8aRev2019.PDF

5.- Mamografía. (n.d.). Retrieved July 19, 2019, from https://www.nibib.nih.gov/espanol/temas-cientificos/mamografía

6.- Leher, D., Dr. (2014, March). La invención del mamógrafo. (M. E. Azar Dra., Ed.). Retrieved July 19, 2019, from http://www.samas.org.ar/index.php/blog-infosam/124-la-invencion-del-mamografo-un-paso-fundamental-en-la-prevencion

7.- Pisano, E. D., Gatsonis, C., Hendrick, E., Yaffe, M., Baum, J. K., Acharyya, S., . . . Rebner, M. (2005). Diagnostic Performance of Digital versus Film Mammography for Breast-Cancer Screening. New England Journal of Medicine,353(17), 1773-1783. doi:10.1056/nejmoa052911

8.- The American Society of Breast Surgeons Foundation (n.d.). Breast Cancer Screening 101. Retrieved July 23, 2019, from https://breast360.org/topics/2017/01/01/breast-cancer-screening-101/

9.- Willey, S. C., MD FACS, Whitworth, P., MD FACS, & Boolbol, S. K., MD. (2019, May 3). The American Society of Breast Surgeons – Official Statement: Position statement about screening mamography [PDF]. Dallas, Texas: The American Society of Breast Surgeons.

10.- The American Society of Breast Surgeons Foundation, (n.d.). Understanding Breast Imaging. Retrieved July 23, 2019, from https://breast360.org/topics/2017/01/01/understanding-breast-imaging/

11.- Secretaría de Salud. 2011. Norma Oficial Mexicana NOM 041-SSA2-2011, Para la Prevención, Diagnóstico, Tratamiento, Control y Vigilancia Epidemiológica del Cáncer de Mama. Publicada el 09 de Junio 2011 en el Diario Oficial de la Federación. Texto Vigente, de http://dof.gob.mx/nota_detalle.php?codigo=5194157&fecha=09/06/2011

12.- Burnside, E. S., Sickles, E. A., Bassett, L. W., Rubin, D. L., Lee, C. H., Ikeda, D. M., … D’Orsi, C. J. (2009). The ACR BI-RADS experience: learning from history. Journal of the American College of Radiology : JACR, 6(12), 851–860. doi:10.1016/j.jacr.2009.07.023

13.- The American Cancer Society. (2017, September 1). Mammogram Basics: How Does A Mammogram Work? Retrieved July 24, 2019, from https://www.cancer.org/cancer/breast-cancer/screening-tests-and-early-detection/mammograms/mammogram-basics.html

14.- The United States Environmental Protection Agency. (2019, June 14). Radiation Sources and Doses. Retrieved July 24, 2019, from https://www.epa.gov/radiation/radiation-sources-and-doses

15.- The United States Environmental Protection Agency. (2019, July 08). Radiation Health Effects. Retrieved July 24, 2019, from https://www.epa.gov/radiation/radiation-health-effects

16.- The United States Environmental Protection Agency. (2017, October 30). Radiation Terms and Units. Retrieved July 24, 2019, from https://www.epa.gov/radiation/radiation-terms-and-units