Radiology In Breast Cancer Imaging

Breast cancer affects one in eight women throughout her life. Although also seen in men, it is much rarer. While the risk of contracting breast cancer in men is 0.1% throughout their lives, it is 12-13% in women. Growing awareness, early diagnosis with screening methods and the development in treatment methods have substantially lowered the mortality rate from breast cancer in recent years. Eighty-five percent of diagnosed breast cancer patients do not have a close relative with breast cancer. Therefore, not having a family history does not prevent one from contracting breast cancer. Only 15% of breast cancer patients have a close family member previously diagnosed with breast cancer. As ovarian cancer can also be passed on with similar genes, women who have a close family member with ovarian cancer are under a similar risk as with breast cancer. Therefore it is of vital importance to consult a doctor and have regular check-ups for those with a family history. The most important factor in reducing the mortality rate in breast cancer is early diagnosis. With early diagnosis the patients are cured at a high rate such as;90-93%.

Early diagnosis starts with regular check-ups and breast examination. Radiological examinations are important screening methods in early diagnosis.

Current suggested methods for early diagnosis are;

  • Starting from age 20, self examination of breasts at the end of the menstrual cycle (once a month)
  • Between the ages 20-30, clinical breast examination by a doctor (1 to 3 years)
  • From age 40, clinical examination by a doctor and mammography (yearly)

Who Should Have Mammography Screening?

The best method of radiological imaging for breast cancer in a patient with no complaints is mammography.Therefore women over the age of 40, even if they have no complaints,should have yearly regular mammography scans. For patients with a lump that is felt manually, bloody discharge from nipples, retraction in the nipple or breast skin, breast skin taking the form similar to orange peel and similar changes, a mammography may be taken for diagnosis after the age 30-35.

How is a Mammography Applied?

A mammography is taking films of the breast from top to bottom and from medial to lateral by a radiology technician by positioning the breast accordingly with the utilization of X-rays. A slight compression is put on the breast during screening in order to avoid movement, have a clear image, to apply less radiation on the breast and to get a better image by thinning the breast. This compression usually lasts for only a few seconds and although it may vary from person to person, there is usualy a short and tolerable pain. At the end of the procedure, there are a total of 4 images, 2 for each breast. The images are either displayed on a monitor or printed on film and evaluated by a radiology specialist.

Who Should Evaluate Mammograms?

Ideally, the radiological screening should be carried out and evaluated by radiology specialists with a high knowledge on the subject. Along with the experience of the doctor, the quality of the screening device and a qualified and well trained radiology technician who will perform the screening and give the most appropriate position are all very important factors in the accurate diagnosis.

How is a Mammography Evaluated?

The radiology specialist evaluates the normal breast structure first. In the breast tissue there are milk ducts, connective tissue and fat tissue in different proportions according to different women and different ages.The fat tissue appears as dark grey or close to black in a mammography, whereas connective tissue and milk ducts appear as white. The cancer tissue also appears as a white mass, distortion or asymmetry. Especially in dense breast tissues as it is difficult to perceive white on a white background, a mammogram may not be sufficient in diagnosing cancer. This is the main reason for not being able to diagnose breast cancer with a mammography. Therefore this method can be supported with ultrasonography, 3 dimension mammography (tomosynthesis) and breast MRI.

Why is Mammography İndispensable?

Apart from the conditions mentioned above, another method of diagnosing cancer is detecting calcium accumulations at cell level (calcification). These calcifications are very important in early diagnosis as they usually show microscopic groups before a mass that can be detected by ultrasonography or hand has been formed. For this reason, a mammography is a vital screening method as these groups are either not seen at all or can easily be overlooked in ultrasonographic examinations.

Are There any Harmful Effects of Mammography?

Since mammography is a screening method in which X-rays are used, theoretically it has a certain amount of harmful effect on the tissues. Compared with other screening methods that use X-rays, the radiation dose the tissue is exposed to during a mammography is as follows:

Screening Type * Approx.dose of radiation exposure Radiation equivalent of natural environment ** Additional lifelong risk of fatal cancer
Tooth x-ray 0.005 mSv 1 day Can be neglected
Bone Densitometry(DEXA) 0.001 mSv 3 hours Can be neglected
Mammography 0.4 mSv 7 weeks Very low
Lung X-ray 0.1 mSv 10 days Minimum
Spine X-ray 1.5 mSv 6 months Very low
Kidney film (IVP) 3 mSv 1 year Low
Brain Tomography(Cranial CT) 2-4 mSv 8-16 months Low
Heart Tomography(Coronary CT) 12 mSv 4 years Low
Lung Tomography(Thorax CT) 7 mSv 2 years Low
İAbdominopelvic CT 20 mSv 7 years Medium
These values are for a person of normal height-weight and may vary according to the structure of the person and the facility where the examination is made.

** Risk level Additional risk of fatal cancer following examination
Minimum

Very Low

Low

Medium

Less than 1 in 1,000,000

1 in 100,000 to 1,000,000

1 in 10,000 to 100,000

1 in 1000 to 10,000 -1 in 500 to 1000

Note:These risk levels are very low additional risks in addition to the risk of dying from cancer which is 1 in 5 for everyone.

As can be seen from the above chart, the radiation exposure from a mammography is defined as 1 in 10 to 50 of computerized tomography examinations like direct X-ray examinations. Also the radiation exposure received from one mammogram scan is equivalent to the natural environment radiation of the earth received in 2-3 months of living in the world. According to the data from studies held in the last 30-40 years when mammography was first widely used in the world, there are no proven breast cancer cases which developed due to the harmful effects of radiation received during a mammography. This subject is still debated over in scientific platforms, although a theoretical risk can be mentioned.

There are some other unwanted side effects of mammography apart from the harmful effects of radiation which is the greatest anxiety among the public. There may be cases in which a biopsy is required due to suspicion although there is no cancer present in the end. Also a follow-up may be required for benign lesions and as mentioned above, a mammogram may not be able to detect all cases of cancer.

As a result; when the harm/benefit ratio is taken into consideration, with the present scientific data; mammography screening is vital. Also, when the studies of the past 30-40 years are evaluated, the mortality rate from brom breast cancer has decreased by approximately 30% due to early diagnosis with mammography screening.

Should Mammography be Digital?

Until the early 2000’s, mammography was performed using X-rays with non-digital (analogue-conventional) methods. The images were recorded on receivers called cassettes and a film was developed using wet bath method. No alterations or changes could be made on the images. At the beginning of the 2000’s, when digital systems became wide spread, mammography devices also started to change to the digital system. The digital system also uses X-rays and records the images on a cassette system with a different technology and after digitally processing them, reflects them on monitors. The images can be saved both in a digital environment or as a film. Changes can be made on these images. A study in 2005, has shown that a digital mammography had higher accuracy values and a superiority in diagnosis especially in women under the age of 50, who had entered or were about to enter the menopause with a dense breast tissue. Apart from this, the digital mammography applies 15-30 % less radiation compared to the old analogue mammographies, puts less compression on the breast and a better image is obtained.

At Which Stage of the Menstrual Cycle Should a Mammography be Applied?

For women who are menstruating, there is no need to make an arrangement according to a certain period of the menstrual cycle. However in some women who experience breast pain and sensitivity before and during the first days of menstruation, if there is no emergency, having the mammography after the end of the menstrual cycle or taking a mild analgesic a few hours before the screening may be suggested. There is no evidence showing the fact that a breast cancer case may not be seen or overlooked because the mammography was taken before or during the menstrual cycle.

Is it Harmful to Undergo Frequent Mammographies?

The most common causes for frequent mammography screenings in our country are that some patients apply to different facilities for diagnosis or that the patients lose their documents/films and therefore can not properly inform their doctors, and that the quality of the film in some facilities (due to the devices or development process of the film) are poor and needs to be repeated. In order to avoid this, the medical documents must be kept by the patient and submitted to the doctor at each visit. Repeating the examination due to poor quality of the film or mammography examination in an additional position does not have a harmful effect; on the contrary, a late diagnosis of cancer due to an overlooked or incomplete or inappropriate examination could have much more unwanted effects. Also one must keep in mind that the recommendation for an addditional film or a repeated film in 6 months made especially by a radiology specialist is always made by taking the benefit/harm ratio related to the patient into consideration.

Can Mammography Detect all Breast Cancers?

As mentioned above, especially in cases with a dense breast tissue, mammography is inadequate in detecting cancer. This is the main reason that a cancer may not be detected in a mammography. Therefore, in women with a dense breast tissue, this method should be supported with an additional ultrasonography examination and 3 D mammography (tomosynthesis) method which has been put into use in the past few years.

Can Breast Ultrasonography be Used in Breast Cancer Screenings?

Although breast ultrasonography is a safe method which only uses sound waves, it is not suggested as the only method used in breast cancer screenings. As mentioned above, a mammogram can not detect all cancers in women with a dense breast tissue where the accurate diagnosis can be as low as 60%. In this case this method should be supported by an additional ultrasonography examination in patients with a dense breast tissue. The main reason that ultrasonography is not used in breast cancer screening is that an ultrasonography can not detect cell level calcium accumulations which is an early sign of breast cancer. Other reasons that ultrasonography is not preferred for screening are that ultrasonography can detect many non-cancerous and biopsy requiring tissue formations and cause unnecessary follow-ups and biopsies, causing a loss in time and labor.

Işıl Tunçbilek, MD,

Radiologist