As if we're likely to forget, October is Breast Cancer Awareness month. Between the football players in pink and the constant inundation with Breast Cancer promotions (guilty!) we can't help but notice that the world seems to turn pink this time of year. Behind the hype is a very important message though - breast cancer happens. The best way to treat it is to not get it in the first place and if you do get it, detect it early so treatment has a chance at cure. Throughout this month, I’ll post about how we screen for breast cancer and what the various modalities mean.
WEEK 1: Why screen? What does “typical” screening include?
Survival rates for breast cancer continue to improve. New therapies, better imaging, and increased awareness have all helped. One thing hasn’t changed - the smaller the cancer is when it’s diagnosed, the better the prognosis.
Breast cancer screening isn't perfect. It can be very confusing when deciding what test to get, what exams to do or not do, and who to talk to about all of this. I think the punchline is, however, you know your body so get to know your body.
What is Breast Cancer Screening? Formally, there are two parts to breast cancer screening – clinical breast exam, and imaging. Clinical breast exam is simply palpating the breast. If you examine your breasts every so often, you should notice if something changes - really changes. Most breast cancers feel like rock-hard lumps that don't move around with the rest of the breast. They are usually not subtle. That said, nasty things CHANGE.
If you feel something, maybe wait a few weeks and feel it again. Measure it if you can – see if it grows. Mark when during your menstrual cycle you felt it and examine the area at the opposite time (if you had your period when you felt it, feel again about two weeks later). If something is changing in your breast, it's an issue, still probably not a cancer, but an issue – get it looked at. Clinical breast exam should be performed with your annual exam, whether you see a primary care provider or an OB/GYN.
Imaging is the most important part of breast cancer screening. It can be a life-saver. “Imaging” means evaluating the breast with various techniques until we’re satisfied we know what’s going on. Most often, this means a mammogram and you’re done. Sometimes, radiologists aren’t sure and they’ll recommend extra X-ray views of the breast (this is becoming less common with 3D mammography which we’ll discuss in a few weeks), ultrasound, MRI, or various other less frequently used breast imaging techniques.
Why image? Most cancers can't be felt until they're about 1cm in size and even then, how palpable they are depends on their size, the density of the breast tissue, and location within the breast. Mammography can detect cancers at about 3mm in diameter. If we think the average (if there is such a thing) cancer doubles in size every year, mammography has the potential to detect a cancer almost 2 YEARS before it can be felt.
What is Mammography?
Mammography is an X-ray of the breast. It started when a surgeon in the 1910s started messing around with (what was then new) X-ray technology on mastectomy specimens. He noticed that often, there were changes visible on X-ray where the tumors were. Since then, there have been variations and improvement on his idea but basically we’re still looking for characteristic changes cancers generate that are visible on X-ray.
To obtain an image the X-ray beam passes through the breast to the detector (whether film or digital) and records differences in how the beam travels through the tissue. Compressing the breast (other than being something designed by men to inflict discomfort on us) splays the tissue out in hopes of getting a better image. A lot of normal breast tissue piled on top of itself can generate a misleading image that’s something’s wrong.
A traditional mammographic series consists of two views – CC and MLO. The CC view (cranio-caudal) means the breast is squished on the detector horizontally when the image is taken (Image 1 above). The X-ray beam goes from top to bottom through the breast (cranial-to-caudal, head-to-tail). The CC view gives an image of the breast from right to left. For the MLO view, the breast is squished more or less vertically (Image 2 above). It’s canted toward the armpit somewhat to be sure all of the breast tissue is on the image. The X-ray beam goes from medial-to-lateral through the breast (the O accounts for the slight tilting of the image). This one results in an image of the breast from top to bottom.
Mammography works because of two characteristics of cancer:
- Cancer cells, by definition, are cells that are dividing when they’re not supposed to. The new cancer cells aren’t very sturdy so they actually die pretty quickly. The problem is that more are being produced than are dying. As your body clears away the dead-cell debris, sometimes what gets left behind is calcium. It can happen in any scar but luckily it happens frequently in the breast. Calcium shows up on X-ray (Image 3 above).
The presence of new calcifications on mammography can signal something is wrong. Not always though. If they’re really small or singular sometimes they bear watching. Watching, however, means that you have to watch. The “follow-up” mammogram in six months or whenever is very important – don’t skip it. They’re looking for change, again – nasty things CHANGE.
- Cancer causes an inflammatory reaction in the surrounding tissue. Your body knows those cells aren’t supposed to be there. It tries to fight them. This inflammation creates scar tissue – this is what makes cancers feel so solid. On X-ray the process of scarring looks like a black hole – everything in the vicinity is being pulled toward the center (actually the scar is white on X-ray but the effect is the same). In doctor-speak this is architectural distortion due to a desmoplastic reaction. It shows up pretty well on mammography (Image 4 above).
So, in general (very general), mammographers are looking for calcium, architectural distortion of the breast, and change.
That change thing is why you should, if you can, get your mammogram within the same health system every year. With digital mammography, images from any location within a healthcare organization should be available everywhere so it doesn’t have to be the same physical place - just be sure whoever is reading your mammogram has access to your old ones. Comparing previous mammograms to the current one is almost as important as the current image itself. Change.
This post carries my usual disclaimer. My ramblings are intended as general information. I cannot be responsible for how you use what is written here. I am not YOUR doctor, so seek one out if you are confused or have questions.