Breast cysts and breast cancer: How can you tell the difference?

Many women will experience a breast cyst at some point in their lives. Though they tend to be more common among women between the ages of 30 and 50, breast cysts can develop at any age.

So, what causes breast cysts? Is there any way to treat them? And how do you tell if a lump is breast cancer or just a cyst? 

We went to breast surgical oncologist Ana Paula Correa Refinetti, M.D., for answers.

What are breast cysts?

Cysts are just fluid-filled sacs. The lining of the cyst produces fluid, which fills up the space, almost like a balloon.

Are there different types of breast cysts?

Yes. The vast majority fall into one of three categories.

• Simple: These cysts look like balls filled with fluid.
• Complicated: These cysts have little septations — or membranes — that divvy up the areas inside of them and create small pockets or chambers. Sometimes, they can also have debris on the bottom that looks like sand.
• Complex: This is just a step up from “complicated.” It could indicate the cysts have more solid parts, or that the walls or membranes are thicker. 

Microcysts, which are tiny little painless cysts scattered throughout the breast tissue, fall into the “simple” category. 

Why do breast cysts form?

Breast tissue is active throughout a woman’s life. It’s hormone-driven. That’s why breasts can feel different before, during and after your period. There is also a change in the ratio of milk glands to fatty tissue as women get older. But these changes are not necessarily a sign of disease. Breasts will change throughout your life. It’s a normal physiological process. 

Breast cysts usually happen due to the normal hormonal fluctuations that take place in a woman’s body during her menstrual cycle. That’s why they’re most common among women who are still of child-bearing age. Only a small proportion of breast cysts occurs in post-menopausal women.

Are the symptoms of breast cysts different from those of breast cancer? 

Actually, yes. About 99% of breast cancers will not cause any pain. Even if they’re detected as a lump, bump or mass in the breast, they’re usually painless. 

Breast cysts, on the other hand, if they develop quickly, often compress the tissue around them and can cause pain. So, while some breast cysts may be painless, they tend to appear as a lump that hurts.

How are breast cysts treated?

The vast majority of breast cysts — about 70% — will go away on their own. So, unless they’re causing severe pain, we usually just leave them alone, after confirming the diagnosis of a simple breast cyst. A lot of women will always have breast cysts, but won’t necessarily have any symptoms related to them. 

That being said, any time a woman comes into our clinic with a lump in her breast, we are going to do a complete work-up to make sure it’s not breast cancer. Depending on her age, that process could involve a diagnostic mammogram and/or a breast ultrasound.

Here’s how we handle the different categories of breast cysts:

• Simple: If one of these is causing a lot of pain, we might draw out the fluid with a syringe to provide some relief. But if there’s nothing abnormal about it, nothing more needs to be done. So, we won’t remove it surgically, biopsy it or even require the patient to follow up with additional diagnostic imaging. 
• Complicated: We may ask the patient to follow up with us in six months to make sure nothing has changed.
• Complex: Usually, the lining of a cyst with fluid inside it can be seen on an ultrasound. But if a physical exam and ultrasound can’t rule out cancer, we may order a biopsy. 

Is a breast cyst the same thing as a galactocele?

No. A galactocele is also a fluid-filled sac, but it’s just a clogged milk duct. Those occur most often among nursing women. They only happen rarely in someone who’s not lactating or recently stopped.

What is fibrocystic breast syndrome?

Fibrocystic breast syndrome is when women develop breast pain and tender nodules throughout their breast tissue. While most breast cysts are localized and feel like a single mass causing pain in one particular spot, fibrocystic breast syndrome is a different process. It can occur in both breasts and it is diffuse. 

Women with this condition report diffuse pain throughout their breasts and multiple small bumps scattered throughout the tissue. These give their breasts an almost “textured” feeling to the touch.   

What’s the most important thing women should know about breast cysts and cancer?

Simple cysts are not associated with an increased risk of breast cancer. 

A lot of women come in scared, thinking the fact that they’ve developed a breast cyst makes them more likely to develop breast cancer later on. But that’s not true. 

Assuming there are no other factors at play, such as genetic mutations or inheritable conditions that might make someone more likely to develop cancer, these women will have the same level of risk as the average person.

But any time a woman feels something unusual in her breasts, she should contact her healthcare provider.

Request an appointment at MD Anderson online or by calling 1-877-632-6789.