@Carolinejane: I just went through exactly what you are experiencing, so I know how you feel. It is terrifying, but the worst thing to do about it is nothing.
You should schedule an appointment with your gyno asap. I found a lump in my right breast one night a few months ago, and the next morning called my doctor and they got me right in. I am only 22.
At your appointment, your doctor will do a breast exam and probably refer you to get a sonogram of your breast. This is normal. My doctor thought I might have a cyst or a fibroadenoma, which feels like it moves around in your breast when you touch it (some people have nick-named them “breast mice” because they are always hiding from your fingers), is smooth, somewhat hard, and can be painful. Mind was very tender when touched. These masses CANNOT turn cancerous, as pp’s have said. They never turn into cancer, but they are a huge pain in the ass as they can be painful and cause you to worry.
When you get a sonogram, they look to see if the edges of your mass are smooth, or if they look rough or jagged. Smoothness is a good thing, as cancerous masses are generally the ones that look rough, jagged, or assymetric. My mass looked like a small, smooth, round oval, about 1 cm in size when sonogrammed, so the doctor sat me down and gave me advice.
He told me that at my age, the chances of this mass being cancer (especially as evidenced by the sonogram images) were extremely slim. He told me I most likely had a fibroadenoma, and that there was only one other type of tumor that it had a tiny chance of being, which is a phyllodes tumor. Fibroadenomas are benign tumors (not cancerous), and most of the time phyllodes are benign, though they have I believe a 10% chance of being cancerous. He told me that if I was his daughter, he wouldn’t recommend a surgical biopsy, and that I should just come back every six months for a sonogram to make sure nothing looked suspicious.
This advice was not good enough for my worrying mind. Yes, the chances of having breast cancer in your 20s is very slim, but in the rare cases of women who do have it this young, it is more deadly. Your chances of surviving breast cancer at a young age are much lower than your chances when you get it in your 40s or 50s.
Because sonograms are not the most accurate way to diagnose breast cancer, my gyno wanted me to have a core needle biopsy, where they stick a needle into your breast and take core samples to be looked at in a laboratory. This sounded alright to me, and more definite than guessing from a picture.
THE ONLY WAY to be sure a lump is not cancerous is to take everything out surgically. This is what the surgeon I was referred to told me, and ultimately I decided that a complete surgical biopsy (not a needle biopsy) was the only way I would be able to live in peace. I had my surgery a little over a month ago. It was not bad, and not disfiguring in any way (breast tissue grows in where the lump was previously). They made the incision around the edge of my nipple to minimize visible scarring, and the doctor completely excised my lump.
The conclusion? Fibroadenoma. I was so relieved I wanted to cry.
Will some say surgery is extreme? Yes. But after reading so many stories about women who listened to the sonogram doctor and did nothing, and then found out they had cancer when it was in later stages, I didn’t want to take any chances. I am so completely happy with how everything turned out. Yes, it was somewhat painful, and yes, the timing was awful for me, but I acted fast on the situation, and that could have saved my life had it been cancer. The scar tissue from a surgical biopsy can make it harder to see other lumps on a sonogram or mammogram if they grow behind it later on, but that was a chance I decided I was willing to take. Everyone is different, and a surgery may end up being too invasive for some. To me, it sounded better than constantly worrying.
Sorry to write so much, but I really hope my experience can help you take the right steps in figuring out what is wrong. People will be very supportive and helpful if you tell them what is wrong–they were for me even when I didn’t really expect them to.
Don’t be scared, and get things checked out sooner than later, you will be fine!