The first symptom that you may have breast cancer is finding a lump in one of your breasts. Usually the lump will end up being benign which is a huge relief for that means that it is not breast cancer.
Sometimes it doesn't even have to be lump, it can be a change in the nipple, the shape of the breast or nipple, getting some sort of oozing out of the nipple that is blood stained a rash that doesn't go away or even a swelling in your armpit. Getting any of this doesn't mean you have breast cancer but it is definitely something you should not wait to get checked out by your doctor as soon as possible.
Breast cancers have typical symptoms depending on their type. If the breasts keep getting very red, increasingly hard and sore, and sometimes get "bumpy" as if there are small hives near the inflamed area, it is inflammatory breast cancer. If the breasts are very itchy, develop red scaly rashes and can easily be mistaken, as it usually is, for eczema, it's the Pagent's disease. Do not stay in doubt, get it checked out.
A cyst is just a sac filled with harmless fluids. Sometimes, cysts are all there is to the lumps. These cysts can be easily and very quickly removing by inserting a needle into them and taking out all the fluid accumulated inside the cyst. If, in such a case, no fluid comes out, the needle can still be used to extract a small tissue sample from the breast, to be tested for cancer. This procedure is called a biopsy.
Sometimes lumps in the breast can be nothing by a type of cyst, which is just a type of sac that is filled with fluid. That is simple to take care of and can be done quickly and painlessly by just inserting a needle into it and removing the fluid that is accumulating in it. If there is no fluid to be found then they can still use that needle to take a small tissue sample to be tested for cancer, which is called a biopsy.
All in all, cancer is not a laughing matter. Make sure you know about the causes and symptoms for breast cancer. If you start showing symptoms yourself, please do not delay contacting your doctor. Breast cancer for you implies your daughter's risk of developing it goes up. Brushing that off with a shrug is not an option. Your doctor will tend to the rest.