A breast cyst or a fibroadenoma are both very common and innocuous conditions of the breast. A woman may feel one of these as a lump, or it may be something that shows up on a breast ultrasound done for a different reason. A simple cyst or a fibroadenoma does not transform to breast cancer. Nevertheless they're common enough to be dangerous and here's why.
1) They forgive negligent behavior and breed it
As cysts and fibroadenomas are more common than cancer, it is likely that most undiagnosed or neglected breast problems amongst women are benign. For this reason, say 80% or more women who neglect seeking attention for a breast lump, are lucky enough to get away with it, based on statistical probability alone. This forgives and fosters a culture of negligence. Adversely affected are the smaller fraction of unlucky women whose undiagnosed problem is in fact a cancer, but who don't seek timely attention.
Point to Remember: Just because someone else got away with ignoring a breast lump, doesn't mean you will.
2) They cause "availability error"
A woman may have a history of cysts or fibroadenomas in her young days. When she develops a new lump in her 40s or 50s, she easily assumes its probably the "same thing" she had before. Its possible that this new lump she has now, is cancer and unrelated the old condition. Often someone in the family, say mother or sister is familiar with cysts and fibroadenomas and tries to reassure the patient "You probably have the same cyst-like thing I have". Its easy to imagine, if there was no such thing as benign breast lumps, the cancers wouldn't be as easily ignored.
Point to remember: A new lump, no matter what your personal or family history, should always be investigated afresh to obtain an accurate diagnosis.
3) Sometimes a fibroadenoma is not a fibroadenoma
There are occurrences, albeit rare when certain types of breast cancers look strikingly similar to fibroadenomas on imaging. Relying on imaging alone without completing the recommended needle biopsy can lead to a delayed or a missed diagnosis in these masqueraders. A solid lesion in the breast should be subjected to a triple test ( clinical exam by a specialist+ imaging+ needle biopsy) for a complete diagnosis. There are shortcuts, but there are no safe shortcuts.
So lets see do a Q and A to see if we have a take-home message here
Q: "Which breast lumps should be investigated?"
A: "All of them"
Q: "How do you know if the lump you found on self exam is a fibroadenoma or a cancer?"
A: " Its my job to figure that out, not yours" :)