Mammograms and Breast Cancer Screening: Coverage and Frequency

Question
I am 37 yrs old, had 1st mammogram 2 yrs ago, have & still have small something or other near the edges of my left breast (near breast bone), I wonder if this even made it on the Breast mammogram, it is so close to my bone area.  I was told the mammogram was fine & not to have to get another until 40 yrs.  It just bothers me that this is there(Been there for as long as I can remember).  I know if I go back to the Gynocologist again, he will just send me for another mammogram that might not even pick this up.  Wondering if the area of the breats that are compressed in those machines ALWAYS cover the areas that the Breasts GET CANCER?? If so, I will not worry about this any more.   I have no family history of Breast cancer.  I did have a non-cancerous small lump I found on my own removed 4 yrs ago- on the other breast.    Do calcifications always happen on the breast edges--probably what this is.  I just don't want another mammogram if not nesecarry-nothing has changed.   CAn I go to a Doctor and request that he stick a needle thru this for more information -but no mammogram?  Thanks !  

Answer
There is NO medical investigation technique that is 100% perfect, BUT it is possible to come close. With regards to the margins of a mammography X-ray field there may be some uncertainty. However you state that these changes have been there as long as you can remember. It is therefore highly unlikely that they represent anything pathological. However, let a surgeon (not your gynecologist) check these things to be on the safe side! You can ALWAYS ask for a thin needle aspiration cytological biopsy so you get a pathology report showing what these things are. Good luck!