[Brenda_D]

I'm still new to all of this, but I also had a rapid growth tumor.

I think when they say it takes years to develope, they are referring to normal slower growing tumors.

I had a mammo a year ago (first mammo) and it showed an area of dense tissue. I had a US a week later and they couldn't find it on US. That was on the outside of the right breast.
They had me come back for a 6 month diagnostic follow up and that mammo was "clear" and I got the little postcard saying it was "normal". I felt relieved.
In Nov. I got the letter for my 6 month diagnostic follow up and before I made the appointment, I found a large lump in that same breast, but on the inner side, not the outside where they saw the dense tissue.
I called the doc, got the appt. for the mammo and US. Then the biopsy. It was a rapid growth IDC. Ki-67 came back as 70%. My doc and the radiologist went over the previous mammo with a "fine tooth comb" and saw no sign of anything in that breast as of 6 months ago.
I had a lumpectomy with axillary node removal. The tumor itself was 3.7 cm.
So, yes, tumors can and do grow rapidly.
I did everything "right". I did my mammos, and follow ups, and still ended up with a large invasive tumor, that has spread to inner mammary node chain and bone (according to Pet/Ct scan).
I'm not trying to scare anyone, but it can and does happen, and faster than most medical professionals realize.