And how painful it is?

Pain is in the late stages of the cancer. my friends breast cancer was found when we went for our first mammogram and seemingly she had it for a while and then needed a mastectomy and followed by radiotherapy and is now in recovery. last year my sister found a lump but no pain and breast cancer and lymph nodes removed, she is now finished her chemo and radiotherapy and in remission. Normally you find the lump long before any pain. good Luck.

As others have said, there's usually no pain with breast cancer. where there is pain, it's because the cancer is advanced.

My stage 3 tumour was painful; when I had my mastectomy some muscle had to be removed – with the result that I'm kinda concave rather than flat – and I assume it was the tumour invading the muscle that s the cause of the pain

There is usually little or no pain with breast cancer.

Mine was quite tender when I was diagnosed at stage 3.

It had been tender for as long as I had felt the lump, whch is why I hadn't worried about it.

Breast cancer is not always pain free, just pain is more commonly associated with a cyst.

When breast cancer causes pain it is usually at stage 4.
It is most often painful when it has broken through the skin, invaded the chest wall or metastasized to the bones.