Breast cancer usually starts off in the milk duct and as it grows, it break the wall of the milk duct, forming a lump.
On the other hand, in the case of Infiltrating Duct Carcinoma, the breast cancer grows without breaking the wall of the milk duct and spreads along the milk duct, so it is difficult to feel a lump. For even doctors, it is difficult to find by palpation.
What is a sign of Infiltration Duct Carcinoma?
That is brownish spots on the brassiere.
This brownish spots are bleeding from the nipple. So it is recommended to often check the inner side of the brassiere.