Breasts are constructed of fat, ligament, and gland tissue separated into lobes.
A network of ducts spreads from the lobes towards nipple.
Diagram showing the lobes and ducts of the breast
Breast size and density
One breast is usually smaller compared to one other. Your breasts may feel different at different times inside the month. Fairly for breasts to feel lumpy ahead of your period.
Younger ladies have more glandular tissue than fat of their breasts, making them dense.
After the menopause the glandular tissue is gradually substituted with fat, that is less dense.
Where it starts?
Breast cancers normally starts from the cells that line the ducts from the breast.
Nine out of ten of those cancers have zero special features if the cells are looked over underneath the microscope. These are called invasive breast cancers (NST). NST stands for No Special Type.
Around 10 % breast cancers (10%) are invasive lobular carcinoma. Which means the cancer got going in the cells that line the lobules with the breast.
There are more rarer types of cancer of the breast.