Keeping Abreast: Introduction clip 1.1

The Biology of the Breast and Breast Cancer

clip 1.1 of animated video

Partial storyboard of animation 1.1

This diagram of the quadrant incidence of breast cancer, maps out a stunning statistic about the distribution of the disease. The upper outer quadrant (UOQ) contains as much as 50% of all tumors; an amount that is apparently on the increase.
A generally accepted explanation for this disproportionate distribution of tumors is that the UOQ contains up to 50% of the glandular tissues or parenchyma. this is unlikely to be the only explanation. The division lines on this diagram look very much like cross hairs in a scope: an appropriate image for setting our sights on investigating and formulating questions on the biology of the breast and breast cancer

The upper outer quadrant may have more parenchyma in certain body positions but as much as 50%? Lets investigate.
This is a simulation of a twenty-five-year-old female's "owner's eye view" of her breast tissue from a standing up and looking down position,
as for a standard mammogram view of a horizontally-compressed breast.
Mammograms however can only distinguish dense tissues such as the parenchyma and supporting stromal-matrix from the less opaque fatty tissues and a twenty-five-year-old's breast is usually too dense to detect tumors by a mammogram.
A mediolateral-oblique (MLO) mammogram is taken of a diagonally compressed breast and gives a better view of the outer auxiliary tail of the breast.
This is the area farthest from the nipple but usually contains less than 1% of tumors.
Lying on one's back, much of the parenchyma does slump towards the outer quadrants.
But so does the nipple: the reference point for segmentating the quadrants.
When lying on one's stomach for an MRI the breast hangs udder-like and the 3D composition of the parenchyma suspended by connective tissue of the matrix can be visualized more clearly.
Sometimes the parenchyma can be seen to extend further into the UOQ.
This is the inside of the breast from an "owner's eye" view.
There are substantial differences in the quantity and distribution of mammary components at different ages and between individuals.
Variations in the amount of fat and parenchyma make up some of the large differences in breast size
There is a fat pad covering and sectors of fat between the parenchyma.


The parenchyma consists of an array of 12 or so discrete lobes,
each consisting of lobules connected to the nipple by a series of ducts.
In the lactating Breast, milk is produced in the lobule structures
and drains towards the nipple through the series of ducts.
So the parenchyma is made up of an array of lobes consisting of branched ducts and lobules which are surrounded and suspended by a matrix of connective tissue that fastens them to the chest and points along the skin.
This gives the parenchyma a lot of latitude for movement, tethered to the chest wall by matrix, the branched ductal system is free to move at the nipple end.
This freedom of movement increases with age and decreasing breast density, and may have biological significance

NEXT 2 - Breast development, lobes and ducts

3- The terminal ductal units (TDLU)