Breast cancer

Breasts are not classified as organs with a specific energy so one can use body mapping.
Possible mapping: 
--- Wind energy by chakral location
--- left breast may be attributed to A-Wind, right - To Um-Wind 
--- treated on Wind meridian on left hand and right hand respectively.

Another mapping:

--- region 2 - left breast - Heat
--- region 5 - right breast - Dryness

This is generally for elder women and man, for young+middle-age women there's generally reversed mapping i.e.:
--- left breast - Dryness
--- right breast - Heat

  Meridian N4, green

  The same recommendations for meridian choice as in
   previous posts.

In Diamond Energy System it may be:

--- generally Wind meridian (by location), also if the process is fast

--- Upper Core meridian if chronic process and/or tends to spread deep into organs like
methastasis in lungs.

Besides, both these meridians in Diamond Energy System actually cover the whole

body above diaphragm so will act on any methastases formed there.

 In Cylindrical Spiral system vertical meridians cross breasts right through the middle:
--- left breast by Wind vertical meridian
--- right - by Cold meridian
in general spin for the body (anticlockwise)

Breast cancer develops fast in many cases, so use of Hetero=vertical meridians
can make a difference.
Considering that, good choice may be:

--- the little finger of left hand, controlled by Wind

--- vertical meridians of Wind or Cold
Using spiral meridians combines the benefits of vertical and horizontal meridians.

One may also use the Spiral system right on the breast:

As breasts are rich in lymph nodes, this brings additional troubles:

--- one may expect cancer cells spreading at relatively early stages

--- Wind forms Yin-Yang pair with Dampness on every level so any action on it will affect Dampness energy

--- on the other hand, Dampness directly controls lymphatic system, the way cancer cells spread.

Similar situation is for liver and gall bladder controlled by Wind, however it's breasts which have especially dense lymphatic system.