The pathology report is first and foremost a medical report prepared by medical professionals for medical professionals. Hence, you will find that the report is filled with many medical terms that you may be unfamiliar with and trying to make sense of the information can be overwhelming.

You’re not expected to know every aspect of the report, but understanding the basic sections of the report will give you a better idea of your diagnosis. The most important section to look out for is the diagnosis or final diagnosis which may include the following key information:
 
1. Microscopic Description or Diagnosis
The crux of the diagnosis which details what the pathologist saw and measured. Based on this information, your doctor will be able to explain to you the key information relevant to your condition which include tumour size, tumour grade, and if your cancer is non-invasive or invasive.

2. Tumour Size 
In general, the smaller the tumour size, the better the prognosis (outlook).

3. Tumour Grade
In the case of invasive breast cancers, the pathologist will compare how different the cancer cells are to normal breast cells. The more the cancer cells look like normal breast cells, the better the prognosis (outlook).

4. Non-Invasive vs Invasive
The pathologist will determine if the cancer is Non-Invasive, meaning it is contained within the milk ducts or it is Invasive, meaning it has spread (metastasize) beyond the breast.

5. Nuclear Grade
The pathologist will compare how different or closely the nuclei of cancer cells look to the nuclei of normal breast cells. The higher the nuclei grade, the more abnormal the cells are and more aggressive they tend to be. 

6. Hormone Receptor Status
The hormone receptor status will help guide your treatment plan. If your hormone receptor status is positive, your treatment plan will include hormone therapy such as tamoxifen or aromatase inhibitors. 

7. HER2 Status (Human Epidermal Growth Factor Receptor 2)
This is a protein found on the surface of some breast cancer cells and determines the pathway for cell growth and survival. The HER2 Status will also help guide your treatment plan. For HER2-positive cancers, anti-HER2-drugs such as trastuzumab (Herceptin) may be administered. 

8. Tumour Margins
If a surgical biopsy was carried out, a rim of normal breast tissue surrounding the suspected area will be removed for testing. The margins will help indicate whether or not all of the tumour was removed and whether further surgery is required.

9. Lympho-vascular Invasion
This will show if the cancer has invaded the lymph system. 

10. Lymph node status
If lymph nodes in the underarm area were removed during surgery, the pathologist will study them to determine whether they contain cancer or not. This will indicate if the cancer may have spread beyond the breast.
 
It is important to note that if you are diagnosed with Ductal Carcinoma in Situ (DCIS), your pathology report may not contain all the sections mentioned above.
Breastcancer.org has developed a comprehensive guide which can be extremely helpful in understanding your breast cancer pathology report. Download the guide here.