Invasive Ductal Carcinoma, IDC or Infiltrating Ductal Carcinoma
Invasive Ductal Carcinoma or Infiltrating ductal carcinoma indicates that the cancer cells that are in the milk ducts (Ductal Carcinoma in-situ) are now beginning to infiltrate and replace the normal surrounding tissues of the duct walls.
Furthermore, the cancer cells have broken through the basement membrane of the duct and into the surrounding breast tissue, resulting in a mass. Invasive ductal carcinoma accounts for up to 80 % of all breast cancers.
This page focuses on understanding the histopathology about invasive ductal carcinoma. However, we have a newer post on invasive cancers, including invasive ductal carcinoma, with up-to-date references, and general information.
Often the phrase ‘invasive ductal carcinoma’ is used as a label for all carcinomas not otherwise designated as a recognizable type. (NOS or ‘not otherwise specified’)
The prognosis for invasive ductal carcinoma varies
The prognosis for Invasive Ductal Carcinoma (IDC) depends upon all sorts of factors including:-
- The type of breast cancer
- Size of the tumor
- The amount of spread
- The histological grade
- hormonal indicators
A trip back in time …
Imagine you are a doctor about 100 years ago, before these cancers had names. Imagine looking through a microscope, trying to understand what you are seeing. You gradually learn “that is a milk duct“, “that’s normal fibrous tissue“, “that’s glands forming milk“… then… holy cow.. this area looks abnormal! Why?
In the image below we can see microcalcifications and other debris beginning to block the duct, and the infiltration of breast cancer cells into the duct wall. It appears that some malignant cells have also begun to invade the surrounding tissue (could be DCIS with microinvasion or invasive ductal carcinoma). Three words you might run into again and again.
- infiltrating or invading the duct wall
Image of Invasive Ductal Carcinoma Cells
In the image below malignant cells (tumor cells) are proliferating through the breast ducts, which are also somewhat failing and disorganized at this point.
There is actually quite a lot of cancer on this image. Every dark dot is the nucleus of a cell, and you are seeing far too many of those cells. They are stacking up, crowding each other, like too many people trying to exit an airplane at the same time.
Clusters of Cells
In the image below we can see clusters of malignant cells within breast ducts. Also there are other clusters of cells which have begun to proliferate the surrounding tissue.
Infiltrating vs. Invasive breast cancer: depends upon the ‘extent’
Whether or not the breast cancer is termed ‘invasive’ or ‘infiltrating’ will depend upon the extent of the malignant cells. There is a kind of informal progression from ‘ductal carcinoma in situ‘ ( DCIS ) in which the carcinoma is still well contained within the breast ducts and is not yet moving into the duct wall (non-invasive breast cancer).
“Infiltrating” ductal carcinoma implies that the malignant cells are now inside the duct wall and threatening to grow into surrounding breast tissue or elsewhere in the body such as migration to the lymph nodes.
“Invasive” ductal carcinoma means that the breast carcinoma has moved beyond the breast duct walls altogether and is spreading into other body tissues.
Some Q and A’s fit nicely here
Where does invasive ductal carcinoma metastasis to?
The usual places for metastatic breast cancer are firstly to the lymph nodes and then into the bones. Meanwhile, it can be spreading between the ribs and towards the lung surface. After that, it can appear in the liver and lungs.
What is high grade, and poorly differentiated?
They are different things, but both of them carry a worse prognosis. The high grade refers to having lots of cell-division happening and lots of mitosis visible in the cell nuclei. The poor differentiation refers to the overall shapes of the epithelial cells of the breast ducts being uglier, less oval, more weird and variable.
What is invasive ductal carcinoma with lobular features?
It’s a mix of ductal and lobular breast cancer. On the microscope specimen, the pathologist sees both kinds, but don’t worry about it too much, because some pathologists like using plenty of descriptive words, sometimes too wordy. Just treat it like IDC.
What is grade 3 and grade 2?
What types of invasive ductal carcinomas are there?
Not all cancers of the breast are the same. Breast carcinoma is classified according to where the abnormal cells originate. So if the abnormal cells begin in the milk ducts, even if they are not malignant but just changed this is known as atypical ductal hyperplasia.
If there is cancer contained within the ducts this is ductal carcinoma in situ and if these abnormal cells break out of the breast ducts and into surrounding breast tissue this is invasive ductal carcinoma.
Some cancers start in the lobules of the breast (the milk-producing glands) and can also break out into surrounding tissue which would be invasive lobular carcinoma. However, there are also specific classifications of ductal cancers such as papillary breast cancer, which is a carcinoma that has very unique characteristics and growth patterns. Your pathology report will help you identify the type of cancer that you have.
In thinking about treatment of cancer should I consider clinical trials?
For any type or stage of breast cancer it is well worth researching clinical trials for treatment options. Indeed, due to breast cancer patients taking part in clinical trials advances in treatment have improved immensely.
There are many agencies that conduct trials and most in the US are funded by the National Cancer Institute (NCI) which is part of the National Institute of Health (nih.gov). It may well be worth researching your own area and the trials available.
What are the signs and symptoms of invasive ductal carcinoma?
Often early changes in the cells such as ductal hyperplasia and even DCIS do not have any noticeable signs and symptoms. Often these early conditions are detected on mammogram screening and biopsy results such as fine-needle aspiration or core needle biopsy.
However, invasive ductal cancer may present with:-
- A breast lump or breast tumor
- Rash or redness of the breast
- Inverted nipple
- Nipple discharge
- Enlarged axillary lymph nodes.
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