Invasive Breast Cancer
Making Sense of Early Invasive Breast Cancer
When breast cancer moves beyond the milk ducts or lobules and into the surrounding breast tissue, it is called invasive breast cancer. Most breast cancers fall into this category. Within invasive breast cancer, there are different subtypes—each with its own characteristics. The two most common are invasive ductal carcinoma (IDC) and invasive lobular carcinoma (ILC).
Invasive Ductal Carcinoma (IDC)
IDC is the most common form of breast cancer. It begins in the lining of the milk ducts and, over time, can break through the duct wall and grow into nearby breast tissue. You may hear your care team use the term infiltrating ductal carcinoma to refer to IDC.
How is IDC Diagnosed?
What are the Symptoms of IDC?
Invasive Lobular Carcinoma (ILC)
ILC is a less common form of breast cancer that starts in the lobules, the glands that produce milk. Like other invasive cancers, ILC develops when cancer cells move beyond the lobule and into nearby breast tissue. Unlike IDC, which often forms a distinct lump, ILC can grow in a more subtle “sheet-like” or linear pattern, making it harder to detect upon physical examination or from a mammogram. ILC is also slightly more likely than other invasive cancers to occur in both breasts. You may hear it referred to as invasive lobular carcinoma or lobular breast cancer; these terms mean the same thing.
How is ILC Found and Diagnosed?
What are the Symptoms of ILC?
Less Common Types of Invasive Breast Cancer
There are several rare subtypes of invasive breast cancer that each make up fewer than 5% of all cases. These cancers are often named for how the cells appear under the microscope. Some subtypes tend to have a more favorable outlook, while others behave more aggressively.
Less Common Sub-Types Include:
- Mixed carcinoma (features of both ductal and lobular cancers)
- Adenoid cystic (adenocystic) carcinoma
- Medullary carcinoma
- Mucinous (colloid) carcinoma
- Papillary carcinoma
- Tubular carcinoma
- Metaplastic carcinomas (such as spindle cell or squamous types)
- Neuroendocrine carcinoma
- Micropapillary carcinoma
- Cribriform carcinoma
What stages are considered early invasive breast cancer?
When doctors talk about early invasive breast cancer, they’re usually referring to stages I through III. These stages describe how much the cancer has grown and whether it has reached nearby lymph nodes, but they do not include distant metastatic (stage IV) disease.
- Stage I – At this stage, the cancer has begun to grow into nearby breast tissue. It may not have reached the lymph nodes at all (stage 1A) or may have spread only slightly into the lymph nodes (stage 1B).
- Stage II – These tumors tend to be larger or involve 1-3 lymph nodes.
- Stage III – Stage III breast cancer has spread more extensively within the breast area or to a greater number of lymph nodes, but it has not traveled to distant organs. It is still considered non-metastatic and is treated with the goal of cure.
Please note: You may find the word “metastasis” referring to lymph nodes near the breast. These are regional metastasis, and not stage IV disease.
Treating Early Invasive Breast Cancer
It’s totally understandable if treatment conversations stir fear, confusion, and uncertainty. You’re not expected to have answers yet; this is a moment for patience, support, and small steps. The good news: Early-stage invasive breast cancer is highly treatable, and your care team will guide you toward a plan that fits your cancer’s characteristics. Most treatment plans include one or more of the following:
Surgery
Surgery removes the tumor from the breast. Options include a lumpectomy (removing the tumor and a small rim of tissue around it) or a mastectomy (removing the entire breast)
Radiation
After surgery, radiation is often used to destroy any microscopic cancer cells that may remain near the tumor site.
Chemotherapy
Chemotherapy may be given before or after surgery to kill cancer cells. Not everyone with invasive breast cancer benefits from chemo—your care team will help you understand whether it’s recommended for you.
Endocrine (Hormonal) Therapy
If your cancer is hormone-receptor-positive, endocrine therapy helps block hormones that fuel cancer growth.
Targeted Therapy
Targeted therapies work on specific proteins that help cancer cells grow and spread. These treatments slow down or destroy cancer cells in a highly focused way.
Immunotherapy
Immunotherapy helps your immune system recognize and destroy cancer cells more effectively.
