Types of Breast Cancer

Author: Shazia Abou Talib•Reading Time: 7 Minutes

Breast cancer is not one single disease. Different types can begin in different parts of the breast, behave differently, and require different approaches to treatment.

You may hear unfamiliar terms such as ductal carcinoma, lobular carcinoma, invasive breast cancer, or carcinoma in situ. These names can feel difficult when you first see them in a medical report, but each one provides a specific piece of information.

The main questions are where the abnormal cells began and whether they have moved beyond their original location into the surrounding breast tissue. The most common breast cancer types begin in the milk ducts or lobules. National Cancer Institute

This guide explains the main types of breast cancer, the difference between noninvasive and invasive disease, and some of the less common forms you may encounter.

Understanding the Basic Structure of the Breast

The breast contains lobules, ducts, fatty tissue, connective tissue, blood vessels, and lymph vessels.

The lobules are glands that can produce milk. Small tubes called ducts carry milk from the lobules toward the nipple.

Most breast cancers begin in the cells lining the ducts or lobules. This is why the words “ductal” and “lobular” appear frequently in breast cancer reports.

Noninvasive and Invasive Breast Cancer

One of the first distinctions you may see is whether the abnormal cells are described as in situ or invasive.

“In situ” means that the abnormal cells remain within the place where they began. They have not grown into the surrounding breast tissue.

“Invasive” means that the cancer cells have moved beyond the duct or lobule and entered nearby breast tissue.

The word invasive can sound alarming, but it does not automatically mean that the cancer has spread to distant parts of the body. Invasive breast cancer can be diagnosed at different stages. The cancer stage is determined using additional information about the tumor, lymph nodes, and any spread beyond the breast.

Ductal Carcinoma in Situ

Ductal carcinoma in situ, commonly shortened to DCIS, involves abnormal cells contained within a milk duct. These cells have not invaded the surrounding breast tissue.

DCIS is often described as noninvasive breast cancer, preinvasive breast cancer, or stage 0 breast cancer. The term “in situ” means that the cells remain in their original place. Mayo Clinic

DCIS is commonly detected through a mammogram rather than a noticeable lump or other physical symptom.

Although DCIS is not invasive, it should not be ignored. Some cases may develop into invasive breast cancer, but doctors cannot always predict which cases will progress. Treatment recommendations depend on the size and grade of the DCIS, the area involved, the person’s health, and other medical findings.

Invasive Ductal Carcinoma

Invasive ductal carcinoma, usually shortened to IDC, is the most common type of breast cancer.

It begins in the cells lining a milk duct and then grows beyond the duct into surrounding breast tissue. It may also be called infiltrating ductal carcinoma or invasive breast carcinoma of no special type.

IDC does not behave identically in every person. Its grade, size, receptor status, lymph node involvement, and stage provide further information about its behavior and possible treatment.

Some invasive ductal cancers are detected as a lump. Others are first noticed through breast imaging or investigated because of a change in the breast or nipple.

Invasive Lobular Carcinoma

Invasive lobular carcinoma, known as ILC, begins in the lobules and grows into the surrounding breast tissue.

It is the second most common histological type of breast cancer after invasive ductal carcinoma. “Histological type” refers to the way a cancer is classified when its tissue is examined in a laboratory. National Cancer Institute SEER

Invasive lobular carcinoma may not always form a firm, clearly defined lump. It can sometimes cause an area of thickening, fullness, or a change in the shape or texture of the breast.

Knowing whether a cancer is ductal or lobular is important, but it is only one part of the diagnosis. Other findings in the pathology report help complete the medical picture.

Is Lobular Carcinoma in Situ Breast Cancer?

Lobular carcinoma in situ, commonly called LCIS, involves abnormal cells within the lobules. Despite the word “carcinoma” in its name, classic LCIS is not considered breast cancer.

LCIS indicates an increased risk of developing breast cancer in the future. The increased risk can involve either breast, not only the breast where LCIS was found. National Cancer Institute

LCIS is different from invasive lobular carcinoma. If LCIS appears in your report, the recommended plan may include closer monitoring, risk assessment, medication to reduce risk in some circumstances, or other individualized measures.

Inflammatory Breast Cancer

Inflammatory breast cancer is an uncommon and fast-growing form of invasive breast cancer. It develops when cancer cells block lymph vessels in the skin of the breast.

Instead of producing a distinct lump, it may cause rapid changes such as:

Swelling or enlargement of the breast
Redness or a change in skin color
Warmth or heaviness
Thickened or pitted skin resembling an orange peel
An inverted or flattened nipple
Tenderness, aching, or discomfort

These changes can also occur with infections and other conditions. However, rapid breast swelling, redness, or skin changes require prompt medical assessment, particularly when they do not improve as expected. National Cancer Institute

Paget Disease of the Breast

Paget disease of the breast is a rare cancer involving the skin of the nipple and usually the areola, the darker area surrounding the nipple.

Possible changes include itching, redness, burning, crusting, flaking, thickened skin, nipple flattening, or discharge. Because these symptoms may resemble eczema or another skin condition, the diagnosis can sometimes be delayed.

Persistent changes affecting one nipple should be medically assessed, especially when they do not improve with ordinary treatment.

Paget disease is often associated with DCIS or invasive cancer within the same breast. Further examination and imaging may be needed to identify any underlying abnormality. National Cancer Institute

Less Common Invasive Breast Cancer Types

Some breast cancers are classified according to the distinctive appearance of their cells under a microscope.

Tubular Carcinoma

Tubular carcinoma is an uncommon form of invasive breast cancer. Its cells form tube-shaped structures when examined under a microscope.

It is often small and slow growing when diagnosed, but its grade, stage, and other findings still need to be considered.

Mucinous Carcinoma

Mucinous carcinoma, sometimes called colloid carcinoma, is an uncommon invasive breast cancer in which cancer cells are surrounded by mucus.

Some tumors are described as pure mucinous carcinoma, while others contain a mixture of mucinous and more common invasive cancer cells.

Metaplastic Breast Cancer

Metaplastic breast cancer is a rare invasive cancer in which some cells have changed into forms that resemble other types of tissue.

It may behave differently from more common breast cancers and requires careful pathological assessment.

Micropapillary Carcinoma

Invasive micropapillary carcinoma has a distinctive pattern under a microscope. It is uncommon and may be found alone or together with another form of invasive breast cancer.

These uncommon names can be unsettling when they appear in a report. Their presence does not explain the whole diagnosis by itself. The stage, grade, receptor findings, and individual health circumstances remain important.

Rare Tumors That Begin in Other Breast Tissues

Not every tumor found in the breast begins in the ducts or lobules.

Phyllodes Tumors

Phyllodes tumors begin in the connective tissue of the breast. Most are benign, but some are classified as borderline or malignant.

A phyllodes tumor is different from the more common breast carcinomas. Its treatment and follow-up depend on its size, microscopic features, and whether it is benign, borderline, or malignant. National Cancer Institute

Angiosarcoma of the Breast

Angiosarcoma is a very rare cancer that begins in cells lining blood or lymph vessels. It can develop without a known cause or, in uncommon circumstances, occur after previous radiation therapy or long-standing lymphedema.

Breast Lymphoma

Lymphoma begins in cells of the lymphatic system. It rarely begins in the breast and is treated differently from cancers that begin in the milk ducts or lobules.

These rare conditions need specialist assessment because their classification and treatment differ from those of typical breast cancer.

Can Different Types Occur Together?

A breast tumor can contain more than one pattern of cancer cells. A pathology report may use terms such as mixed ductal and lobular carcinoma or describe a special feature within a more common invasive cancer.

This does not necessarily mean that a person has several unrelated cancers. It may mean that the tumor contains more than one microscopic pattern.

A person may also have DCIS near an invasive breast cancer. The pathology report brings these findings together so the medical team can understand the complete diagnosis.

How Type Differs From Receptor Status, Grade, and Stage

These terms answer different questions.

Type identifies where the cancer began and how the cells appear.
Receptor status describes whether the cells have certain biological features, including estrogen receptors, progesterone receptors, or HER2.
Grade describes how different the cancer cells look from normal cells and gives information about how quickly they may grow.
Stage describes the extent of the cancer, including its size and whether it has reached lymph nodes or distant parts of the body.

For example, a person may have invasive ductal carcinoma that is hormone receptor-positive, grade 2, and stage 1. These descriptions refer to different aspects of the same diagnosis.

Finding the Type in a Pathology Report

The exact type is usually confirmed by examining tissue collected through a biopsy or surgery.

The diagnosis section of the pathology report may identify whether the finding is DCIS, invasive ductal carcinoma, invasive lobular carcinoma, or another type. Additional sections may report the grade, receptor status, margins, lymph node findings, and other details.

You can read How to Understand a Biopsy Report: Pathology Results Explained for help locating and understanding these sections. Benign, Malignant, Positive and Negative Biopsy Results also explains several result terms that may appear in medical discussions.

Questions to Take to an Appointment

You do not need to memorize every breast cancer type. Focus on understanding the words that apply to your own diagnosis.

It may help to ask:

What is the exact name of the breast cancer?
Is it in situ or invasive?
Is more than one type or pattern present?
What information is still pending?
What do the type, grade, receptor status, and stage each mean in this case?
How do these findings affect the next step?

If someone attends the appointment with you, they can take notes with your permission. They can also help organize reports and record questions without taking control of the conversation.

Frequently Asked Questions

What Is the Most Common Type of Breast Cancer?

Invasive ductal carcinoma is the most common type of breast cancer. Invasive lobular carcinoma is the second most common histological type.

Does Invasive Breast Cancer Mean Stage 4?

No. Invasive means that the cancer has grown beyond the duct or lobule into surrounding breast tissue. Stage 4 means that breast cancer has spread to distant parts of the body. These terms do not mean the same thing.

Is DCIS Really Breast Cancer?

DCIS is commonly described as a noninvasive or stage 0 breast cancer because the abnormal cells remain inside the milk ducts. It is different from invasive breast cancer but still requires an individualized care plan.

Is LCIS the Same as Invasive Lobular Carcinoma?

No. Classic LCIS is not considered breast cancer, although it indicates an increased future risk. Invasive lobular carcinoma is cancer that has grown beyond the lobules into surrounding tissue.

Can Men Develop These Types of Breast Cancer?

Yes. Men can develop breast cancer because they have a small amount of breast tissue. Invasive ductal carcinoma is the most common type diagnosed in men.

Key Takeaways

Breast cancer includes several diseases rather than one single type.
Most breast cancers begin in the milk ducts or lobules.
In situ cells remain within their original location, while invasive cancer has entered surrounding breast tissue.
Invasive ductal carcinoma is the most common breast cancer type.
Invasive does not automatically mean metastatic or stage 4.
LCIS is not the same as invasive lobular carcinoma.
Inflammatory breast cancer may cause rapid skin and breast changes without a distinct lump.
Paget disease can cause persistent changes involving the nipple and areola.
Type, receptor status, grade, and stage describe different parts of the same diagnosis.
The pathology report provides the most reliable information about the type present.

References

Mayo Clinic. Breast cancer types: What your type means. Retrieved from https://www.mayoclinic.org/diseases-conditions/breast-cancer/in-depth/breast-cancer/art-20045654

Mayo Clinic. Ductal carcinoma in situ. Retrieved from https://www.mayoclinic.org/diseases-conditions/dcis/symptoms-causes/syc-20371889

National Cancer Institute. Breast cancer types. Retrieved from https://www.cancer.gov/types/breast/breast-cancer-types

National Cancer Institute. Inflammatory breast cancer. Retrieved from https://www.cancer.gov/types/breast/breast-cancer-types/inflammatory

National Cancer Institute. Paget disease of the breast. Retrieved from https://www.cancer.gov/types/breast/breast-cancer-types/paget-disease-breast

National Cancer Institute SEER. Cancer stat facts: Invasive lobular carcinoma. Retrieved from https://seer.cancer.gov/statfacts/html/ilc.html

Medical Disclaimer

This source-supported article provides reliable information to strengthen your understanding of breast cancer and complement personalized medical guidance from a qualified healthcare professional.