Breast Cancer Grading

Breast cancer grade describes how the cancer cells look under a microscope and how quickly they may be growing. It is usually included in the pathology report after tissue from a biopsy or surgery has been examined.

The grade does not show where the cancer is located or how far it has spread. It describes the appearance and behavior of the cells in the tissue sample.

Breast cancer is usually assigned grade 1, grade 2, or grade 3. A lower grade generally means the cells look more like normal breast cells and tend to grow more slowly. A higher grade means the cells look more abnormal and may grow more quickly.

The grade is only one part of the diagnosis. Doctors also consider the type of breast cancer, tumor size, lymph node findings, hormone receptor status, HER2 status, stage, general health, and other individual factors.

How Breast Cancer Grade Is Determined

A pathologist examines the breast tissue under a microscope. For invasive breast cancer, a commonly used method is the Nottingham grading system.

The pathologist assesses three features:

1. Tubule or gland formationThis shows how much of the tumor is forming structures that resemble normal breast ducts or glands.
2. Nuclear appearanceThis describes the size, shape, and appearance of the nuclei inside the cancer cells. The nucleus contains the cell’s genetic material.
3. Mitotic activityThis measures how many cells appear to be dividing. A higher number of dividing cells suggests that the cancer may be growing more quickly.

Each feature receives a score from 1 to 3. The three scores are added together to produce a total between 3 and 9. That total determines the final grade. Johns Hopkins Pathology

The individual scores may appear in the pathology report before the final grade. For example, a report may show three separate numbers followed by an overall Nottingham score.

You do not need to calculate the grade yourself. The final grade should be clearly stated in the report.

Grade 1 Breast Cancer

Grade 1 cancer cells look more like normal breast cells than higher-grade cancer cells. They usually form more recognizable gland or tubule structures and tend to divide more slowly.

Grade 1 may also be described as:

• Low grade
• Well differentiated
• Nottingham grade 1
• Histologic grade 1

The word “differentiated” refers to how closely the cancer cells resemble normal cells. Well-differentiated cells retain more features of normal breast tissue.

Grade 1 cancers generally tend to grow and spread more slowly than grade 2 or grade 3 cancers. However, grade 1 does not mean that treatment is unnecessary. The complete diagnosis still determines the care plan.

Grade 2 Breast Cancer

Grade 2 cancer cells have features between grade 1 and grade 3. They look more abnormal than grade 1 cells but less abnormal than grade 3 cells.

Grade 2 may also be described as:

• Intermediate grade
• Moderately differentiated
• Nottingham grade 2
• Histologic grade 2

Grade 2 is a common result and does not mean that the pathologist is uncertain. It is a defined category based on the total score.

A grade 2 cancer may behave differently from one person to another because grade is not the only feature that affects cancer behavior. Receptor results, HER2 status, tumor size, lymph node findings, and other medical information remain important.

Grade 3 Breast Cancer

Grade 3 cancer cells look very different from normal breast cells. They tend to form fewer recognizable gland structures and show more signs of active cell division.

Grade 3 may also be described as:

• High grade
• Poorly differentiated
• Nottingham grade 3
• Histologic grade 3

Grade 3 cancers generally have the potential to grow and spread more quickly than lower-grade cancers. This information helps the medical team assess the cancer and plan treatment. American Cancer Society

A grade 3 result does not tell you that the cancer has already spread. It also does not predict exactly how the cancer will respond to treatment.

Some faster-growing cancers may respond well to treatments that target rapidly dividing cells. The grade should therefore be understood as part of the complete medical picture rather than as a prediction by itself.

Grade and Stage Are Different

Grade and stage describe different aspects of breast cancer.

Grade 3 does not mean stage 3.

A person may have a small, early-stage cancer that is grade 3. Another person may have a more advanced cancer that is grade 1 or grade 2.

This distinction is important because the numbers can easily be confused when they appear together in a medical report.

Grade and Cancer Type Are Different

The type of breast cancer identifies the kind of cancer found in the tissue. Examples include invasive ductal carcinoma and invasive lobular carcinoma.

The grade describes how abnormal the cancer cells look and how actively they appear to be growing.

A report may therefore describe a cancer as “invasive ductal carcinoma, grade 2.” The first part names the cancer type, while grade 2 describes the appearance and likely behavior of its cells.

These are two parts of one diagnosis.

Grade and Receptor Status Are Different

The grade is also separate from hormone receptor and HER2 results.

Receptor testing may describe breast cancer as:

• Estrogen receptor-positive or ER-positive
• Progesterone receptor-positive or PR-positive
• HER2-positive or HER2-negative
• Triple-negative

These findings help doctors identify treatments that may target particular features of the cancer cells.

Grade describes how the cells look and how quickly they appear to be dividing. Receptor status describes whether certain proteins or hormone receptors are present.

Both findings can influence treatment, but they answer different questions.

Grading Ductal Carcinoma in Situ

Ductal carcinoma in situ, or DCIS, is noninvasive. The abnormal cells remain inside the milk ducts and have not grown into the surrounding breast tissue.

DCIS may be described as:

• Low grade
• Intermediate grade
• High grade

Low-grade DCIS cells look more like normal breast cells and generally grow more slowly. Intermediate-grade DCIS falls between low and high grade. High-grade DCIS cells look more abnormal and tend to grow more quickly.

The pathology report may also mention necrosis, which refers to areas of dead or dying cells. The term “comedo necrosis” may be used when a breast duct contains dead cells. This finding is more often associated with high-grade DCIS. American Cancer Society

DCIS grading and invasive breast cancer grading are related concepts, but the report should be interpreted according to the exact diagnosis.

Grade from a Biopsy and Grade after Surgery

A core needle biopsy examines samples taken from part of the abnormal area. Surgery may provide a larger amount of tissue for examination.

In some cases, the grade reported after surgery may differ from the grade found in the biopsy sample. This can happen because different areas of a tumor may not look exactly the same, and the surgical specimen allows the pathologist to examine more tissue.

A difference does not automatically mean that the earlier report was incorrect. The two reports were based on different amounts of tissue.

Ask which result the medical team is using for treatment planning if more than one grade appears in your records.

The Role of Grade in Treatment Planning

Grade helps doctors understand the likely behavior of the cancer, but it does not determine treatment by itself.

The treatment plan may also consider:

• Whether the cancer is invasive or noninvasive
• Tumor size
• Lymph node involvement
• Cancer stage
• ER and PR results
• HER2 status
• Menopausal status
• Results from genomic or multigene testing when appropriate
• Previous health conditions
• Personal treatment preferences

Two people with the same grade may receive different recommendations because their complete diagnoses are different.

A higher grade may influence discussions about systemic treatment, but no treatment decision should be assumed from the grade alone.

Words That May Appear Beside the Grade

Pathology reports may use several terms that describe cell appearance.

• Well differentiated usually corresponds to grade 1.
• Moderately differentiated usually corresponds to grade 2.
• Poorly differentiated usually corresponds to grade 3.
• Nuclear pleomorphism refers to variation in the size and shape of the cancer cell nuclei.
• Mitotic count describes the number of cells seen dividing.
• Tubule formation describes how much the cancer tissue forms structures resembling normal breast glands or ducts.
• Histologic grade refers to the overall grade based on the microscopic appearance of the tissue.

These terms can sound alarming when read without context. They are part of the structured method the pathologist uses to classify the sample.

Understanding the Grade in Your Breast Cancer Report

Begin with the final grade rather than trying to interpret every individual score.

The following questions may help during your appointment:

1. What grade is shown in my pathology report?
2. Is this the grade of invasive cancer or DCIS?
3. Was the grade determined from a biopsy or surgical specimen?
4. What is the Nottingham score?
5. Are the grade and receptor results complete?
6. Does this grade affect the recommended treatment?
7. Are any additional pathology tests still pending?
8. Which findings are most important for my care plan?

You may also ask for your diagnosis to be written in one complete sentence. This can make it easier to understand how the cancer type, grade, receptor status, and other findings fit together.

Supporting Someone Reading a Pathology Report

A family member or caregiver can help without trying to interpret the report independently.

Useful support may include:

• Reading the report together only when the person feels ready
• Writing down unfamiliar terms
• Preparing questions for the appointment
• Taking notes with the patient’s permission
• Keeping biopsy and surgical reports organized
• Avoiding conclusions based on the grade alone
• Reminding the person that one number does not define the full diagnosis

Searching for general information may be helpful, but comparisons with another person’s grade or treatment can create unnecessary fear. The same grade can appear in cancers with very different stages, receptor results, and treatment options.

Frequently Asked Questions

Does Grade 3 Mean Stage 3

Grade 3 describes cells that look more abnormal and may grow more quickly. Stage 3 describes the extent of cancer in the breast, nearby tissue, and lymph nodes. They are not interchangeable.

Does Grade 1 Breast Cancer Require Treatment

Grade 1 cancer generally tends to grow more slowly, but treatment decisions depend on the complete diagnosis.

Does Grade 2 Mean the Pathologist Is Uncertain

Grade 2 does not mean that the pathologist is unsure. It is the intermediate category produced by a total Nottingham score of 6 or 7.

Does a Higher Grade Mean the Cancer Has Spread

Grade describes the appearance and likely behavior of the cancer cells. Tests and staging findings are needed to determine whether cancer has spread.

Can the Breast Cancer Grade Change After Surgery

A surgical specimen contains more tissue than a needle biopsy. Examination of the larger sample may provide additional information and occasionally result in a different grade.

Key Takeaways

• Breast cancer grade describes how cancer cells look and how quickly they may be growing.
• Invasive breast cancer is commonly classified as grade 1, grade 2, or grade 3.
• The Nottingham system assesses tubule formation, nuclear appearance, and mitotic activity.
• Grade 1 cells look more like normal cells and generally grow more slowly.
• Grade 2 has features between grades 1 and 3.
• Grade 3 cells look more abnormal and may grow more quickly.
• Grade and stage are not the same.
• Grade 3 does not mean stage 3.
• DCIS may be described as low, intermediate, or high grade.
• Treatment decisions are based on the complete diagnosis, not grade alone.

Related Reading

• Types of Breast Cancer
• How to Understand a Biopsy Report: Pathology Results Explained
• Benign, Malignant, Positive and Negative Biopsy Results

References

American Cancer Society. Breast Cancer Grades. Retrieved from https://www.cancer.org/cancer/types/breast-cancer/understanding-a-breast-cancer-diagnosis/breast-cancer-grades.html

Johns Hopkins Pathology. Staging and Grade. Retrieved from https://pathology.jhu.edu/breast/staging-grade

National Cancer Institute. Stages of Breast Cancer. Retrieved from https://www.cancer.gov/types/breast/stages

Cancer Research UK. About Cancer Staging and Grades. Retrieved from https://www.cancerresearchuk.org/about-cancer/breast-cancer/stages-grades/about

Medical Disclaimer

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