What's new in Breast Cancer Staging

Introduction

Hello everyone. My name is Mohammad Eghtedari, and I'm one of the radiologists at UC San Diego Health Breast Imaging section. Today I'm going to talk to you about the breast cancer staging based on the new AJCC eighth edition. Welcome to this course.

I don't have any financial disclosure relevant to this talk.

Objectives

  • Understand the American Joint Committee on Cancer (AJCC) and its role.
  • Learn the new breast cancer staging criteria based on the AJCC eighth edition.
  • Discuss the history and evolution of breast cancer treatment.
  • Review the integration of molecular profiling into breast cancer staging.

Topics

1. Overview of AJCC and Breast Cancer Staging

The AJCC is a committee with 22 organization members, including the American Cancer Society and the National Cancer Institute. They define the staging of breast cancer in the United States and other countries that follow similar guidelines. The staging system helps predict patient outcomes and determine appropriate treatments.

The reason behind this staging is that it has been found for many cancers that the stage or level of advancement of the cancer at the time of initial diagnosis is usually a good predictor of what is going to happen in terms of outcome to the patient and also is a good way to determine appropriate treatment for the patient.

2. History and Evolution of Breast Cancer Treatment

The treatment of breast cancer has evolved significantly over the years. Here is a brief overview of key milestones:

  • 1894: Radical mastectomy introduced, involving removal of the breast, pectoralis muscle, and axillary contents.
  • 1937: Radiotherapy added to radical mastectomy.
  • 1948: Modified radical mastectomy introduced, sparing the pectoral muscle.
  • 1985: Lumpectomy and radiation therapy became standard, focusing on removing only the tumor and surrounding tissue.
  • 1994: Sentinel lymph node biopsy introduced, reducing the need for extensive lymph node removal.
  • 2016: Targeted axillary dissection refined to further minimize surgical intervention.

The goal has been to move from aggressive treatments to more targeted and less invasive procedures, improving patient quality of life and outcomes.

3. Molecular Profiling in Breast Cancer Staging

In addition to traditional TNM staging (Tumor size, Node involvement, Metastasis), the eighth edition of AJCC incorporates molecular profiling. This includes tumor grade, estrogen and progesterone receptors, HER2 status, and genomic assays. These additional factors provide a more accurate prognostic staging.

Key Points:

  • The traditional TNM staging is now supplemented with molecular profiling for better accuracy.
  • Molecular tests like Oncotype and MammaPrint help determine the need for chemotherapy in early-stage breast cancer.
  • Pathologists use tumor grade and markers to classify tumors into categories such as Luminal A, Luminal B, HER2 enriched, and Basal-like.

Molecular Profiling Details:

The eighth edition of AJCC staging includes important molecular markers:

  • Oncotype: Evaluates 21 genes to give a recurrence score, helping to decide on chemotherapy.
  • MammaPrint: Analyzes 70 genes to classify tumors as high or low risk for recurrence.
  • Estrogen and Progesterone Receptors: Tumors with these receptors (ER/PR positive) respond well to hormonal treatments.
  • HER2 Status: HER2 positive tumors are more aggressive but can be treated with targeted therapies.
  • KI67: A marker for cell proliferation; higher levels indicate more aggressive tumors.

Grading and Classification:

Pathologists determine tumor grade by evaluating:

  • Tubule formation
  • Mitotic count
  • Nuclear polymorphism

Tumors are graded as low (score 3-5), intermediate (score 6-7), or high (score 8-9) based on these features.

Breast Cancer Categories:

  • Luminal A: ER/PR positive, HER2 negative, low KI67. Best prognosis.
  • Luminal B: ER/PR positive, higher grade and KI67 than Luminal A. Good prognosis.
  • HER2 Enriched: HER2 positive, ER/PR negative. Aggressive but treatable with targeted therapy.
  • Basal-like (Triple Negative): ER/PR negative, HER2 negative. Most aggressive, treated with conventional chemotherapy.

Conclusion

The AJCC eighth edition has introduced significant improvements in breast cancer staging by incorporating molecular profiling alongside traditional anatomical staging. This integration allows for more accurate prognostic information and appropriate treatment strategies. The evolution of breast cancer treatment continues to move towards less aggressive methods, improving patient outcomes and quality of life.

Thank you very much for your attention and hope that you learned something new about AJCC eighth edition for staging of breast cancer. Thank you.