What Is Luminal A Breast Cancer?

Breast cancer is one of the most common cancers for women, with approximately 1.3 million new cases diagnosed worldwide each year. Breast cancer can be divided into two overarching categories: Invasive (meaning it has spread) or non-invasive (localized). Luminal A is one of the four types of invasive breast cancer.

Learn more about luminal A breast cancer, its symptoms, causes, diagnosis, treatment, and more.

Types of Breast Cancer

Breast cancer is generally considered non-invasive or invasive. Non-invasive breast cancer is localized or contained within breast's milk ducts or lobules. Invasive breast cancer means cancer has spread or metastasized outside of these areas.

Non-Invasive Breast Cancer

Types of non-invasive breast cancer fall into one of these two broad categories:

• Ductal carcinoma in situ (DCIS): DICS is non-invasive cancer within the lining of the milk ducts in the breast tissue.
• Lobular carcinoma in situ (LCIS): LCIS is not considered cancerous but is a risk factor for breast cancer. LCIS means there are abnormal cells in the lobes of the breast.

Invasive Breast Cancer

Most breast cancers are considered invasive, meaning the abnormal cancer cells have grown outside the initial point of origin and are now growing in the surrounding breast tissue. Invasive breast cancers tend to fall into four main categories, based on hormone receptor (HR) sensitivity and human epidermal growth factor receptor 2 (HER2) sensitivity (a protein on the outside of breast cells that instructs them to grow).

The four main categories of invasive breast cancer include:

• Luminal A (HR+/HER2-): Luminal A is the most common type of breast cancer. It tends to grow slowly and is less aggressive than other types. Luminal A is considered to have a favorable prognosis because it is hormone receptor sensitive and is HER2-negative.
• Luminal B (HR+/HER2+): Luminal B is hormone receptor sensitive, but the cancerous tumors associated with Luminal B tend to be a higher grade (more abnormal) than Luminal A. Additionally, Luminal B is HER2-positive, so outcomes tend to be poorer.
• Basal-like (HR-/HER2-): Sometimes referred to as triple-negative breast cancer, basal-like breast cancer tend to have poorer outcomes due to lags in treatment advances. In addition, basal-like breast cancer tends to occur more frequently in Black women, pre-menopausal women, and women with a BRCA1 gene mutation.
• HER2-enriched (HR-/HER2+): Despite significantly improved outcomes due to treatment advances, HER2-enriched breast cancers are among the most challenging types of breast cancer to treat.

Breast Cancer Symptoms

Depending on the breast tissue density, it can be difficult to notice symptoms of breast cancer early on. Performing monthly self-breast examinations can assist with the early detection of breast cancer by identifying subtle changes associated with it, such as:

• Nipple or breast changes, such as unexplained size or shape changes, skin dimpling, or newly identified asymmetry of the breast
• Changes in skin texture or enlargement of the breast skin pores, sometimes described as feeling or looking like an orange peel or a lump not present before
• Nipple discharge in the absence of breastfeeding, which could appear clear, milk-like, or bloody
• Newly identified tenderness in a specific area of the breast, or the nipple
  

Causes

Most of the time, there is no known cause of breast cancer, also known as idiopathic. Cancer grows due to damaged DNA in a cell; environment, genetics, or a combination of environment and genetics can result in breast cancer. However, some inherent risk factors for breast cancer cannot be changed or avoided. These include:

• Sex (assigned at birth): Breast cancer occurs in women at a rate 100 times that of men.
• Age: Breast cancer is more prevalent in women over age 55.
• Race: Breast cancer is more prevalent in White women than in any other race.
• Family history: A family history of breast cancer increases breast cancer risk, particularly if there is a known genetic mutation in the BRCA1 or BRCA2 genes.
• Menstrual and reproductive factors: Menstruation onset before the age of 12, menopause after age 55, giving birth to a first child at an older maternal age, or never having given birth are risk factors for breast cancer.

Other risk factors that can be controlled or changed to minimize the risk of developing breast cancer include:

• Obesity
• Inactivity
• Unhealthy or unbalanced diet
• Alcohol use
• Radiation therapy to the chest
• Menopausal hormone therapy
  

Diagnosis

A breast cancer diagnosis is primarily made through mammography. Other technologies used in addition to mammography include breast ultrasound, breast magnetic resonance imaging (MRI), and molecular breast imaging.

Additional testing that may be done following mammography findings include:

• Breast biopsy
• Genetic testing of blood samples
  

Treatment

Treatment options should be discussed with your healthcare provider and may depend on preferences, risks, stage of cancer, and tumor size, among other factors. Breast cancer treatment often includes:

• Hormone therapy
• Chemotherapy
• Surgery
• Radiation therapy
• Targeted medication therapy
• Immunotherapy

Studies have shown that luminal A breast cancer responds best to hormone therapy. Luminal A breast cancer tends not to respond to chemotherapy or radiation therapy as well as it does to hormone therapy.

Prognosis

Many factors affect a breast cancer prognosis, including:

• Type of breast cancer (such as the presence of hormone receptors or HER2)
• Invasive versus non-invasive breast cancer
• Stage of breast cancer
• Risk factors

It is essential to have discussions with your healthcare provider about how different factors might impact your breast cancer diagnosis.

Luminal A breast cancer has a 75% to 80% response rate with hormone therapy and has a 90% or higher 10-year survival rate.

Coping

Unfortunately, invasive breast cancer affects approximately 1 in 8 women and kills 1 in 39 women. Receiving a breast cancer diagnosis is often overwhelming, but there are many organizations available to help with support and resources.

For example, the American Cancer Society can assist with transportation to treatment and other cancer-related needs or places to stay if treatment options are far from home and provide a helpline available 24/7 to answer questions.

Summary

Breast cancer affects many women worldwide. Luminal A is one of the most common forms of invasive breast cancer. Understanding your risk factors and early detection and diagnosis is essential for long-term outcomes.

Many breast cancer treatment options exist, but luminal A breast cancers respond best to hormone therapy. The prognosis for luminal A breast cancer is good, with high survival rates. If you need help after a breast cancer diagnosis, many organizations are available to assist with resources and support.

A Word From Verywell

Being told you have breast cancer can be frightening and overwhelming. Understanding what type of breast cancer you have, available treatment options, and where or who you can turn to for support is important in taking an active role in your recovery. Remember that you are not alone and that luminal A breast cancer survival rates are high.