Luminal Breast Cancer: Types, Symptoms, Risk factors
Learn about Luminal breast cancer, including its types (Luminal A & B), symptoms, risk factors.
Luminal Breast Cancer
Luminal breast cancer is the most common subtype of breast cancer, accounting for approximately 70% of all cases. This subtype is hormone receptor–positive and depends on the presence of estrogen receptors (ER) and/or progesterone receptors (PR) for tumor growth.
Luminal breast cancer is further classified into luminal A and luminal B subtypes based on hormone receptor expression, the proliferation marker Ki-67, and HER2 status. Luminal A tumors typically have lower Ki-67 levels and a better prognosis, whereas luminal B tumors show higher proliferative activity and are generally more aggressive.
Diagnosis involves biomarker testing (ER, PR, HER2, Ki-67) to classify the tumor.
Related Article- Triple-Negative Breast Cancer
Types of Luminal Breast cancer
Luminal A breast cancer
Luminal A is the most common molecular subtype of breast cancer, accounting for approximately 50–60% of all breast cancer cases.
Receptors
Luminal A breast cancer is characterized by estrogen receptor–positive (ER-positive) and progesterone receptor–positive (PR-positive) status and the absence of HER2 overexpression (HER2-negative). Tumor cells in luminal A breast cancer generally resemble normal breast epithelial cells, are well differentiated, and are associated with a lower proliferation rate.
Proliferation
In luminal A breast cancer, the expression of the proliferation marker Ki-67 is low. Ki-67 is a protein associated with cell proliferation, and its low expression indicates slower tumor cell growth compared with other breast cancer subtypes, which contributes to a better response to treatment.
Luminal B breast cancer
Luminal B breast cancers are less common than luminal A breast cancer, accounting for 15% to 20% of breast cancer cases.
Receptors
Luminal B breast cancer is hormone receptor–positive and may be either HER2-positive or HER2-negative. Luminal B tumors express at least one hormone receptor—estrogen receptor (ER) and/or progesterone receptor (PR). In most cases, luminal B breast cancers are estrogen receptor–positive, while some tumors may be progesterone receptor–positive.
Proliferation
In the luminal B subtype of breast cancer, the expression of the proliferation marker Ki-67 is high. Elevated Ki-67 expression indicates that cancer cells proliferate more rapidly compared with other breast cancer subtypes, which can make treatment more challenging.
Luminal Breast Cancer Symptoms
Breast lump: A new lump in the breast, armpit, or near the collarbone.
Breast thickening: Thickening or hardening of breast tissue.
Size or shape changes: A noticeable change in breast size or shape
Nipple changes: Sores, inversion, or other changes in the nipple.
Nipple discharge: Unexplained bloody or clear fluid discharge from the nipple.
Skin changes: Redness, dimpling, puckering, or an orange-peel–like appearance of the skin.
Breast tenderness: Persistent tenderness in the breast.
Breast pain: Ongoing or unexplained breast pain.
Luminal breast cancer risk factors
Age: The risk of luminal breast cancer increases in women over 50 years of age.
Family history: A family history of breast or ovarian cancer raises the likelihood of developing luminal breast cancer.
Dense breasts: Dense breast tissue is associated with a higher risk of luminal breast cancer and can make detection more difficult.
Early menstruation: Early onset of menstruation increases lifetime estrogen exposure, raising breast cancer risk.
Radiation exposure: Previous radiation therapy to the chest area increases the risk of developing breast cancer later in life.
Hormone therapy: Long-term use of hormone therapy medications can increase the risk of luminal breast cancer.
Luminal A tumors typically respond well to hormone therapy
Luminal A tumors typically respond well to hormone therapy and have the most favorable prognosis among the other breast cancer subtypes. Due to their low Ki-67 expression, these tumors grow more slowly and have a lower risk of recurrence. Consequently, patients with luminal A breast cancer have the highest survival rates.
In contrast to subtype A, Luminal B tumors are higher grade and has worse prognosis.
Fast growth: Due to the high proliferative activity of luminal B breast cancers, they grow more rapidly than luminal A tumors.
Larger size: At diagnosis, luminal B breast cancers are often larger than luminal A tumors.
More aggressive: Luminal B cancers are more aggressive as compared with luminal A cancers.
Higher recurrence: Luminal B breast cancers are more likely to recur after treatment compared with luminal A cancers.
Poorer prognosis: Overall, luminal B breast cancers are associated with a less favorable prognosis than luminal A breast cancers.
Related Article:
