Actress Olivia Munn has shared that she was diagnosed with luminal B breast cancer in April 2023 and has since undergone surgical removal of both of her breasts.

“[Munn’s OBYGYN] looked at factors like my age, familial breast cancer history, and the fact that I had my first child after the age of 30. She discovered my lifetime risk was at 37 percent,” Munn wrote in an Instagram post. “Because of that score, I was sent to get an MRI, which led to an ultrasound, which then led to a biopsy. The biopsy showed I had Luminal B cancer in both breasts.”

What is luminal B breast cancer?

In order to find the most effective way to treat cancer, it’s now common for doctors to analyze the DNA of cancer cells. This gives an idea as to the kind of characteristics the cancer has and thus, what to use to target it. Based on this analysis, breast cancers can be split into four main groups: basal-like or triple-negative, HER2 positive, luminal A, and luminal B.

The type of breast cancer that Munn was diagnosed with, luminal B, is a particularly aggressive, fast-growing form. This is because it produces too many proteins that promote cell growth and proliferation.

You might hear of this cancer as hormone receptor positive (for either or both estrogen and progesterone) and with high levels of Ki-67. Luminal B cancers can also be positive for HER2, a protein receptor involved in cell proliferation.

How common is it?

The Centers for Disease Control and Prevention (CDC) estimates that around 242,000 cases of breast cancer are diagnosed in the United States each year. Of these, around 10 percent are classed as luminal B.

Who’s at risk?

Though there aren’t any factors that put a person at risk of developing luminal B breast cancer specifically, there are some factors that contribute to an increased risk of breast cancer in general. These include:

• Being female, though males can get breast cancer too
• Carrying certain genetic mutations, such as in BRCA1 and BRCA2 genes – that’s why breast cancer can sometimes run in families
• Age
• Starting periods before age 12 and starting menopause after age 55
• Having had breast cancer before

What are the signs and symptoms?

The signs and symptoms of luminal B breast cancer can be the same as breast cancer in general. Some of the symptoms may include:

• Changes in skin texture, e.g. puckering/dimpling
• Swelling in your armpit or around your collarbone
• Lumps and thickening
• Nipple discharge
• A sudden, unusual change in size or shape
• Nipple inversion and changes in direction
• A rash or crusting of the nipple or surrounding area
• Constant, unusual pain in your breast or armpit

Can it be treated?

Treatment for luminal B breast cancer might depend on a number of factors, taking into account elements like the proteins that characterize this subtype, how far the cancer has spread, your age, and your health. Together, this is what’s known as personalized medicine, which is becoming an increasingly common approach in cancer prevention, diagnosis, and treatment.

Luminal B breast cancer can often be treated with chemotherapy, but might also involve hormone therapy, treatments that target HER2, or surgery. In Munn’s case, she opted for a double mastectomy – surgical removal of both breasts. 

What’s the prognosis like?

Though the survival rate of luminal B cancer can depend on whether it has spread or not, out of the four breast cancer subtypes, it has the second-highest five-year survival rate, sitting at 90.7 percent.

All “explainer” articles are confirmed by fact checkers to be correct at time of publishing. Text, images, and links may be edited, removed, or added to at a later date to keep information current.  

The content of this article is not intended to be a substitute for professional medical advice, diagnosis, or treatment. Always seek the advice of qualified health providers with questions you may have regarding medical conditions.