Can Breast Cancer Affect Your Period?

Though breast cancer doesn’t appear to affect your menstrual cycle’s flow or timing, research shows a link between breast cancer risk and the age at which a person starts and stops menstruating.

In addition, specific breast cancer treatments can impact your period by temporarily pausing or sometimes stopping it permanently.

This article discusses the link between breast cancer risk and the menstrual cycle.

Early Onset of Menstruation

Estrogen is important for sexual development and other major bodily functions. It helps with breast tissue development and stimulation when a person starts menstruating. But the amount of estrogen you’re exposed to throughout your life can also increase the risk of breast cancer.

Starting your period at an earlier-than-average age is linked to a higher risk of developing breast cancer. One study found that people who start their periods before 11 may have a 15–20% higher risk of developing breast cancer than those who start menstruating at age 15 or older.

Another analysis of more than 100 studies estimated that for each year younger a person was when they got their first period, breast cancer risk increased by 5%.

Menstruating Later in Life

After your first period, menstruation continues until you reach menopause (when your menstrual cycle ends). This typically occurs between the ages of 40 and 58, with the average age for menopause in the United States being 52.

Reaching menopause after 55 increases the risk of developing breast cancer. Experts believe this is likely due to a longer lifetime exposure to estrogen. The longer it takes a person to reach menopause, the longer the breast tissue is exposed to estrogen—thus increasing breast cancer risk for this group.

Reducing Breast Cancer Risks

Breast cancer research has found many different risk factors for and potential causes of breast cancer.

Some of these risk factors, such as reducing your alcohol intake, are changeable. Others, like having a family history of breast cancer, are out of our control. Because there's no way to impact when your first period starts or when you reach menopause, those risk factors are not changeable.

That said, experts recommend considering lifestyle adjustments to help reduce your overall risk, such as:

• Maintaining a healthy weight for your body type and overall health
• Limiting alcohol intake
• Getting plenty of exercise
• Reducing additional estrogen exposure by limiting hormone therapy for menopause

In addition, regular mammogram screenings are an important tool for diagnosing breast cancer in earlier stages, when it may be more easily treatable.

Periods and Breast Cancer Treatments

People who have already been diagnosed with breast cancer and are undergoing treatment may find that their period is impacted. Some breast cancer treatments can affect how your ovaries function—disrupting the menstrual cycle. For example:

• Chemotherapy (chemo): Treatment is designed to kill breast cancer cells but can also affect other cells in the body, like those in your ovaries. As a result, chemo often interrupts the menstrual cycle, pausing periods temporarily or stopping them altogether.
• Estrogen-blocking therapy: Medications like tamoxifen and a class of drugs known as aromatase inhibitors affect how estrogen interacts in the body. This can sometimes cause irregular periods or lead to a permanent halt in the menstrual cycle.
• Immunotherapy drugs: This newer class of medications attacks cancer cells by using your immune system. Initial evidence shows that it may impact the ovaries and menstrual cycle, but more research is needed on its long-term effects on reproduction.
  

Summary

Though irregular periods are not a sign of breast cancer, research shows that breast cancer risk and treatments are linked to the menstrual cycle in other ways. Studies suggest that breast cancer risk is connected to a person's long-term exposure to estrogen. This means that starting your period at an early age and entering menopause at a later age can contribute to an increased breast cancer risk. Separately, specific breast cancer treatments can impact the menstrual cycle by temporarily pausing your period—or stopping it permanently.

A Word From Verywell

Though research shows that the timing of your first and last menstrual periods are related to breast cancer risk, keep in mind that these increased risks are relatively small in the grand scheme of things. Many other factors can contribute to a person's breast cancer risk, so try to focus on the lifestyle modifications over which you have control. And always check with a healthcare provider if you have concerns about your chances of developing breast cancer.