Breast cancer

What are the signs of breast cancer in breastfeeding mothers?

Breast cancer can be hard to detect, because its symptoms may be similar to those of other conditions and it shows up in many ways. Mothers should see their health-care providers if they have an unusual or persistent breast mass, two or more episodes of blocked ducts or mastitis in one area, or bleeding from a nipple or through the skin of the breast. Similarly, persistent mastitis, a lingering areolar rash, and thickened skin on the breast need attention. Cancer tests include ultrasounds, mammograms, magnetic resonance imaging, and biopsies. An ultrasound is usually the first step; a core biopsy, in which a piece of breast tissue is removed by needle, can identify the type of cell causing the lump; and a mammogram may show the extent of disease. Mothers who are at high risk of breast cancer should continue to have regular checks while are breastfeeding.

A) Diagnosing breast cancer

Breast cancer is the most common cancer in young women and the most common cancer in women worldwide, with 1 in 20 women developing it during their lifetime (Fitzmaurice 2018). 

Breast cancer can develop in pregnant and breastfeeding women. It may be hard to detect because in the early stages as it may feel like a normal breast lump or behave like other problems that develop in breastfeeding women. This difficulty can delay diagnosis and treatment and contribute to poor survival rates (Callihan 2013).

Mothers at risk of breast cancer should follow regular guidelines for breast cancer screening. These vary slightly between countries. Mammograms including digital breast tomosynthesis, are most commonly used for screening (ACR 2018; Kieturakis 2021).

B) Signs of breast cancer

Breast cancer can show up in many ways. Please see your health-care providers if:

  • You have a breast mass that:
    • Is different from other lumps in your breasts.
    • Is hard, more irregular, doesn’t move, or is growing.
    • Doesn’t clear within one week.
  • You have two or more episodes of plugged ducts or mastitis in the same area.
  • You have mastitis that does not get better within a week of starting an antibiotic.
  • There is bleeding from the nipple or through the skin of the breast.
  • There is a red rash on one areola that does not clear.
  • There is pulling or puckering of the skin.
  • The skin of part or all of the breast is thickened.
  • You have other breast problems that do not get better with appropriate treatment.

Breast cancer may or may not hurt. Sometimes, a baby will reject a breast with cancer.

C) Tests for breast cancer

Breast cancer tests include:

  • Ultrasounds
  • Mammograms
  • 3D mammography (digital breast tomosynthesis)
  • Magnetic resonance imaging (MRI)
  • Biopsies

These can all be done safely on breastfeeding mothers (ACR 2018: Kieturakis 2021). Ultrasound, digital breast tomosynthesis, and core biopsies are generally favoured for testing breastfeeding mothers.

An ultrasound is usually the first step in making sure there is no cancer (Vashi 2013). 

Digital breast tomosynthesis is a type of mammogram. It is more able to detect abnormal areas than regular mammograms.

Regular mammograms can show calcium deposits that are signs of breast cancer and are not seen on ultrasound. They can also help to show the extent of disease. They may not be quite as accurate in breastfeeding women compared to women who are not breastfeeding. Having dense breasts can also reduce their accuracy.   

Both digital breast tomosynthesis and regular mammograms are best done right after breastfeeding or expressing, so mothers having the test may want to bring the baby or expressing tools with them. This will help the health-care providers interpret the test and will minimize its pain.

In a core biopsy, a needle with a hollow core is used to obtain a piece of the breast tissue of concern. It is an accurate test to identify the type of cells causing the lump. If the lump is small, ultrasound may be used to guide the needle. There is a very small risk of developing an infection or a milk fistula with this procedure.

D) Breast cancer that can mimic a breastfeeding problem

1) Cancer that looks like mastitis

Inflammatory breast cancer accounts for 2% to 4% of all breast cancers (Menta 2018). It causes the breast to become red and inflamed and can be confused with mastitis.

2) Cancer that looks like nipple yeast or eczema of the areola

Paget disease is a type of breast cancer that accounts for 1% to 3% of all breast cancers (Dubar 2017). It may appear as persistent skin changes with possible oozing starting on the nipple and spreading to the areola. It can look like a nipple yeast infection or eczema.

A nipple adenoma may look like a lump on the nipple, nipple skin breakdown, or nipple discharge. Nipple adenomas are not cancerous but may be a sign of abnormal changes in the breast (Spohn 2016). 

E) Effect of breast cancer treatment on breastfeeding

1) Current cancer treatment

Chemotherapy treatment of breast cancer during pregnancy may reduce the amount of milk she is able to make (Stopenski 2017).  

Mothers undergoing chemotherapy or hormonal treatment and wish to breastfeed need to proceed very carefully because of the risk of such medication to the baby and discuss each medication with their health-care providers. Breastfeeding while receiving chemotherapy is not recommended.

2) Previous cancer treatment

Breastfeeding after breast cancer does not appear to increase the risk of breast cancer returning (Lambertini 2018).

Mothers who have had previous breast cancer treatment can breastfeed from the unaffected breast and possibly from the affected one. However, breast cancer surgery, breast radiation, and chemotherapy can all reduce the amount of breast milk a mother can make (Green 1989; Guix 2000; Leal 2013; Mohamad 2016; Tralins 1995). Radiation of the chest for other cancer types can also decrease milk supply.

There is no information about the safety of herbs or medication to increase the amount of milk when used by breast cancer survivors (Bhurosy 2020; Johnson 2020).

Mothers who have had breast cancer treatment need to ensure that their babies are getting enough milk and if not, supplement them with extra milk. Some mothers may have enough milk in the healthy breast to compensate for a low milk supply in the affected one but other mothers may not.


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