Pregnancy can be associated with the development of desmoid tumors, soft tissue growths that can occur anywhere in the body. Desmoid tumors that develop during or after pregnancy usually occur in the abdominal wall. Although the term “tumor” may suggest cancer, desmoid tumors are noncancerous. They’re generally found in one area and do not metastasize (spread) to other areas.

Researchers believe that changes in the soft tissue of the abdominal wall and hormone changes during pregnancy may contribute to desmoid tumor formation. Doctors and researchers aren’t sure how these changes play a role.

Desmoid tumors are very rare. Very few pregnant or postpartum individuals will develop desmoid tumors. Your health care team can help you understand if you have other risk factors associated with desmoid tumors.

According to the National Cancer Institute, desmoid tumors are more common in women between the ages of 15 to 60. Although the majority of desmoid tumors develop spontaneously, around 5 percent to 10 percent of cases are related to a genetic condition called “familial adenomatous polyposis.”

Doctors usually use imaging tests like magnetic resonance imaging (MRI) or computed tomography (CT) scans to see the tumor. A biopsy, where a small sample of the tumor is taken and examined under a microscope, is often needed to confirm the diagnosis.

Read more about how desmoid tumors are diagnosed.

Hormonal Changes in Pregnancy

During pregnancy, the body begins making more estrogen and progesterone. These hormones help support the developing fetus. Estrogen tells the uterus to grow as the fetus grows. Progesterone helps relax the walls of the uterus. Your estrogen levels are significantly higher during pregnancy than at any other time in the reproductive cycle.

The exact connection between estrogen levels and desmoid tumors is not certain. Historically, researchers reported that some desmoid tumors responded to medications that block estrogen, like tamoxifen. This finding suggested that there may be a connection between estrogen and desmoid tumor growth. The use of hormonal therapies for the treatment of desmoid tumors, however, has fallen out of favor in recent years.

Changes in the Abdominal Wall During Pregnancy

Another change that occurs in pregnancy is the stretching of the abdominal wall. The abdominal wall includes the skin, connective tissue, and muscle that protect the organs inside your abdomen. During pregnancy, the muscles in the abdominal wall will stretch to accommodate the growing uterus. Most desmoid tumors associated with pregnancy are in the abdominal wall.

The connective tissue in the abdominal wall is made of a specific type of cell known as a fibroblast. These cells play a role in the formation of connective tissue and wound healing. A desmoid tumor can form when certain cells mutate (change abnormally) and multiply. Abdominal wall stretching during pregnancy might be a reason why desmoid tumors develop.

Management of Desmoid Tumors in Pregnancy

Finding out you have a desmoid tumor during pregnancy can be a scary experience. Having the right health care providers can help make the process a little easier. Your care team may include your obstetrician, oncologists (sometimes called sarcoma specialists), and other support staff.

Your health care team will tailor your treatment plan to your symptoms and tumor location. Your care team’s recommendations may be different depending on whether you’re pregnant or if you’ve already delivered your baby. Recommendations for care may also differ depending on whether you’re currently breastfeeding or plan to breastfeed your baby.

Below are possible treatment options. Desmoid tumors associated with pregnancy are rare, and there isn’t one treatment approach that is firmly proven as being best.

You’ll need to work closely with your obstetrics team and desmoid tumor team to decide the best course of action.

Active Surveillance

Active surveillance is usually the preferred approach for managing desmoid tumors associated with pregnancy. This approach is also recommended for the majority of desmoid tumors that are not related to pregnancy. Active surveillance, also called “watchful waiting,” means that your health care team will monitor your tumor without beginning treatment.

Some people’s tumors shrink on their own without treatment. Your doctor may recommend active surveillance if your tumor is stable (not growing) and isn’t causing any symptoms.

Medications

Often, in people who are not pregnant, systemic medications (drugs that affect the entire body) are recommended for desmoid tumors that progress. These might include targeted therapies or chemotherapy.

The safety labels for certain targeted therapies used for desmoid tumors state that they are not appropriate for pregnancy because they may cause harm to the fetus. It’s possible to receive chemotherapy during the second and third trimesters, although this is a general recommendation for treating cancer.

Make sure to discuss breastfeeding with your doctor because this will help your care team determine what treatment is best for you.

Cryoablation

Cryoablation is an alternative treatment to surgery. This method uses extremely cold gas to freeze cells and possibly shrink desmoid tumors.

Surgery

Surgical resection (removal) of a desmoid tumor can be an option if its size or location is causing uncomfortable symptoms. Surgery to remove an abdominal wall desmoid tumor can be an appropriate option if you’re pregnant. Surgery for most people, however, has become less favored in recent years, given the high risk for recurrence.

Read more about new treatments for desmoid tumors.

What To Expect in Future Pregnancies

Going through a pregnancy with a desmoid tumor can be challenging. You may also wonder if this will affect future pregnancies. Doctors aren’t sure what causes a desmoid tumor in pregnancy nor are they certain that future pregnancies may lead to a desmoid tumor.

In general, having a desmoid tumor shouldn’t affect your ability to get pregnant again. It’s always best to speak to your doctor about how having a desmoid tumor might affect future pregnancies.

Talk With Others Who Understand

MyDesmoidTumorTeam is the social network for people with desmoid tumors and their loved ones. On MyDesmoidTumorTeam, members come together to ask questions, give advice, and share their stories with others who understand life with desmoid tumors.

Are you pregnant and living with a desmoid tumor? How has your doctor treated it? Share your experience in the comments below, or start a conversation by posting on your Activities page.