Cancers In Pregnancy: Types, Diagnosis And Treatment

The incidence of cancers in pregnancy is relatively high. The most common cancers during pregnancy are breast cancers and cervical cancers. Cancers in pregnant women account for 0.05-0.01% of all malignancies. This accounts for 0.02-0.1% of all pregnancies, and one in 1000 to 1500 pregnancies can be complex due to maternal cancers (1).

It is challenging to diagnose and treat cancer during pregnancy. The symptoms of pregnancy may mask the cancer symptoms, and the treatment options are often restricted because of the teratogenic and toxic effects on the fetus. However, the treatment strategies are selected based on the pregnancy stage and the cancer type.

Read about the types, diagnoses, and treatment options for cancer during pregnancy.

What Types Of Cancer Are Common During Pregnancy?

Breast cancer is the most common cancer seen in pregnant women. Around one in 3,000 pregnant women are diagnosed with breast cancer. Some other cancers that might occur in pregnancy are (2) (3):

• Cervical cancer is the cancer of cells in the cervix, the lower part of the uterus connecting the vagina. If detected in the early stages, cervical cancer can be treated after delivery, but detection in advanced stages may require immediate intervention. Sometimes, cervical cancer can be present before pregnancy and diagnosed during prenatal Pap smear (4).

• Thyroid cancer affects the thyroid gland in the neck. This is the second most common cancer in pregnancy, affecting around 14 in 100,000 live births. Iodine deficiency and ionizing radiation can trigger thyroid cancers. Thyroid size and activity can normally increase during pregnancy due to changes in human chorionic gonadotropin (hCG) and estrogen levels (5).

• Gestational trophoblastic disease (GTD) is a rare, malignant disorder where abnormal trophoblast grows inside the uterus after conception. Molar pregnancy or hydatidiform mole is a common type of GTD that occurs due to problems with fertilized eggs. Choriocarcinoma is a malignant form of GTD that can invade the uterus wall. These growths are non-viable pregnancies and require removal (6).

• Lymphomas are cancers with uncontrolled proliferation of the lymphocytes. Weight loss, night sweats, and lymphadenopathy are common symptoms of this This includes Hodgkin lymphoma with Reed-Sternberg cells and non-Hodgkin lymphoma without these cells (7).

• Leukemia is the cancer of blood and bone marrow. Abnormal cell growth in the bone marrow causes a rise in immature blood cells in the body. Acute leukemia, rapidly progressive blood cancer, accounts for 90% of leukemia in pregnancy (8).

• Melanoma is a type of skin cancer affecting the pigment-producing cells of the skin. This type of cancer can be diagnosed and treated during pregnancy. However, there is an increased risk of recurrence after two to three years of initial treatment (9).

Some theories suggest that hormonal changes in pregnancy are responsible for breast cancer and other cancers. However, sufficient scientific evidence is not available to establish these links. These cancers are also common in younger women who are not pregnant.

What Are The Effects Of Cancer On Pregnancy And Fetus?

Although rare, maternal cancers in pregnancy can increase the risk for fatal outcomes, the effects of cancer on the pregnancy, fetus, and mother may vary depending on the type and stage of cancer. A study based on health registers from Sweden shows a higher risk for the following conditions in cancers during pregnancy (10):

• Stillbirth

• Fetal growth restriction

• Neonatal mortality

• Iatrogenic preterm birth or provider-initiated preterm birth

• Teratogenic and toxic effects of cancer treatment

• Fetal hypoxia

• Chronic inflammation in the fetus

• Malnutrition in infants

Infant mortality associated with maternal cancers can be due to preterm birth and intrauterine growth restriction. Careful monitoring of fetal growth and planning preterm delivery, provided the risks outweigh the benefits, can reduce these fatal outcomes.

Can A Pregnant Woman Pass Cancer To Her Baby?

Although transplacental transmission of cancer cells is possible, it is extremely rare for maternal cancer to spread to the growing fetus. The cancer cells should pass through the placental barrier to reach the baby. It is even rare that maternal cancer spreads to the placenta. The mother and the child reported same cancer in most cases (11).

According to Cancer Council Australia, only 17 suspected cases of maternal-fetal cancer spread are reported. Melanoma and leukemia or lymphoma were the common cancers that passed from mother to child. This may indicate the possibility of transmission may depend on the ability of cancer cells to migrate, infiltrate and metastasize (12).

How Is Cancer During Pregnancy Diagnosed?

Clinical diagnosis of cancer is often delayed in pregnancy since many cancer symptoms, such as breast lumps, rectal bleeding, headaches, and bloating, are common during pregnancy. Breast changes, including tenderness and texture changes, can also appear normal. Some cancers are revealed in pregnancy during prenatal examinations, including ultrasounds and Pap tests.

Some imaging tests involving ionizing radiation and contrasts are harmful to the fetus. Doctors may order the following tests for cancer diagnosis (2):

• Magnetic resonance imaging (MRI) scan without contrast is considered a safe imaging modality during pregnancy. MRI using gadolinium contrast is only done if the risks outweigh the benefits.

• Ultrasound helps visualize the Abdominal ultrasound does not harm the fetus. However, the visualization of cancers can be limited in certain cases.

• X-ray imaging with an abdominal shield to protect the fetus is often done. Abdominal and pelvic X-rays are usually avoided.

• Computed tomography (CT) scans are done if there is no possibility of other tests since they emanate higher amounts of radiation. Abdominal CT may be done in the chest, limbs, or head with an abdominal shield in some cases.

• Ultrasound-guided biopsy and surgical biopsy are safe during pregnancy. This is necessary to understand the characteristics of tumor cells.

• Serum biomarkers such as cancer antigen 15-3 (CA-15-3), alpha-fetoprotein (AFP), lactate dehydrogenase (LDH), and carcinoembryonic antigen (CEA) can be increased in many cancers. These markers are not usually increased in pregnancy. However, the sensitivity of these tests in pregnancy is less due to physiological changes in the body.

Nuclear imaging with radioactive substances is also avoided in pregnancy since these substances are teratogenic. Therefore, doctors may order the least harmful method of diagnosis during pregnancy. In unavoidable circumstances, the decision is made based on the risks and requirements.

How Is Cancer During Pregnancy Treated?

Treatment for cancer in pregnancy is decided based on the type of cancer, spread, and gestational age. A multidisciplinary team of specialists, including obstetricians and oncologists, are involved in pregnant women’s cancer care. Both mother’s and baby’s health are monitored throughout the treatment.

The following cancer treatments are relatively safe during pregnancy (2) (3):

• Surgery is the removal of the tumor and some healthy tissue around it. There is little risk to the fetus, and surgery is safely done during all trimesters of pregnancy. Some cancers, such as breast cancer, are often treated with radical mastectomy.

• Chemotherapy using certain cancer medications is safe during the second and early weeks of the third trimester. These medications can destroy and arrest the growth of cancer cells. Usually, drugs that do not cross the placental barrier are given. It is therefore not known to cause health issues or growth and development problems in babies.

In some cases, if it is safe to deliver, doctors may consider an early delivery to begin cancer treatment and protect the baby from the treatment effects. These decisions may vary in each case depending on various factors. For example, breastfeeding is often contraindicated if the mother is receiving chemotherapy. However, available infant formula can meet the baby’s nutritional needs.

Does Pregnancy Affect Cancer Treatment?

Pregnancy does not directly affect the effectiveness of cancer treatment. However, late diagnosis and not beginning the treatment on time can impact the outcomes. For example, the diagnosis can be delayed in some women since the pregnancy symptoms may mask the cancer symptoms (3).

Sometimes, cancer identified in the early stages of pregnancy can become prevalent by later weeks, which can be the reason for poor outcomes of cancer treatment.

When To Delay Cancer Treatment In Pregnancy?

Certain cancer treatments are delayed or avoided during pregnancy depending on the weeks of gestation (2):

• Chemotherapy is delayed during the first three months (first trimester)  since it may result in pregnancy loss or birth defects during this time. The baby’s organs, including the brain, are in the development phase in the first trimester, and some drugs can affect normal development.

• Although the baby is fully formed, chemotherapy is also not advised in the later weeks since the side effects such as low blood counts can increase the risk of infections during and immediately after birth.

• Radiation therapy is usually avoided at any time in the pregnancy. However, the risk may vary depending on the location of cancer and the dose of radiation to destroy cancer cells. Doctors may plan radiation therapy after childbirth in some cases. Cancer such as lymphoma may require radiation therapy, and it is often delayed until delivery.

• If the cancer diagnosis is made in the last stages of pregnancy, treatments often begin after delivery. This helps avoid the harmful effects of treatments on the

• Treatment is often delayed until delivery in the early stages of some cancers, such as cervical cancers, since this may not impact the pregnancy and the

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