Pregnancy and cancer

DEFINITION: While pregnancy is not a risk factor for cancer, cancer can develop during pregnancy or the postpartum period in association with the hormonal changes in a woman’s body. A woman with a diagnosis of cancer or who is a survivor of cancer, remitted or cured, should consult with her doctor regarding any potential impact of the disease or its treatment on the prospect of becoming pregnant, the expected course of a pregnancy, and the prospective outcome of a pregnancy. The use of chemotherapy and radiation is restricted in pregnancy due to their toxic effects on fetuses, and breastfeeding is also not advised for those undergoing such treatments.

Incidence, death, and survival statistics: Maternal malignancy occurs in approximately 1 in 1,000 pregnancies. Rarer is a malignancy present in the placenta or fetus originating from maternal cancer. Among cancers occurring in pregnant and postpartum, lactating women, breast and cervical cancers are most common, followed by leukemia and lymphoma. The incidence of breast cancer is 1 in 3,000 pregnancies, and the incidence of cervical cancer is 15 to 35 in 100,000 pregnancies, usually in women between thirty-two and thirty-eight. The incidence of these cancers during pregnancy may increase because of the trend of women bearing children when they are older. The average estimated incidence of ovarian tumors in pregnancy is 1 in 15,000 to 1 to 32,000 pregnancies. The use of ultrasound in early fetal evaluation may contribute to the earlier detection and, therefore, increased diagnosis of ovarian cancer.

While rare, there may also be an increase in the incidence of lung cancer during pregnancy due to smoking or delayed age of childbearing. Malignant melanomas, a serious type of invasive skin cancer, represent 8 percent of cancers diagnosed during pregnancy. Hodgkin disease, a type of blood cancer, may occur in 1 per 1,000 to 1 per 6,000 deliveries. The incidence of the disease is highest during a woman’s childbearing years, ages twenty to forty. It is the fourth most common cancer in pregnant women. Non-Hodgkin lymphoma (NHL), another common cancer in pregnancy, has an age-dependent increase in incidence (with more cases occurring in midlife). Thus, there are relatively few reports of its incidence during pregnancy.

Risk statistics: Various risk factors have been reported to increase the chance of a woman’s developing cancer during pregnancy, including age, history of prior pregnancies, and factors associated with pregnancy.

Breast cancer risks. Women who have never been pregnant or who became pregnant after the age of thirty are at a slightly higher risk of developing breast cancer than women who became pregnant when younger than thirty. A woman who has her first child after thirty-five has twice the risk of developing breast cancer as that of her counterpart under twenty. Some studies indicate that pregnancy and breastfeeding may slightly reduce the risk for breast cancer because, particularly for those women who breastfeed at least two years of their lives, these conditions reduce the number of menstrual cycles in a woman’s life span. A pregnant woman has a 2.5-fold higher risk of being diagnosed with metastatic breast cancer and a decreased chance of being diagnosed with stage 1 breast cancer (the early stage of invasive breast cancer), probably in part because of pregnancy-induced engorgement of the breast masking the detection of small lumps.

After giving birth, a woman is at increased risk of developing breast cancer for several years. A woman who took diethylstilbestrol (DES), a synthetic form of estrogen given during pregnancy between the early 1940s and 1971 to reduce the risk of repeated miscarriage or premature delivery, is at an increased risk of developing breast cancer. However, exposure to DES before birth in DES daughters does not appear to increase the risk of breast cancer in these daughters.

Other risks for breast cancer that may place a woman at risk during her pregnancy include a family history of breast cancer in first-degree relatives, certain breast conditions, and the onset of menses before age twelve.

Cervical cancer risks. Pregnant women infected with the human papillomavirus (HPV) may be at risk for cancer during pregnancy, although that is unlikely. HPV comprises a group of sexually transmitted viruses. High-risk strains are the leading cause of cervical cancer and often do not present symptoms for some time following exposure to the virus. Some strains produce highly contagious genital warts. HPV-infected pregnant women with genital warts may experience growth in the warts during pregnancy because of the moist cervical environment in which the warts thrive, the hormonal changes attending pregnancy, and changes in the woman’s immune system. Regular screenings for cervical cancer and physician-conducted breast examinations are, therefore, important components of prenatal visits.

Although the presence of genital warts or abnormal cervical changes warrants medical follow-up, the presence of HPV is unlikely to affect the pregnancy or the newborn’s health. Also, while the genital warts may disappear on their own, or a pregnant woman may wait until after delivery for their removal, the warts can be removed safely during the pregnancy using conventional procedures such as cryotherapy or the loop electrical excisional procedure (LEEP).

Diagnosing and treating cancers during pregnancy: As a woman’s breasts change and grow during pregnancy with the development of milk ducts, breasts feel lumpier and bumpier, rendering early detection of breast cancer during pregnancy difficult. However, about 80 percent of painless lumps detected during or soon after pregnancy are noncancerous. The woman’s doctor should conduct regular clinical breast examinations during prenatal visits.

A pregnant woman who detects a lump should visit the doctor promptly and request a diagnostic evaluation of any suspicious mass rather than delaying until after childbirth. Mammography does not harm the fetus for screening those who have signs or symptoms of a breast problem, and a mammogram can be taken as long as a lead shield is placed over the abdomen to block the effects of radiation. However, because the accuracy of mammogram results during pregnancy is not as reliable as it is for nonpregnant women, an ultrasound can be conducted before the mammogram to detect palpable lumps. A woman should discuss with her doctor the use of magnetic resonance imaging (MRI). In the final analysis, however, a tissue biopsy, either needle or excisional, is the most accurate tool for diagnosing breast cancer, and it allows the physician to remove tissue from a suspicious mass at the same time. Although the resulting sample may be difficult to interpret during pregnancy, it offers the most conclusive results. Treatment of breast cancer during pregnancy should follow the standard for all women with modifications during pregnancy, such as avoiding chemotherapy during the first trimester.

Pregnant women with early-stage cervical cancer are often asymptomatic or may have symptoms similar to those of their nonpregnant counterparts, such as vaginal bleeding, pain, and discharge. Pregnant women with suspicious lesions should see their doctor or prenatal provider for a Pap test with endocervical sampling and a lesion biopsy. Although pregnancy offers an opportunity for screening for cervical cancer during prenatal care, colposcopy (viewing the inside of the cervix with a microscope-like device) is technically more complex. The complication rate following biopsy (if necessary) is higher, and vaginal bleeding due to cancer may be misdiagnosed as pregnancy related.

Although noninvasive cervical cancer is rare during pregnancy, if detected in stage 1, treatment for common subtypes may be delayed until the second trimester or after childbirth. Studies have shown no adverse outcomes for the fetus or mother when treatment is delayed, and a woman with pregnancy-associated cervical cancer has an overall better prognosis than that of a nonpregnant woman (probably because of the likelihood of detecting any abnormalities in cervical cells during regular prenatal visits). Despite the potential postponement of treatment, however, a pregnant woman with this diagnosis should see her doctor to be reevaluated because of the limitations in accurately diagnosing disease during pregnancy. Cervical cancer during pregnancy does not appear to affect the newborn adversely. However, for those diagnosed with advanced-stage cervical cancer, standard cancer treatment involving chemotherapy and radiation, both toxic to fetuses, is recommended.

For melanoma detected during pregnancy, the standard treatment for early disease in pregnant women is surgery, as it would for nonpregnant women. Most studies of the effects of melanoma on the survival rate in pregnant women when subjects were matched for age, anatomic site, and stage show no difference in survival rates for pregnant as opposed to nonpregnant women.

Although Hodgkin's disease is relatively rare in pregnant women, there are standard guidelines for diagnosing and treating it during pregnancy. Typically, chemotherapy is delayed until after the first trimester, and radiotherapy may be used on tumors above the diaphragm, with proper shielding for the fetus. Labor may be induced several weeks early to enable quicker treatment of the mother. There does not appear to be an effect of pregnancy on the survival rates of women diagnosed with Hodgkin's disease during pregnancy.

Factors to consider if a woman and her doctor are deciding whether to treat cancer occurring during pregnancy include the gestational age of the fetus (the trimester of pregnancy), the location and type of cancer, how aggressively the cancer is growing, the stage of cancer, and the overall health of the mother. Although some chemotherapies can be used after the first trimester, during critical fetal development, women are advised to consult with their doctors before starting treatment during the pregnancy. Chemotherapeutic medication can affect the fetus when it crosses the placenta and can increase the risk of miscarriage, low birth weight, or premature birth.

Survival perspective and prospects: The five-year survival rate for pregnant women with early-stage breast cancer is comparable to that of nonpregnant women. However, for late-stage cancer, after metastasis, the five-year survival rate is only 10 percent. Whether pregnancy itself is an independent factor for poorer prognosis remains subject to investigation.

Although rarely occurring during pregnancy, cervical cancer during pregnancy also results in survival rates similar to those for nonpregnant women who were diagnosed at least five years following delivery. However, the survival rate of women diagnosed during the first six months postpartum is significantly worse than those diagnosed during pregnancy or nonpregnant counterparts diagnosed years later. Women diagnosed with cervical cancer during pregnancy may want to consult with their medical provider regarding options for delivery, such as by cesarean section rather than vaginally.

Women who have cancer or a history of the disease should talk with their doctors if they are considering becoming pregnant. Certain cancer treatments can affect fertility, and women may wish to preserve their fertility. Considerations include estrogen receptors of cancer cells, difficulty in becoming pregnant, chemotherapy’s effect on a woman’s ovaries, and delaying childbearing until two to five years following treatment. Also, fertility treatment options for a woman with cancer or a history of cancer who wishes to become pregnant may be restricted due to the need to stimulate hormones during most fertility treatments.

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