Obstetric providers are being called upon to care for an increasing number of cancer survivors. Whether it was a childhood cancer or one faced in early adulthood, pregnant cancer survivors raise a unique set of questions and concerns. A general knowledge about management is essential in counseling these women prior to and early in pregnancy.
For the woman who presents preconception, one of the most common questions is when is the best time for pregnancy. Importantly, there are no absolute guidelines on how long a woman should be “disease free.” Many providers suggest waiting 2 years from the time of diagnosis. This “conventional wisdom” is not based on evidence ( Oncology 2005;19:693-7 ). Instead, the type of cancer and the length of treatment can help determine the answer.
Many oncologists prefer a specific time for monitoring after treatment to ensure that initial treatment has been successful. For example, in the case of melanoma, after 2 years, the estimate of recurrence risk may be more accurate ( Cancer Causes Control 2008;19:437-42 ). After breast cancer, women are often followed with MRI with contrast and mammogram. Since both are problematic in pregnancy, 3-5 years may be more appropriate.
Many patients are concerned about the risk of recurrence during pregnancy. Though data are limited, pregnancy does not appear to increase the risk of disease recurrence or decrease disease-free survival, even in the case of more aggressive cancers such as melanoma. This remains true in the setting of hormone receptor–positive cancers, specifically breast cancer ( Lancet 1997;350:319-22 ).
Preconception counseling
The risks for a cancer survivor during pregnancy will vary depending on the treatments she has received. Preconception evaluation should be modified for the specific oncologic therapies. For example, women who received chest radiation, or anthracycline-based chemotherapies (or any cardiotoxic medications) should have a cardiac evaluation as they are at risk of cardiac dysfunction prior to and during pregnancy ( Matern. Child. Health J. 2006;10[suppl. 1]:165-8 ).
Additionally, because chemotherapy may be hepatotoxic or nephrotoxic, baseline liver and renal function tests should almost always be performed. It is not unreasonable to follow these during pregnancy given the physiologic changes.
Many women also are concerned about the risks that prior cancer therapies may have for their baby. Prior chemotherapy and radiation therapy do not appear to confer any increased risk for genetic conditions, anomalies, or childhood cancer ( Am. J. Obstet. Gynecol. 2002;187:1070-80 ). Additionally, previous chemotherapy alone does not increase the risk of adverse pregnancy outcomes.
In contrast, prior radiation to the abdomen and pelvis has been associated with an increased risk of miscarriage, growth restriction, preterm delivery, and stillbirth ( J. Natl. Cancer Instit. Monogr. 2005;34:64-8 ; Lancet 2010;376:624-30 ). There is an increased risk of cancer in the offspring of women whose cancer is the result of hereditary cancer syndromes, such as BRCA or hereditary nonpolyposis colorectal cancer. Discussions with a genetics counselor may be helpful if there are any questions related to these syndromes.
Pregnancy management
Once pregnant, management requires a multidisciplinary approach. Surveillance options are limited during pregnancy. CT should be avoided, and radiographs limited. Ultrasound of the abdomen is safe, but optimal images are often obscured in later trimesters. Ultimately, indicated imaging should not be forsaken if there are any signs or symptoms that raise concerns for recurrence. Additionally, many tumor markers may be unreliable during pregnancy, such as CA-125 in the first trimester, or alpha-FP and CEA anytime.
Specific recommendations for antenatal testing do not exist and should be assessed on a case-by-case basis; especially in the case of women who have had prior radiation therapy. Our recommendation is to perform growth surveillance, which may include sonography at varying intervals. Also consider weekly fetal testing from 32 weeks in normally growing fetuses.
Solely being a cancer survivor is not an indication for early delivery or induction of labor. In the majority of cases, mode of delivery should be guided by obstetric indications, though previous pelvic surgery and reconstruction may be indications for cesarean delivery. Despite being in remission, some cancers metastasize to the placenta, most commonly melanoma and hematologic cancers. Very rarely, these cancers can also metastasize to the fetus. Thus, the placenta should be sent for histologic evaluation, with a notation to the pathologist about the patient’s prior cancer ( Obstet. Gynecol. Surv. 1989;44:535-40 ; Ultrasound. Obstet. Gynecol. 2009;33:235-44 ).
In most cases, pregnancy after cancer is uncomplicated with good outcomes for both mother and baby. However, there are potential medical and obstetric complications that cannot be overlooked. Interdisciplinary management is crucial to ensure a safe transition from cancer survivor to mother.
What to consider when counseling cancer survivors about pregnancy
• The recommended disease-free interval prior to pregnancy may vary by cancer type, and is largely driven by disease surveillance needs and recurrence intervals.
• Prior cancer, associated operations, and chemotherapies do not typically confer additional risks in pregnancy. Exceptions include melanoma and blood cell cancers, which may metastasize to the placenta and fetus, even following periods of remission.
• Radiation therapy to the abdomen and pelvis may induce changes that predispose to growth restriction, preterm birth, and stillbirth. Enhanced surveillance may be reasonable in these cases.
• Preconception or early pregnancy assessment for end organ dysfunction is recommended for women who have received certain therapies: cardiac evaluation following chest radiation or anthracycline-based therapy; liver and kidney function for most chemotherapies.
Dr. Ivester is an associate professor of maternal-fetal medicine and an associate professor of maternal and child health at the University of North Carolina at Chapel Hill. Dr. Dotters-Katz is a maternal-fetal medicine fellow at University of North Carolina at Chapel Hill, who completed her ob.gyn. residency at Duke University. Her academic interests include oncology and infectious diseases as they relate to pregnancy. The authors reported having no financial disclosures. Email them at obnews@frontlinemedcom.com.
