The American Society of Clinical Oncology (ASCO), reports that a new cancer diagnosis occurs in approximately one in 1,000-2,000 pregnancies. Due to the unique clinical and psychosocial considerations of cancer during pregnancy, this intersection of oncology and obstetrics represents a particularly complex and sensitive concern for women.
Today, we’re examining that intersection by comparing clinical guidance from two medical societies side by side. We are taking a look at ASCO’s guideline, Management of Cancer During Pregnancy, along with guidance from the Society for Maternal-Fetal Medicine (SMFM).
Guidance for Comparison
| Item | Cancer in Pregnancy | Management of Cancer During Pregnancy |
|---|---|---|
| Authoring Organization | Society for Maternal-Fetal Medicine | American Society of Clinical Oncology |
| Publication Date | March 2026 | December 2025 |
| Links | Summary / Full Text | Summary / Full Text |
Scope of the Guidance
The SMFM guidance document features 14 recommendations while the ASCO guideline features 67 recommendations. Outlined in the table below are the recommendations from both the SMFM guidance and the ASCO guideline. For the complete look at the clinical guidance recommendations and their supporting rationale, consult the full-text links above.
Side-by-Side Comparison of Recommendations
| Item | SMFM | ASCO |
|---|---|---|
| Evaluation / Diagnosis | We suggest that ultrasonography and non-contrast MRI be used as first-line imaging techniques in the evaluation of a pregnant person with suspected cancer. Although non-contrast MRI and ultrasonography are first-line diagnostic imaging modalities in pregnancy, we recommend that CT with or without contrast, gadolinium contrast for MRI, and 18-FDG-PET/CT not be withheld from a pregnant person if clinically indicated. | For pregnant patients with a palpable mass or signs or symptoms suspicious for, but without confirmation of malignancy, clinicians should immediately refer for diagnostic imaging with clear communication to the imaging facility that the patient is pregnant to ensure appropriate imaging protocols. Ionizing radiation-based procedures should only be used when clinically necessary, following the “as low as reasonably achievable” (ALARA) principle to minimize fetal exposure. Clinicians should order ultrasound as the first-line imaging tool whenever possible due to its safety and absence of radiation exposure. Clinicians may use MRI without contrast when further staging or clarification is necessary. Clinicians should avoid routine use of gonadal and fetal shielding devices during X-ray–based diagnostic imaging, as they provide minimal benefit, can reduce radiological image quality, and may increase scatter, potentially exposing embryo or fetus to higher radiation levels. Clinicians may use X-rays of the head and neck, chest, or extremities when clinically indicated, as fetal radiation exposure is minimal. Clinicians may use mammography as an adjunct to ultrasound in pregnant patients with suspicious breast findings. When mammography is performed, bilateral imaging is recommended as part of the diagnostic workup to avoid missing bilateral disease. For pregnant patients requiring advanced imaging for malignancy, clinicians should avoid abdominal CT, abdominal X-ray, PET-CT, bone scintigraphy, and other radionuclide studies unless essential for diagnosis, staging, and/or treatment planning. If required or indicated, timing should be individualized considering the urgency of diagnosis, the potential impact of delayed cancer detection or inaccurate staging, and the risks to both the patient and her embryo or fetus. Dose-reduction techniques should be applied to reduce fetal exposure. Clinicians should avoid GBCAs unless absolutely necessary due to potential fetal exposure and risks of neonatal rheumatic and inflammatory conditions or stillbirth. If there are no safer alternatives and GBCA use is unavoidable, clinicians should use the lowest possible dose. For pregnant patients requiring iodinated contrast for imaging, clinicians should be aware of the risk of neonatal hypothyroidism. When no safer alternatives are available and iodinated contrast is unavoidable, its use should be carefully evaluated through transdisciplinary collaboration. Neonates exposed to iodinated contrast in utero should have thyroid function evaluated through standard newborn screening for congenital hypothyroidism at birth. For pregnant patients requiring imaging for thyroid cancer, radioactive iodine is contraindicated. Clinicians should use ultrasound as the first-line imaging tool. For pregnant patients with suspected malignancy, clinicians should not rely solely on serum tumor markers for cancer diagnosis, as physiological changes during pregnancy can alter some marker levels and reduce sensitivity and specificity. When tumor markers are tested, results should be interpreted with caution and in conjunction with other assessments. When biopsy is planned, clinicians should prioritize core needle biopsy or excisional biopsy over fine-needle aspiration, to preserve tissue architecture and reduce diagnostic delays. This is an important consideration in all patients, but especially in pregnancy, where timely diagnosis can be critical for optimizing maternal and fetal outcomes. For pregnant patients who would benefit from sentinel lymph node evaluation, clinicians should perform SLNB, with technetium-99m (Tc-99) preferred over blue dye to reduce the risk of maternal anaphylaxis. When clinically appropriate, a 1-day, low-dose Tc-99 protocol can be used to minimize fetal radiation exposure. For pregnant patients with suspected cervical cancer, clinicians may perform colposcopy during any trimester when necessary to establish a diagnosis. Endocervical curettage should be avoided to reduce preterm labor risks. For pregnant patients requiring GI endoscopy for suspected cancer, clinicians may perform endoscopic procedures, with transdisciplinary discussions about risk and timing. For pregnant patients with abnormal noninvasive prenatal screening results that may be suggestive of possible cancer, clinicians should evaluate with appropriate workup. |
| Multidisciplinary Care Teams | No recommendation. | For pregnant patients with cancer, multidisciplinary teams including hematologists/oncologists, obstetricians, radiologists, neonatologists, maternal-fetal medicine specialists, primary care clinicians, nurses, advanced practice providers, and pharmacists should collaborate frequently to develop and adjust individualized treatment plans based on the patient's condition and response to treatment. Clinicians should engage in comprehensive multidisciplinary informed consent discussions with pregnant patients with cancer and their caregiver(s) before initiating or continuing any procedure or therapy. These discussions should clearly outline known risks to the patient and to the embryo or fetus (ie, using clinical and animal data available in the drug label), potential benefits, and treatment timelines. Patients should be informed of the risks associated with both pursuing and delaying cancer-directed therapy, as well as the right to change their minds at any point, understanding that doing so may alter risks, benefits, and available treatment options. |
| Individualized Management and Shared Decision-Making | No recommendation. | Clinicians should prioritize autonomy and support informed decision making for pregnant patients with cancer, including whether the person decides to end or to continue their pregnancy while undergoing treatment. For patient and clinician support in complex or challenging decision making about cancer management during pregnancy, clinicians should involve medical ethicists and, when appropriate, legal counsel. When managing cancer during pregnancy, clinicians should consider fetal viability in the context of maternal health and cancer prognosis. Maternal survival is essential to fetal survival, particularly in early gestation, and treatment should prioritize maternal health. Patients should be counseled accordingly, especially if the fetus has not yet reached viability. Treatment should be individualized based on cancer type, goals of therapy, gestational age, maternal and fetal risks, and patient autonomy including preference regarding treatment options, and pregnancy continuation or termination. Despite clear guidance that individuals undergoing cancer treatment should use highly effective contraception, pregnancies may still occur. In such cases, acknowledging the limitations of existing evidence and the uncertainty regarding treatment-related harms in many settings, clinicians should engage in timely, individualized discussions that address the risks of in utero exposure to cancer treatment, including fetal harm and pregnancy complications; the risks to the pregnant patient of withholding further cancer treatment including potential reduction in likelihood of cancer response and/or cure; and the consideration of pregnancy termination. |
| Thromboprophylaxis | We recommend initiating thromboprophylaxis for all patients with active hematological or gynecological cancers during pregnancy and considering thromboprophylaxis for all patients with nonhematological or nongynecological cancers during pregnancy, based on individual risk factors. | No recommendation. |
| Radiation Therapy | No recommendation. | If radiation therapy is required for pregnant patients with cancer, the radiation oncology team should ensure cumulative fetal exposure remains below 100 mGy and use appropriate abdominal shielding to reduce fetal exposure. Abdominal and pelvic radiation should be avoided to minimize fetal risks. |
| Surgery | We recommend that surgery for the treatment of cancer not be delayed or withheld from a pregnant patient at any gestational age in pregnancy. | Surgeons should perform surgery on pregnant patients with cancer when clinically indicated, implementing strategies to optimize maternal and fetal outcomes. To minimize risks, the surgical team should prevent maternal hypoxia, avoid supine positioning after 20 weeks' gestation, use regional anesthesia when feasible, and coordinate with a multidisciplinary team to guide perioperative management. |
| Systemic Therapy | We recommend that chemotherapy generally be administered after 12 weeks of gestation, provided that the patient desires to continue the pregnancy and that delaying treatment until after 12 weeks of gestation is not expected to significantly change the pregnant patient's prognosis compared with initiating treatment immediately after diagnosis. | For pregnant patients with cancer requiring systemic therapy, if the patient intends to continue the pregnancy, clinicians should try to avoid administering conventional cytotoxic chemotherapy during the first trimester due to high teratogenic or abortifacient risks. Clinicians may administer alkylating agents such as cyclophosphamide, ifosfamide, and dacarbazine in the second and third trimesters. Clinicians should not administer methotrexate in any trimester due to its teratogenic and abortifacient effects. Alternative treatments should be offered, or therapy should be delayed until after delivery. Before initiating fluoropyrimidine chemotherapy such as 5-FU and capecitabine in pregnant patients with cancer, the Panel recommends genetic testing to identify those with DPD deficiency due to genetic variations in the DPYD gene, to mitigate the risk of serious adverse reactions. Clinicians may administer 5-FU and capecitabine in the second and third trimesters, with DPYD genotype-guided treatment modification when indicated. Gemcitabine may also be administered in the second and third trimesters. Clinicians may administer platinum agents such as carboplatin, cisplatin, and oxaliplatin in the second and third trimesters. Carboplatin is preferred over cisplatin due to lower fetal ototoxicity risks when compared with cisplatin Clinicians may administer anthracyclines such as doxorubicin, epirubicin, and daunorubicin in the second and third trimesters. Clinicians should avoid the use of idarubicin in all trimesters, due to risk of congenital malformations, fetal cardiotoxicity, and pregnancy loss. If no other anthracycline is felt to be an appropriate substitute, the patient should be counseled about limited safety data for using idarubicin in pregnancy. Clinicians may administer topoisomerase inhibitors such as irinotecan and etoposide in the second and third trimesters. Clinicians may administer vinca alkaloids such as vincristine, vinblastine, and vinorelbine in the second and third trimesters. Clinicians may administer taxanes such as paclitaxel and docetaxel in the second and third trimesters. Clinicians should not administer tamoxifen, aromatase inhibitors, or GnRH agonists in any trimester due to risks of teratogenicity, fetal development complications, and spontaneous abortion. Alternative antineoplastic therapy should be offered, or therapy should be delayed until after delivery. Clinicians should not administer HER2-targeted therapies, such as trastuzumab, pertuzumab, lapatinib, and neratinib in any trimester due to risks of oligohydramnios, IUGR, and need for more safety data. Therapy should be delayed until after delivery. Clinicians should not administer VEGF inhibitors such as bevacizumab, ramucirumab, or aflibercept in any trimester due to risks of IUGR, miscarriage, and maternal vascular complications. Alternative treatments should be offered, or therapy should be delayed until after delivery. Clinicians should avoid cetuximab use in all trimesters due to a lack of experience in pregnancy and need for more safety data. If treatment cannot be safely deferred until the postpartum period, cautious use and close monitoring is advised. Clinicians may administer EGFR-targeted TKIs such as erlotinib, gefitinib, afatinib, or osimertinib in the second and third trimesters. Clinicians should avoid ALK-targeted therapies such as crizotinib and alectinib in all trimesters due to limited reports of use in pregnancy and need for more safety data. If treatment cannot be safely deferred until the postpartum period, cautious use after first trimester and close monitoring is advised. Clinicians may administer ABL-targeted TKIs such as imatinib and nilotinib in the second and third trimesters. Clinicians should not administer dasatinib in any trimester due to risks of teratogenicity, growth restrictions, and spontaneous abortion. Alternative treatments should be offered, or therapy should be delayed until after delivery. Clinicians may administer CD20-targeted agents such as rituximab in the second and third trimesters with close monitoring for fetal development and neonatal hematologic abnormalities. Clinicians should not administer MEK inhibitors such as trametinib in any trimester due to risks of teratogenicity, growth restriction, and neonatal toxicity. Alternative treatments should be offered, or therapy should be delayed until after delivery. Clinicians may administer BRAF-targeted TKIs such as vemurafenib in the second and third trimesters. Clinicians should generally avoid antibody-drug conjugates such as trastuzumab emtansine, trastuzumab deruxtecan, sacituzumab govitecan, mirvetuximab soravtansine, tisotumab vedotin, enfortumab vedotin, datopotamab deruxtecan, brentuximab vedotin, etc, during all trimesters of pregnancy due to concerns for fetal toxicity based on mechanism of action and lack of safety data. Clinicians should avoid the use of checkpoint inhibitors such ipilimumab, nivolumab, and pembrolizumab in all trimesters due to potential fetal immune system disruption, fetal autoimmune complications, and increased risk of miscarriage, stillbirth, and preterm labor. If use is essential, restrict to 12-32 weeks of gestation. Clinicians may administer interferon-α for chronic myeloid leukemia in any trimester. Clinicians should not administer PARP inhibitors in any trimester due to lack of human data and findings from animal studies indicating risks of teratogenicity, embryo-fetal toxicity, and fetal death. Alternative treatments should be offered, or therapy should be delayed until after delivery. |
| Cellular Therapies, Hematopoietic Cell Transplant, Radiopharmaceuticals | No recommendation. | Clinicians should not use cellular therapies, hematopoietic cell transplant, and radiopharmaceuticals due to insufficient safety evidence. Alternative treatments should be offered, or therapy should be delayed until after delivery. |
| Supportive Care | We recommend intravenous methylprednisolone, 62.5 mg (corresponding to 10 mg of dexamethasone), or oral prednisolone, 30 mg (corresponding to 6 mg of dexamethasone), as first-line therapy for chemotherapy-induced nausea when corticosteroids are indicated. | Clinicians may offer antiemetics such as ondansetron or metoclopramide for treatment-induced nausea and vomiting. Use of other antiemetic agents such as prochlorperazine, olanzapine, and NK1 receptor antagonists should be guided by multidisciplinary consultation, as efficacy for treatment-induced nausea and vomiting and/or fetal safety data remain limited. Glucocorticoids, preferably prednisolone or methylprednisolone, may be used when needed. Clinicians may offer G-CSF to reduce the risk of febrile neutropenia when clinically indicated, such as with myelosuppressive chemotherapy. Decisions should be based on individual risk factors, gestational age, and benefits versus risks. Clinicians may administer broad-spectrum antimicrobials as indicated for sepsis in pregnant patients with cancer. |
| Fetal Ultrasound Surveillance | We recommend serial fetal growth surveillance every 3–4 weeks in pregnancies with an active cancer diagnosis, regardless of treatment. We recommend initiation of antenatal fetal surveillance starting at 32 weeks of gestation in pregnancies with an active cancer diagnosis, regardless of treatment, unless indicated earlier for maternal or fetal reasons. | For pregnant patients undergoing cancer treatment, clinicians should schedule fetal monitoring that includes at least every three-to-four-week ultrasounds starting at 22-24 weeks to assess fetal growth, amniotic fluid levels, and placental function. |
| Obstetrical Management | We recommend that planned delivery prior to 37 weeks of gestation in pregnant patients with cancer generally be avoided unless indicated for medical or obstetrical reasons. We recommend that chemotherapy treatment generally be stopped by 34 weeks of gestation to allow 3–4 weeks for recovery of myelosuppression before spontaneous labor or planned delivery, except for weekly paclitaxel, which can be administered up to 35 or 36 weeks, as only 1–2 weeks are necessary for recovery before delivery. We recommend that the mode of delivery be determined by routine obstetrical indications for most patients with cancer in pregnancy. We recommend a placental pathology examination in all cases of cancer during pregnancy, regardless of cancer type or treatment. To improve long-term neurodevelopmental outcomes of children exposed to chemotherapy in utero, we suggest avoiding clinician-initiated preterm delivery when possible. | Obstetricians and oncologists should collaborate closely to plan delivery at or after 37 weeks of gestation to minimize prematurity risks, unless maternal or fetal health conditions require earlier intervention. Clinicians should plan to administer the last chemotherapy dose 2-4 weeks, or one complete cycle, prior to delivery, to minimize the risks of maternal and neonatal myelosuppression at delivery. Clinicians should prioritize vaginal delivery, as per standard practice and considerations, unless standard obstetric conditions or malignancies such as cervical or vulvar cancer necessitate cesarean section to optimize maternal and neonatal outcomes. Clinicians may administer a single course of antenatal corticosteroids to promote fetal lung maturation for pregnant patients with delivery planned or imminent prior to 37 weeks. For postpartum patients with cancer, clinicians may initiate VTE prophylaxis with low molecular weight heparin for at least 6 weeks to reduce clotting risks. Decisions regarding VTE prophylaxis should be individualized based on factors such as a history of VTE, cancer type and stage, obstetric mode of delivery, immobility, ongoing cancer therapy, and benefits versus risks. A histological evaluation of the placenta is recommended immediately after delivery in pregnant patients with a cancer diagnosis to guide oncological evaluation in the neonate. If placental metastases are detected, consult with a neonatologist for follow-up of neonate. For postpartum patients immediately undergoing chemotherapy, hormonal, or targeted therapy, clinicians should discourage breastfeeding and offer counseling on alternative feeding methods. For neonates exposed to in utero cancer therapies, pediatricians should monitor for therapy-related complications to ensure early detection and intervention. This may include, but is not limited to, baseline clinical laboratory tests (complete blood count, liver function tests, kidney function) for chemotherapy or targeted therapy exposure, auditory screening for exposure to platinum agents, and fetal thyroid monitoring for exposure to iodinated contrast enhanced CT imaging. |
| Prenatal Aneuploidy Screening with cfDNA Impacting Detection of Occult Malignancies | We recommend that cancer be considered as part of the differential diagnosis for pregnant patients with multiple chromosomal aneuploidies or single autosomal monosomy detected by cfDNA screening that is discordant with fetal findings. | No recommendation. |
| Psychological and Social Support | No recommendation. | For pregnant patients with cancer, clinicians should refer for psychosocial support to address emotional and social challenges, to help alleviate distress and to facilitate decision making. For pregnant patients with cancer, their caregivers, and their families, clinicians should engage a social worker or patient navigator to provide practical support, assist with care coordination, help navigate health care systems and access community resources and peer support groups. Psychosocially complex cases should be referred to a psychologist. |
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