Managing breast cancer in pregnancy: What to use, what to avoid
Survival outcomes of women diagnosed with breast cancer during pregnancy are similar to that of non-pregnant women, according to a presentation at ESMO Asia 2017. However, it is important to identify the dos and don’ts when diagnosing and treating breast cancer in this population.
According to Dr Smruti Koppikar from the Bombay Hospital Institute of Medical Sciences in Mumbai, India, breast cancer comprises almost 20 percent of cancers seen in pregnant women, one of the main reasons for which is the delaying of childbearing beyond age 30 years.
While there is little difference between the types of breast cancer occurring in pregnant and non-pregnant young patients, the predominant breast cancers presenting during pregnancy are basal and HER2 types, thus more aggressive forms of cancer, said Koppikar. While there are incidences of luminal types, triple-negative and HER2-positive cases are the most common.
The first and most important question is whether the pregnancy should be continued, she said, stressing that pregnancy termination does not benefit the patient.
Staging breast cancer in pregnancy
“There are several dos and don’ts and the main aim is to see that the foetus does not receive any radiation,” said Koppikar.
“Breast ultrasound is a good technique to detect solid or cystic mass [while] breast MRI … can tell us about the [involved and opposite breast],” she said.
Mammograms should be avoided unless absolute indispensable, but if necessary, should be done with shielding, said Koppikar.
In terms of metastatic workup, MRI is a good technique to identify bone or brain involvement, but there should be no use of gadolinium due to its ability to cross the placental barrier and potentially result in nephrotoxicity in the foetus.
Whole body CT scan, PET scan, and bone scan are contraindicated, while pelvic ultrasound should be used to determine foetal age and viability. As obstetric observation and pregnancy assessment is crucial prior to decision-making regarding treatment, consulting the patient’s obstetrician is vital.
“Multidisciplinary management is the key to success,” said Koppikar.
Treatment-determining considerations during pregnancy
According to several studies, there is little difference in the survival outcomes between pregnant and non-pregnant women with breast cancer. [Oncologist 2013;18:369-376; J Clin Oncol 2013;31:2532-2539]
“Pregnant women diagnosed with breast cancer should be treated with standard of care given to non-pregnant patients with a few exceptions and precautions,” said Koppikar.
Following disease staging, the next step is to determine which locoregional treatment to use and when, she said. Next would be determining the necessity and safety of systemic therapies such as chemotherapy, hormonal therapy, or targeted therapy, and finally, the optimal timing of delivery as well as the long-term impact of treatment on both the mother and the new-born.
“Quite a number of foetal cognitive defects can be because of premature delivery,” said Koppikar, highlighting the importance of extending the pregnancy to at least 37 weeks to minimize cognitive defects in the foetus.
Timing, dosing, and monitoring are important in systemic therapy, she said.
Administration of chemotherapy during the first trimester raises the risk for spontaneous abortion, foetal death, and malformations, with an elevated risk of major congenital abnormalities occurring with chemotherapy exposure during organogenesis. [Lancet Oncol 2004;5:283-291]
“Chemotherapy should be started 14 weeks after gestation and preferably in the second and third trimester … and should be withheld after the 35th week to avoid foetal and maternal neutropenia,” she said.
It is also important not to increase the dose of chemotherapy as the pharmacokinetics of drugs differ in pregnant women, she said. Ultrasound-guided monitoring should be used to assess foetal viability, age, and growth prior to commencement and before each chemotherapy course.
Taxanes can be used during pregnancy, with paclitaxel being the preferred option, though the doses should not be increased. Anthracyclines can be safely used during the second and third trimesters, methotrexate should be avoided, and 5-FU can be omitted, she said.
Trastuzumab should be avoided during pregnancy, though if there is accidental exposure during the first trimester, trastuzumab should be stopped and the pregnancy continued. Hormonal therapy should not be given during pregnancy.
Endocrine therapy, radiotherapy, and trastuzumab can only be used after delivery, she added.
Surgery can be done in all trimesters, and breast conservation surgery is feasible, particularly in the third trimester with radiotherapy postponed until post-delivery. [Gynecol Surg 2014;11:279-284]
However, surgery is preferable only after the first trimester to reduce the risk of spontaneous abortion, said Koppikar, and foetal monitoring during surgery is vital.
Sentinel node biopsy can be done during pregnancy but without using blue dye, she said.
Supportive measures should also be considered. The anti-emetics ondansetron and granisetron are safe. Due to lack of data, fosaprepitant and aprepitant should only be utilized if necessary. Corticosteroids should be avoided during the first trimester, while methylprednisolone is preferred over dexamethasone and betamethasone, both of which can cause attention deficits. Ranitidine can be used, while proton pump inhibitors can lead to muscle relaxation and regurgitation. There is limited data available on growth factors, thus, they should not be used unless necessary, said Koppikar.
“You have to remember that you are managing two when cancer and pregnancy coincide,” concluded Koppikar, emphasizing on the use of optimal treatment for pregnant women without harming the foetus.