Women with breast cancer during pregnancy may have a good prognosis and a low risk of adverse obstetric and perinatal outcomes, according to three recent studies published by Lundberg et al in Acta Obstetricia et Gynecologica Scandinavica, Gkekos et al in ESMO Open, and Lundberg et al in Acta Obstetricia et Gynecologica Scandinavica.
Background
Cancer during pregnancy can be a challenge for the patient and treating physician. Although several international studies have reported on outcomes in these patients and their children, most studies have been small and inconclusive because of the rarity of cancer during pregnancy.
Study Methods and Results
In the recent studies, investigators used data from the Swedish Medical Birth Register, the Swedish Cancer Register, and the National Quality Register for Breast Cancer to identify 4,629 women who were diagnosed with cancer during pregnancy and within 1 year following delivery between 1973 and 2017.
The investigators found that the incidence of cancer during pregnancy increased among the patients involved in the study—with breast cancer, cutaneous malignant melanoma, and cervical cancer being the three most common cancer types observed. From 2015 to 2017, cancer was diagnosed during pregnancy in about 50 per 100,000 deliveries and within the first year following delivery in about 110 per 100,000 patients.
The ongoing trend of postponing childbearing to higher ages may partly explain the increase; however, other risk factors may be responsible. For instance, in two studies, the investigators determined that breast cancer diagnosed during pregnancy and within 1 year after delivery had more adverse tumor characteristics such as advanced stage and triple-negative subtype. Notably, the survival rates did not differ between these patients and other patients with breast cancer who had the same tumor types. The only exception was women diagnosed during the second trimester of pregnancy, where a modestly increased mortality rate was found.
Additionally, women diagnosed with breast cancer had higher risks of preterm births and perinatal outcomes related to preterm births, including low birth weight. No other risks—such as maternal pregnancy complications or adverse outcomes in the neonatal patients—were found.
Conclusions
“Planned preterm birth is sometimes necessary to enable onset of cancer treatment, yet it is reassuring for both the women and the treating [physicians] that no other risks were identified in these women or in their children”, underscored senior study author Anna Johansson, MSc, PhD, Research Group Leader in the Department of Medical Epidemiology and Biostatistics at the Karolinska Institutet. “Due to the rarity of cancer during pregnancy, many [oncologists] will only experience a handful of cases over their careers. This shows the importance of undertaking clinically relevant studies using register data and high-quality epidemiologic methods in close collaboration with clinicians,” she concluded.
Disclosure: The research in these studies was funded by the Swedish Cancer Society, Radiumhemmet Research Foundations, and the Swedish Breast Cancer Association. For full disclosures of the study authors, visit obgyn.onlinelibrary.wiley.com, esmoopen.com, and obgyn.onlinelibrary.wiley.com.
