Cancer survival in women diagnosed with pregnancy-associated cancer: An overview using nationwide registry data in Sweden 1970–2018

Anna L.V Johansson,Irma Fredriksson,Lene Mellemkjaer,Hanne Stensheim,Päivi Lähteenmäki,Jeanette F Winther,Gustav J Ullenhag,Frida E Lundberg

doi:10.1016/j.ejca.2021.07.008

Abstract

BackgroundPregnancy-associated cancer (PAC) is increasing over time in many countries. We provide a comprehensive, population-based overview of cancer survival in women with PAC across five decades. MethodsWe performed a nationwide cohort study of 121,382 women diagnosed with cancer at age 15–49 between 1970 and 2018 using birth and cancer registers in Sweden. Pregnancy-associated cancer was defined as diagnosed during pregnancy and within one year of delivery, while non-PAC was outside this window. Cox regression estimated adjusted hazard ratios (HRs) with 95% confidence intervals (CIs) comparing cancer mortality for PAC versus non-PAC. ResultsIn total, 5079 women had a diagnosis of PAC. Cutaneous malignant melanoma, breast, cervical, thyroid and central nervous system (CNS) were the most common sites of PAC. A higher cancer mortality was observed in PAC versus non-PAC for breast (HR = 1.72, 95% CI 1.54–1.93) and uterine cancer (myometrium/unspecified) (8.62, 2.80–26.53), in which all PAC deaths were uterine sarcomas. Increased mortality was also observed in upper digestive tract cancer diagnosed during pregnancy and colon cancer diagnosed during first year after delivery. Contrary, the HR for CNS tumours was significantly decreased (0.71, 0.55–0.91). Survival after PAC improved for most sites over time, with survival after breast cancer during pregnancy in recent years being similar to that of non-pregnancy associated breast cancer. ConclusionFor the majority of sites, PAC was not associated with poorer prognosis compared to non-PAC, a finding which was stable over time. The main exceptions were breast cancer and rarer cancers, such as uterine sarcoma.

Highlights

Cancer during pregnancy and breastfeeding is increasing in numbers worldwide, likely due to postponement of childbearing [1e3]
The incidence of Pregnancy-associated cancer (PAC) increased over time, with the incidence during pregnancy being about half of the incidence during the firstand second-year post-delivery (Fig. 1)
We found that neither cutaneous malignant melanoma (CMM) nor cervical cancer were associated with a poorer prognosis if diagnosed during or within a year of pregnancy

Summary

Introduction

Cancer during pregnancy and breastfeeding is increasing in numbers worldwide, likely due to postponement of childbearing [1e3]. An estimated 80e140/100,000 deliveries are affected by pregnancy-associated cancer (PAC), which is commonly defined as cancer during pregnancy and up to one year postpartum [4]. Reliable survival estimates are lacking for many cancer types. Single- and multi-center survival studies of PAC often focus on the most common cancer types, e.g. breast and cervix, and many under-report cancer types often not treated by oncologists, e.g. cutaneous malignant melanoma (CMM). Population-based studies on PAC survival are needed to achieve sufficient power for rarer cancers and to reflect all patients in the population. Population-based data can provide important time trends in PAC survival, which is a powerful tool to assess the impact of management and treatment changes over time for this special patient group

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