LAUSR

Founded in 2005 at the KU Leuven, Belgium, the International Network on Cancer, Infertility and Pregnancy (INCIP), set its ambitious goal to improve evidence on all aspects concerning cancer during pregnancy. In the past two decades, the network has grown, now consisting of over 95 member medical centers from over 30 different countries worldwide. Currently, incidence of cancer in pregnancy is estimated at one in 1000 pregnancies [1, 2]. With maternal age at first childbirth increasing [3], we anticipate this number to increase in the coming years. To provide future patients with comprehensive and evidence-based information on both oncological and obstetric management and outcome, INCIP initiated various research projects to study a broad range of issues related to cancer in pregnancy; from analysis of the effects of oncological treatment on maternal and fetal outcome to follow-up of children that were antenatally exposed to these treatments and assessment of psychological impact on patients and their partners diagnosed with cancer in pregnancy. Recently, INCIP published results of an ongoing 20year cohort study on both the oncological and obstetric management and outcomes of 1170 patients [4]. This study included patients both retrospectively (before 2005) and prospectively (from 2005 onward) who were diagnosed with primary invasive cancer during pregnancy, analyzed the advancement of oncological management during pregnancy in the past decades, and the observed obstetric and neonatal outcomes. Breast cancer was the most common cancer type during pregnancy (39.5%), followed by gynecological (13% cervical cancer and 7% ovarian cancer) and hematological (10% lymphoma and 6% leukemia) cancers. Most patients were diagnosed in their second trimester, with locally-staged disease. The majority of patients were multiparous at time of diagnosis. It was found that two-thirds of all patients received some sort of oncological treatment during pregnancy, with the likelihood of receiving treatment during pregnancy increasing with 10% every five years in the last twenty years (RR 1.10; 95% CI 1.05-1.15). Simultaneously, every five years more live births (RR 1.04; 1.01-1.06) and fewer iatrogenic preterm births (RR 0.91; 0.84-0.98) were observed. Twenty-one percent of the neonates were born small for gestational age (SGA), defined as a birth weight below the 10th percentile. Multivariate analysis showed increased risks on SGA after antenatal chemotherapy exposure consisting in general (p<0.0001), specifically after exposure to platinum derivatives or taxanes (OR 3.12 (95% CI 1.45-6.70) and 2.07 (95% CI 1.11-3.86), respectively). Also, the frequency of SGA rose for each 5-year study period, reflecting the increasing tendency to treat during pregnancy. With preterm birth being associated with reduced cognitive development [5], the observed decrease in incidence of iatrogenic prematurity is considered a positive advancement. However, the potential negative effects of children born SGA should not be underestimated, as perinatal mortality and morbidity, and cardiovascular and metabolic disorders later in life are more common in these children [6]. Despite the extensive network and careful efforts of all participating specialists involved in registering patients into the INCIP registry, the partial retrospective study design entails the risk of selection bias. Also, as included patients were diagnosed in varying countries and at various time points (diagnosis between 1996 and 2016), factors regarding diagnosis and treatment could greatly vary between patients. Missing data on fetal growth during pregnancy prevent to identify intra-uterine growth restricted fetuses [7], which definition is based on different criteria (declining growth (crossing centiles more than 2 quartiles) in sequential ultrasound measurements, Doppler measurements (Pulsatility Index of the umbilical artery >95th percentile), abdominal circumference <10th percentile) compared to SGA. Cytotoxic drugs during pregnancy have the potential to affect placental function. Editorial