PREGNANCY AND NEONATAL OUTCOMES AMONG EARLY-ONSET COLORECTAL CANCER SURVIVORS: A NATIONWIDE STUDY

BACKGROUND
Early-onset colorectal cancer (CRC diagnosed before age 50) has risen worldwide, with an increasing number of survivors of reproductive age. We aimed to investigate the risk of adverse pregnancy and neonatal outcomes among early-onset CRC survivors.

METHODS
We conducted a nationwide study of 207 births in women with early-onset CRC and 1019 births in women without CRC from the general Swedish population (1992-2019), matched on age, calendar year, parity, and county of residence. To further adjust for confounding, we identified 146 births in female siblings of women with early-onset. Early-onset CRC cases were identified through the Swedish Cancer Register. Sibling identification and outcome data were retrieved through linkage of the Swedish Multi-generation Register, Medical Birth Register, and National Patient Register. Using conditional logistic regression, we estimated multivariable-adjusted odds ratios (ORs) and 95% confidence intervals (CIs).

RESULTS
Compared to women without prior CRC, early-onset CRC survivors who gave birth had increased risk of pre-eclampsia (7.2% vs 3.2%; OR=2.52, 95%CI 1.25-5.08), any Cesarean delivery (C-section) (24.6% vs 19.4%; OR=1.43, 95%CI 1.00-2.06), particularly emergency C-section (17.4% vs 10.5%; OR=1.79, 95%CI 1.17-2.75), after adjustment for maternal education level, country of birth, body mass index and smoking in early pregnancy, and comorbidities. Sibling analyses showed similar trends. Maternal history of early-onset CRC was also associated with offspring preterm birth (12.1% vs 5.2%; OR=2.31, 95%CI 1.34-3.99), delineated as spontaneous (OR=1.06, 95%CI 0.47-2.39) or medically-indicated preterm birth (OR=4.48, 95%CI 2.05-9.79). There was no increased risk of congenital malformation or small for gestational age birth.

CONCLUSIONS
In this population-based study, maternal history of early-onset CRC was associated with risk of both adverse pregnancy (pre-eclampsia, C-section) and neonatal outcomes (preterm birth).