Cesarean delivery associated with colorectal cancer

Cesarean delivery associated with colorectal cancer | Image Credit: © natalialeb - © natalialeb - stock.adobe.com.

The risk of early-onset colorectal cancer (CRC) is greater in female individuals born by cesarean delivery, according to a recent study published in JAMA Network Open.

An increased incidence of CRC in individuals aged under 50 years has been observed in many regions worldwide. Factors associated with early-onset CRC include obesity, diabetes, prolonged sitting, and metabolic syndrome. These factors indicatea role of the gut microbiome in early-onset CRC.

In the United States, a greater incidence of early-onset CRC has been observed in each successive birth cohort, supporting the hypothesis early life exposures impact CRC risk. Many countries with rising early-onset CRC prevalence have also seen increased rates of cesarean birth, with the US cesarean delivery rate rising from 5% in the 1970s to about 30% after 2009.

As rates of cesarean birth rise, there is a need to understand associated future health outcomes. To understand the association between cesarean delivery and risk of early-onset CRC, investigators conducted a nationwide, population-based case-control study.

The study was conducted using the Epidemiology Strengthened by Histopathology Reports in Sweden (ESPRESSO) cohort, a data harmonizing effort including all of Sweden’s pathology departments and any gastrointestinal (GI) pathology reports for clinic purposes from 1965 to 2017.

ESPRESSO data was linked to the Swedish Medical Birth Register (MBR), containing data on 98% of births in Sweden. This includes data from the first antenatal visit through delivery and hospital discharge and has received cross-comparison with the Total Population Register.

Evaluations included individuals with GI tract histopathologic findings in the ESPRESSO cohort which matched a CRC incidence diagnosis when aged 18 to 49 years from 1991 to 2017. Potential cases were matched with their inpatient and outpatient records to obtain compatible histopathologic findings and registry-level case confirmation.

Individuals with CRC incidence were matched with control individuals based on sex, calendar year, country of residence, and age at index. Cases of prior inflammatory bowel disease (IBD) and hereditary cancers were excluded from the analysis.

Covariates included maternal factors such as maternal history of cesarean delivery, country of birth, age at delivery, living with a partner, education level, comorbidities, and parity. Birth characteristics such as birth weight, gestational age, and birth length were also collected from the MBR.

There were 564 cases in the final analysis, 49.6% of which were female patients. All cases were matched with 1 or more controls, with 89.5% matched with 3 to 5 controls. Case patient mothers more often had IBD, diabetes, and a history of cesarean delivery.

Of patients with early-onset CRC, 9.8% were born through cesarean delivery, compared to 8% of controls. A positive association between cesarean delivery and early-onset CRC was found among female patients, but not male patients. This association was also not significant after multivariable adjustment.

Similar associations were seen in patients aged 35 years and older, along with those without a maternal history of cesarean delivery, diabetes, gestational diabetes, hypertension, preeclampsia, or IBD. When examining anatomic sites of CRC, colon cancer had an adjusted odds ratio (aOR) of 1.77 and rectal cancer an aOR of 1.29.

The association between cesarean delivery and early-onset CRC was not mediated by birth characteristics, indicating an increased risk of early-onset CRC among women birthed by cesarean delivery.

Reference

Cao Y, Nguyen LH, Tica S, et al. Evaluation of birth by cesarean delivery and development of early-onset colorectal cancer. JAMA Netw Open. 2023;6(4):e2310316. doi:10.1001/jamanetworkopen.2023.10316