ADN Fœtal Circulant, Grossesse et Pathologies Malignes

Cancer is associated with pregnancy in 1 in 1,000 to 1 in 1,500 pregnant women,but the estimated incidence varies depending on whether cancers pre-existing before pregnancy, cancers diagnosed during pregnancy, and sometimes those discovered in the postpartum period are included. The cancers most frequently encountered in the context of pregnancy are breast cancer, cervical cancer, melanoma, and thyroid cancer.

In 2015, D. Bianchi's team⁵ was the first to report the possibility of incidentally detecting cancers in pregnant women during the analysis of circulating cell-free DNA (cfDNA) performed for fetal chromosomal abnormality screening. In a cohort of 125,426 tests, 10 maternal cancers were identified. Since then, around one hundred cases have been reported, most often as case reports or small series.

Maternal cancer may be suspected when the cfDNA test result (performed for trisomies 21, 18, and 13, or as part of expanded screening) shows either multiple chromosomal abnormalities or an abnormality known to be associated with a certain type of cancer, such as some lymphomas.

In oncology, circulating tumor DNA (ctDNA) is studied for cancer detection, prognostic evaluation, and monitoring the effectiveness of certain treatments. The presence of ctDNA has been known since 1989. It originates from cells of the primary tumor and reflects genetic alterations (copy number variations, somatic mutations, methylation changes, etc.). The amount of ctDNA depends on tumor size, tumor type, cellular turnover, tumor location, and disease stage. ctDNA levels are higher in advanced stages of cancer, but the tumor fraction may remain very low even in cases of metastatic disease.

Inclusion criteria

• Inclusion Criteria (Cases):
• Adult patient (≥18 years old);
• Pregnant patient with a cancer known prior to pregnancy or diagnosed during pregnancy;
• Pregnancy at a gestational age > 10 weeks of amenorrhea at the time of inclusion;
• Patient informed and having signed the informed consent form to participate in the study.

Exclusion criteria

• Multiple pregnancy;
• Patient with a history of organ transplantation; Patient having received an allogeneic stem cell transplant;
• Known maternal mosaic chromosomal abnormality and copy number variation (CNV);
• Patient presenting with one or more known uterine fibroids at the time of inclusion;
• Technical inability to conduct a teleconsultation via a secure video connection and to complete an electronic signature.