Pregnancy-associated cancers increase overall 5-year mortality

Key takeaways :

• Women diagnosed with cancer during and in the year after pregnancy were more likely to die than those diagnosed at other times.
• Future research on cancer sites is needed to guide counseling and clinical care.

Cancers diagnosed during pregnancy or 1 year post-partum had greater overall 5-year mortality compared with those not diagnosed near pregnancy, but risks were not the same for all cancer sites, researchers reported in JAMA Oncology.

“Pregnancy-associated breast cancers have been well established as having an increased mortality compared with breast cancers diagnosed outside of pregnancy or postpartum. However, evidence on long-term health outcomes following diagnosis of cancer other than breast cancer is limited,” Zoe F. Cairncross, MPH, research associate in the department of obstetrics and gynecology at the University of Calgary in Alberta, Canada, and colleagues wrote. “One possible explanation for poorer survival associated with pregnancy-associated breast cancer is that hormonal changes in pregnancy, delivery and lactation enhance the growth of malignant cells, producing a more aggressive and advanced disease at time of diagnosis. Diagnostic delay may also play a role because common physiologic changes during pregnancy and postpartum may mimic early physical symptoms of cancer.”

This population-based retrospective cohort study included 1,014 participants diagnosed with cancer during pregnancy from conception to delivery, 3,074 who were diagnosed during the postpartum period up to 1 year post-delivery and 20,219 who were diagnosed during periods remote from pregnancy. All participants were premenopausal women aged 18 to 50 years living in Alberta, British Columbia and Ontario, Canada, and were diagnosed with cancer between 2003 and 2016.

The primary outcomes were overall survival at 1 and 5 years and time from cancer diagnosis to death due to any cause.

Across the three participant groups, 1-year survival was similar. However, overall 5-year survival was lower among participants who were diagnosed with cancer during pregnancy or the postpartum period.

Researchers observed greater mortality risks with pregnancy-associated cancer among participants who were diagnosed during pregnancy (adjusted HR = 1.79; 95% CI, 1.51-2.13) and postpartum (aHR = 1.49; 95% CI, 1.33-1.67) compared with cancers diagnosed during a time remote from pregnancy. Mortality risks varied across cancer sites, with increased mortality risks for breast cancer (aHR = 2.01; 95% CI, 1.58-2.56), ovarian cancer (aHR = 2.6; 95% CI, 1.12-6.03) and stomach cancer (aHR = 10.37; 95% CI, 3.56-30.24) during pregnancy compared with times remote from pregnancy. In addition, researchers noted increased mortality risks among participants diagnosed with brain cancer (aHR = 2.75; 95% CI, 1.28-5.9), breast cancer (aHR = 1.61; 95% CI, 1.32-1.95) and melanoma cancers (aHR = 1.84; 95% CI, 1.02-3.3) during the postpartum period compared with times remote from pregnancy.

“More research on each cancer site is required to provide robust evidence to guide counseling and clinical care of affected patients,” the researchers wrote.