Association of pregnancy and mortality in women diagnosed with breast cancer: A Nationwide Population Based Study in Taiwan

• Published in: International journal of cancer Vol. 143; no. 10; pp. 2416 - 2424
• Main Authors: Chuang, Shu‐Chun, Lin, Ching‐Hung, Lu, Yen‐Shen, Hsiung, Chao Agnes
• Format: Journal Article
• Language: English
• Published: Hoboken, USA John Wiley & Sons, Inc 15.11.2018; Wiley Subscription Services, Inc
• Subjects: Breast cancer; Cancer; Death; Diagnosis; Health risk assessment; Medical diagnosis; Medical research; Mortality; Patients; Population studies; Population-based studies; Postpartum; Pregnancy; Statistical models; Taiwan; breast cancer; pregnancy
• ISSN: 0020-7136; 1097-0215
• DOI: 10.1002/ijc.31777

We examined the associations between breast cancer diagnosed during pregnancy and up to 5 years postpartum and total mortality. Breast cancer patients were identified from the Taiwan Cancer Registry (2002–2014). All pregnancies up to 5 years before breast cancer diagnosis were ed from the National Health Insurance database and data were then linked to the Taiwan National Death Certificate Database. Follow‐up was calculated from the date of breast cancer diagnosis to the date of death or 31 December, 2014, whichever came first. The hazard ratios (HRs) and the 95% confidence intervals (CI) of the association between pregnancy and total mortality were estimated using Cox proportional hazard models. Among the 30,230 breast cancer patients, 90 were diagnosed during pregnancy, 347 within a year postpartum, and 1993 during 1–5 years postpartum. By the end of 2014, 2,920 patients were dead. The major cause of death was breast cancer (89%). Compared to patients without pregnancy records, the HRs were 1.42 (95% CI = 0.83–2.45) for patients diagnosed during pregnancy, 1.29 (0.96–1.74) for those diagnosed within a year postpartum, 1.27 (0.95–1.70) for those diagnosed within 1 to 2 years postpartum, and 1.06 (0.88–1.27) for those diagnosed ≥2 to 5 years postpartum, after adjustment for tumor characteristics and treatment. Subgroup analyses revealed an increased risk of mortality for patients diagnosed within a year postpartum in ER+ cancers (HR = 2.11, 95% CI = 1.28–3.47). Our results suggested a recent pregnancy may be associated with higher mortality among ER+ patients. What's new? A current or recent pregnancy may reduce the chance of surviving breast cancer. Using data from the Taiwan Cancer Registry, these authors identified patients who were diagnosed during pregnancy, within one year postpartum, and within 5 years postpartum. Cancers diagnosed during or shortly after pregnancy tended to be larger and more advanced; after controlling for clinical characteristics, there was no association between total mortality and pregnancy. For women with ER+ cancers, however, those who were diagnosed during pregnancy, or within the first year after delivery, experienced higher mortality.