Fig. 1.

The diagram demonstrates a big range in PABC prevalence recorded worldwide. The earliest study (in years 1963–2002) performed in Sweden based on The Swedish Cancer Register and Swedish Multi-Generation Register considering premenopausal women aged between 15 and 44 years old demonstrated the 7% prevalence of PABC defined as the breast cancer diagnosed during pregnancy and up to 2 years of postpartum [22]. The population-based study (in years 1977–2006) performed in Denmark based on Danish Cancer Registry considering premenopausal women aged between 15 and 44 years old demonstrated 4.5% prevalence of PABC defined as the breast cancer diagnosed during pregnancy and up to 1 year of postpartum [125]. The large-scaled study (in years 1999–2013) performed in South Korea based on Korean Breast Cancer Registry (102 hospitals) considering premenopausal women aged between 20 and 45 years old demonstrated 0.9% PABC prevalence defined as breast cancer (invasive ductal carcinoma, invasive lobular carcinoma, ductal carcinoma in situ) diagnosis during pregnancy up to 1 year postpartum [4]. The large-scaled study (in years 1998–2011) performed in Nigeria based on the database of the University College Hospital in Ibadan considering premenopausal women aged between 21 and 50 years old demonstrated 21.2% PABC prevalence defined as breast cancer diagnosis during pregnancy up to 2 years postpartum; this study specifically fixed the following inclusion criteria for matching the PABC versus non-PABC patients for comparison: age at menarche, parity, age at the first live birth, duration of breastfeeding, and abortion [12]