Pregnancy related cancer in Apulia. A population based linkage study

Despite a quite large number of papers in literature, the current incidence of pregnancy associated cancer still remains uncertain. Moreover, different inclusion criteria and time intervals considered after delivery make these data poorly comparable. The aim of this study was to investigate the incidence of PACs in Apulia, an Italian region, while stressing differences or similarities with other populations.

We collected 682,173 pregnancies from national discharge forms, regarding hospitals in Apulia from January 2003 to December 2015. Our aim was not only to obtain the raw incidence of PACs but also to estimate the odds ratio (OR) for some potential risk predictors such as calendar year, age, nationality and pregnancy outcome using a logistic model. Women were sorted into different groups by age (<30, 30-34, 35-39, >=40) and by nationality (Italian or foreign nationals). Each pregnancy had two possible outcomes: delivery or abortion.

We achieved a final cohort of 867 PACs: therefore, the raw incidence is 127.1 per 100,000 pregnancies. Breast cancer was the most common cancer (37.7 cases per 100,000 pregnancies) and as a typical feature in our population thyroid cancers followed it by incidence (22.3 per 100,000 pregnancies). Cervical cancer is, as expected, the first gynaecological cancer by incidence(3.8 per 100,000). Younger women have the lowest risk for PACs (64.5 per 100,000, OR = 1) while the highest risk for PACs was for women aged >=40 years (OR = 4.29, p < 0.05). Considering calendar years, we observed an increased OR from 2006 to 2009 (OR = 1.39 and OR = 1.41 respectively) without spotting a trend throughout the whole decade.

The ranking of each tumour by incidence more or less reflects its demographics in reproductive age females in western countries and the incidence for any cancer is expected to grow as the rate of first deliveries in older women continues to rise. We reported noticeable differences regarding the incidence of some cancers (such as thyroid cancer) with previous literature, reflecting an epidemiologic feature of our cohort. Women older than 40 years have a more than fourfold risk for oncologic diagnosis during pregnancy, and this finding is of pivotal clinical and social importance because of the tendency of women living in developed countries to postpone childbearing.