Cohort study of 1.5 million young women: Contraceptive pill increases cancer risk 10 years after discontinuation!

Hundreds of millions of women worldwide use hormonal contraceptives (HC), many of which are at a worrisome risk of breast cance.

These differences can be explained by age and parity of subjects, prescribing bias, study design (cohort versus case-control), and definition of exposure (current versus former use.

The goal of this study was to investigate the risk of breast cancer in current users of HC, especially the progestin-only approac.

In this nationwide prospective cohort study, all Swedish women aged 15-34 were studied from January 1. In 2005, or those who turned 15 during the study period, were followed until December 31, 201 Using information from 7 national registries, Poisson regression was used to assess the incidence of breast cancer and breast cancer in situ across different HC.

The cohort included 5 million women and analyzed more than 14 million person-years of dat.

Compared to users who had never used any HC, the researchers found no increased risk of breast cancer in current users of any combined HC, with an IRR of 03 (91-16), compared with users of current progestin-only methods Increased risk of cancer with an IRR of 32 (20-45.

Among all types of HC, breast cancer risk appeared to be highest in the first five years of use (HC IRR 39 (14-69); progestogen-only approach IRR 74 (44-10.

In this cohort of women, Swedish women aged 15-34 who were currently using a progestin-only method had a slightly increased risk of breast cancer or breast cancer in situ compared with women who had never used hormonal contraceptive.

Original source:

Niemeyer Hultstrand J, Gemzell-Danielsson K, Kallner HK, Lindman H, Wikman P, Sundström-Poromaa .