BACKGROUND

Menopausal hormone therapy (MHT) has been associated with various malignancies.

AIMS

To investigate the association of various MHT regimens with the risk of colorectal cancer (CRC).

METHODS

MHT use may decrease colorectal adenocarcinoma risk, for both E-MHT and EP-MHT, and especially in past users.

All MHT ever-users were included through the Swedish Prescribed Drug Registry. Ever-users were defined as women who received systemic MHT during 2005-2012 in Sweden. All cases after drug initiation were extracted from the Swedish Cancer Registry.

The association was considering different regimens, duration and age at treatment initiation.

RESULTS

Compared with non-users, MHT users had an overall reduced odds for colon and rectal adenocarcinoma, especially among women aged 40-60 years. Current users of oestrogen-only preparations (E-MHT) showed reduced odds compared to non-users, particularly with oestradiol and oestriol. Past E-MHT use showed stronger odds reductions. Current use of oestrogen combined progestin therapy (EP-MHT) indicated a less prominent odds reduction in colon adenocarcinoma and rectal adenocarcinoma than past users. Tibolone showed an increased risk of left-sided colorectal adenocarcinoma. Oral and cutaneous MHT usage showed similar patterns.

CONCLUSIONS

MHT use may decrease colorectal adenocarcinoma risk, for both E-MHT and EP-MHT, and especially in past users.