Menopausal hormone therapy and cancer risk: An overestimated risk?

• Published in: European journal of cancer (1990) 2017-10, Vol.84, p.60-68
• Main Authors: Simin, Johanna, Tamimi, Rulla, Lagergren, Jesper, Adami, Hans-Olov, Brusselaers, Nele
• Format: Article
• Language: English
• Subjects: Adult; Aged; Breast cancer; Breast neoplasms; Breast Neoplasms - chemically induced; Breast Neoplasms - epidemiology; Cancer; Colon; Confidence intervals; Digestive system neoplasms; Digestive System Neoplasms - epidemiology; Digestive System Neoplasms - prevention & control; Drug Administration Schedule; Drug Compounding; Endocrine therapy; Endometrial Neoplasms - chemically induced; Endometrial Neoplasms - epidemiology; Endometrium; Esophagus; Estrogen Replacement Therapy - adverse effects; Estrogens; Estrogens - administration & dosage; Estrogens - adverse effects; Female; Genital neoplasms; Health risks; Hormone replacement therapy; Humans; Incidence; Invasiveness; Liver; Medicin och hälsovetenskap; Menopause; Middle Aged; Neoplasms; Neoplasms - chemically induced; Neoplasms - diagnosis; Neoplasms - epidemiology; Neoplasms - prevention & control; Oestrogen replacement therapy; Ovarian cancer; Ovarian Neoplasms - chemically induced; Ovarian Neoplasms - epidemiology; Population studies; Progestin; Progestins - administration & dosage; Progestins - adverse effects; Protective Factors; Registries; Risk Assessment; Risk Factors; Sweden - epidemiology; Therapy; Time Factors; Tumors
• ISSN: 0959-8049; 1879-0852; 1879-0852
• DOI: 10.1016/j.ejca.2017.07.012

We aimed to assess the overall cancer risk among contemporary menopausal hormone therapy (MHT) users in Sweden and the risk for different cancer types. A nationwide Swedish population-based cohort study including all 290,186 women aged ≥ 40 years having used systemic MHT during the study period (July 2005 and December 2012), compared with the Swedish female background population. MHT ever-use (all MHT, oestrogen-only MHT [E-MHT] and oestrogen plus progestin MHT [EP-MHT]) was based on the nationwide Prescribed Drug Registry. Cancer diagnoses were grouped into 16 different anatomical locations, for which standardised incidence ratios (SIRs) and 95% confidence intervals (CIs) were calculated. The SIR of any cancer was 1.09 (95% CI: 1.07–1.11) following ever MHT, 1.04 (95% CI: 1.01–1.06) for E-MHT and 1.14 (95% CI: 1.12–1.17) for EP-MHT. The highest SIR was found for EP-MHT among users aged ≥70 years (SIR = 1.33, 95% CI: 1.26–1.40). The risk for invasive breast, endometrial or ovarian cancer combined was increased for any MHT (SIR = 1.31, 95% CI: 1.28–1.34). The risk of invasive breast cancer was increased following MHT and increased with age for EP-MHT users. The risk of gastrointestinal cancers combined was decreased (SIR = 0.90, 95% CI: 0.86–0.94), particularly the oesophagus (SIR = 0.81, 95% CI: 0.64–1.00), liver (SIR = 0.81, 95% CI: 0.65–0.99) and colon (SIR = 0.90, 95% CI: 0.84–0.95). MHT, notably EP-MHT, was associated with a limited increase in overall cancer risk. The increased risk of female reproductive organ cancers was almost balanced by a decreased risk of gastrointestinal cancers. •Menopausal hormone therapy (MHT) is the single most effective treatment for menopause-related symptoms.•Its use declined after 2002 because of a reported elevated breast cancer risk. Little is known on the overall cancer risk or other cancer types.•This contemporary MHT study showed a 9% increased cancer risk, with a decreased risk of all gastrointestinal cancer.•The cancer risk was more limited than expected, with variations for MHT types, formulations and regimens.