title: Risk of breast cancer among patients with bioprosthetic or mechanical valve replacement: a population-based study in Sweden.
abstract: The association between breast cancer and warfarin is inconclusive as most previous studies examined their association using patients with thromboembolism, whereas thromboembolism itself is a risk factor for cancer. We explored this issue using patients received mechanical heart valves replacement as a proxy for warfarin exposure as these patients need a lifelong warfarin treatment, and compared them with patients received bioprosthesis valves replacement (short-term warfarin treatment) in Sweden between 1987 and 2010. Patients who were operated on for valve replacement were identified from the Swedish Hospital Discharge Registry and linked to the Swedish Cancer Registry to examine the hazard ratios of subsequent breast cancer. A total of 12,242 women were operated on for valve replacement (5481 with mechanical valve and 6401 with bioprosthetic valve). For the entire cohort, the HR of breast cancer was 1.49 (95 % CI 1.09-2.02) among patients with mechanical valve replacement compared to those with bioprosthetic valve replacement. After controlling for a number of confounding factors using propensity score weighting, the HR was 1.69 (95 % CI 1.15-2.47). Our study found that patients with mechanical valve replacement have an increased risk of breast cancer compared to those with bioprosthetic valve replacement. If confirmed, this increased risk should be considered when recommending breast cancer screening for women with mechanical valve replacement. Long-term use of warfarin may explain the observed increase. If so, patients who have used warfarin long-term for other reasons should be studied for a possible increased risk of breast cancer.
authors.affiliation: Center for Primary Health Care Research, CRC, Lund University/Region Skåne, Skåne University Hospital, Building 28, Floor 11, Jan Waldenströms gata 35, 205 02, Malmö, Sweden. Jianguang.ji@med.lu.se.
authors.forename: Jianguang
authors.initials: J
authors.lastname: Ji
authors.affiliation: Center for Primary Health Care Research, CRC, Lund University/Region Skåne, Skåne University Hospital, Building 28, Floor 11, Jan Waldenströms gata 35, 205 02, Malmö, Sweden.
authors.forename: Bengt
authors.initials: B
authors.lastname: Zöller
authors.affiliation: Stanford Prevention Research Center, Stanford University, Stanford, CA, USA.
authors.forename: Amato
authors.initials: A
authors.lastname: Giaccia
authors.affiliation: Stanford Prevention Research Center, Stanford University, Stanford, CA, USA.
authors.forename: Robert
authors.initials: R
authors.lastname: Haile
authors.affiliation: Center for Primary Health Care Research, CRC, Lund University/Region Skåne, Skåne University Hospital, Building 28, Floor 11, Jan Waldenströms gata 35, 205 02, Malmö, Sweden.|Stanford Prevention Research Center, Stanford University, Stanford, CA, USA.
authors.forename: Jan
authors.initials: J
authors.lastname: Sundquist
authors.affiliation: Center for Primary Health Care Research, CRC, Lund University/Region Skåne, Skåne University Hospital, Building 28, Floor 11, Jan Waldenströms gata 35, 205 02, Malmö, Sweden.|Stanford Prevention Research Center, Stanford University, Stanford, CA, USA.
authors.forename: Kristina
authors.initials: K
authors.lastname: Sundquist
mesh_terms: D000368:Aged; D000369:Aged, 80 and over; D001705:Bioprosthesis / Q000009:adverse effects*; D001943:Breast Neoplasms / Q000453:epidemiology* / Q000209:etiology*; D005260:Female; D005500:Follow-Up Studies; D006350:Heart Valve Prosthesis / Q000009:adverse effects*; D006801:Humans; D008875:Middle Aged; D011159:Population Surveillance; D012042:Registries; D012306:Risk; D013548:Sweden / Q000453:epidemiology; D014859:Warfarin / Q000009:adverse effects
chemical_list: D014859:Warfarin
keywords: Breast cancer; Valve replacement; Warfarin