Swedish Mammography Cohort - SMC

The Swedish Mammography Cohort (SMC) is a multidisciplinary longitudinal project on the association of lifestyle and genetic factors with morbidity and mortality in middle-aged and elderly women. This large population-based prospective cohort was established in 1987 in central Sweden.

Between 1987 and 1990, all women born between 1914 and 1948 who lived in the Uppsala County and in the adjacent Västmanland County, both in central Sweden, received an invitation by mail to participate in a mammography screening program, 90,303 women. The invitation included a six-page questionnaire that sought information on diet and alcohol intake, parity, age at first childbirth, family history of breast cancer, weight, height, education level, and marital status, and gave a response rate of 74%. After exclusions the cohort were formed by a total of 61,433 women.

In 1997 a second questionnaire was sent to all cohort members of the Swedish Mammography Cohort who were still living in the study area. The aim was to update the information about diet. The questionnaire was extended to include information on physical activity, medical history, age at menarche, history of oral contraceptive use, age at menopause, postmenopausal hormone use and lifestyle factors such as cigarette smoking history and use of dietary supplements (70% response rate). The 1997 follow up resulted in 38,984 valid answers.

All members of the Swedish Mammography Cohort who had completed the 1987 FFQ received a third questionnaire in 2008. The 2008 Health questionnaire with a response rate of 63% and 30,621 valid answers, collected information on general health status, disease diagnoses, current body weight, height, waist and hip circumferences, dental health, medication use, sleep habits, urine and bowel habits, family history of selected diseases, stress, and social support.

To cohort members who completed the 2008 Health questionnaire a fourth questionnaire was sent in 2009. The 2009 Lifestyle questionnaire had a response rate of 84% and 25,332 valid answers. The questionnaire collected information on diet, dietary supplements, smoking, physical activity, and sun habits.

A fourth follow up of the Swedish Mammography Cohort was performed in 2019 using the same questionnaires as in 2008/2009. The Health questionnaire was sent in January 2019 to all 34,473 living participants in the cohort, resulting in 19,081 valid answers and a response rate of 55%. The Lifestyle questionnaire was sent in September 2019 to all 18,930 living respondents answering the Health questionnaire resulting in 14,922 valid answers and a response rate of 79%.

The Swedish Mammography Cohort will be extended with information on polymorphisms in low risk genes during 2020. Numbers are pending, but are in the range between 7000 and 8000 participants. This will facilitate studies of genetic susceptibility and of interplay/interactions between lifestyle factors and genes in the development of chronic diseases. For more information you are welcome to contact the SIMPLER office.