Swedish Mammography Cohort – SMC

The large, population-based prospective Swedish Mammography Cohort (SMC) was established in 1987 in central Sweden.

Women born between 1914 and 1948, living in Västmanland County between 1987 and 1989 or living in Uppsala County between 1988 and 1990, received an invitation by mail to participate in a mammography screening program. In total, 90,303 women were invited to participate. The invitation included a six-page questionnaire Pdf, 140 kB. (pdf) that sought information on diet and alcohol intake (67-item food frequency questionnaire), parity, age at first childbirth, family history of breast cancer, weight, height, education level, and marital status. It gave a response rate of 74 %. After exclusions, the cohort was formed by a total of 61,433 women.

In 1997, a second questionnaire Pdf, 1 MB. (pdf) was sent to all cohort members of SMC who still lived 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 the use of dietary supplements. It gave a 70 % response rate. The 1997 follow up resulted in 38,984 valid answers.

All members of SMC who had completed the 1987 food frequency questionnaire received a third questionnaire in 2008. The 2008 Health questionnaire Pdf, 223 kB. (pdf), 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.

All cohort members who received the 2008 Health questionnaire was sent a fourth questionnaire in 2009. The 2009 Lifestyle questionnaire Pdf, 443 kB. (pdf) had a response rate of 84 % and 25,259 valid answers. The questionnaire collected information on diet (132-item food frequency questionnaire), dietary supplements, smoking, physical activity, and sun habits.

A fourth follow up of SMC was performed in 2019 using the same questionnaires as in 2008/2009. In January 2019, the Health questionnaire Pdf, 223 kB. (pdf) was sent to all living participants in the cohort: 34,473 women, resulting in 19,081 valid answers and a response rate of 55 %. In September 2019, the Lifestyle questionnaire Pdf, 418 kB. (pdf) was sent to all still-living respondents answering the Health questionnaire: 18,930 women, resulting in 14,923 valid answers and a response rate of 79 %.

SMC include genome-wide association studies (GWAS) for approximately 12,000 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.