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The Adolescent Risk Factors Study (ARFS)

Margaret Wrensch, Terri Chew, Georgianna Farren, Janice Barlow, Flavia Belli, Christina Clarke, Christine A. Erdmann, Marion Lee, Michelle Moghadassi, Roni Peskin-Mentzer, Charles P. Quesenberry Jr, Virginia Souders-Mason, Linda Spence, Marisa Suzuki and Mary Gould

University of California, San Francisco
Zero Breast Cancer
Northern California Cancer Center Lawrence Berkeley National Laboratory
Kaiser Foundation Research Institute

California Breast Cancer Research Programs

The Adolescent Risk Factors Study was designed to understand if adolescent and pre-adolescent exposures and experiences differ between women with and without breast cancer in Marin County.

Interviews were conducted with approximately 300 Marin County women diagnosed between July 1, 2023 and June 30, 2023 with breast cancer (cases), and 300 Marin County women without breast cancer (controls), matched for age and ethnicity.

Factors used for comparison between cases and controls included:

  • Physical development and changes
  • Adolescent stress, family and social connections
  • Detailed adolescent and contemporary socioeconomic factors
  • Passive and active smoking
  • Alcohol use
  • Residency and migration
  • Standard breast cancer risk factors

Results of the study found striking similarities between the cases and controls as well as several differences that were significant.


Resulting Similarities

  • Lifetime number of years lived in Marin was 24.2 years for both groups
  • The mean age first lived in Marin was 28.8 for controls and 29.6 for cases


Other factors that were not found to be significantly different between controls and cases:

  • Having a first degree relative with breast cancer (20 percent of controls and 18 percent of cases)
  • History of a non-cancerous breast biopsy
  • Current socioeconomic status
  • Age at first birth or pregnancy (mean of 25.1 for controls and 25.3 for cases)
  • Use of hormone replacement therapy
  • Height
  • Health insurance status
  • Frequency of pelvic exams and pap tests


Resulting Differences

Cases were more likely than controls to report:

  • A high socioeconomic status before the age of 21
  • Four or more mammograms in 1990-1994
  • Giving birth without breastfeeding
  • Being premenopausal
  • Never having used birth control pills
  • Having a lower highest body mass index
  • Beginning drinking after age 21
  • Drinking on average two or more drinks per day
  • Being raised in an organized religion

The similarities between cases and controls in this study and the high incidence of some breast cancer risk factors that were found in many areas, suggest that both groups are at a high risk for breast cancer. Specific findings, in combination with the results of other recent prospective studies, suggest that decreased alcohol consumption and increased breastfeeding after childbirth—modifiable risk factors in adults—might help to reduce breast cancer risk.


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