Risk factors for breast cancer in a population with high incidence rates

Breast Cancer Research

Table 1 Participation rates, age and ethnicity of women with breast cancer and controls, Marin County, California, 1997–99

^aCases eligibility: less than 50 years old, newly diagnosed with primary breast cancer between 1 July 1997 and 30 June 1999 or at least 50 years old and diagnosed between 1 July 1997 and 22 March 1999. For controls, 3945 random digit numbers were called: 1640 (41%) either were not in service, were a business, fax or modem number, or were outside Marin County; 920 (23%) were reached but no resident was eligible; 289 (7%) yielded refusal with no additional information; 733 (19%) were in service but were either busy or did not answer (of which 394 were closed out after 10 call attempts and 339 had fewer than 10 call attempts made and were not closed out by the time that control recruitment ended); and 347 (9%) yielded an eligible subject. Of 347 women identified as eligible, 328 were contacted. ^bFive control women refused any participation and two could not be contacted. Thirty-six cases refused any participation, physicians refused contact for three cases, two cases could not be interviewed in English, we were unable to contact six cases, and three cases were mistakenly coded as ineligible.

ISSN: 1465-542X