OCCUPATION AND BREAST-CANCER MORTALITY IN A PROSPECTIVE COHORT OF US WOMEN

The authors examined the association between main lifetime occupation and subsequent breast cancer mortality in a large prospective study of US adults. After 9 years of follow-up, 1,780 cases of fatal breast ca ncer were observed among 563,395 women who were cancer-free at intervi ew in 1982. Main lifetime occupation was derived based on self-reports of current and former occupational titles and was classified into 14 broad occupational groups and 16 more narrowly defined occupational ti tles. Results from Cox proportional hazards models, adjusted for breas t cancer risk factors, revealed little variability in breast cancer mo rtality by occupation. Two significant associations were observed: In comparison with housewives, women in ''administrative support, includi ng clerical'' occupations were at a small increased risk (rate ratio ( RR) = 1.14, 95% confidence interval (CI) 1,01-1.31), and an increased risk was seen for ''executives'' (RR = 1.93, 95% CI 1,03-3.62), based on 10 breast cancer deaths. No significant increases in risk were obse rved for teachers and librarians (RR = 0.89), nurses (RR = 0.84), mana gers (RR = 0,89), or women employed in sales (RR = 0.88) or service (R R = 0.84) occupations. When analyses were limited to women who had wor ked in their occupation for 10 or more years, the results for each occ upational title were virtually unchanged. These results offer little s upport for an association between occupation and breast cancer mortali ty in general or for particular occupational titles, including teacher s and nurses.