Effects of life event stress and social support on the odds of a ≥2 cm breast cancer

To examine the contribution of life event and social support factors to diagnosis with aor= 2 cm breast cancer.We studied 1,459 Australian women aged 40-69 diagnosed in 2002-2003 with a first primary invasive breast cancer 1.1 cm or larger. We measured stressful life events, perceived stress levels, and social support in the year before diagnosis and collected information on other potential risk factors and confounders.The odds of aor= 2 cm breast cancer relative to a 1.1-1.9 cm breast cancer were reduced in women who reported tension or change in an intimate relationship in the year before diagnosis (OR=0.71 95% CI 0.54-0.92; p=0.009); the reduction was greatest in women living with a partner (OR=0.64 95% CI 0.47-0.88; p=0.006) and was largely unaffected by adjustment for other variables independently associated with aor= 2 cm breast cancer in our study. There was no evidence that the total number or severity of all studied life events influenced cancer size. Low partner support increased the odds of aor= 2 cm cancer but only in women not living with a partner.Intimate relationship stress may reduce risk of aor= 2 cm breast cancer. Suppression by stress of estrogen synthesis and metabolism is a possible mechanism.