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New-Onset Breast Tenderness after Initiation of Estrogen Plus Progestin Therapy and Breast Cancer Risk

 

Carolyn J. Crandall; Aaron K. Aragaki; Rowan T. Chlebowski; Anne McTiernan; Garnet Anderson; Susan L. Hendrix; Barbara B. Cochrane; Lewis H. Kuller; Jane A. Cauley.   Arch Intern Med. 2009;169(18):1684-1691.

It is well established that long term use of oral oestrogen plus progestin therapy (EPT) in postmenopausal women is associated with an increase in the risk of invasive breast cancer. A paper published in the Archives of Internal Medicine has explored this issue further.

The authors provide the first evidence that women with breast tenderness 12 months after commencing EPT are at greater risk of subsequently developing breast cancer on EPT than women without breast tenderness.

The study authors analysed information from the Women's Health Initiative Estrogen plus Progestin Trial which involved 16608 women randomly allocated to treatment with oral conjugated equine estrogen 0.625mg plus medroxyprogesterone acetate 5mg daily or an identical placebo. Women received treatment for an average of 5.6 years.

Although new onset breast tenderness is not a highly sensitive guide to breast cancer risk the study provides strong evidence that women should report to their doctor if they have new onset breast tenderness associated with taking postmenopausal hormone therapy, and that their dose should be lowered or the treatment modified if that is the case.

The main study findings were:

  • Women who had no breast tenderness when commencing EPT but who reported breast tenderness at 12 months ( described as new onset breast tenderness) had a greater risk ( 1.48 fold increase in risk) of breast cancer than women who did not experience new onset breast tenderness. In most instances (77%) the breast tenderness was reported as mild.
  •  New  onset breast tenderness appeared ( statistically) to account for 24% of the effect of EPT on breast cancer risk. Thus the effect of EPT on breast cancer risk was analysed taking into account new onset breast tenderness, the effect of EPT was no longer significant.
  •  The sensitivity of new onset breast tenderness for predicting breast cancer in the women in the study was 41% ie 41% of women who developed breast cancer during the study had new onset breast tenderness and the remainder did not
  • The specificity of new onset breast tenderness for predicting breast cancer in the women in the study was 64%, that means that 64% of the women who did not develop breast cancer also did not have breast tenderness.