Cohort study of association of risk of breast cancer with cyst type in women with gross cystic disease of the breast

BMJ. 1997 Mar 29;314(7085):925-8. doi: 10.1136/bmj.314.7085.925.


Objective: To assess correlation between type of breast cyst and risk of breast cancer in women with gross cystic disease of the breast.

Design: Cohort study of women with breast cysts aspirated between 1983 and 1993 who were followed up until December 1994 for occurrence of breast cancer.

Setting: Major cancer prevention centre.

Subjects: 802 women with aspirated breast cysts.

Main outcome measures: Type of breast cyst based on cationic content of cyst fluid: type I (potassium:sodium ratio > 1.5), type II (potassium:sodium ratio < 1.5), or mixed (both types). Subsequent occurrence and type of breast cancer.

Results: After median follow up of six years (range 2-12 years) 15 cases of invasive breast cancer and two ductal carcinomas in situ were diagnosed in the cohort: 12 invasive cancers (and two carcinomas in situ) among the 417 women with type I cysts, two cancers among the 325 women with type II cysts, and one among the 60 women with mixed cysts. The incidence of breast cancer in women with type I cysts was significantly higher than that in women with type II cysts (relative risk 4.62 (95% confidence interval 1.26 to 29.7)). These results were confirmed after adjustment for several risk factors for breast cancer (relative risk 4.24 (1.12 to 27.5)).

Conclusions: The increased risk of breast cancer of women with breast cysts seems to be concentrated among women with type I breast cysts.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Adult
  • Aged
  • Breast Neoplasms / etiology*
  • Cohort Studies
  • Female
  • Fibrocystic Breast Disease / classification
  • Fibrocystic Breast Disease / complications*
  • Fibrocystic Breast Disease / metabolism
  • Fibrocystic Breast Disease / pathology
  • Follow-Up Studies
  • Humans
  • Middle Aged
  • Potassium / metabolism
  • Risk Factors
  • Sodium / metabolism


  • Sodium
  • Potassium