Radiation-Associated Breast Cancer and Hormone Exposure: a CCSS* Report

Chest radiation is a well known risk factor for the subsequent development of breast cancer. This study was aimed at exploring the relationship between hormonal factors and the risk of radiation-associated breast cancer among survivors of childhood cancer.

Included in the study were 1,108 females diagnosed from 1970 to 1986 who were treated with chest radiation and survived to ages of >/= 20 years.

Results:

  • 195 women were diagnosed with breast cancer 80% of whom were estrogen receptor positive [ER+] and 112 of whom were diagnosed before they turned 40
  • The risk of developing ER+ breast cancer and breast cancer diagnosed before 40 years of age were significantly increased when women had had > 10 years of ovarian function when compared to those with < 10 years of ovarian function
  • A similar pattern as above was observed in women who received chest radiation within a year of menarche as opposed to > 1 year after menarche
  • Of the 259 women who were post-menopausal, their breast cancer risk was moderately higher in those treated with estrogen and progesterone therapy when compared to women who were not although this finding was not statistically significant
  • In survivors who went through menopause at < 20 years of age treated with estrogen + progesterone had a lower risk of breast cancer than premenopausal women

Conclusions:

  • Endogenous hormones, hormones naturally produced by the endocrine system are key contributors to radiation-associated breast cancer among childhood cancer survivors
  • The use of hormone therapy for premature ovarian insufficiency doesn’t appear to fully replace the function of endogenous hormones in the development of radiation-associated breast cancer

Questions to ask your healthcare provider:

  1. Is there a role for estrogen and progesterone given your personal treatment history?
  2. What are the benefits and what are the risks across time?
  3. Are there other options beside hormone therapy?
  4. Is it reasonable to consider prophylactic mastectomy subsequent to chest radiation?

Action steps for you to take:

  1. Know your breasts: monthly self breast exam and annual clinical breast exam by your healthcare provider
  2. Be faithful to breast screening as outlined survivorship guidelines recommended by the Childrens Oncology Group and those from the American Cancer Society

*Childhood Cancer Survivor Study

For the abstract of this study by Moscowitz et al click here

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